rockbox/apps/plugins/jpeg.c

/***************************************************************************
*             __________               __   ___.
*   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
*   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
*   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
*   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
*                     \/            \/     \/    \/            \/
* $Id$
*
* JPEG image viewer
* (This is a real mess if it has to be coded in one single C file)
*
* File scrolling addition (C) 2005 Alexander Spyridakis
* Copyright (C) 2004 Jörg Hohensohn aka [IDC]Dragon
* Heavily borrowed from the IJG implementation (C) Thomas G. Lane
* Small & fast downscaling IDCT (C) 2002 by Guido Vollbeding  JPEGclub.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/

#include "plugin.h"
#include "playback_control.h"
#include "oldmenuapi.h"
#include "helper.h"
#include "lib/configfile.h"

#ifdef HAVE_LCD_BITMAP
#include "grey.h"
#include "xlcd.h"

PLUGIN_HEADER

/* variable button definitions */
#if CONFIG_KEYPAD == RECORDER_PAD
#define JPEG_ZOOM_IN BUTTON_PLAY
#define JPEG_ZOOM_OUT BUTTON_ON
#define JPEG_UP BUTTON_UP
#define JPEG_DOWN BUTTON_DOWN
#define JPEG_LEFT BUTTON_LEFT
#define JPEG_RIGHT BUTTON_RIGHT
#define JPEG_NEXT BUTTON_F3
#define JPEG_PREVIOUS BUTTON_F2
#define JPEG_MENU BUTTON_OFF

#elif CONFIG_KEYPAD == ARCHOS_AV300_PAD
#define JPEG_ZOOM_IN BUTTON_SELECT
#define JPEG_ZOOM_OUT BUTTON_ON
#define JPEG_UP BUTTON_UP
#define JPEG_DOWN BUTTON_DOWN
#define JPEG_LEFT BUTTON_LEFT
#define JPEG_RIGHT BUTTON_RIGHT
#define JPEG_NEXT BUTTON_F3
#define JPEG_PREVIOUS BUTTON_F2
#define JPEG_MENU BUTTON_OFF

#elif CONFIG_KEYPAD == ONDIO_PAD
#define JPEG_ZOOM_PRE BUTTON_MENU
#define JPEG_ZOOM_IN (BUTTON_MENU | BUTTON_REL)
#define JPEG_ZOOM_OUT (BUTTON_MENU | BUTTON_DOWN)
#define JPEG_UP BUTTON_UP
#define JPEG_DOWN BUTTON_DOWN
#define JPEG_LEFT BUTTON_LEFT
#define JPEG_RIGHT BUTTON_RIGHT
#define JPEG_NEXT (BUTTON_MENU | BUTTON_RIGHT)
#define JPEG_PREVIOUS (BUTTON_MENU | BUTTON_LEFT)
#define JPEG_MENU BUTTON_OFF

#elif (CONFIG_KEYPAD == IRIVER_H100_PAD) || \
      (CONFIG_KEYPAD == IRIVER_H300_PAD)
#define JPEG_ZOOM_IN BUTTON_SELECT
#define JPEG_ZOOM_OUT BUTTON_MODE
#define JPEG_UP BUTTON_UP
#define JPEG_DOWN BUTTON_DOWN
#define JPEG_LEFT BUTTON_LEFT
#define JPEG_RIGHT BUTTON_RIGHT
#if (CONFIG_KEYPAD == IRIVER_H100_PAD)
#define JPEG_NEXT BUTTON_ON
#define JPEG_PREVIOUS BUTTON_REC
#else
#define JPEG_NEXT BUTTON_REC
#define JPEG_PREVIOUS BUTTON_ON
#endif
#define JPEG_MENU BUTTON_OFF
#define JPEG_RC_MENU BUTTON_RC_STOP

#elif (CONFIG_KEYPAD == IPOD_4G_PAD) || (CONFIG_KEYPAD == IPOD_3G_PAD) || \
      (CONFIG_KEYPAD == IPOD_1G2G_PAD)
#define JPEG_ZOOM_IN BUTTON_SCROLL_FWD
#define JPEG_ZOOM_OUT BUTTON_SCROLL_BACK
#define JPEG_UP BUTTON_MENU
#define JPEG_DOWN BUTTON_PLAY
#define JPEG_LEFT BUTTON_LEFT
#define JPEG_RIGHT BUTTON_RIGHT
#define JPEG_MENU (BUTTON_SELECT | BUTTON_MENU)
#define JPEG_NEXT (BUTTON_SELECT | BUTTON_RIGHT)
#define JPEG_PREVIOUS (BUTTON_SELECT | BUTTON_LEFT)

#elif CONFIG_KEYPAD == IAUDIO_X5M5_PAD
#define JPEG_ZOOM_PRE BUTTON_SELECT
#define JPEG_ZOOM_IN (BUTTON_SELECT | BUTTON_REL)
#define JPEG_ZOOM_OUT (BUTTON_SELECT | BUTTON_REPEAT)
#define JPEG_UP BUTTON_UP
#define JPEG_DOWN BUTTON_DOWN
#define JPEG_LEFT BUTTON_LEFT
#define JPEG_RIGHT BUTTON_RIGHT
#define JPEG_MENU BUTTON_POWER
#define JPEG_NEXT BUTTON_PLAY
#define JPEG_PREVIOUS BUTTON_REC

#elif CONFIG_KEYPAD == GIGABEAT_PAD
#define JPEG_ZOOM_IN BUTTON_VOL_UP
#define JPEG_ZOOM_OUT BUTTON_VOL_DOWN
#define JPEG_UP BUTTON_UP
#define JPEG_DOWN BUTTON_DOWN
#define JPEG_LEFT BUTTON_LEFT
#define JPEG_RIGHT BUTTON_RIGHT
#define JPEG_MENU BUTTON_MENU
#define JPEG_NEXT (BUTTON_A | BUTTON_RIGHT)
#define JPEG_PREVIOUS (BUTTON_A | BUTTON_LEFT)

#elif CONFIG_KEYPAD == SANSA_E200_PAD
#define JPEG_ZOOM_PRE           BUTTON_SELECT
#define JPEG_ZOOM_IN            (BUTTON_SELECT | BUTTON_REL)
#define JPEG_ZOOM_OUT           (BUTTON_SELECT | BUTTON_REPEAT)
#define JPEG_UP                 BUTTON_UP
#define JPEG_DOWN               BUTTON_DOWN
#define JPEG_LEFT               BUTTON_LEFT
#define JPEG_RIGHT              BUTTON_RIGHT
#define JPEG_MENU               BUTTON_POWER
#define JPEG_SLIDE_SHOW         BUTTON_REC
#define JPEG_NEXT               BUTTON_SCROLL_FWD
#define JPEG_NEXT_REPEAT        (BUTTON_SCROLL_FWD|BUTTON_REPEAT)
#define JPEG_PREVIOUS           BUTTON_SCROLL_BACK
#define JPEG_PREVIOUS_REPEAT    (BUTTON_SCROLL_BACK|BUTTON_REPEAT)

#elif CONFIG_KEYPAD == SANSA_C200_PAD
#define JPEG_ZOOM_PRE           BUTTON_SELECT
#define JPEG_ZOOM_IN            (BUTTON_SELECT | BUTTON_REL)
#define JPEG_ZOOM_OUT           (BUTTON_SELECT | BUTTON_REPEAT)
#define JPEG_UP                 BUTTON_UP
#define JPEG_DOWN               BUTTON_DOWN
#define JPEG_LEFT               BUTTON_LEFT
#define JPEG_RIGHT              BUTTON_RIGHT
#define JPEG_MENU               BUTTON_POWER
#define JPEG_SLIDE_SHOW         BUTTON_REC
#define JPEG_NEXT               BUTTON_VOL_UP
#define JPEG_NEXT_REPEAT        (BUTTON_VOL_UP|BUTTON_REPEAT)
#define JPEG_PREVIOUS           BUTTON_VOL_DOWN
#define JPEG_PREVIOUS_REPEAT    (BUTTON_VOL_DOWN|BUTTON_REPEAT)

#elif CONFIG_KEYPAD == IRIVER_H10_PAD
#define JPEG_ZOOM_PRE BUTTON_PLAY
#define JPEG_ZOOM_IN (BUTTON_PLAY | BUTTON_REL)
#define JPEG_ZOOM_OUT (BUTTON_PLAY | BUTTON_REPEAT)
#define JPEG_UP BUTTON_SCROLL_UP
#define JPEG_DOWN BUTTON_SCROLL_DOWN
#define JPEG_LEFT BUTTON_LEFT
#define JPEG_RIGHT BUTTON_RIGHT
#define JPEG_MENU BUTTON_POWER
#define JPEG_NEXT BUTTON_FF
#define JPEG_PREVIOUS BUTTON_REW

#elif CONFIG_KEYPAD == MROBE500_PAD
#define JPEG_ZOOM_IN    BUTTON_RC_VOL_UP
#define JPEG_ZOOM_OUT   BUTTON_RC_VOL_DOWN
#define JPEG_UP         BUTTON_RC_PLAY
#define JPEG_DOWN       BUTTON_RC_DOWN
#define JPEG_LEFT       BUTTON_LEFT
#define JPEG_RIGHT      BUTTON_RIGHT
#define JPEG_MENU       BUTTON_POWER
#define JPEG_NEXT       BUTTON_RC_HEART
#define JPEG_PREVIOUS   BUTTON_RC_MODE

#elif CONFIG_KEYPAD == GIGABEAT_S_PAD
#define JPEG_ZOOM_IN    BUTTON_VOL_UP
#define JPEG_ZOOM_OUT   BUTTON_VOL_DOWN
#define JPEG_UP         BUTTON_UP
#define JPEG_DOWN       BUTTON_DOWN
#define JPEG_LEFT       BUTTON_LEFT
#define JPEG_RIGHT      BUTTON_RIGHT
#define JPEG_MENU       BUTTON_MENU
#define JPEG_NEXT       BUTTON_NEXT
#define JPEG_PREVIOUS   BUTTON_PREV

#elif CONFIG_KEYPAD == MROBE100_PAD
#define JPEG_ZOOM_IN BUTTON_SELECT
#define JPEG_ZOOM_OUT BUTTON_PLAY
#define JPEG_UP BUTTON_UP
#define JPEG_DOWN BUTTON_DOWN
#define JPEG_LEFT BUTTON_LEFT
#define JPEG_RIGHT BUTTON_RIGHT
#define JPEG_MENU BUTTON_MENU
#define JPEG_NEXT (BUTTON_DISPLAY | BUTTON_RIGHT)
#define JPEG_PREVIOUS (BUTTON_DISPLAY | BUTTON_LEFT)

#elif CONFIG_KEYPAD == IAUDIO_M3_PAD
#define JPEG_ZOOM_PRE    BUTTON_RC_PLAY
#define JPEG_ZOOM_IN     (BUTTON_RC_PLAY|BUTTON_REL)
#define JPEG_ZOOM_OUT    (BUTTON_RC_PLAY|BUTTON_REPEAT)
#define JPEG_UP          BUTTON_RC_VOL_UP
#define JPEG_DOWN        BUTTON_RC_VOL_DOWN
#define JPEG_LEFT        BUTTON_RC_REW
#define JPEG_RIGHT       BUTTON_RC_FF
#define JPEG_MENU        BUTTON_RC_REC
#define JPEG_NEXT        BUTTON_RC_MODE
#define JPEG_PREVIOUS    BUTTON_RC_MENU

#elif CONFIG_KEYPAD == COWOND2_PAD

#else
#error No keymap defined!
#endif

#ifdef HAVE_TOUCHPAD
#ifndef JPEG_UP
#define JPEG_UP         BUTTON_TOPMIDDLE
#endif
#ifndef JPEG_DOWN
#define JPEG_DOWN       BUTTON_BOTTOMMIDDLE
#endif
#ifndef JPEG_LEFT
#define JPEG_LEFT       BUTTON_MIDLEFT
#endif
#ifndef JPEG_RIGHT
#define JPEG_RIGHT      BUTTON_MIDRIGHT
#endif
#ifndef JPEG_ZOOM_IN
#define JPEG_ZOOM_IN    BUTTON_TOPRIGHT
#endif
#ifndef JPEG_ZOOM_OUT
#define JPEG_ZOOM_OUT   BUTTON_TOPLEFT
#endif
#ifndef JPEG_MENU
#define JPEG_MENU       (BUTTON_CENTER|BUTTON_REL)
#endif
#ifndef JPEG_NEXT
#define JPEG_NEXT       BUTTON_BOTTOMRIGHT
#endif
#ifndef JPEG_PREVIOUS
#define JPEG_PREVIOUS   BUTTON_BOTTOMLEFT
#endif
#endif

/* different graphics libraries */
#if LCD_DEPTH < 8
#define USEGSLIB
GREY_INFO_STRUCT
#define MYLCD(fn) grey_ub_ ## fn
#define MYLCD_UPDATE()
#define MYXLCD(fn) grey_ub_ ## fn
#else
#define MYLCD(fn) rb->lcd_ ## fn
#define MYLCD_UPDATE() rb->lcd_update();
#define MYXLCD(fn) xlcd_ ## fn
#endif

#define MAX_X_SIZE LCD_WIDTH*8

/* Min memory allowing us to use the plugin buffer
 * and thus not stopping the music
 * *Very* rough estimation:
 * Max 10 000 dir entries * 4bytes/entry (char **) = 40000 bytes
 * + 20k code size = 60 000
 * + 50k min for jpeg = 120 000
 */
#define MIN_MEM 120000

/* Headings */
#define DIR_PREV  1
#define DIR_NEXT -1
#define DIR_NONE  0

#define PLUGIN_OTHER 10 /* State code for output with return. */

/******************************* Globals ***********************************/

static const struct plugin_api* rb;
MEM_FUNCTION_WRAPPERS(rb);

/* for portability of below JPEG code */
#define MEMSET(p,v,c) rb->memset(p,v,c)
#define MEMCPY(d,s,c) rb->memcpy(d,s,c)
#define INLINE static inline
#define ENDIAN_SWAP16(n) n /* only for poor little endian machines */

static int slideshow_enabled = false;   /* run slideshow */
static int running_slideshow = false;   /* loading image because of slideshw */
#ifndef SIMULATOR
static int immediate_ata_off = false;   /* power down disk after loading */
#endif

/* Persistent configuration */
#define JPEG_CONFIGFILE             "jpeg.cfg"
#define JPEG_SETTINGS_MINVERSION    1
#define JPEG_SETTINGS_VERSION       2

/* Slideshow times */
#define SS_MIN_TIMEOUT 1
#define SS_MAX_TIMEOUT 20
#define SS_DEFAULT_TIMEOUT 5

enum color_modes
{
    COLOURMODE_COLOUR = 0,
    COLOURMODE_GRAY,
    COLOUR_NUM_MODES
};

enum dither_modes
{
    DITHER_NONE = 0,    /* No dithering */
    DITHER_ORDERED,     /* Bayer ordered */
    DITHER_DIFFUSION,   /* Floyd/Steinberg error diffusion */
    DITHER_NUM_MODES
};

struct jpeg_settings
{
    int colour_mode;
    int dither_mode;
    int ss_timeout;
};

static struct jpeg_settings jpeg_settings =
    { COLOURMODE_COLOUR, DITHER_NONE, SS_DEFAULT_TIMEOUT };
static struct jpeg_settings old_settings;

static struct configdata jpeg_config[] =
{
#ifdef HAVE_LCD_COLOR
   { TYPE_ENUM, 0, COLOUR_NUM_MODES, &jpeg_settings.colour_mode,
     "Colour Mode", (char *[]){ "Colour", "Grayscale" }, NULL },
   { TYPE_ENUM, 0, DITHER_NUM_MODES, &jpeg_settings.dither_mode,
     "Dither Mode", (char *[]){ "None", "Ordered", "Diffusion" }, NULL },
#endif
   { TYPE_INT, SS_MIN_TIMEOUT, SS_MAX_TIMEOUT, &jpeg_settings.ss_timeout,
     "Slideshow Time", NULL, NULL},
};

#if LCD_DEPTH > 1
fb_data* old_backdrop;
#endif

/**************** begin JPEG code ********************/

INLINE unsigned range_limit(int value)
{
#if CONFIG_CPU == SH7034
    unsigned tmp;
    asm (  /* Note: Uses knowledge that only low byte of result is used */
        "mov     #-128,%[t]  \n"
        "sub     %[t],%[v]   \n"  /* value -= -128; equals value += 128; */
        "extu.b  %[v],%[t]   \n"
        "cmp/eq  %[v],%[t]   \n"  /* low byte == whole number ? */
        "bt      1f          \n"  /* yes: no overflow */
        "cmp/pz  %[v]        \n"  /* overflow: positive? */
        "subc    %[v],%[v]   \n"  /* %[r] now either 0 or 0xffffffff */
    "1:                      \n"
        : /* outputs */
        [v]"+r"(value),
        [t]"=&r"(tmp)
    );
    return value;
#elif defined(CPU_COLDFIRE)
    asm (  /* Note: Uses knowledge that only the low byte of the result is used */
        "add.l   #128,%[v]   \n"  /* value += 128; */
        "cmp.l   #255,%[v]   \n"  /* overflow? */
        "bls.b   1f          \n"  /* no: return value */
        "spl.b   %[v]        \n"  /* yes: set low byte to appropriate boundary */
    "1:                      \n"
        : /* outputs */
        [v]"+d"(value)
    );
    return value;
#elif defined(CPU_ARM)
    asm (  /* Note: Uses knowledge that only the low byte of the result is used */
        "add     %[v], %[v], #128    \n"  /* value += 128 */
        "cmp     %[v], #255          \n"  /* out of range 0..255? */
        "mvnhi   %[v], %[v], asr #31 \n"  /* yes: set all bits to ~(sign_bit) */
        : /* outputs */
        [v]"+r"(value)
    );
    return value;
#else
    value += 128;

    if ((unsigned)value <= 255)
        return value;

    if (value < 0)
        return 0;

    return 255;
#endif
}

/* IDCT implementation */


#define CONST_BITS 13
#define PASS1_BITS 2


/* Some C compilers fail to reduce "FIX(constant)" at compile time, thus
* causing a lot of useless floating-point operations at run time.
* To get around this we use the following pre-calculated constants.
* If you change CONST_BITS you may want to add appropriate values.
* (With a reasonable C compiler, you can just rely on the FIX() macro...)
*/
#define FIX_0_298631336  2446 /* FIX(0.298631336) */
#define FIX_0_390180644  3196 /* FIX(0.390180644) */
#define FIX_0_541196100  4433 /* FIX(0.541196100) */
#define FIX_0_765366865  6270 /* FIX(0.765366865) */
#define FIX_0_899976223  7373 /* FIX(0.899976223) */
#define FIX_1_175875602  9633 /* FIX(1.175875602) */
#define FIX_1_501321110 12299 /* FIX(1.501321110) */
#define FIX_1_847759065 15137 /* FIX(1.847759065) */
#define FIX_1_961570560 16069 /* FIX(1.961570560) */
#define FIX_2_053119869 16819 /* FIX(2.053119869) */
#define FIX_2_562915447 20995 /* FIX(2.562915447) */
#define FIX_3_072711026 25172 /* FIX(3.072711026) */



/* Multiply an long variable by an long constant to yield an long result.
* For 8-bit samples with the recommended scaling, all the variable
* and constant values involved are no more than 16 bits wide, so a
* 16x16->32 bit multiply can be used instead of a full 32x32 multiply.
* For 12-bit samples, a full 32-bit multiplication will be needed.
*/
#define MULTIPLY16(var,const)  (((short) (var)) * ((short) (const)))


/* Dequantize a coefficient by multiplying it by the multiplier-table
* entry; produce an int result.  In this module, both inputs and result
* are 16 bits or less, so either int or short multiply will work.
*/
/* #define DEQUANTIZE(coef,quantval)  (((int) (coef)) * (quantval)) */
#define DEQUANTIZE MULTIPLY16

/* Descale and correctly round an int value that's scaled by N bits.
* We assume RIGHT_SHIFT rounds towards minus infinity, so adding
* the fudge factor is correct for either sign of X.
*/
#define DESCALE(x,n) (((x) + (1l << ((n)-1))) >> (n))



/*
* Perform dequantization and inverse DCT on one block of coefficients,
* producing a reduced-size 1x1 output block.
*/
void idct1x1(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line)
{
    (void)skip_line; /* unused */
    *p_byte = range_limit(inptr[0] * quantptr[0] >> 3);
}



/*
* Perform dequantization and inverse DCT on one block of coefficients,
* producing a reduced-size 2x2 output block.
*/
void idct2x2(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line)
{
    int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5;
    unsigned char* outptr;

    /* Pass 1: process columns from input, store into work array. */

    /* Column 0 */
    tmp4 = DEQUANTIZE(inptr[8*0], quantptr[8*0]);
    tmp5 = DEQUANTIZE(inptr[8*1], quantptr[8*1]);

    tmp0 = tmp4 + tmp5;
    tmp2 = tmp4 - tmp5;

    /* Column 1 */
    tmp4 = DEQUANTIZE(inptr[8*0+1], quantptr[8*0+1]);
    tmp5 = DEQUANTIZE(inptr[8*1+1], quantptr[8*1+1]);

    tmp1 = tmp4 + tmp5;
    tmp3 = tmp4 - tmp5;

    /* Pass 2: process 2 rows, store into output array. */

    /* Row 0 */
    outptr = p_byte;

    outptr[0] = range_limit((int) DESCALE(tmp0 + tmp1, 3));
    outptr[1] = range_limit((int) DESCALE(tmp0 - tmp1, 3));

    /* Row 1 */
    outptr = p_byte + skip_line;

    outptr[0] = range_limit((int) DESCALE(tmp2 + tmp3, 3));
    outptr[1] = range_limit((int) DESCALE(tmp2 - tmp3, 3));
}



/*
* Perform dequantization and inverse DCT on one block of coefficients,
* producing a reduced-size 4x4 output block.
*/
void idct4x4(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line)
{
    int tmp0, tmp2, tmp10, tmp12;
    int z1, z2, z3;
    int * wsptr;
    unsigned char* outptr;
    int ctr;
    int workspace[4*4]; /* buffers data between passes */

    /* Pass 1: process columns from input, store into work array. */

    wsptr = workspace;
    for (ctr = 0; ctr < 4; ctr++, inptr++, quantptr++, wsptr++)
    {
        /* Even part */

        tmp0 = DEQUANTIZE(inptr[8*0], quantptr[8*0]);
        tmp2 = DEQUANTIZE(inptr[8*2], quantptr[8*2]);

        tmp10 = (tmp0 + tmp2) << PASS1_BITS;
        tmp12 = (tmp0 - tmp2) << PASS1_BITS;

        /* Odd part */
        /* Same rotation as in the even part of the 8x8 LL&M IDCT */

        z2 = DEQUANTIZE(inptr[8*1], quantptr[8*1]);
        z3 = DEQUANTIZE(inptr[8*3], quantptr[8*3]);

        z1 = MULTIPLY16(z2 + z3, FIX_0_541196100);
        tmp0 = DESCALE(z1 + MULTIPLY16(z3, - FIX_1_847759065), CONST_BITS-PASS1_BITS);
        tmp2 = DESCALE(z1 + MULTIPLY16(z2, FIX_0_765366865), CONST_BITS-PASS1_BITS);

        /* Final output stage */

        wsptr[4*0] = (int) (tmp10 + tmp2);
        wsptr[4*3] = (int) (tmp10 - tmp2);
        wsptr[4*1] = (int) (tmp12 + tmp0);
        wsptr[4*2] = (int) (tmp12 - tmp0);
    }

    /* Pass 2: process 4 rows from work array, store into output array. */

    wsptr = workspace;
    for (ctr = 0; ctr < 4; ctr++)
    {
        outptr = p_byte + (ctr*skip_line);
        /* Even part */

        tmp0 = (int) wsptr[0];
        tmp2 = (int) wsptr[2];

        tmp10 = (tmp0 + tmp2) << CONST_BITS;
        tmp12 = (tmp0 - tmp2) << CONST_BITS;

        /* Odd part */
        /* Same rotation as in the even part of the 8x8 LL&M IDCT */

        z2 = (int) wsptr[1];
        z3 = (int) wsptr[3];

        z1 = MULTIPLY16(z2 + z3, FIX_0_541196100);
        tmp0 = z1 + MULTIPLY16(z3, - FIX_1_847759065);
        tmp2 = z1 + MULTIPLY16(z2, FIX_0_765366865);

        /* Final output stage */

        outptr[0] = range_limit((int) DESCALE(tmp10 + tmp2,
            CONST_BITS+PASS1_BITS+3));
        outptr[3] = range_limit((int) DESCALE(tmp10 - tmp2,
            CONST_BITS+PASS1_BITS+3));
        outptr[1] = range_limit((int) DESCALE(tmp12 + tmp0,
            CONST_BITS+PASS1_BITS+3));
        outptr[2] = range_limit((int) DESCALE(tmp12 - tmp0,
            CONST_BITS+PASS1_BITS+3));

        wsptr += 4;     /* advance pointer to next row */
    }
}



/*
* Perform dequantization and inverse DCT on one block of coefficients.
*/
void idct8x8(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line)
{
    long tmp0, tmp1, tmp2, tmp3;
    long tmp10, tmp11, tmp12, tmp13;
    long z1, z2, z3, z4, z5;
    int * wsptr;
    unsigned char* outptr;
    int ctr;
    int workspace[64];  /* buffers data between passes */

    /* Pass 1: process columns from input, store into work array. */
    /* Note results are scaled up by sqrt(8) compared to a true IDCT; */
    /* furthermore, we scale the results by 2**PASS1_BITS. */

    wsptr = workspace;
    for (ctr = 8; ctr > 0; ctr--)
    {
    /* Due to quantization, we will usually find that many of the input
    * coefficients are zero, especially the AC terms.  We can exploit this
    * by short-circuiting the IDCT calculation for any column in which all
    * the AC terms are zero.  In that case each output is equal to the
    * DC coefficient (with scale factor as needed).
    * With typical images and quantization tables, half or more of the
    * column DCT calculations can be simplified this way.
    */

        if ((inptr[8*1] | inptr[8*2] | inptr[8*3]
           | inptr[8*4] | inptr[8*5] | inptr[8*6] | inptr[8*7]) == 0)
        {
            /* AC terms all zero */
            int dcval = DEQUANTIZE(inptr[8*0], quantptr[8*0]) << PASS1_BITS;

            wsptr[8*0] = wsptr[8*1] = wsptr[8*2] = wsptr[8*3] = wsptr[8*4]
                       = wsptr[8*5] = wsptr[8*6] = wsptr[8*7] = dcval;
            inptr++;      /* advance pointers to next column */
            quantptr++;
            wsptr++;
            continue;
        }

        /* Even part: reverse the even part of the forward DCT. */
        /* The rotator is sqrt(2)*c(-6). */

        z2 = DEQUANTIZE(inptr[8*2], quantptr[8*2]);
        z3 = DEQUANTIZE(inptr[8*6], quantptr[8*6]);

        z1 = MULTIPLY16(z2 + z3, FIX_0_541196100);
        tmp2 = z1 + MULTIPLY16(z3, - FIX_1_847759065);
        tmp3 = z1 + MULTIPLY16(z2, FIX_0_765366865);

        z2 = DEQUANTIZE(inptr[8*0], quantptr[8*0]);
        z3 = DEQUANTIZE(inptr[8*4], quantptr[8*4]);

        tmp0 = (z2 + z3) << CONST_BITS;
        tmp1 = (z2 - z3) << CONST_BITS;

        tmp10 = tmp0 + tmp3;
        tmp13 = tmp0 - tmp3;
        tmp11 = tmp1 + tmp2;
        tmp12 = tmp1 - tmp2;

        /* Odd part per figure 8; the matrix is unitary and hence its
           transpose is its inverse.  i0..i3 are y7,y5,y3,y1 respectively. */

        tmp0 = DEQUANTIZE(inptr[8*7], quantptr[8*7]);
        tmp1 = DEQUANTIZE(inptr[8*5], quantptr[8*5]);
        tmp2 = DEQUANTIZE(inptr[8*3], quantptr[8*3]);
        tmp3 = DEQUANTIZE(inptr[8*1], quantptr[8*1]);

        z1 = tmp0 + tmp3;
        z2 = tmp1 + tmp2;
        z3 = tmp0 + tmp2;
        z4 = tmp1 + tmp3;
        z5 = MULTIPLY16(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */

        tmp0 = MULTIPLY16(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
        tmp1 = MULTIPLY16(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
        tmp2 = MULTIPLY16(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
        tmp3 = MULTIPLY16(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
        z1 = MULTIPLY16(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
        z2 = MULTIPLY16(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
        z3 = MULTIPLY16(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
        z4 = MULTIPLY16(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */

        z3 += z5;
        z4 += z5;

        tmp0 += z1 + z3;
        tmp1 += z2 + z4;
        tmp2 += z2 + z3;
        tmp3 += z1 + z4;

        /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */

        wsptr[8*0] = (int) DESCALE(tmp10 + tmp3, CONST_BITS-PASS1_BITS);
        wsptr[8*7] = (int) DESCALE(tmp10 - tmp3, CONST_BITS-PASS1_BITS);
        wsptr[8*1] = (int) DESCALE(tmp11 + tmp2, CONST_BITS-PASS1_BITS);
        wsptr[8*6] = (int) DESCALE(tmp11 - tmp2, CONST_BITS-PASS1_BITS);
        wsptr[8*2] = (int) DESCALE(tmp12 + tmp1, CONST_BITS-PASS1_BITS);
        wsptr[8*5] = (int) DESCALE(tmp12 - tmp1, CONST_BITS-PASS1_BITS);
        wsptr[8*3] = (int) DESCALE(tmp13 + tmp0, CONST_BITS-PASS1_BITS);
        wsptr[8*4] = (int) DESCALE(tmp13 - tmp0, CONST_BITS-PASS1_BITS);

        inptr++; /* advance pointers to next column */
        quantptr++;
        wsptr++;
    }

    /* Pass 2: process rows from work array, store into output array. */
    /* Note that we must descale the results by a factor of 8 == 2**3, */
    /* and also undo the PASS1_BITS scaling. */

    wsptr = workspace;
    for (ctr = 0; ctr < 8; ctr++)
    {
        outptr = p_byte + (ctr*skip_line);
        /* Rows of zeroes can be exploited in the same way as we did with columns.
        * However, the column calculation has created many nonzero AC terms, so
        * the simplification applies less often (typically 5% to 10% of the time).
        * On machines with very fast multiplication, it's possible that the
        * test takes more time than it's worth.  In that case this section
        * may be commented out.
        */

#ifndef NO_ZERO_ROW_TEST
        if ((wsptr[1] | wsptr[2] | wsptr[3]
           | wsptr[4] | wsptr[5] | wsptr[6] | wsptr[7]) == 0)
        {
            /* AC terms all zero */
            unsigned char dcval = range_limit((int) DESCALE((long) wsptr[0],
                PASS1_BITS+3));

            outptr[0] = dcval;
            outptr[1] = dcval;
            outptr[2] = dcval;
            outptr[3] = dcval;
            outptr[4] = dcval;
            outptr[5] = dcval;
            outptr[6] = dcval;
            outptr[7] = dcval;

            wsptr += 8; /* advance pointer to next row */
            continue;
        }
#endif

        /* Even part: reverse the even part of the forward DCT. */
        /* The rotator is sqrt(2)*c(-6). */

        z2 = (long) wsptr[2];
        z3 = (long) wsptr[6];

        z1 = MULTIPLY16(z2 + z3, FIX_0_541196100);
        tmp2 = z1 + MULTIPLY16(z3, - FIX_1_847759065);
        tmp3 = z1 + MULTIPLY16(z2, FIX_0_765366865);

        tmp0 = ((long) wsptr[0] + (long) wsptr[4]) << CONST_BITS;
        tmp1 = ((long) wsptr[0] - (long) wsptr[4]) << CONST_BITS;

        tmp10 = tmp0 + tmp3;
        tmp13 = tmp0 - tmp3;
        tmp11 = tmp1 + tmp2;
        tmp12 = tmp1 - tmp2;

        /* Odd part per figure 8; the matrix is unitary and hence its
        * transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively. */

        tmp0 = (long) wsptr[7];
        tmp1 = (long) wsptr[5];
        tmp2 = (long) wsptr[3];
        tmp3 = (long) wsptr[1];

        z1 = tmp0 + tmp3;
        z2 = tmp1 + tmp2;
        z3 = tmp0 + tmp2;
        z4 = tmp1 + tmp3;
        z5 = MULTIPLY16(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */

        tmp0 = MULTIPLY16(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
        tmp1 = MULTIPLY16(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
        tmp2 = MULTIPLY16(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
        tmp3 = MULTIPLY16(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
        z1 = MULTIPLY16(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
        z2 = MULTIPLY16(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
        z3 = MULTIPLY16(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
        z4 = MULTIPLY16(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */

        z3 += z5;
        z4 += z5;

        tmp0 += z1 + z3;
        tmp1 += z2 + z4;
        tmp2 += z2 + z3;
        tmp3 += z1 + z4;

        /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */

        outptr[0] = range_limit((int) DESCALE(tmp10 + tmp3,
            CONST_BITS+PASS1_BITS+3));
        outptr[7] = range_limit((int) DESCALE(tmp10 - tmp3,
            CONST_BITS+PASS1_BITS+3));
        outptr[1] = range_limit((int) DESCALE(tmp11 + tmp2,
            CONST_BITS+PASS1_BITS+3));
        outptr[6] = range_limit((int) DESCALE(tmp11 - tmp2,
            CONST_BITS+PASS1_BITS+3));
        outptr[2] = range_limit((int) DESCALE(tmp12 + tmp1,
            CONST_BITS+PASS1_BITS+3));
        outptr[5] = range_limit((int) DESCALE(tmp12 - tmp1,
            CONST_BITS+PASS1_BITS+3));
        outptr[3] = range_limit((int) DESCALE(tmp13 + tmp0,
            CONST_BITS+PASS1_BITS+3));
        outptr[4] = range_limit((int) DESCALE(tmp13 - tmp0,
            CONST_BITS+PASS1_BITS+3));

        wsptr += 8; /* advance pointer to next row */
    }
}



/* JPEG decoder implementation */


#define HUFF_LOOKAHEAD 8 /* # of bits of lookahead */

struct derived_tbl
{
    /* Basic tables: (element [0] of each array is unused) */
    long mincode[17]; /* smallest code of length k */
    long maxcode[18]; /* largest code of length k (-1 if none) */
    /* (maxcode[17] is a sentinel to ensure huff_DECODE terminates) */
    int valptr[17]; /* huffval[] index of 1st symbol of length k */

    /* Back link to public Huffman table (needed only in slow_DECODE) */
    int* pub;

    /* Lookahead tables: indexed by the next HUFF_LOOKAHEAD bits of
    the input data stream.  If the next Huffman code is no more
    than HUFF_LOOKAHEAD bits long, we can obtain its length and
    the corresponding symbol directly from these tables. */
    int look_nbits[1<<HUFF_LOOKAHEAD]; /* # bits, or 0 if too long */
    unsigned char look_sym[1<<HUFF_LOOKAHEAD]; /* symbol, or unused */
};

#define QUANT_TABLE_LENGTH  64

/* for type of Huffman table */
#define DC_LEN 28
#define AC_LEN 178

struct huffman_table
{   /* length and code according to JFIF format */
    int huffmancodes_dc[DC_LEN];
    int huffmancodes_ac[AC_LEN];
};

struct frame_component
{
    int ID;
    int horizontal_sampling;
    int vertical_sampling;
    int quanttable_select;
};

struct scan_component
{
    int ID;
    int DC_select;
    int AC_select;
};

struct bitstream
{
    unsigned long get_buffer; /* current bit-extraction buffer */
    int bits_left; /* # of unused bits in it */
    unsigned char* next_input_byte;
    unsigned char* input_end; /* upper limit +1 */
};

struct jpeg
{
    int x_size, y_size; /* size of image (can be less than block boundary) */
    int x_phys, y_phys; /* physical size, block aligned */
    int x_mbl; /* x dimension of MBL */
    int y_mbl; /* y dimension of MBL */
    int blocks; /* blocks per MB */
    int restart_interval; /* number of MCUs between RSTm markers */
    int store_pos[4]; /* for Y block ordering */

    unsigned char* p_entropy_data;
    unsigned char* p_entropy_end;

    int quanttable[4][QUANT_TABLE_LENGTH]; /* raw quantization tables 0-3 */
    int qt_idct[2][QUANT_TABLE_LENGTH]; /* quantization tables for IDCT */

    struct huffman_table hufftable[2]; /* Huffman tables  */
    struct derived_tbl dc_derived_tbls[2]; /* Huffman-LUTs */
    struct derived_tbl ac_derived_tbls[2];

    struct frame_component frameheader[3]; /* Component descriptor */
    struct scan_component scanheader[3]; /* currently not used */

    int mcu_membership[6]; /* info per block */
    int tab_membership[6];
    int subsample_x[3]; /* info per component */
    int subsample_y[3];
};


/* possible return flags for process_markers() */
#define HUFFTAB   0x0001 /* with huffman table */
#define QUANTTAB  0x0002 /* with quantization table */
#define APP0_JFIF 0x0004 /* with APP0 segment following JFIF standard */
#define FILL_FF   0x0008 /* with 0xFF padding bytes at begin/end */
#define SOF0      0x0010 /* with SOF0-Segment */
#define DHT       0x0020 /* with Definition of huffman tables */
#define SOS       0x0040 /* with Start-of-Scan segment */
#define DQT       0x0080 /* with definition of quantization table */

/* Preprocess the JPEG JFIF file */
int process_markers(unsigned char* p_src, long size, struct jpeg* p_jpeg)
{
    unsigned char* p_bytes = p_src;
    int marker_size; /* variable length of marker segment */
    int i, j, n;
    int ret = 0; /* returned flags */

    p_jpeg->p_entropy_end = p_src + size;

    while (p_src < p_bytes + size)
    {
        if (*p_src++ != 0xFF) /* no marker? */
        {
            p_src--; /* it's image data, put it back */
            p_jpeg->p_entropy_data = p_src;
            break; /* exit marker processing */
        }

        switch (*p_src++)
        {
        case 0xFF: /* Fill byte */
            ret |= FILL_FF;
        case 0x00: /* Zero stuffed byte - entropy data */
            p_src--; /* put it back */
            continue;

        case 0xC0: /* SOF Huff  - Baseline DCT */
            {
                ret |= SOF0;
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */
                n = *p_src++; /* sample precision (= 8 or 12) */
                if (n != 8)
                {
                    return(-1); /* Unsupported sample precision */
                }
                p_jpeg->y_size = *p_src++ << 8; /* Highbyte */
                p_jpeg->y_size |= *p_src++; /* Lowbyte */
                p_jpeg->x_size = *p_src++ << 8; /* Highbyte */
                p_jpeg->x_size |= *p_src++; /* Lowbyte */

                n = (marker_size-2-6)/3;
                if (*p_src++ != n || (n != 1 && n != 3))
                {
                    return(-2); /* Unsupported SOF0 component specification */
                }
                for (i=0; i<n; i++)
                {
                    p_jpeg->frameheader[i].ID = *p_src++; /* Component info */
                    p_jpeg->frameheader[i].horizontal_sampling = *p_src >> 4;
                    p_jpeg->frameheader[i].vertical_sampling = *p_src++ & 0x0F;
                    p_jpeg->frameheader[i].quanttable_select = *p_src++;
                    if (p_jpeg->frameheader[i].horizontal_sampling > 2
                     || p_jpeg->frameheader[i].vertical_sampling > 2)
                    return -3; /* Unsupported SOF0 subsampling */
                }
                p_jpeg->blocks = n;
            }
            break;

        case 0xC1: /* SOF Huff  - Extended sequential DCT*/
        case 0xC2: /* SOF Huff  - Progressive DCT*/
        case 0xC3: /* SOF Huff  - Spatial (sequential) lossless*/
        case 0xC5: /* SOF Huff  - Differential sequential DCT*/
        case 0xC6: /* SOF Huff  - Differential progressive DCT*/
        case 0xC7: /* SOF Huff  - Differential spatial*/
        case 0xC8: /* SOF Arith - Reserved for JPEG extensions*/
        case 0xC9: /* SOF Arith - Extended sequential DCT*/
        case 0xCA: /* SOF Arith - Progressive DCT*/
        case 0xCB: /* SOF Arith - Spatial (sequential) lossless*/
        case 0xCD: /* SOF Arith - Differential sequential DCT*/
        case 0xCE: /* SOF Arith - Differential progressive DCT*/
        case 0xCF: /* SOF Arith - Differential spatial*/
            {
                return (-4); /* other DCT model than baseline not implemented */
            }

        case 0xC4: /* Define Huffman Table(s) */
            {
                unsigned char* p_temp;

                ret |= DHT;
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */

                p_temp = p_src;
                while (p_src < p_temp+marker_size-2-17) /* another table */
                {
                    int sum = 0;
                    i = *p_src & 0x0F; /* table index */
                    if (i > 1)
                    {
                        return (-5); /* Huffman table index out of range */
                    }
                    else if (*p_src++ & 0xF0) /* AC table */
                    {
                        for (j=0; j<16; j++)
                        {
                            sum += *p_src;
                            p_jpeg->hufftable[i].huffmancodes_ac[j] = *p_src++;
                        }
                        if(16 + sum > AC_LEN)
                            return -10; /* longer than allowed */

                        for (; j < 16 + sum; j++)
                            p_jpeg->hufftable[i].huffmancodes_ac[j] = *p_src++;
                    }
                    else /* DC table */
                    {
                        for (j=0; j<16; j++)
                        {
                            sum += *p_src;
                            p_jpeg->hufftable[i].huffmancodes_dc[j] = *p_src++;
                        }
                        if(16 + sum > DC_LEN)
                            return -11; /* longer than allowed */

                        for (; j < 16 + sum; j++)
                            p_jpeg->hufftable[i].huffmancodes_dc[j] = *p_src++;
                    }
                } /* while */
                p_src = p_temp+marker_size - 2; /* skip possible residue */
            }
            break;

        case 0xCC: /* Define Arithmetic coding conditioning(s) */
            return(-6); /* Arithmetic coding not supported */

        case 0xD8: /* Start of Image */
        case 0xD9: /* End of Image */
        case 0x01: /* for temp private use arith code */
            break; /* skip parameterless marker */


        case 0xDA: /* Start of Scan */
            {
                ret |= SOS;
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */

                n = (marker_size-2-1-3)/2;
                if (*p_src++ != n || (n != 1 && n != 3))
                {
                    return (-7); /* Unsupported SOS component specification */
                }
                for (i=0; i<n; i++)
                {
                    p_jpeg->scanheader[i].ID = *p_src++;
                    p_jpeg->scanheader[i].DC_select = *p_src >> 4;
                    p_jpeg->scanheader[i].AC_select = *p_src++ & 0x0F;
                }
                p_src += 3; /* skip spectral information */
            }
            break;

        case 0xDB: /* Define quantization Table(s) */
            {
                ret |= DQT;
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */
                n = (marker_size-2)/(QUANT_TABLE_LENGTH+1); /* # of tables */
                for (i=0; i<n; i++)
                {
                    int id = *p_src++; /* ID */
                    if (id >= 4)
                    {
                        return (-8); /* Unsupported quantization table */
                    }
                    /* Read Quantisation table: */
                    for (j=0; j<QUANT_TABLE_LENGTH; j++)
                        p_jpeg->quanttable[id][j] = *p_src++;
                }
            }
            break;

        case 0xDD: /* Define Restart Interval */
            {
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */
                p_jpeg->restart_interval = *p_src++ << 8; /* Highbyte */
                p_jpeg->restart_interval |= *p_src++; /* Lowbyte */
                p_src += marker_size-4; /* skip segment */
            }
            break;

        case 0xDC: /* Define Number of Lines */
        case 0xDE: /* Define Hierarchical progression */
        case 0xDF: /* Expand Reference Component(s) */
        case 0xE0: /* Application Field 0*/
        case 0xE1: /* Application Field 1*/
        case 0xE2: /* Application Field 2*/
        case 0xE3: /* Application Field 3*/
        case 0xE4: /* Application Field 4*/
        case 0xE5: /* Application Field 5*/
        case 0xE6: /* Application Field 6*/
        case 0xE7: /* Application Field 7*/
        case 0xE8: /* Application Field 8*/
        case 0xE9: /* Application Field 9*/
        case 0xEA: /* Application Field 10*/
        case 0xEB: /* Application Field 11*/
        case 0xEC: /* Application Field 12*/
        case 0xED: /* Application Field 13*/
        case 0xEE: /* Application Field 14*/
        case 0xEF: /* Application Field 15*/
        case 0xFE: /* Comment */
            {
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */
                p_src += marker_size-2; /* skip segment */
            }
            break;

        case 0xF0: /* Reserved for JPEG extensions */
        case 0xF1: /* Reserved for JPEG extensions */
        case 0xF2: /* Reserved for JPEG extensions */
        case 0xF3: /* Reserved for JPEG extensions */
        case 0xF4: /* Reserved for JPEG extensions */
        case 0xF5: /* Reserved for JPEG extensions */
        case 0xF6: /* Reserved for JPEG extensions */
        case 0xF7: /* Reserved for JPEG extensions */
        case 0xF8: /* Reserved for JPEG extensions */
        case 0xF9: /* Reserved for JPEG extensions */
        case 0xFA: /* Reserved for JPEG extensions */
        case 0xFB: /* Reserved for JPEG extensions */
        case 0xFC: /* Reserved for JPEG extensions */
        case 0xFD: /* Reserved for JPEG extensions */
        case 0x02: /* Reserved */
        default:
            return (-9); /* Unknown marker */
        } /* switch */
    } /* while */

    return (ret); /* return flags with seen markers */
}


void default_huff_tbl(struct jpeg* p_jpeg)
{
    static const struct huffman_table luma_table =
    {
        {
            0x00,0x01,0x05,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,0x00,0x00,0x00,
            0x00,0x00,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B
        },
        {
            0x00,0x02,0x01,0x03,0x03,0x02,0x04,0x03,0x05,0x05,0x04,0x04,0x00,0x00,0x01,0x7D,
            0x01,0x02,0x03,0x00,0x04,0x11,0x05,0x12,0x21,0x31,0x41,0x06,0x13,0x51,0x61,0x07,
            0x22,0x71,0x14,0x32,0x81,0x91,0xA1,0x08,0x23,0x42,0xB1,0xC1,0x15,0x52,0xD1,0xF0,
            0x24,0x33,0x62,0x72,0x82,0x09,0x0A,0x16,0x17,0x18,0x19,0x1A,0x25,0x26,0x27,0x28,
            0x29,0x2A,0x34,0x35,0x36,0x37,0x38,0x39,0x3A,0x43,0x44,0x45,0x46,0x47,0x48,0x49,
            0x4A,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0x63,0x64,0x65,0x66,0x67,0x68,0x69,
            0x6A,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0x83,0x84,0x85,0x86,0x87,0x88,0x89,
            0x8A,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9A,0xA2,0xA3,0xA4,0xA5,0xA6,0xA7,
            0xA8,0xA9,0xAA,0xB2,0xB3,0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0xC2,0xC3,0xC4,0xC5,
            0xC6,0xC7,0xC8,0xC9,0xCA,0xD2,0xD3,0xD4,0xD5,0xD6,0xD7,0xD8,0xD9,0xDA,0xE1,0xE2,
            0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xF1,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8,
            0xF9,0xFA
        }
    };

    static const struct huffman_table chroma_table =
    {
        {
            0x00,0x03,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,0x00,
            0x00,0x00,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B
        },
        {
            0x00,0x02,0x01,0x02,0x04,0x04,0x03,0x04,0x07,0x05,0x04,0x04,0x00,0x01,0x02,0x77,
            0x00,0x01,0x02,0x03,0x11,0x04,0x05,0x21,0x31,0x06,0x12,0x41,0x51,0x07,0x61,0x71,
            0x13,0x22,0x32,0x81,0x08,0x14,0x42,0x91,0xA1,0xB1,0xC1,0x09,0x23,0x33,0x52,0xF0,
            0x15,0x62,0x72,0xD1,0x0A,0x16,0x24,0x34,0xE1,0x25,0xF1,0x17,0x18,0x19,0x1A,0x26,
            0x27,0x28,0x29,0x2A,0x35,0x36,0x37,0x38,0x39,0x3A,0x43,0x44,0x45,0x46,0x47,0x48,
            0x49,0x4A,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0x63,0x64,0x65,0x66,0x67,0x68,
            0x69,0x6A,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0x82,0x83,0x84,0x85,0x86,0x87,
            0x88,0x89,0x8A,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9A,0xA2,0xA3,0xA4,0xA5,
            0xA6,0xA7,0xA8,0xA9,0xAA,0xB2,0xB3,0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0xC2,0xC3,
            0xC4,0xC5,0xC6,0xC7,0xC8,0xC9,0xCA,0xD2,0xD3,0xD4,0xD5,0xD6,0xD7,0xD8,0xD9,0xDA,
            0xE2,0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8,
            0xF9,0xFA
        }
    };

    MEMCPY(&p_jpeg->hufftable[0], &luma_table, sizeof(luma_table));
    MEMCPY(&p_jpeg->hufftable[1], &chroma_table, sizeof(chroma_table));

    return;
}

/* Compute the derived values for a Huffman table */
void fix_huff_tbl(int* htbl, struct derived_tbl* dtbl)
{
    int p, i, l, si;
    int lookbits, ctr;
    char huffsize[257];
    unsigned int huffcode[257];
    unsigned int code;

    dtbl->pub = htbl; /* fill in back link */

    /* Figure C.1: make table of Huffman code length for each symbol */
    /* Note that this is in code-length order. */

    p = 0;
    for (l = 1; l <= 16; l++)
    {    /* all possible code length */
        for (i = 1; i <= (int) htbl[l-1]; i++)  /* all codes per length */
            huffsize[p++] = (char) l;
    }
    huffsize[p] = 0;

    /* Figure C.2: generate the codes themselves */
    /* Note that this is in code-length order. */

    code = 0;
    si = huffsize[0];
    p = 0;
    while (huffsize[p])
    {
        while (((int) huffsize[p]) == si)
        {
            huffcode[p++] = code;
            code++;
        }
        code <<= 1;
        si++;
    }

    /* Figure F.15: generate decoding tables for bit-sequential decoding */

    p = 0;
    for (l = 1; l <= 16; l++)
    {
        if (htbl[l-1])
        {
            dtbl->valptr[l] = p; /* huffval[] index of 1st symbol of code length l */
            dtbl->mincode[l] = huffcode[p]; /* minimum code of length l */
            p += htbl[l-1];
            dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */
        }
        else
        {
            dtbl->maxcode[l] = -1;  /* -1 if no codes of this length */
        }
    }
    dtbl->maxcode[17] = 0xFFFFFL; /* ensures huff_DECODE terminates */

    /* Compute lookahead tables to speed up decoding.
    * First we set all the table entries to 0, indicating "too long";
    * then we iterate through the Huffman codes that are short enough and
    * fill in all the entries that correspond to bit sequences starting
    * with that code.
    */

    MEMSET(dtbl->look_nbits, 0, sizeof(dtbl->look_nbits));

    p = 0;
    for (l = 1; l <= HUFF_LOOKAHEAD; l++)
    {
        for (i = 1; i <= (int) htbl[l-1]; i++, p++)
        {
            /* l = current code's length, p = its index in huffcode[] & huffval[]. */
            /* Generate left-justified code followed by all possible bit sequences */
            lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l);
            for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--)
            {
                dtbl->look_nbits[lookbits] = l;
                dtbl->look_sym[lookbits] = htbl[16+p];
                lookbits++;
            }
        }
    }
}


/* zag[i] is the natural-order position of the i'th element of zigzag order.
 * If the incoming data is corrupted, decode_mcu could attempt to
 * reference values beyond the end of the array.  To avoid a wild store,
 * we put some extra zeroes after the real entries.
 */
static const int zag[] =
{
     0,  1,  8, 16,  9,  2,  3, 10,
    17, 24, 32, 25, 18, 11,  4,  5,
    12, 19, 26, 33, 40, 48, 41, 34,
    27, 20, 13,  6,  7, 14, 21, 28,
    35, 42, 49, 56, 57, 50, 43, 36,
    29, 22, 15, 23, 30, 37, 44, 51,
    58, 59, 52, 45, 38, 31, 39, 46,
    53, 60, 61, 54, 47, 55, 62, 63,
     0,  0,  0,  0,  0,  0,  0,  0, /* extra entries in case k>63 below */
     0,  0,  0,  0,  0,  0,  0,  0
};

void build_lut(struct jpeg* p_jpeg)
{
    int i;
    fix_huff_tbl(p_jpeg->hufftable[0].huffmancodes_dc,
        &p_jpeg->dc_derived_tbls[0]);
    fix_huff_tbl(p_jpeg->hufftable[0].huffmancodes_ac,
        &p_jpeg->ac_derived_tbls[0]);
    fix_huff_tbl(p_jpeg->hufftable[1].huffmancodes_dc,
        &p_jpeg->dc_derived_tbls[1]);
    fix_huff_tbl(p_jpeg->hufftable[1].huffmancodes_ac,
        &p_jpeg->ac_derived_tbls[1]);

    /* build the dequantization tables for the IDCT (De-ZiZagged) */
    for (i=0; i<64; i++)
    {
        p_jpeg->qt_idct[0][zag[i]] = p_jpeg->quanttable[0][i];
        p_jpeg->qt_idct[1][zag[i]] = p_jpeg->quanttable[1][i];
    }

    for (i=0; i<4; i++)
        p_jpeg->store_pos[i] = i; /* default ordering */

    /* assignments for the decoding of blocks */
    if (p_jpeg->frameheader[0].horizontal_sampling == 2
        && p_jpeg->frameheader[0].vertical_sampling == 1)
    {   /* 4:2:2 */
        p_jpeg->blocks = 4;
        p_jpeg->x_mbl = (p_jpeg->x_size+15) / 16;
        p_jpeg->x_phys = p_jpeg->x_mbl * 16;
        p_jpeg->y_mbl = (p_jpeg->y_size+7) / 8;
        p_jpeg->y_phys = p_jpeg->y_mbl * 8;
        p_jpeg->mcu_membership[0] = 0; /* Y1=Y2=0, U=1, V=2 */
        p_jpeg->mcu_membership[1] = 0;
        p_jpeg->mcu_membership[2] = 1;
        p_jpeg->mcu_membership[3] = 2;
        p_jpeg->tab_membership[0] = 0; /* DC, DC, AC, AC */
        p_jpeg->tab_membership[1] = 0;
        p_jpeg->tab_membership[2] = 1;
        p_jpeg->tab_membership[3] = 1;
        p_jpeg->subsample_x[0] = 1;
        p_jpeg->subsample_x[1] = 2;
        p_jpeg->subsample_x[2] = 2;
        p_jpeg->subsample_y[0] = 1;
        p_jpeg->subsample_y[1] = 1;
        p_jpeg->subsample_y[2] = 1;
    }
    if (p_jpeg->frameheader[0].horizontal_sampling == 1
        && p_jpeg->frameheader[0].vertical_sampling == 2)
    {   /* 4:2:2 vertically subsampled */
        p_jpeg->store_pos[1] = 2; /* block positions are mirrored */
        p_jpeg->store_pos[2] = 1;
        p_jpeg->blocks = 4;
        p_jpeg->x_mbl = (p_jpeg->x_size+7) / 8;
        p_jpeg->x_phys = p_jpeg->x_mbl * 8;
        p_jpeg->y_mbl = (p_jpeg->y_size+15) / 16;
        p_jpeg->y_phys = p_jpeg->y_mbl * 16;
        p_jpeg->mcu_membership[0] = 0; /* Y1=Y2=0, U=1, V=2 */
        p_jpeg->mcu_membership[1] = 0;
        p_jpeg->mcu_membership[2] = 1;
        p_jpeg->mcu_membership[3] = 2;
        p_jpeg->tab_membership[0] = 0; /* DC, DC, AC, AC */
        p_jpeg->tab_membership[1] = 0;
        p_jpeg->tab_membership[2] = 1;
        p_jpeg->tab_membership[3] = 1;
        p_jpeg->subsample_x[0] = 1;
        p_jpeg->subsample_x[1] = 1;
        p_jpeg->subsample_x[2] = 1;
        p_jpeg->subsample_y[0] = 1;
        p_jpeg->subsample_y[1] = 2;
        p_jpeg->subsample_y[2] = 2;
    }
    else if (p_jpeg->frameheader[0].horizontal_sampling == 2
        && p_jpeg->frameheader[0].vertical_sampling == 2)
    {   /* 4:2:0 */
        p_jpeg->blocks = 6;
        p_jpeg->x_mbl = (p_jpeg->x_size+15) / 16;
        p_jpeg->x_phys = p_jpeg->x_mbl * 16;
        p_jpeg->y_mbl = (p_jpeg->y_size+15) / 16;
        p_jpeg->y_phys = p_jpeg->y_mbl * 16;
        p_jpeg->mcu_membership[0] = 0;
        p_jpeg->mcu_membership[1] = 0;
        p_jpeg->mcu_membership[2] = 0;
        p_jpeg->mcu_membership[3] = 0;
        p_jpeg->mcu_membership[4] = 1;
        p_jpeg->mcu_membership[5] = 2;
        p_jpeg->tab_membership[0] = 0;
        p_jpeg->tab_membership[1] = 0;
        p_jpeg->tab_membership[2] = 0;
        p_jpeg->tab_membership[3] = 0;
        p_jpeg->tab_membership[4] = 1;
        p_jpeg->tab_membership[5] = 1;
        p_jpeg->subsample_x[0] = 1;
        p_jpeg->subsample_x[1] = 2;
        p_jpeg->subsample_x[2] = 2;
        p_jpeg->subsample_y[0] = 1;
        p_jpeg->subsample_y[1] = 2;
        p_jpeg->subsample_y[2] = 2;
    }
    else if (p_jpeg->frameheader[0].horizontal_sampling == 1
        && p_jpeg->frameheader[0].vertical_sampling == 1)
    {   /* 4:4:4 */
        /* don't overwrite p_jpeg->blocks */
        p_jpeg->x_mbl = (p_jpeg->x_size+7) / 8;
        p_jpeg->x_phys = p_jpeg->x_mbl * 8;
        p_jpeg->y_mbl = (p_jpeg->y_size+7) / 8;
        p_jpeg->y_phys = p_jpeg->y_mbl * 8;
        p_jpeg->mcu_membership[0] = 0;
        p_jpeg->mcu_membership[1] = 1;
        p_jpeg->mcu_membership[2] = 2;
        p_jpeg->tab_membership[0] = 0;
        p_jpeg->tab_membership[1] = 1;
        p_jpeg->tab_membership[2] = 1;
        p_jpeg->subsample_x[0] = 1;
        p_jpeg->subsample_x[1] = 1;
        p_jpeg->subsample_x[2] = 1;
        p_jpeg->subsample_y[0] = 1;
        p_jpeg->subsample_y[1] = 1;
        p_jpeg->subsample_y[2] = 1;
    }
    else
    {
        /* error */
    }

}


/*
* These functions/macros provide the in-line portion of bit fetching.
* Use check_bit_buffer to ensure there are N bits in get_buffer
* before using get_bits, peek_bits, or drop_bits.
*  check_bit_buffer(state,n,action);
*    Ensure there are N bits in get_buffer; if suspend, take action.
*  val = get_bits(n);
*    Fetch next N bits.
*  val = peek_bits(n);
*    Fetch next N bits without removing them from the buffer.
*  drop_bits(n);
*    Discard next N bits.
* The value N should be a simple variable, not an expression, because it
* is evaluated multiple times.
*/

INLINE void check_bit_buffer(struct bitstream* pb, int nbits)
{
    if (pb->bits_left < nbits)
    {   /* nbits is <= 16, so I can always refill 2 bytes in this case */
        unsigned char byte;

        byte = *pb->next_input_byte++;
        if (byte == 0xFF) /* legal marker can be byte stuffing or RSTm */
        {   /* simplification: just skip the (one-byte) marker code */
            pb->next_input_byte++;
        }
        pb->get_buffer = (pb->get_buffer << 8) | byte;

        byte = *pb->next_input_byte++;
        if (byte == 0xFF) /* legal marker can be byte stuffing or RSTm */
        {   /* simplification: just skip the (one-byte) marker code */
            pb->next_input_byte++;
        }
        pb->get_buffer = (pb->get_buffer << 8) | byte;

        pb->bits_left += 16;
    }
}

INLINE int get_bits(struct bitstream* pb, int nbits)
{
    return ((int) (pb->get_buffer >> (pb->bits_left -= nbits))) & ((1<<nbits)-1);
}

INLINE int peek_bits(struct bitstream* pb, int nbits)
{
    return ((int) (pb->get_buffer >> (pb->bits_left - nbits))) & ((1<<nbits)-1);
}

INLINE void drop_bits(struct bitstream* pb, int nbits)
{
    pb->bits_left -= nbits;
}

/* re-synchronize to entropy data (skip restart marker) */
void search_restart(struct bitstream* pb)
{
    pb->next_input_byte--; /* we may have overread it, taking 2 bytes */
    /* search for a non-byte-padding marker, has to be RSTm or EOS */
    while (pb->next_input_byte < pb->input_end &&
        (pb->next_input_byte[-2] != 0xFF || pb->next_input_byte[-1] == 0x00))
    {
        pb->next_input_byte++;
    }
    pb->bits_left = 0;
}

/* Figure F.12: extend sign bit. */
#define HUFF_EXTEND(x,s)  ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))

static const int extend_test[16] =   /* entry n is 2**(n-1) */
{
    0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
    0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000
};

static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
{
    0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
    ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
    ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
    ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1
};

/* Decode a single value */
INLINE int huff_decode_dc(struct bitstream* bs, struct derived_tbl* tbl)
{
    int nb, look, s, r;

    check_bit_buffer(bs, HUFF_LOOKAHEAD);
    look = peek_bits(bs, HUFF_LOOKAHEAD);
    if ((nb = tbl->look_nbits[look]) != 0)
    {
        drop_bits(bs, nb);
        s = tbl->look_sym[look];
        check_bit_buffer(bs, s);
        r = get_bits(bs, s);
        s = HUFF_EXTEND(r, s);
    }
    else
    {   /*  slow_DECODE(s, HUFF_LOOKAHEAD+1)) < 0); */
        long code;
        nb=HUFF_LOOKAHEAD+1;
        check_bit_buffer(bs, nb);
        code = get_bits(bs, nb);
        while (code > tbl->maxcode[nb])
        {
            code <<= 1;
            check_bit_buffer(bs, 1);
            code |= get_bits(bs, 1);
            nb++;
        }
        if (nb > 16) /* error in Huffman */
        {
            s=0; /* fake a zero, this is most safe */
        }
        else
        {
            s = tbl->pub[16 + tbl->valptr[nb] + ((int) (code - tbl->mincode[nb])) ];
            check_bit_buffer(bs, s);
            r = get_bits(bs, s);
            s = HUFF_EXTEND(r, s);
        }
    } /* end slow decode */
    return s;
}

INLINE int huff_decode_ac(struct bitstream* bs, struct derived_tbl* tbl)
{
    int nb, look, s;

    check_bit_buffer(bs, HUFF_LOOKAHEAD);
    look = peek_bits(bs, HUFF_LOOKAHEAD);
    if ((nb = tbl->look_nbits[look]) != 0)
    {
        drop_bits(bs, nb);
        s = tbl->look_sym[look];
    }
    else
    {   /*  slow_DECODE(s, HUFF_LOOKAHEAD+1)) < 0); */
        long code;
        nb=HUFF_LOOKAHEAD+1;
        check_bit_buffer(bs, nb);
        code = get_bits(bs, nb);
        while (code > tbl->maxcode[nb])
        {
            code <<= 1;
            check_bit_buffer(bs, 1);
            code |= get_bits(bs, 1);
            nb++;
        }
        if (nb > 16) /* error in Huffman */
        {
            s=0; /* fake a zero, this is most safe */
        }
        else
        {
            s = tbl->pub[16 + tbl->valptr[nb] + ((int) (code - tbl->mincode[nb])) ];
        }
    } /* end slow decode */
    return s;
}


#ifdef HAVE_LCD_COLOR

/* JPEG decoder variant for YUV decoding, into 3 different planes */
/*  Note: it keeps the original color subsampling, even if resized. */
int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[3],
                int downscale, void (*pf_progress)(int current, int total))
{
    struct bitstream bs; /* bitstream "object" */
    int block[64]; /* decoded DCT coefficients */

    int width, height;
    int skip_line[3]; /* bytes from one line to the next (skip_line) */
    int skip_strip[3], skip_mcu[3]; /* bytes to next DCT row / column */

    int i, x, y; /* loop counter */

    unsigned char* p_line[3] = {p_pixel[0], p_pixel[1], p_pixel[2]};
    unsigned char* p_byte[3]; /* bitmap pointer */

    void (*pf_idct)(unsigned char*, int*, int*, int); /* selected IDCT */
    int k_need; /* AC coefficients needed up to here */
    int zero_need; /* init the block with this many zeros */

    int last_dc_val[3] = {0, 0, 0}; /* or 128 for chroma? */
    int store_offs[4]; /* memory offsets: order of Y11 Y12 Y21 Y22 U V */
    int restart = p_jpeg->restart_interval; /* MCUs until restart marker */

    /* pick the IDCT we want, determine how to work with coefs */
    if (downscale == 1)
    {
        pf_idct = idct8x8;
        k_need = 64; /* all */
        zero_need = 63; /* all */
    }
    else if (downscale == 2)
    {
        pf_idct = idct4x4;
        k_need = 25; /* this far in zig-zag to cover 4*4 */
        zero_need = 27; /* clear this far in linear order */
    }
    else if (downscale == 4)
    {
        pf_idct = idct2x2;
        k_need = 5; /* this far in zig-zag to cover 2*2 */
        zero_need = 9; /* clear this far in linear order */
    }
    else if (downscale == 8)
    {
        pf_idct = idct1x1;
        k_need = 0; /* no AC, not needed */
        zero_need = 0; /* no AC, not needed */
    }
    else return -1; /* not supported */

    /* init bitstream, fake a restart to make it start */
    bs.next_input_byte = p_jpeg->p_entropy_data;
    bs.bits_left = 0;
    bs.input_end = p_jpeg->p_entropy_end;

    width  = p_jpeg->x_phys / downscale;
    height = p_jpeg->y_phys / downscale;
    for (i=0; i<3; i++) /* calculate some strides */
    {
        skip_line[i] = width / p_jpeg->subsample_x[i];
        skip_strip[i] = skip_line[i]
                        * (height / p_jpeg->y_mbl) / p_jpeg->subsample_y[i];
        skip_mcu[i] = width/p_jpeg->x_mbl / p_jpeg->subsample_x[i];
    }

    /* prepare offsets about where to store the different blocks */
    store_offs[p_jpeg->store_pos[0]] = 0;
    store_offs[p_jpeg->store_pos[1]] = 8 / downscale; /* to the right */
    store_offs[p_jpeg->store_pos[2]] = width * 8 / downscale; /* below */
    store_offs[p_jpeg->store_pos[3]] = store_offs[1] + store_offs[2]; /* r+b */

    for(y=0; y<p_jpeg->y_mbl && bs.next_input_byte <= bs.input_end; y++)
    {
        for (i=0; i<3; i++) /* scan line init */
        {
            p_byte[i] = p_line[i];
            p_line[i] += skip_strip[i];
        }
        for (x=0; x<p_jpeg->x_mbl; x++)
        {
            int blkn;

            /* Outer loop handles each block in the MCU */
            for (blkn = 0; blkn < p_jpeg->blocks; blkn++)
            {   /* Decode a single block's worth of coefficients */
                int k = 1; /* coefficient index */
                int s, r; /* huffman values */
                int ci = p_jpeg->mcu_membership[blkn]; /* component index */
                int ti = p_jpeg->tab_membership[blkn]; /* table index */
                struct derived_tbl* dctbl = &p_jpeg->dc_derived_tbls[ti];
                struct derived_tbl* actbl = &p_jpeg->ac_derived_tbls[ti];

                /* Section F.2.2.1: decode the DC coefficient difference */
                s = huff_decode_dc(&bs, dctbl);

                last_dc_val[ci] += s;
                block[0] = last_dc_val[ci]; /* output it (assumes zag[0] = 0) */

                /* coefficient buffer must be cleared */
                MEMSET(block+1, 0, zero_need*sizeof(block[0]));

                /* Section F.2.2.2: decode the AC coefficients */
                for (; k < k_need; k++)
                {
                    s = huff_decode_ac(&bs, actbl);
                    r = s >> 4;
                    s &= 15;

                    if (s)
                    {
                        k += r;
                        check_bit_buffer(&bs, s);
                        r = get_bits(&bs, s);
                        block[zag[k]] = HUFF_EXTEND(r, s);
                    }
                    else
                    {
                        if (r != 15)
                        {
                            k = 64;
                            break;
                        }
                        k += r;
                    }
                }  /* for k */
                /* In this path we just discard the values */
                for (; k < 64; k++)
                {
                    s = huff_decode_ac(&bs, actbl);
                    r = s >> 4;
                    s &= 15;

                    if (s)
                    {
                        k += r;
                        check_bit_buffer(&bs, s);
                        drop_bits(&bs, s);
                    }
                    else
                    {
                        if (r != 15)
                            break;
                        k += r;
                    }
                }  /* for k */

                if (ci == 0)
                {   /* Y component needs to bother about block store */
                    pf_idct(p_byte[0]+store_offs[blkn], block,
                        p_jpeg->qt_idct[ti], skip_line[0]);
                }
                else
                {   /* chroma */
                    pf_idct(p_byte[ci], block, p_jpeg->qt_idct[ti],
                        skip_line[ci]);
                }
            } /* for blkn */
            p_byte[0] += skip_mcu[0]; /* unrolled for (i=0; i<3; i++) loop */
            p_byte[1] += skip_mcu[1];
            p_byte[2] += skip_mcu[2];
            if (p_jpeg->restart_interval && --restart == 0)
            {   /* if a restart marker is due: */
                restart = p_jpeg->restart_interval; /* count again */
                search_restart(&bs); /* align the bitstream */
                last_dc_val[0] = last_dc_val[1] =
                                 last_dc_val[2] = 0; /* reset decoder */
            }
        } /* for x */
        if (pf_progress != NULL)
            pf_progress(y, p_jpeg->y_mbl-1); /* notify about decoding progress */
    } /* for y */

    return 0; /* success */
}
#else /* !HAVE_LCD_COLOR */

/* a JPEG decoder specialized in decoding only the luminance (b&w) */
int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[1], int downscale,
                void (*pf_progress)(int current, int total))
{
    struct bitstream bs; /* bitstream "object" */
    int block[64]; /* decoded DCT coefficients */

    int width, height;
    int skip_line; /* bytes from one line to the next (skip_line) */
    int skip_strip, skip_mcu; /* bytes to next DCT row / column */

    int x, y; /* loop counter */

    unsigned char* p_line = p_pixel[0];
    unsigned char* p_byte; /* bitmap pointer */

    void (*pf_idct)(unsigned char*, int*, int*, int); /* selected IDCT */
    int k_need; /* AC coefficients needed up to here */
    int zero_need; /* init the block with this many zeros */

    int last_dc_val = 0;
    int store_offs[4]; /* memory offsets: order of Y11 Y12 Y21 Y22 U V */
    int restart = p_jpeg->restart_interval; /* MCUs until restart marker */

    /* pick the IDCT we want, determine how to work with coefs */
    if (downscale == 1)
    {
        pf_idct = idct8x8;
        k_need = 64; /* all */
        zero_need = 63; /* all */
    }
    else if (downscale == 2)
    {
        pf_idct = idct4x4;
        k_need = 25; /* this far in zig-zag to cover 4*4 */
        zero_need = 27; /* clear this far in linear order */
    }
    else if (downscale == 4)
    {
        pf_idct = idct2x2;
        k_need = 5; /* this far in zig-zag to cover 2*2 */
        zero_need = 9; /* clear this far in linear order */
    }
    else if (downscale == 8)
    {
        pf_idct = idct1x1;
        k_need = 0; /* no AC, not needed */
        zero_need = 0; /* no AC, not needed */
    }
    else return -1; /* not supported */

    /* init bitstream, fake a restart to make it start */
    bs.next_input_byte = p_jpeg->p_entropy_data;
    bs.bits_left = 0;
    bs.input_end = p_jpeg->p_entropy_end;

    width  = p_jpeg->x_phys / downscale;
    height = p_jpeg->y_phys / downscale;
    skip_line = width;
    skip_strip = skip_line * (height / p_jpeg->y_mbl);
    skip_mcu = (width/p_jpeg->x_mbl);

    /* prepare offsets about where to store the different blocks */
    store_offs[p_jpeg->store_pos[0]] = 0;
    store_offs[p_jpeg->store_pos[1]] = 8 / downscale; /* to the right */
    store_offs[p_jpeg->store_pos[2]] = width * 8 / downscale; /* below */
    store_offs[p_jpeg->store_pos[3]] = store_offs[1] + store_offs[2]; /* r+b */

    for(y=0; y<p_jpeg->y_mbl && bs.next_input_byte <= bs.input_end; y++)
    {
        p_byte = p_line;
        p_line += skip_strip;
        for (x=0; x<p_jpeg->x_mbl; x++)
        {
            int blkn;

            /* Outer loop handles each block in the MCU */
            for (blkn = 0; blkn < p_jpeg->blocks; blkn++)
            {   /* Decode a single block's worth of coefficients */
                int k = 1; /* coefficient index */
                int s, r; /* huffman values */
                int ci = p_jpeg->mcu_membership[blkn]; /* component index */
                int ti = p_jpeg->tab_membership[blkn]; /* table index */
                struct derived_tbl* dctbl = &p_jpeg->dc_derived_tbls[ti];
                struct derived_tbl* actbl = &p_jpeg->ac_derived_tbls[ti];

                /* Section F.2.2.1: decode the DC coefficient difference */
                s = huff_decode_dc(&bs, dctbl);

                if (ci == 0) /* only for Y component */
                {
                    last_dc_val += s;
                    block[0] = last_dc_val; /* output it (assumes zag[0] = 0) */

                    /* coefficient buffer must be cleared */
                    MEMSET(block+1, 0, zero_need*sizeof(block[0]));

                    /* Section F.2.2.2: decode the AC coefficients */
                    for (; k < k_need; k++)
                    {
                        s = huff_decode_ac(&bs, actbl);
                        r = s >> 4;
                        s &= 15;

                        if (s)
                        {
                            k += r;
                            check_bit_buffer(&bs, s);
                            r = get_bits(&bs, s);
                            block[zag[k]] = HUFF_EXTEND(r, s);
                        }
                        else
                        {
                            if (r != 15)
                            {
                                k = 64;
                                break;
                            }
                            k += r;
                        }
                    }  /* for k */
                }
                /* In this path we just discard the values */
                for (; k < 64; k++)
                {
                    s = huff_decode_ac(&bs, actbl);
                    r = s >> 4;
                    s &= 15;

                    if (s)
                    {
                        k += r;
                        check_bit_buffer(&bs, s);
                        drop_bits(&bs, s);
                    }
                    else
                    {
                        if (r != 15)
                            break;
                        k += r;
                    }
                }  /* for k */

                if (ci == 0)
                {   /* only for Y component */
                    pf_idct(p_byte+store_offs[blkn], block, p_jpeg->qt_idct[ti],
                        skip_line);
                }
            } /* for blkn */
            p_byte += skip_mcu;
            if (p_jpeg->restart_interval && --restart == 0)
            {   /* if a restart marker is due: */
                restart = p_jpeg->restart_interval; /* count again */
                search_restart(&bs); /* align the bitstream */
                last_dc_val = 0; /* reset decoder */
            }
        } /* for x */
        if (pf_progress != NULL)
            pf_progress(y, p_jpeg->y_mbl-1); /* notify about decoding progress */
    } /* for y */

    return 0; /* success */
}
#endif /* !HAVE_LCD_COLOR */

/**************** end JPEG code ********************/



/**************** begin Application ********************/


/************************* Types ***************************/

struct t_disp
{
#ifdef HAVE_LCD_COLOR
    unsigned char* bitmap[3]; /* Y, Cr, Cb */
    int csub_x, csub_y;
#else
    unsigned char* bitmap[1]; /* Y only */
#endif
    int width;
    int height;
    int stride;
    int x, y;
};

/************************* Globals ***************************/

/* decompressed image in the possible sizes (1,2,4,8), wasting the other */
struct t_disp disp[9];

/* my memory pool (from the mp3 buffer) */
char print[32]; /* use a common snprintf() buffer */
unsigned char* buf; /* up to here currently used by image(s) */

/* the remaining free part of the buffer for compressed+uncompressed images */
unsigned char* buf_images;

ssize_t buf_size, buf_images_size;
/* the root of the images, hereafter are decompresed ones */
unsigned char* buf_root;
int root_size;

int ds, ds_min, ds_max; /* downscaling and limits */
static struct jpeg jpg; /* too large for stack */

static struct tree_context *tree;

/* the current full file name */
static char np_file[MAX_PATH];
int curfile = 0, direction = DIR_NONE, entries = 0;

/* list of the jpeg files */
char **file_pt;
/* are we using the plugin buffer or the audio buffer? */
bool plug_buf = false;


/************************* Implementation ***************************/

#ifdef HAVE_LCD_COLOR
/*
 * Conversion of full 0-255 range YCrCb to RGB:
 *   |R|   |1.000000 -0.000001  1.402000| |Y'|
 *   |G| = |1.000000 -0.334136 -0.714136| |Pb|
 *   |B|   |1.000000  1.772000  0.000000| |Pr|
 * Scaled (yields s15-bit output):
 *   |R|   |128    0  179| |Y       |
 *   |G| = |128  -43  -91| |Cb - 128|
 *   |B|   |128  227    0| |Cr - 128|
 */
#define YFAC            128
#define RVFAC           179
#define GUFAC           (-43)
#define GVFAC           (-91)
#define BUFAC           227
#define YUV_WHITE       (255*YFAC)
#define NODITHER_DELTA  (127*YFAC)
#define COMPONENT_SHIFT  15
#define MATRIX_SHIFT      7

static inline int clamp_component(int x)
{
    if ((unsigned)x > YUV_WHITE)
        x = x < 0 ? 0 : YUV_WHITE;
    return x;
}

static inline int clamp_component_bits(int x, int bits)
{
    if ((unsigned)x > (1u << bits) - 1)
        x = x < 0 ? 0 : (1 << bits) - 1;
    return x;
}

static inline int component_to_lcd(int x, int bits, int delta)
{
    /* Formula used in core bitmap loader. */
    return (((1 << bits) - 1)*x + (x >> (8 - bits)) + delta) >> COMPONENT_SHIFT;
}

static inline int lcd_to_component(int x, int bits, int delta)
{
    /* Reasonable, approximate reversal to get a full range back from the
       quantized value. */
    return YUV_WHITE*x / ((1 << bits) - 1);
    (void)delta;
}

#define RED 0
#define GRN 1
#define BLU 2

struct rgb_err
{
    int16_t errbuf[LCD_WIDTH+2]; /* Error record for line below            */
} rgb_err_buffers[3];

fb_data rgb_linebuf[LCD_WIDTH];  /* Line buffer for scrolling when
                                    DITHER_DIFFUSION is set                */

struct rgb_pixel
{
    int r, g, b;                 /* Current pixel components in s16.0      */
    int inc;                     /* Current line increment (-1 or 1)       */
    int row;                     /* Current row in source image            */
    int col;                     /* Current column in source image         */
    int ce[3];                   /* Errors to apply to current pixel       */
    struct rgb_err *e;           /* RED, GRN, BLU                          */
    int epos;                    /* Current position in error record       */
};

struct rgb_pixel *pixel;

/** round and truncate to lcd depth **/
static fb_data pixel_to_lcd_colour(void)
{
    struct rgb_pixel *p = pixel;
    int r, g, b;

    r = component_to_lcd(p->r, LCD_RED_BITS, NODITHER_DELTA);
    r = clamp_component_bits(r, LCD_RED_BITS);

    g = component_to_lcd(p->g, LCD_GREEN_BITS, NODITHER_DELTA);
    g = clamp_component_bits(g, LCD_GREEN_BITS);

    b = component_to_lcd(p->b, LCD_BLUE_BITS, NODITHER_DELTA);
    b = clamp_component_bits(b, LCD_BLUE_BITS);

    return LCD_RGBPACK_LCD(r, g, b);
}

/** write a monochrome pixel to the colour LCD **/
static fb_data pixel_to_lcd_gray(void)
{
    int r, g, b;

    g = clamp_component(pixel->g);
    r = component_to_lcd(g, LCD_RED_BITS, NODITHER_DELTA);
    b = component_to_lcd(g, LCD_BLUE_BITS, NODITHER_DELTA);
    g = component_to_lcd(g, LCD_GREEN_BITS, NODITHER_DELTA);

    return LCD_RGBPACK_LCD(r, g, b);
}

/**
 * Bayer ordered dithering - swiped from the core bitmap loader.
 */
static fb_data pixel_odither_to_lcd(void)
{
    /* canonical ordered dither matrix */
    static const unsigned char dither_matrix[16][16] = {
        {   0,192, 48,240, 12,204, 60,252,  3,195, 51,243, 15,207, 63,255 },
        { 128, 64,176,112,140, 76,188,124,131, 67,179,115,143, 79,191,127 },
        {  32,224, 16,208, 44,236, 28,220, 35,227, 19,211, 47,239, 31,223 },
        { 160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95 },
        {   8,200, 56,248,  4,196, 52,244, 11,203, 59,251,  7,199, 55,247 },
        { 136, 72,184,120,132, 68,180,116,139, 75,187,123,135, 71,183,119 },
        {  40,232, 24,216, 36,228, 20,212, 43,235, 27,219, 39,231, 23,215 },
        { 168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87 },
        {   2,194, 50,242, 14,206, 62,254,  1,193, 49,241, 13,205, 61,253 },
        { 130, 66,178,114,142, 78,190,126,129, 65,177,113,141, 77,189,125 },
        {  34,226, 18,210, 46,238, 30,222, 33,225, 17,209, 45,237, 29,221 },
        { 162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93 },
        {  10,202, 58,250,  6,198, 54,246,  9,201, 57,249,  5,197, 53,245 },
        { 138, 74,186,122,134, 70,182,118,137, 73,185,121,133, 69,181,117 },
        {  42,234, 26,218, 38,230, 22,214, 41,233, 25,217, 37,229, 21,213 },
        { 170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85 }
    };

    struct rgb_pixel *p = pixel;
    int r, g, b, delta;

    delta = dither_matrix[p->col & 15][p->row & 15] << MATRIX_SHIFT;

    r = component_to_lcd(p->r, LCD_RED_BITS, delta);
    r = clamp_component_bits(r, LCD_RED_BITS);

    g = component_to_lcd(p->g, LCD_GREEN_BITS, delta);
    g = clamp_component_bits(g, LCD_GREEN_BITS);

    b = component_to_lcd(p->b, LCD_BLUE_BITS, delta);
    b = clamp_component_bits(b, LCD_BLUE_BITS);

    p->col += p->inc;

    return LCD_RGBPACK_LCD(r, g, b);
} 

/**
 * Floyd/Steinberg dither to lcd depth.
 *
 * Apply filter to each component in serpentine pattern. Kernel shown for
 * L->R scan. Kernel is reversed for R->L.
 *        *   7
 *    3   5   1     (1/16)
 */
static inline void distribute_error(int *ce, struct rgb_err *e,
                                    int err, int epos, int inc)
{
    *ce                  = (7*err >> 4) + e->errbuf[epos+inc];
    e->errbuf[epos+inc]  =   err >> 4;
    e->errbuf[epos]     += 5*err >> 4;
    e->errbuf[epos-inc] += 3*err >> 4;
}

static fb_data pixel_fsdither_to_lcd(void)
{
    struct rgb_pixel *p = pixel;
    int rc, gc, bc, r, g, b;
    int inc, epos;

    /* Full components with error terms */
    rc = p->r + p->ce[RED];
    r  = component_to_lcd(rc, LCD_RED_BITS, 0);
    r  = clamp_component_bits(r, LCD_RED_BITS);

    gc = p->g + p->ce[GRN];
    g  = component_to_lcd(gc, LCD_GREEN_BITS, 0);
    g  = clamp_component_bits(g, LCD_GREEN_BITS);

    bc = p->b + p->ce[BLU];
    b  = component_to_lcd(bc, LCD_BLUE_BITS, 0);
    b  = clamp_component_bits(b, LCD_BLUE_BITS);

    /* Get pixel errors */
    rc -= lcd_to_component(r, LCD_RED_BITS, 0);
    gc -= lcd_to_component(g, LCD_GREEN_BITS, 0);
    bc -= lcd_to_component(b, LCD_BLUE_BITS, 0);

    /* Spead error to surrounding pixels. */
    inc      = p->inc;
    epos     = p->epos;
    p->epos += inc;

    distribute_error(&p->ce[RED], &p->e[RED], rc, epos, inc);
    distribute_error(&p->ce[GRN], &p->e[GRN], gc, epos, inc);
    distribute_error(&p->ce[BLU], &p->e[BLU], bc, epos, inc);

    /* Pack and return pixel */
    return LCD_RGBPACK_LCD(r, g, b);
}

/* Functions for each output mode, colour then grayscale. */
static fb_data (* const pixel_funcs[COLOUR_NUM_MODES][DITHER_NUM_MODES])(void) =
{
    [COLOURMODE_COLOUR] =
    {
        [DITHER_NONE]      = pixel_to_lcd_colour,
        [DITHER_ORDERED]   = pixel_odither_to_lcd,
        [DITHER_DIFFUSION] = pixel_fsdither_to_lcd,
    },
    [COLOURMODE_GRAY] =
    {
        [DITHER_NONE]      = pixel_to_lcd_gray,
        [DITHER_ORDERED]   = pixel_odither_to_lcd,
        [DITHER_DIFFUSION] = pixel_fsdither_to_lcd,
    },
};
 
/**
 * Draw a partial YUV colour bitmap
 *
 * Runs serpentine pattern when dithering is DITHER_DIFFUSION, else scan is
 * always L->R.
 */
void yuv_bitmap_part(unsigned char *src[3], int csub_x, int csub_y,
                     int src_x, int src_y, int stride,
                     int x, int y, int width, int height)
{
    fb_data *dst, *dst_end;
    fb_data (*pixel_func)(void);
    struct rgb_pixel px;

    if (x + width > LCD_WIDTH)
        width = LCD_WIDTH - x; /* Clip right */
    if (x < 0)
        width += x, x = 0; /* Clip left */
    if (width <= 0)
        return; /* nothing left to do */

    if (y + height > LCD_HEIGHT)
        height = LCD_HEIGHT - y; /* Clip bottom */
    if (y < 0)
        height += y, y = 0; /* Clip top */
    if (height <= 0)
        return; /* nothing left to do */

    pixel = &px;

    dst = rb->lcd_framebuffer + LCD_WIDTH * y + x;
    dst_end = dst + LCD_WIDTH * height;

    if (jpeg_settings.colour_mode == COLOURMODE_GRAY)
        csub_y = 0; /* Ignore Cb, Cr */

    pixel_func = pixel_funcs[jpeg_settings.colour_mode]
                            [jpeg_settings.dither_mode];

    if (jpeg_settings.dither_mode == DITHER_DIFFUSION)
    {
        /* Reset error terms. */
        px.e = rgb_err_buffers;
        px.ce[RED] = px.ce[GRN] = px.ce[BLU] = 0;
        rb->memset(px.e, 0, 3*sizeof (struct rgb_err));
    }

    do
    {
        fb_data *dst_row, *row_end;
        const unsigned char *ysrc;
        px.inc = 1;

        if (jpeg_settings.dither_mode == DITHER_DIFFUSION)
        {
            /* Use R->L scan on odd lines */
            px.inc -= (src_y & 1) << 1;
            px.epos = x + 1;

            if (px.inc < 0)
                px.epos += width - 1;
        }

        if (px.inc == 1)
        {
            /* Scan is L->R */
            dst_row = dst;
            row_end = dst_row + width;
            px.col  = src_x;
        }
        else
        {
            /* Scan is R->L */
            row_end = dst - 1;
            dst_row = row_end + width;
            px.col  = src_x + width - 1;
        }

        ysrc = src[0] + stride * src_y + px.col;
        px.row = src_y;

        /* Do one row of pixels */
        if (csub_y) /* colour */
        {
            /* upsampling, YUV->RGB conversion and reduction to RGB565 in one go */
            const unsigned char *usrc, *vsrc;

            usrc = src[1] + (stride/csub_x) * (src_y/csub_y)
                                            + (px.col/csub_x);
            vsrc = src[2] + (stride/csub_x) * (src_y/csub_y)
                                            + (px.col/csub_x);
            int xphase = px.col % csub_x;
            int xphase_reset = px.inc * csub_x;
            int y, v, u, rv, guv, bu;

            v     = *vsrc - 128;
            vsrc += px.inc;
            u     = *usrc - 128;
            usrc += px.inc;
            rv    =           RVFAC*v;
            guv   = GUFAC*u + GVFAC*v;
            bu    = BUFAC*u;

            while (1)
            {
                y     = YFAC*(*ysrc);
                ysrc += px.inc;
                px.r  = y + rv;
                px.g  = y + guv;
                px.b  = y + bu;

                *dst_row = pixel_func();
                dst_row += px.inc;

                if (dst_row == row_end)
                    break;

                xphase += px.inc;
                if ((unsigned)xphase < (unsigned)csub_x)
                    continue;

                /* fetch new chromas */
                v     = *vsrc - 128;
                vsrc += px.inc;
                u     = *usrc - 128;
                usrc += px.inc;
                rv    =           RVFAC*v;
                guv   = GUFAC*u + GVFAC*v;
                bu    = BUFAC*u;

                xphase -= xphase_reset;
            }
        }
        else /* monochrome */
        {
            do
            {
                /* Set all components the same for dithering purposes */
                px.g  = px.r = px.b = YFAC*(*ysrc);
                *dst_row = pixel_func();
                ysrc    += px.inc;
                dst_row += px.inc;
            }
            while (dst_row != row_end);
        }

        src_y++;
        dst += LCD_WIDTH;
    }
    while (dst < dst_end);
}

#endif /* HAVE_LCD_COLOR */


/* support function for qsort() */
static int compare(const void* p1, const void* p2)
{
    return rb->strcasecmp(*((char **)p1), *((char **)p2));
}

bool jpg_ext(const char ext[])
{
    if(!ext)
        return false;
    if(!rb->strcasecmp(ext,".jpg") ||
       !rb->strcasecmp(ext,".jpe") ||
       !rb->strcasecmp(ext,".jpeg"))
            return true;
    else
            return false;
}

/*Read directory contents for scrolling. */
void get_pic_list(void)
{
    int i;
    long int str_len = 0;
    char *pname;
    tree = rb->tree_get_context();

#if PLUGIN_BUFFER_SIZE >= MIN_MEM
    file_pt = rb->plugin_get_buffer((size_t *)&buf_size);
#else
    file_pt = rb->plugin_get_audio_buffer((size_t *)&buf_size);
#endif

    for(i = 0; i < tree->filesindir; i++)
    {
        if(jpg_ext(rb->strrchr(&tree->name_buffer[str_len],'.')))
            file_pt[entries++] = &tree->name_buffer[str_len];

        str_len += rb->strlen(&tree->name_buffer[str_len]) + 1;
    }

    rb->qsort(file_pt, entries, sizeof(char**), compare);

    /* Remove path and leave only the name.*/
    pname = rb->strrchr(np_file,'/');
    pname++;

    /* Find Selected File. */
    for(i = 0; i < entries; i++)
        if(!rb->strcmp(file_pt[i], pname))
            curfile = i;
}

int change_filename(int direct)
{
    int count = 0;
    direction = direct;

    if(direct == DIR_PREV)
    {
        do
        {
            count++;
            if(curfile == 0)
                curfile = entries - 1;
            else
                curfile--;
        }while(file_pt[curfile] == '\0' && count < entries);
        /* we "erase" the file name if  we encounter
         * a non-supported file, so skip it now */
    }
    else /* DIR_NEXT/DIR_NONE */
    {
        do
        {
            count++;
            if(curfile == entries - 1)
                curfile = 0;
            else
                curfile++;
        }while(file_pt[curfile] == '\0' && count < entries);
    }

    if(count == entries && file_pt[curfile] == '\0')
    {
        rb->splash(HZ, "No supported files");
        return PLUGIN_ERROR;
    }
    if(rb->strlen(tree->currdir) > 1)
    {
        rb->strcpy(np_file, tree->currdir);
        rb->strcat(np_file, "/");
    }
    else
        rb->strcpy(np_file, tree->currdir);

    rb->strcat(np_file, file_pt[curfile]);

    return PLUGIN_OTHER;
}

/* switch off overlay, for handling SYS_ events */
void cleanup(void *parameter)
{
    (void)parameter;
#ifdef USEGSLIB
    grey_show(false);
#endif
}

#define VSCROLL (LCD_HEIGHT/8)
#define HSCROLL (LCD_WIDTH/10)

#define ZOOM_IN  100 /* return codes for below function */
#define ZOOM_OUT 101

#ifdef HAVE_LCD_COLOR
bool set_option_grayscale(void)
{
    bool gray = jpeg_settings.colour_mode == COLOURMODE_GRAY;
    rb->set_bool("Grayscale", &gray);
    jpeg_settings.colour_mode = gray ? COLOURMODE_GRAY : COLOURMODE_COLOUR;
    return false;
}

bool set_option_dithering(void)
{
    static const struct opt_items dithering[DITHER_NUM_MODES] = {
        [DITHER_NONE]      = { "Off",       -1 },
        [DITHER_ORDERED]   = { "Ordered",   -1 },
        [DITHER_DIFFUSION] = { "Diffusion", -1 },
    };

    rb->set_option("Dithering", &jpeg_settings.dither_mode, INT,
                   dithering, DITHER_NUM_MODES, NULL);
    return false;
}

static void display_options(void)
{
    static const struct menu_item items[] = {
        { "Grayscale", set_option_grayscale },
        { "Dithering", set_option_dithering },
    };

    int m = menu_init(rb, items, ARRAYLEN(items),
                          NULL, NULL, NULL, NULL);
    menu_run(m);
    menu_exit(m);
}
#endif /* HAVE_LCD_COLOR */

int show_menu(void) /* return 1 to quit */
{
#if LCD_DEPTH > 1
    rb->lcd_set_backdrop(old_backdrop);
#ifdef HAVE_LCD_COLOR
    rb->lcd_set_foreground(rb->global_settings->fg_color);
    rb->lcd_set_background(rb->global_settings->bg_color);
#else
    rb->lcd_set_foreground(LCD_BLACK);
    rb->lcd_set_background(LCD_WHITE);
#endif
#endif
    int m;
    int result;

    enum menu_id
    {
        MIID_QUIT = 0,
        MIID_TOGGLE_SS_MODE,
        MIID_CHANGE_SS_MODE,
#if PLUGIN_BUFFER_SIZE >= MIN_MEM
        MIID_SHOW_PLAYBACK_MENU,
#endif
#ifdef HAVE_LCD_COLOR
        MIID_DISPLAY_OPTIONS,
#endif
        MIID_RETURN,
    };

    static const struct menu_item items[] = {
        [MIID_QUIT] =
            { "Quit", NULL },
        [MIID_TOGGLE_SS_MODE] =
            { "Toggle Slideshow Mode", NULL },
        [MIID_CHANGE_SS_MODE] =
            { "Change Slideshow Time", NULL },
#if PLUGIN_BUFFER_SIZE >= MIN_MEM
        [MIID_SHOW_PLAYBACK_MENU] =
            { "Show Playback Menu", NULL },
#endif
#ifdef HAVE_LCD_COLOR
        [MIID_DISPLAY_OPTIONS] =
            { "Display Options", NULL },
#endif
        [MIID_RETURN] =
            { "Return", NULL },
    };

    static const struct opt_items slideshow[2] = {
        { "Disable", -1 },
        { "Enable", -1 },
    };

    m = menu_init(rb, items, sizeof(items) / sizeof(*items),
                      NULL, NULL, NULL, NULL);
    result=menu_show(m);

    switch (result)
    {
        case MIID_QUIT:
            menu_exit(m);
            return 1;
            break;
        case MIID_TOGGLE_SS_MODE:
            rb->set_option("Toggle Slideshow", &slideshow_enabled, INT,
                           slideshow , 2, NULL);
            break;
        case MIID_CHANGE_SS_MODE:
            rb->set_int("Slideshow Time", "s", UNIT_SEC,
                        &jpeg_settings.ss_timeout, NULL, 1,
                        SS_MIN_TIMEOUT, SS_MAX_TIMEOUT, NULL);
            break;

#if PLUGIN_BUFFER_SIZE >= MIN_MEM
        case MIID_SHOW_PLAYBACK_MENU:
            if (plug_buf)
            {
                playback_control(rb, NULL);
            }
            else
            {
                rb->splash(HZ, "Cannot restart playback");
            }
            break;
#endif
#ifdef HAVE_LCD_COLOR
        case MIID_DISPLAY_OPTIONS:
            display_options();
            break;
#endif
        case MIID_RETURN:
            break;
    }

#if !defined(SIMULATOR) && !defined(HAVE_FLASH_STORAGE)
    /* change ata spindown time based on slideshow time setting */
    immediate_ata_off = false;
    rb->ata_spindown(rb->global_settings->disk_spindown);

    if (slideshow_enabled)
    {
        if(jpeg_settings.ss_timeout < 10)
        {
            /* slideshow times < 10s keep disk spinning */
            rb->ata_spindown(0);
        }
        else if (!rb->mp3_is_playing())
        {
            /* slideshow times > 10s and not playing: ata_off after load */
            immediate_ata_off = true;
        }
    }
#endif
#if LCD_DEPTH > 1
    rb->lcd_set_backdrop(NULL);
    rb->lcd_set_foreground(LCD_WHITE);
    rb->lcd_set_background(LCD_BLACK);
#endif
    rb->lcd_clear_display();
    menu_exit(m);
    return 0;
}
/* interactively scroll around the image */
int scroll_bmp(struct t_disp* pdisp)
{
    int lastbutton = 0;

    while (true)
    {
        int button;
        int move;

        if (slideshow_enabled)
            button = rb->button_get_w_tmo(jpeg_settings.ss_timeout * HZ);
        else button = rb->button_get(true);

        running_slideshow = false;

        switch(button)
        {
        case JPEG_LEFT:
            if (!(ds < ds_max) && entries > 0 && jpg.x_size <= MAX_X_SIZE)
                return change_filename(DIR_PREV);
        case JPEG_LEFT | BUTTON_REPEAT:
            move = MIN(HSCROLL, pdisp->x);
            if (move > 0)
            {
                MYXLCD(scroll_right)(move); /* scroll right */
                pdisp->x -= move;
#ifdef HAVE_LCD_COLOR
                yuv_bitmap_part(
                    pdisp->bitmap, pdisp->csub_x, pdisp->csub_y,
                    pdisp->x, pdisp->y, pdisp->stride,
                    0, MAX(0, (LCD_HEIGHT-pdisp->height)/2), /* x, y */
                    move, MIN(LCD_HEIGHT, pdisp->height));   /* w, h */
#else
                MYXLCD(gray_bitmap_part)(
                    pdisp->bitmap[0], pdisp->x, pdisp->y, pdisp->stride,
                    0, MAX(0, (LCD_HEIGHT-pdisp->height)/2), /* x, y */
                    move, MIN(LCD_HEIGHT, pdisp->height));   /* w, h */
#endif
                MYLCD_UPDATE();
            }
            break;

        case JPEG_RIGHT:
            if (!(ds < ds_max) && entries > 0 && jpg.x_size <= MAX_X_SIZE)
                return change_filename(DIR_NEXT);
        case JPEG_RIGHT | BUTTON_REPEAT:
            move = MIN(HSCROLL, pdisp->width - pdisp->x - LCD_WIDTH);
            if (move > 0)
            {
                MYXLCD(scroll_left)(move); /* scroll left */
                pdisp->x += move;
#ifdef HAVE_LCD_COLOR
                yuv_bitmap_part(
                    pdisp->bitmap, pdisp->csub_x, pdisp->csub_y,
                    pdisp->x + LCD_WIDTH - move, pdisp->y, pdisp->stride,
                    LCD_WIDTH - move, MAX(0, (LCD_HEIGHT-pdisp->height)/2), /* x, y */
                    move, MIN(LCD_HEIGHT, pdisp->height));   /* w, h */
#else
                MYXLCD(gray_bitmap_part)(
                    pdisp->bitmap[0], pdisp->x + LCD_WIDTH - move,
                    pdisp->y, pdisp->stride,
                    LCD_WIDTH - move, MAX(0, (LCD_HEIGHT-pdisp->height)/2), /* x, y */
                    move, MIN(LCD_HEIGHT, pdisp->height));   /* w, h */
#endif
                MYLCD_UPDATE();
            }
            break;

        case JPEG_UP:
        case JPEG_UP | BUTTON_REPEAT:
            move = MIN(VSCROLL, pdisp->y);
            if (move > 0)
            {
                MYXLCD(scroll_down)(move); /* scroll down */
                pdisp->y -= move;
#ifdef HAVE_LCD_COLOR
                if (jpeg_settings.dither_mode == DITHER_DIFFUSION)
                {
                    /* Draw over the band at the top of the last update
                       caused by lack of error history on line zero. */
                    move = MIN(move + 1, pdisp->y + pdisp->height);
                }

                yuv_bitmap_part(
                    pdisp->bitmap, pdisp->csub_x, pdisp->csub_y,
                    pdisp->x, pdisp->y, pdisp->stride,
                    MAX(0, (LCD_WIDTH-pdisp->width)/2), 0,   /* x, y */
                    MIN(LCD_WIDTH, pdisp->width), move);     /* w, h */
#else
                MYXLCD(gray_bitmap_part)(
                    pdisp->bitmap[0], pdisp->x, pdisp->y, pdisp->stride,
                    MAX(0, (LCD_WIDTH-pdisp->width)/2), 0,   /* x, y */
                    MIN(LCD_WIDTH, pdisp->width), move);     /* w, h */
#endif
                MYLCD_UPDATE();
            }
            break;

        case JPEG_DOWN:
        case JPEG_DOWN | BUTTON_REPEAT:
            move = MIN(VSCROLL, pdisp->height - pdisp->y - LCD_HEIGHT);
            if (move > 0)
            {
                MYXLCD(scroll_up)(move); /* scroll up */
                pdisp->y += move;
#ifdef HAVE_LCD_COLOR
                if (jpeg_settings.dither_mode == DITHER_DIFFUSION)
                {
                    /* Save the line that was on the last line of the display
                       and draw one extra line above then recover the line with
                       image data that had an error history when it was drawn.
                     */
                    move++, pdisp->y--;
                    MEMCPY(rgb_linebuf,
                           rb->lcd_framebuffer + (LCD_HEIGHT - move)*LCD_WIDTH,
                           LCD_WIDTH*sizeof (fb_data));
                }

                yuv_bitmap_part(
                    pdisp->bitmap, pdisp->csub_x, pdisp->csub_y, pdisp->x,
                    pdisp->y + LCD_HEIGHT - move, pdisp->stride,
                    MAX(0, (LCD_WIDTH-pdisp->width)/2), LCD_HEIGHT - move, /* x, y */
                    MIN(LCD_WIDTH, pdisp->width), move);     /* w, h */

                if (jpeg_settings.dither_mode == DITHER_DIFFUSION)
                {
                    /* Cover the first row drawn with previous image data. */
                    MEMCPY(rb->lcd_framebuffer + (LCD_HEIGHT - move)*LCD_WIDTH,
                           rgb_linebuf,
                           LCD_WIDTH*sizeof (fb_data));
                    pdisp->y++;
                }
#else
                MYXLCD(gray_bitmap_part)(
                    pdisp->bitmap[0], pdisp->x,
                    pdisp->y + LCD_HEIGHT - move, pdisp->stride,
                    MAX(0, (LCD_WIDTH-pdisp->width)/2), LCD_HEIGHT - move, /* x, y */
                    MIN(LCD_WIDTH, pdisp->width), move);     /* w, h */
#endif
                MYLCD_UPDATE();
            }
            break;
        case BUTTON_NONE:
            if (!slideshow_enabled)
                break;
            running_slideshow = true;
            if (entries > 0)
                return change_filename(DIR_NEXT);
            break;

#ifdef JPEG_SLIDE_SHOW
        case JPEG_SLIDE_SHOW:
            slideshow_enabled = !slideshow_enabled;
            running_slideshow = slideshow_enabled;
            break;
#endif

#ifdef JPEG_NEXT_REPEAT
        case JPEG_NEXT_REPEAT:
#endif
        case JPEG_NEXT:
            if (entries > 0)
                return change_filename(DIR_NEXT);
            break;

#ifdef JPEG_PREVIOUS_REPEAT
        case JPEG_PREVIOUS_REPEAT:
#endif
        case JPEG_PREVIOUS:
            if (entries > 0)
                return change_filename(DIR_PREV);
            break;

        case JPEG_ZOOM_IN:
#ifdef JPEG_ZOOM_PRE
            if (lastbutton != JPEG_ZOOM_PRE)
                break;
#endif
            return ZOOM_IN;
            break;

        case JPEG_ZOOM_OUT:
#ifdef JPEG_ZOOM_PRE
            if (lastbutton != JPEG_ZOOM_PRE)
                break;
#endif
            return ZOOM_OUT;
            break;
#ifdef JPEG_RC_MENU
        case JPEG_RC_MENU:
#endif
        case JPEG_MENU:
#ifdef USEGSLIB
            grey_show(false); /* switch off greyscale overlay */
#endif
            if (show_menu() == 1)
                return PLUGIN_OK;

#ifdef USEGSLIB
            grey_show(true); /* switch on greyscale overlay */
#else
            yuv_bitmap_part(
                pdisp->bitmap, pdisp->csub_x, pdisp->csub_y,
                pdisp->x, pdisp->y, pdisp->stride,
                MAX(0, (LCD_WIDTH - pdisp->width) / 2),
                MAX(0, (LCD_HEIGHT - pdisp->height) / 2),
                MIN(LCD_WIDTH, pdisp->width),
                MIN(LCD_HEIGHT, pdisp->height));
            MYLCD_UPDATE();
#endif
            break;
        default:
            if (rb->default_event_handler_ex(button, cleanup, NULL)
                == SYS_USB_CONNECTED)
                return PLUGIN_USB_CONNECTED;
            break;

        } /* switch */

        if (button != BUTTON_NONE)
            lastbutton = button;
    } /* while (true) */
}

/********************* main function *************************/

/* callback updating a progress meter while JPEG decoding */
void cb_progess(int current, int total)
{
    rb->yield(); /* be nice to the other threads */
    if(!running_slideshow)
    {
        rb->gui_scrollbar_draw(rb->screens[SCREEN_MAIN],0, LCD_HEIGHT-8, LCD_WIDTH, 8, total, 0,
                      current, HORIZONTAL);
        rb->lcd_update_rect(0, LCD_HEIGHT-8, LCD_WIDTH, 8);
    }
#ifndef USEGSLIB
    else
    {
        /* in slideshow mode, keep gui interference to a minimum */
        rb->gui_scrollbar_draw(rb->screens[SCREEN_MAIN],0, LCD_HEIGHT-4, LCD_WIDTH, 4, total, 0,
                      current, HORIZONTAL);
        rb->lcd_update_rect(0, LCD_HEIGHT-4, LCD_WIDTH, 4);
    }
#endif
}

int jpegmem(struct jpeg *p_jpg, int ds)
{
    int size;

    size = (p_jpg->x_phys/ds/p_jpg->subsample_x[0])
         * (p_jpg->y_phys/ds/p_jpg->subsample_y[0]);
#ifdef HAVE_LCD_COLOR
    if (p_jpg->blocks > 1) /* colour, add requirements for chroma */
    {
        size += (p_jpg->x_phys/ds/p_jpg->subsample_x[1])
              * (p_jpg->y_phys/ds/p_jpg->subsample_y[1]);
        size += (p_jpg->x_phys/ds/p_jpg->subsample_x[2])
              * (p_jpg->y_phys/ds/p_jpg->subsample_y[2]);
    }
#endif
    return size;
}

/* how far can we zoom in without running out of memory */
int min_downscale(struct jpeg *p_jpg, int bufsize)
{
    int downscale = 8;

    if (jpegmem(p_jpg, 8) > bufsize)
        return 0; /* error, too large, even 1:8 doesn't fit */

    while (downscale > 1 && jpegmem(p_jpg, downscale/2) <= bufsize)
        downscale /= 2;

    return downscale;
}


/* how far can we zoom out, to fit image into the LCD */
int max_downscale(struct jpeg *p_jpg)
{
    int downscale = 1;

    while (downscale < 8 && (p_jpg->x_size > LCD_WIDTH*downscale
                          || p_jpg->y_size > LCD_HEIGHT*downscale))
    {
        downscale *= 2;
    }

    return downscale;
}


/* return decoded or cached image */
struct t_disp* get_image(struct jpeg* p_jpg, int ds)
{
    int w, h; /* used to center output */
    int size; /* decompressed image size */
    long time; /* measured ticks */
    int status;

    struct t_disp* p_disp = &disp[ds]; /* short cut */

    if (p_disp->bitmap[0] != NULL)
    {
        return p_disp; /* we still have it */
    }

    /* assign image buffer */

     /* physical size needed for decoding */
    size = jpegmem(p_jpg, ds);
    if (buf_size <= size)
    {   /* have to discard the current */
        int i;
        for (i=1; i<=8; i++)
            disp[i].bitmap[0] = NULL; /* invalidate all bitmaps */
        buf = buf_root; /* start again from the beginning of the buffer */
        buf_size = root_size;
    }

#ifdef HAVE_LCD_COLOR
    if (p_jpg->blocks > 1) /* colour jpeg */
    {
        int i;

        for (i = 1; i < 3; i++)
        {
            size = (p_jpg->x_phys / ds / p_jpg->subsample_x[i])
                 * (p_jpg->y_phys / ds / p_jpg->subsample_y[i]);
            p_disp->bitmap[i] = buf;
            buf += size;
            buf_size -= size;
        }
        p_disp->csub_x = p_jpg->subsample_x[1];
        p_disp->csub_y = p_jpg->subsample_y[1];
    }
    else
    {
        p_disp->csub_x = p_disp->csub_y = 0;
        p_disp->bitmap[1] = p_disp->bitmap[2] = buf;
    }
#endif
    /* size may be less when decoded (if height is not block aligned) */
    size = (p_jpg->x_phys/ds) * (p_jpg->y_size / ds);
    p_disp->bitmap[0] = buf;
    buf += size;
    buf_size -= size;

    if(!running_slideshow)
    {
        rb->snprintf(print, sizeof(print), "decoding %d*%d",
            p_jpg->x_size/ds, p_jpg->y_size/ds);
        rb->lcd_puts(0, 3, print);
        rb->lcd_update();
    }

    /* update image properties */
    p_disp->width = p_jpg->x_size / ds;
    p_disp->stride = p_jpg->x_phys / ds; /* use physical size for stride */
    p_disp->height = p_jpg->y_size / ds;

    /* the actual decoding */
    time = *rb->current_tick;
#ifdef HAVE_ADJUSTABLE_CPU_FREQ
    rb->cpu_boost(true);
    status = jpeg_decode(p_jpg, p_disp->bitmap, ds, cb_progess);
    rb->cpu_boost(false);
#else
    status = jpeg_decode(p_jpg, p_disp->bitmap, ds, cb_progess);
#endif
    if (status)
    {
        rb->splash(HZ, "decode error %d", status);
        file_pt[curfile] = '\0';
        return NULL;
    }
    time = *rb->current_tick - time;

    if(!running_slideshow)
    {
        rb->snprintf(print, sizeof(print), " %ld.%02ld sec ", time/HZ, time%HZ);
        rb->lcd_getstringsize(print, &w, &h); /* centered in progress bar */
        rb->lcd_putsxy((LCD_WIDTH - w)/2, LCD_HEIGHT - h, print);
        rb->lcd_update();
    }

    return p_disp;
}


/* set the view to the given center point, limit if necessary */
void set_view (struct t_disp* p_disp, int cx, int cy)
{
    int x, y;

    /* plain center to available width/height */
    x = cx - MIN(LCD_WIDTH, p_disp->width) / 2;
    y = cy - MIN(LCD_HEIGHT, p_disp->height) / 2;

    /* limit against upper image size */
    x = MIN(p_disp->width - LCD_WIDTH, x);
    y = MIN(p_disp->height - LCD_HEIGHT, y);

    /* limit against negative side */
    x = MAX(0, x);
    y = MAX(0, y);

    p_disp->x = x; /* set the values */
    p_disp->y = y;
}


/* calculate the view center based on the bitmap position */
void get_view(struct t_disp* p_disp, int* p_cx, int* p_cy)
{
    *p_cx = p_disp->x + MIN(LCD_WIDTH, p_disp->width) / 2;
    *p_cy = p_disp->y + MIN(LCD_HEIGHT, p_disp->height) / 2;
}


/* load, decode, display the image */
int load_and_show(char* filename)
{
    int fd;
    int filesize;
    unsigned char* buf_jpeg; /* compressed JPEG image */
    int status;
    struct t_disp* p_disp; /* currenly displayed image */
    int cx, cy; /* view center */

    fd = rb->open(filename, O_RDONLY);
    if (fd < 0)
    {
        rb->snprintf(print,sizeof(print),"err opening %s:%d",filename,fd);
        rb->splash(HZ, print);
        return PLUGIN_ERROR;
    }
    filesize = rb->filesize(fd);
    rb->memset(&disp, 0, sizeof(disp));

    buf = buf_images + filesize;
    buf_size = buf_images_size - filesize;
    /* allocate JPEG buffer */
    buf_jpeg = buf_images;

    buf_root = buf; /* we can start the decompressed images behind it */
    root_size = buf_size;

    if (buf_size <= 0)
    {
#if PLUGIN_BUFFER_SIZE >= MIN_MEM
        if(plug_buf)
        {
            rb->close(fd);
            rb->lcd_setfont(FONT_SYSFIXED);
            rb->lcd_clear_display();
            rb->snprintf(print,sizeof(print),"%s:",rb->strrchr(filename,'/')+1);
            rb->lcd_puts(0,0,print);
            rb->lcd_puts(0,1,"Not enough plugin memory!");
            rb->lcd_puts(0,2,"Zoom In: Stop playback.");
            if(entries>1)
                rb->lcd_puts(0,3,"Left/Right: Skip File.");
            rb->lcd_puts(0,4,"Off: Quit.");
            rb->lcd_update();
            rb->lcd_setfont(FONT_UI);

            rb->button_clear_queue();

            while (1)
            {
                int button = rb->button_get(true);
                switch(button)
                {
                    case JPEG_ZOOM_IN:
                        plug_buf = false;
                        buf_images = rb->plugin_get_audio_buffer(
                                        (size_t *)&buf_images_size);
                        /*try again this file, now using the audio buffer */
                        return PLUGIN_OTHER;
#ifdef JPEG_RC_MENU
                    case JPEG_RC_MENU:
#endif
                    case JPEG_MENU:
                        return PLUGIN_OK;

                    case JPEG_LEFT:
                        if(entries>1)
                        {
                            rb->lcd_clear_display();
                            return change_filename(DIR_PREV);
                        }
                        break;

                    case JPEG_RIGHT:
                        if(entries>1)
                        {
                            rb->lcd_clear_display();
                            return change_filename(DIR_NEXT);
                        }
                        break;
                    default:
                         if(rb->default_event_handler_ex(button, cleanup, NULL)
                                == SYS_USB_CONNECTED)
                              return PLUGIN_USB_CONNECTED;

                }
            }
        }
        else
#endif
        {
            rb->splash(HZ, "Out of Memory");
            rb->close(fd);
            return PLUGIN_ERROR;
        }
    }

    if(!running_slideshow)
    {
#if LCD_DEPTH > 1
        rb->lcd_set_foreground(LCD_WHITE);
        rb->lcd_set_background(LCD_BLACK);
        rb->lcd_set_backdrop(NULL);
#endif

        rb->lcd_clear_display();
        rb->snprintf(print, sizeof(print), "%s:", rb->strrchr(filename,'/')+1);
        rb->lcd_puts(0, 0, print);
        rb->lcd_update();

        rb->snprintf(print, sizeof(print), "loading %d bytes", filesize);
        rb->lcd_puts(0, 1, print);
        rb->lcd_update();
    }

    rb->read(fd, buf_jpeg, filesize);
    rb->close(fd);

    if(!running_slideshow)
    {
        rb->snprintf(print, sizeof(print), "decoding markers");
        rb->lcd_puts(0, 2, print);
        rb->lcd_update();
    }
#ifndef SIMULATOR
    else if(immediate_ata_off)
    {
        /* running slideshow and time is long enough: power down disk */
        rb->ata_sleep();
    }
#endif

    rb->memset(&jpg, 0, sizeof(jpg)); /* clear info struct */
    /* process markers, unstuffing */
    status = process_markers(buf_jpeg, filesize, &jpg);

    if (status < 0 || (status & (DQT | SOF0)) != (DQT | SOF0))
    {   /* bad format or minimum components not contained */
        rb->splash(HZ, "unsupported %d", status);
        file_pt[curfile] = '\0';
        return change_filename(direction);
    }

    if (!(status & DHT)) /* if no Huffman table present: */
        default_huff_tbl(&jpg); /* use default */
    build_lut(&jpg); /* derive Huffman and other lookup-tables */

    if(!running_slideshow)
    {
        rb->snprintf(print, sizeof(print), "image %dx%d", jpg.x_size, jpg.y_size);
        rb->lcd_puts(0, 2, print);
        rb->lcd_update();
    }
    ds_max = max_downscale(&jpg);            /* check display constraint */
    ds_min = min_downscale(&jpg, buf_size);  /* check memory constraint */
    if (ds_min == 0)
    {
        rb->splash(HZ, "too large");
        file_pt[curfile] = '\0';
        return change_filename(direction);
    }

    ds = ds_max; /* initials setting */
    cx = jpg.x_size/ds/2; /* center the view */
    cy = jpg.y_size/ds/2;

    do  /* loop the image prepare and decoding when zoomed */
    {
        p_disp = get_image(&jpg, ds); /* decode or fetch from cache */
        if (p_disp == NULL)
            return change_filename(direction);

        set_view(p_disp, cx, cy);

        if(!running_slideshow)
        {
            rb->snprintf(print, sizeof(print), "showing %dx%d",
                p_disp->width, p_disp->height);
            rb->lcd_puts(0, 3, print);
            rb->lcd_update();
        }
        MYLCD(clear_display)();
#ifdef HAVE_LCD_COLOR
        yuv_bitmap_part(
            p_disp->bitmap, p_disp->csub_x, p_disp->csub_y,
            p_disp->x, p_disp->y, p_disp->stride,
            MAX(0, (LCD_WIDTH - p_disp->width) / 2),
            MAX(0, (LCD_HEIGHT - p_disp->height) / 2),
            MIN(LCD_WIDTH, p_disp->width),
            MIN(LCD_HEIGHT, p_disp->height));
#else
        MYXLCD(gray_bitmap_part)(
            p_disp->bitmap[0], p_disp->x, p_disp->y, p_disp->stride,
            MAX(0, (LCD_WIDTH - p_disp->width) / 2),
            MAX(0, (LCD_HEIGHT - p_disp->height) / 2),
            MIN(LCD_WIDTH, p_disp->width),
            MIN(LCD_HEIGHT, p_disp->height));
#endif
        MYLCD_UPDATE();

#ifdef USEGSLIB
        grey_show(true); /* switch on greyscale overlay */
#endif

        /* drawing is now finished, play around with scrolling
         * until you press OFF or connect USB
         */
        while (1)
        {
            status = scroll_bmp(p_disp);
            if (status == ZOOM_IN)
            {
                if (ds > ds_min)
                {
                    ds /= 2; /* reduce downscaling to zoom in */
                    get_view(p_disp, &cx, &cy);
                    cx *= 2; /* prepare the position in the new image */
                    cy *= 2;
                }
                else
                    continue;
            }

            if (status == ZOOM_OUT)
            {
                if (ds < ds_max)
                {
                    ds *= 2; /* increase downscaling to zoom out */
                    get_view(p_disp, &cx, &cy);
                    cx /= 2; /* prepare the position in the new image */
                    cy /= 2;
                }
                else
                    continue;
            }
            break;
        }

#ifdef USEGSLIB
        grey_show(false); /* switch off overlay */
#endif
        rb->lcd_clear_display();
    }
    while (status != PLUGIN_OK && status != PLUGIN_USB_CONNECTED
                                       && status != PLUGIN_OTHER);
#ifdef USEGSLIB
    rb->lcd_update();
#endif
    return status;
}

/******************** Plugin entry point *********************/

enum plugin_status plugin_start(const struct plugin_api* api, const void* parameter)
{
    rb = api;

    int condition;
#ifdef USEGSLIB
    long greysize; /* helper */
#endif
#if LCD_DEPTH > 1
    old_backdrop = rb->lcd_get_backdrop();
#endif

    if(!parameter) return PLUGIN_ERROR;

    rb->strcpy(np_file, parameter);
    get_pic_list();

    if(!entries) return PLUGIN_ERROR;

#if (PLUGIN_BUFFER_SIZE >= MIN_MEM) && !defined(SIMULATOR)
    if(rb->audio_status())
    {
        buf = rb->plugin_get_buffer((size_t *)&buf_size) +
             (entries * sizeof(char**));
        buf_size -= (entries * sizeof(char**));
        plug_buf = true;
    }
    else
        buf = rb->plugin_get_audio_buffer((size_t *)&buf_size);
#else
    buf = rb->plugin_get_audio_buffer(&buf_size) +
               (entries * sizeof(char**));
    buf_size -= (entries * sizeof(char**));
#endif

#ifdef USEGSLIB
    if (!grey_init(rb, buf, buf_size, GREY_ON_COP,
                   LCD_WIDTH, LCD_HEIGHT, &greysize))
    {
        rb->splash(HZ, "grey buf error");
        return PLUGIN_ERROR;
    }
    buf += greysize;
    buf_size -= greysize;
#else
    xlcd_init(rb);
#endif

    /* should be ok to just load settings since a parameter is present
       here and the drive should be spinning */
    configfile_init(rb);
    configfile_load(JPEG_CONFIGFILE, jpeg_config,
                    ARRAYLEN(jpeg_config), JPEG_SETTINGS_MINVERSION);
    old_settings = jpeg_settings;

    buf_images = buf; buf_images_size = buf_size;

    /* Turn off backlight timeout */
    backlight_force_on(rb); /* backlight control in lib/helper.c */

    do
    {
        condition = load_and_show(np_file);
    }while (condition != PLUGIN_OK && condition != PLUGIN_USB_CONNECTED
                                          && condition != PLUGIN_ERROR);

    if (rb->memcmp(&jpeg_settings, &old_settings, sizeof (jpeg_settings)))
    {
        /* Just in case drive has to spin, keep it from looking locked */
        rb->splash(0, "Saving Settings");
        configfile_save(JPEG_CONFIGFILE, jpeg_config,
                        ARRAYLEN(jpeg_config), JPEG_SETTINGS_VERSION);
    }

#if !defined(SIMULATOR) && !defined(HAVE_FLASH_STORAGE)
    /* set back ata spindown time in case we changed it */
    rb->ata_spindown(rb->global_settings->disk_spindown);
#endif

    /* Turn on backlight timeout (revert to settings) */
    backlight_use_settings(rb); /* backlight control in lib/helper.c */

#ifdef USEGSLIB
    grey_release(); /* deinitialize */
#endif

    return condition;
}

#endif /* HAVE_LCD_BITMAP */