/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2005 by Dave Chapman
 *
 * Rockbox driver for 16-bit colour LCDs
 *
 * 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.
 *
 ****************************************************************************/


/* to be #included by lcd-16bit*.c */

#if !defined(ROW_INC) || !defined(COL_INC)
#error ROW_INC or COL_INC not defined
#endif

/* Clear the current viewport */
void lcd_clear_viewport(void)
{
    struct viewport *vp = lcd_current_viewport;
    fb_data *dst, *dst_end;
    int x, y, width, height;
    int len, step;

    x = vp->x;
    y = vp->y;
    width = vp->width;
    height = vp->height;

    len  = STRIDE_MAIN(width, height);
    step = STRIDE_MAIN(ROW_INC, COL_INC);

    dst = FBADDR(x, y);
    dst_end = FBADDR(x + width - 1 , y + height - 1);

    if (vp->drawmode & DRMODE_INVERSEVID)
    {
        do
        {
            memset16(dst, vp->fg_pattern, len);
            dst += step;
        }
        while (dst <= dst_end);
    }
    else
    {
        if (lcd_backdrop && vp->buffer == &lcd_framebuffer_default)
        {
            do
            {
                memcpy(dst, PTR_ADD(dst, lcd_backdrop_offset),
                       len * sizeof(fb_data));
                dst += step;
            }
            while (dst <= dst_end);
        }
        else
        {
            do
            {
                memset16(dst, vp->bg_pattern, len);
                dst += step;
            }
            while (dst <= dst_end);
        }
    }

    if (vp == &default_vp)
        lcd_scroll_stop();
    else
        lcd_scroll_stop_viewport(vp);

    vp->flags &= ~(VP_FLAG_VP_SET_CLEAN);
}

/*** low-level drawing functions ***/

static void ICODE_ATTR setpixel(fb_data *address)
{
    *address = lcd_current_viewport->fg_pattern;
}

static void ICODE_ATTR clearpixel(fb_data *address)
{
    *address = lcd_current_viewport->bg_pattern;
}

static void ICODE_ATTR clearimgpixel(fb_data *address)
{
    *address = *PTR_ADD(address, lcd_backdrop_offset);
}

static void ICODE_ATTR flippixel(fb_data *address)
{
    *address = ~(*address);
}

static void ICODE_ATTR nopixel(fb_data *address)
{
    (void)address;
}

lcd_fastpixelfunc_type* const lcd_fastpixelfuncs_bgcolor[8] = {
    flippixel, nopixel, setpixel, setpixel,
    nopixel, clearpixel, nopixel, clearpixel
};

lcd_fastpixelfunc_type* const lcd_fastpixelfuncs_backdrop[8] = {
    flippixel, nopixel, setpixel, setpixel,
    nopixel, clearimgpixel, nopixel, clearimgpixel
};

lcd_fastpixelfunc_type* const * lcd_fastpixelfuncs = lcd_fastpixelfuncs_bgcolor;

/* Fill a rectangular area */
void lcd_fillrect(int x, int y, int width, int height)
{
    struct viewport *vp = lcd_current_viewport;
    unsigned bits = 0;
    enum fill_opt fillopt = OPT_NONE;
    fb_data *dst, *dst_end;
    int len, step;

    if (!clip_viewport_rect(vp, &x, &y, &width, &height, NULL, NULL))
        return;

    /* drawmode and optimisation */
    if (vp->drawmode & DRMODE_INVERSEVID)
    {
        if (vp->drawmode & DRMODE_BG)
        {
            if (!lcd_backdrop)
            {
                fillopt = OPT_SET;
                bits = vp->bg_pattern;
            }
            else
                fillopt = OPT_COPY;
        }
    }
    else
    {
        if (vp->drawmode & DRMODE_FG)
        {
            fillopt = OPT_SET;
            bits = vp->fg_pattern;
        }
    }
    if (fillopt == OPT_NONE && vp->drawmode != DRMODE_COMPLEMENT)
        return;

    dst = FBADDR(x, y);
    dst_end = FBADDR(x + width - 1, y + height - 1);

    len  = STRIDE_MAIN(width, height);
    step = STRIDE_MAIN(ROW_INC, COL_INC);

    do
    {
        switch (fillopt)
        {
          case OPT_SET:
            memset16(dst, bits, len);
            break;

          case OPT_COPY:
            memcpy(dst, PTR_ADD(dst, lcd_backdrop_offset),
                   len * sizeof(fb_data));
            break;

          case OPT_NONE:  /* DRMODE_COMPLEMENT */
          {
            fb_data *start = dst;
            fb_data *end = start + len;
            do
                *start = ~(*start);
            while (++start < end);
            break;
          }
        }
        dst += step;
    }
    while (dst <= dst_end);
}

/* About Rockbox' internal monochrome bitmap format:
 *
 * A bitmap contains one bit for every pixel that defines if that pixel is
 * black (1) or white (0). Bits within a byte are arranged vertically, LSB
 * at top.
 * The bytes are stored in row-major order, with byte 0 being top left,
 * byte 1 2nd from left etc. The first row of bytes defines pixel rows
 * 0..7, the second row defines pixel row 8..15 etc.
 *
 * This is the mono bitmap format used on all other targets so far; the
 * pixel packing doesn't really matter on a 8bit+ target. */

/* Draw a partial monochrome bitmap */

void ICODE_ATTR lcd_mono_bitmap_part(const unsigned char *src, int src_x,
                                     int src_y, int stride, int x, int y,
                                     int width, int height)
{
    struct viewport *vp = lcd_current_viewport;
    if (!clip_viewport_rect(vp, &x, &y, &width, &height, &src_x, &src_y))
        return;

    /* move starting point */
    src += stride * (src_y >> 3) + src_x;
    src_y &= 7;

    unsigned dmask = 0;
    int drmode = vp->drawmode;

    if (drmode & DRMODE_INVERSEVID)
    {
        dmask = 0xff;
        drmode &= DRMODE_SOLID; /* mask out inversevid */
    }

    /* Use extra bit to avoid if () in the switch-cases below */
    if ((drmode & DRMODE_BG) && lcd_backdrop)
        drmode |= DRMODE_INT_BD;

    fb_data* dst = FBADDR(x, y);
    while(height > 0)
    {
        const unsigned char* src_col = src;
        const unsigned char* src_end = src + width;
        fb_data* dst_col = dst;

        unsigned data;
        int fg, bg;
        uintptr_t bo;

        switch (drmode) {
        case DRMODE_COMPLEMENT:
            do {
                data = (*src_col++ ^ dmask) >> src_y;
                if(data & 0x01)
                    *dst_col = ~(*dst_col);

                dst_col += COL_INC;
            } while(src_col != src_end);
            break;

        case DRMODE_BG|DRMODE_INT_BD:
            bo = lcd_backdrop_offset;
            do {
                data = (*src_col++ ^ dmask) >> src_y;
                if(!(data & 0x01))
                    *dst_col = *PTR_ADD(dst_col, bo);

                dst_col += COL_INC;
            } while(src_col != src_end);
            break;

        case DRMODE_BG:
            bg = vp->bg_pattern;
            do {
                data = (*src_col++ ^ dmask) >> src_y;
                if(!(data & 0x01))
                    *dst_col = bg;

                dst_col += COL_INC;
            } while(src_col != src_end);
            break;

        case DRMODE_FG:
            fg = vp->fg_pattern;
            do {
                data = (*src_col++ ^ dmask) >> src_y;
                if(data & 0x01)
                    *dst_col = fg;

                dst_col += COL_INC;
            } while(src_col != src_end);
            break;

        case DRMODE_SOLID|DRMODE_INT_BD:
            fg = vp->fg_pattern;
            bo = lcd_backdrop_offset;
            do {
                data = (*src_col++ ^ dmask) >> src_y;
                if(data & 0x01)
                    *dst_col = fg;
                else
                    *dst_col = *PTR_ADD(dst_col, bo);

                dst_col += COL_INC;
            } while(src_col != src_end);
            break;

        case DRMODE_SOLID:
            fg = vp->fg_pattern;
            bg = vp->bg_pattern;
            do {
                data = (*src_col++ ^ dmask) >> src_y;
                if(data & 0x01)
                    *dst_col = fg;
                else
                    *dst_col = bg;

                dst_col += COL_INC;
            } while(src_col != src_end);
            break;
        }

        src_y = (src_y + 1) & 7;
        if(src_y == 0)
            src += stride;

        dst += ROW_INC;
        height--;
    }
}

/* Draw a full monochrome bitmap */
void lcd_mono_bitmap(const unsigned char *src, int x, int y, int width, int height)
{
    lcd_mono_bitmap_part(src, 0, 0, width, x, y, width, height);
}


/* About Rockbox' internal alpha channel format (for ALPHA_BPP == 4)
 *
 * For each pixel, 4bit of alpha information is stored in a byte-stream,
 * so two pixels are packed into one byte.
 * The lower nibble is the first pixel, the upper one the second. The stride is
 * horizontal. E.g row0: pixel0: byte0[0:3], pixel1: byte0[4:7], pixel2: byte1[0:3],...
 * The format is independant of the internal display orientation and color
 * representation, as to support the same font files on all displays.
 * The values go linear from 0 (fully opaque) to 15 (fully transparent)
 * (note how this is the opposite of the alpha channel in the ARGB format).
 *
 * This might suggest that rows need to have an even number of pixels.
 * However this is generally not the case. lcd_alpha_bitmap_part_mix() can deal
 * with uneven colums (i.e. two rows can share one byte). And font files do
 * exploit this.
 * However, this is difficult to do for image files, especially bottom-up bitmaps,
 * so lcd_bmp() do expect even rows.
 */

#define ALPHA_BPP               4
#define ALPHA_MASK              ((1 << ALPHA_BPP) - 1)
#define ALPHA_PIXELS_PER_BYTE   (CHAR_BIT / ALPHA_BPP)

#define ALPHA_WORD_T            uint32_t
#define ALPHA_WORD_LOAD         load_le32
#define ALPHA_WORDSIZE          sizeof(ALPHA_WORD_T)
#define ALPHA_PIXELS_PER_WORD   (ALPHA_WORDSIZE * CHAR_BIT / ALPHA_BPP)

#ifdef CPU_ARM
#define BLEND_INIT do {} while (0)
#define BLEND_FINISH do {} while(0)
#define BLEND_START(acc, color, alpha) \
    asm volatile("mul %0, %1, %2" : "=&r" (acc) : "r" (color), "r" (alpha))
#define BLEND_CONT(acc, color, alpha) \
    asm volatile("mla %0, %1, %2, %0" : "+&r" (acc) : "r" (color), "r" (alpha))
#define BLEND_OUT(acc) do {} while (0)

#elif defined(CPU_COLDFIRE)
#define ALPHA_BITMAP_READ_WORDS
#define BLEND_INIT \
    unsigned long _macsr = coldfire_get_macsr(); \
    coldfire_set_macsr(EMAC_UNSIGNED)
#define BLEND_FINISH \
    coldfire_set_macsr(_macsr)
#define BLEND_START(acc, color, alpha) \
    asm volatile("mac.l %0, %1, %%acc0" :: "%d" (color), "d" (alpha))
#define BLEND_CONT BLEND_START
#define BLEND_OUT(acc) asm volatile("movclr.l %%acc0, %0" : "=d" (acc))

#else
#define BLEND_INIT do {} while (0)
#define BLEND_FINISH do {} while(0)
#define BLEND_START(acc, color, alpha) ((acc) = (color) * (alpha))
#define BLEND_CONT(acc, color, alpha) ((acc) += (color) * (alpha))
#define BLEND_OUT(acc) do {} while (0)
#endif

/* Blend the given two colors */
static inline unsigned blend_two_colors(unsigned c1, unsigned c2, unsigned a)
{
    a += a >> (ALPHA_BPP - 1);
#if (LCD_PIXELFORMAT == RGB565SWAPPED)
    c1 = swap16(c1);
    c2 = swap16(c2);
#endif
    unsigned c1l = (c1 | (c1 << 16)) & 0x07e0f81f;
    unsigned c2l = (c2 | (c2 << 16)) & 0x07e0f81f;
    unsigned p;
    BLEND_START(p, c1l, a);
    BLEND_CONT(p, c2l, ALPHA_MASK + 1 - a);
    BLEND_OUT(p);
    p = (p >> ALPHA_BPP) & 0x07e0f81f;
    p |= (p >> 16);
#if (LCD_PIXELFORMAT == RGB565SWAPPED)
    return swap16(p);
#else
    return p;
#endif
}

static void ICODE_ATTR lcd_alpha_bitmap_part_mix(
    const fb_data* image, const unsigned char *alpha,
    int src_x, int src_y,
    int x, int y, int width, int height,
    int stride_image, int stride_alpha)
{
    struct viewport *vp = lcd_current_viewport;
    unsigned int dmask = 0;
    int drmode = vp->drawmode;
    fb_data *dst;
#ifdef ALPHA_BITMAP_READ_WORDS
    ALPHA_WORD_T alpha_data, *alpha_word;
    size_t alpha_offset = 0, alpha_pixels;
#else
    unsigned char alpha_data;
    size_t alpha_pixels;
#endif

    if (!clip_viewport_rect(vp, &x, &y, &width, &height, &src_x, &src_y))
        return;

    if (drmode & DRMODE_INVERSEVID)
    {
        dmask = 0xFFFFFFFFu;
        drmode &= ~DRMODE_INVERSEVID;
    }

    if (image != NULL)
        drmode |= DRMODE_INT_IMG;

    if ((drmode & DRMODE_BG) && lcd_backdrop)
        drmode |= DRMODE_INT_BD;

#ifdef ALPHA_BITMAP_READ_WORDS
#define INIT_ALPHA() \
    do { \
        alpha_offset = src_y * stride_alpha + src_x; \
    } while(0)
#define START_ALPHA() \
    do { \
        size_t __byteskip = (uintptr_t)alpha % ALPHA_WORDSIZE; \
        size_t __byteoff = alpha_offset / ALPHA_PIXELS_PER_BYTE; \
        alpha_word = (ALPHA_WORD_T *)ALIGN_DOWN(alpha + __byteoff, ALPHA_WORDSIZE); \
        alpha_data = ALPHA_WORD_LOAD(alpha_word++) ^ dmask; \
        alpha_pixels = ((__byteoff + __byteskip) % ALPHA_WORDSIZE) * ALPHA_PIXELS_PER_BYTE; \
        alpha_pixels += alpha_offset % ALPHA_PIXELS_PER_BYTE; \
        alpha_data >>= alpha_pixels * ALPHA_BPP; \
        alpha_pixels = ALPHA_PIXELS_PER_WORD - alpha_pixels; \
    } while(0)
#define END_ALPHA() \
    do { \
        alpha_offset += stride_alpha; \
    } while(0)
#define READ_ALPHA() \
    ({ \
        if (alpha_pixels == 0) { \
            alpha_data = ALPHA_WORD_LOAD(alpha_word++) ^ dmask; \
            alpha_pixels = ALPHA_PIXELS_PER_WORD; \
        } \
        ALPHA_WORD_T __ret = alpha_data & ALPHA_MASK; \
        alpha_data >>= ALPHA_BPP; \
        alpha_pixels--; \
        __ret; \
    })
#elif ALPHA_BPP == 4
#define INIT_ALPHA() \
    do { \
        alpha_pixels = src_y * stride_alpha + src_x; \
        stride_alpha = stride_alpha - width; \
        alpha += alpha_pixels / ALPHA_PIXELS_PER_BYTE; \
        alpha_pixels &= 1; \
        if (alpha_pixels) { \
            alpha_data = *alpha++ ^ dmask; \
            alpha_data >>= ALPHA_BPP; \
        } \
    } while(0)
#define START_ALPHA() do { } while(0)
#define END_ALPHA() \
    do { \
        if (stride_alpha) { \
            alpha_pixels = stride_alpha - alpha_pixels; \
            alpha += alpha_pixels / ALPHA_PIXELS_PER_BYTE; \
            alpha_pixels &= 1; \
            if (alpha_pixels) { \
                alpha_data = *alpha++ ^ dmask; \
                alpha_data >>= ALPHA_BPP; \
            } \
        } \
    } while(0)
#define READ_ALPHA() \
    ({ \
        if (alpha_pixels == 0) \
            alpha_data = *alpha++ ^ dmask; \
        unsigned char __ret = alpha_data & ALPHA_MASK; \
        alpha_data >>= ALPHA_BPP; \
        alpha_pixels ^= 1; \
        __ret; \
    })
#else
#define INIT_ALPHA() \
    do { \
        alpha_pixels = src_y * stride_alpha + src_x; \
        stride_alpha = stride_alpha - width; \
        alpha += alpha_pixels / ALPHA_PIXELS_PER_BYTE; \
        alpha_data = *alpha++ ^ dmask; \
        alpha_pixels %= ALPHA_PIXELS_PER_BYTE; \
        alpha_data >>= ALPHA_BPP * alpha_pixels; \
        alpha_pixels = ALPHA_PIXELS_PER_BYTE - alpha_pixels; \
    } while(0)
#define START_ALPHA() do { } while(0)
#define END_ALPHA() \
    do { \
        if ((size_t)stride_alpha <= alpha_pixels) \
            alpha_pixels -= stride_alpha; \
        else { \
            alpha_pixels = stride_alpha - alpha_pixels; \
            alpha += alpha_pixels / ALPHA_PIXELS_PER_BYTE; \
            alpha_data = *alpha++ ^ dmask; \
            alpha_pixels %= ALPHA_PIXELS_PER_BYTE; \
            alpha_data >>= ALPHA_BPP * alpha_pixels; \
            alpha_pixels = ALPHA_PIXELS_PER_BYTE - alpha_pixels; \
        } \
    } while(0)
#define READ_ALPHA() \
    ({ \
        if (alpha_pixels == 0) { \
            alpha_data = *alpha++ ^ dmask; \
            alpha_pixels = ALPHA_PIXELS_PER_BYTE; \
        } \
        unsigned char __ret = alpha_data & ALPHA_MASK; \
        alpha_data >>= ALPHA_BPP; \
        alpha_pixels--; \
        __ret; \
    })
#endif

    dst = FBADDR(x, y);
    image += STRIDE_MAIN(src_y * stride_image + src_x,
                         src_x * stride_image + src_y);

    INIT_ALPHA();
    BLEND_INIT;

    do
    {
        intptr_t bo, io;
        unsigned int fg, bg;
        int col = width;
        fb_data *dst_row = dst;

        START_ALPHA();

        switch (drmode)
        {
        case DRMODE_COMPLEMENT:
            do
            {
                *dst = blend_two_colors(*dst, ~(*dst), READ_ALPHA());
                dst += COL_INC;
            } while (--col);
            break;
        case DRMODE_BG|DRMODE_INT_BD:
            bo = lcd_backdrop_offset;
            do
            {
                *dst = blend_two_colors(*PTR_ADD(dst, bo), *dst, READ_ALPHA());
                dst += COL_INC;
            } while (--col);
            break;
        case DRMODE_BG:
            bg = vp->bg_pattern;
            do
            {
                *dst = blend_two_colors(bg, *dst, READ_ALPHA());
                dst += COL_INC;
            } while (--col);
            break;
        case DRMODE_FG|DRMODE_INT_IMG:
            io = image - dst;
            do
            {
                *dst = blend_two_colors(*dst, *(dst + io), READ_ALPHA());
                dst += COL_INC;
            } while (--col);
            break;
        case DRMODE_FG:
            fg = vp->fg_pattern;
            do
            {
                *dst = blend_two_colors(*dst, fg, READ_ALPHA());
                dst += COL_INC;
            } while (--col);
            break;
        case DRMODE_SOLID|DRMODE_INT_BD:
            fg = vp->fg_pattern;
            bo = lcd_backdrop_offset;
            do
            {
                *dst = blend_two_colors(*PTR_ADD(dst, bo), fg, READ_ALPHA());
                dst += COL_INC;
            } while (--col);
            break;
        case DRMODE_SOLID|DRMODE_INT_IMG:
            bg = vp->bg_pattern;
            io = image - dst;
            do
            {
                *dst = blend_two_colors(bg, *(dst + io), READ_ALPHA());
                dst += COL_INC;
            } while (--col);
            break;
        case DRMODE_SOLID|DRMODE_INT_BD|DRMODE_INT_IMG:
            bo = lcd_backdrop_offset;
            io = image - dst;
            do
            {
                *dst = blend_two_colors(*PTR_ADD(dst, bo), *(dst + io), READ_ALPHA());
                dst += COL_INC;
            } while (--col);
            break;
        case DRMODE_SOLID:
            fg = vp->fg_pattern;
            bg = vp->bg_pattern;
            do
            {
                *dst = blend_two_colors(bg, fg, READ_ALPHA());
                dst += COL_INC;
            } while (--col);
            break;
        }

        END_ALPHA();
        image += STRIDE_MAIN(stride_image, 1);
        dst = dst_row + ROW_INC;
    } while (--height);

    BLEND_FINISH;
}