rockbox/apps/plugins/mpegplayer/idct.c

/*
 * idct.c
 * Copyright (C) 2000-2003 Michel Lespinasse <walken@zoy.org>
 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
 *
 * This file is part of mpeg2dec, a free MPEG-2 video stream decoder.
 * See http://libmpeg2.sourceforge.net/ for updates.
 *
 * mpeg2dec 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.
 *
 * mpeg2dec is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "plugin.h"

#include "mpeg2dec_config.h"

#include "mpeg2.h"
#include "attributes.h"
#include "mpeg2_internal.h"

#define W1 2841 /* 2048 * sqrt (2) * cos (1 * pi / 16) */
#define W2 2676 /* 2048 * sqrt (2) * cos (2 * pi / 16) */
#define W3 2408 /* 2048 * sqrt (2) * cos (3 * pi / 16) */
#define W5 1609 /* 2048 * sqrt (2) * cos (5 * pi / 16) */
#define W6 1108 /* 2048 * sqrt (2) * cos (6 * pi / 16) */
#define W7 565  /* 2048 * sqrt (2) * cos (7 * pi / 16) */

/* idct main entry point  */
void (* mpeg2_idct_copy) (int16_t * block, uint8_t * dest, int stride);
void (* mpeg2_idct_add) (int last, int16_t * block,
                         uint8_t * dest, int stride);

/*
 * In legal streams, the IDCT output should be between -384 and +384.
 * In corrupted streams, it is possible to force the IDCT output to go
 * to +-3826 - this is the worst case for a column IDCT where the
 * column inputs are 16-bit values.
 */
#ifdef CPU_COLDFIRE
static inline unsigned CLIP(int value)
{
    asm (  /* Note: Uses knowledge that only the low byte of the result is used */
        "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
static inline unsigned CLIP(int value)
{
    asm volatile ( /* Note: Uses knowledge that only the low byte of the result is used */
        "cmp     %[v], #255          \n"
        "mvnhi   %[v], %[v], asr #31 \n"
        : /* outputs */
        [v]"+r"(value)
    );
    return value;
}
#else
uint8_t mpeg2_clip[3840 * 2 + 256] IBSS_ATTR;
#define CLIP(i) ((mpeg2_clip + 3840)[i])
#endif

#if 0
#define BUTTERFLY(t0,t1,W0,W1,d0,d1) \
    do {                             \
        t0 = W0 * d0 + W1 * d1;      \
        t1 = W0 * d1 - W1 * d0;      \
    } while (0)
#else
#define BUTTERFLY(t0,t1,W0,W1,d0,d1) \
    do {                             \
        int tmp = W0 * (d0 + d1);    \
        t0 = tmp + (W1 - W0) * d1;   \
        t1 = tmp - (W1 + W0) * d0;   \
    } while (0)
#endif

static inline void idct_row (int16_t * const block)
{
    int d0, d1, d2, d3;
    int a0, a1, a2, a3, b0, b1, b2, b3;
    int t0, t1, t2, t3;

    /* shortcut */
    if (likely (!(block[1] | ((int32_t *)block)[1] | ((int32_t *)block)[2] |
                  ((int32_t *)block)[3]))) {
        uint32_t tmp = (uint16_t) (block[0] >> 1);
        tmp |= tmp << 16;
        ((int32_t *)block)[0] = tmp;
        ((int32_t *)block)[1] = tmp;
        ((int32_t *)block)[2] = tmp;
        ((int32_t *)block)[3] = tmp;
        return;
    }

    d0 = (block[0] << 11) + 2048;
    d1 = block[1];
    d2 = block[2] << 11;
    d3 = block[3];
    t0 = d0 + d2;
    t1 = d0 - d2;
    BUTTERFLY (t2, t3, W6, W2, d3, d1);
    a0 = t0 + t2;
    a1 = t1 + t3;
    a2 = t1 - t3;
    a3 = t0 - t2;

    d0 = block[4];
    d1 = block[5];
    d2 = block[6];
    d3 = block[7];
    BUTTERFLY (t0, t1, W7, W1, d3, d0);
    BUTTERFLY (t2, t3, W3, W5, d1, d2);
    b0 = t0 + t2;
    b3 = t1 + t3;
    t0 -= t2;
    t1 -= t3;
    b1 = ((t0 + t1) >> 8) * 181;
    b2 = ((t0 - t1) >> 8) * 181;

    block[0] = (a0 + b0) >> 12;
    block[1] = (a1 + b1) >> 12;
    block[2] = (a2 + b2) >> 12;
    block[3] = (a3 + b3) >> 12;
    block[4] = (a3 - b3) >> 12;
    block[5] = (a2 - b2) >> 12;
    block[6] = (a1 - b1) >> 12;
    block[7] = (a0 - b0) >> 12;
}

static inline void idct_col (int16_t * const block)
{
    int d0, d1, d2, d3;
    int a0, a1, a2, a3, b0, b1, b2, b3;
    int t0, t1, t2, t3;

    d0 = (block[8*0] << 11) + 65536;
    d1 = block[8*1];
    d2 = block[8*2] << 11;
    d3 = block[8*3];
    t0 = d0 + d2;
    t1 = d0 - d2;
    BUTTERFLY (t2, t3, W6, W2, d3, d1);
    a0 = t0 + t2;
    a1 = t1 + t3;
    a2 = t1 - t3;
    a3 = t0 - t2;

    d0 = block[8*4];
    d1 = block[8*5];
    d2 = block[8*6];
    d3 = block[8*7];
    BUTTERFLY (t0, t1, W7, W1, d3, d0);
    BUTTERFLY (t2, t3, W3, W5, d1, d2);
    b0 = t0 + t2;
    b3 = t1 + t3;
    t0 -= t2;
    t1 -= t3;
    b1 = ((t0 + t1) >> 8) * 181;
    b2 = ((t0 - t1) >> 8) * 181;

    block[8*0] = (a0 + b0) >> 17;
    block[8*1] = (a1 + b1) >> 17;
    block[8*2] = (a2 + b2) >> 17;
    block[8*3] = (a3 + b3) >> 17;
    block[8*4] = (a3 - b3) >> 17;
    block[8*5] = (a2 - b2) >> 17;
    block[8*6] = (a1 - b1) >> 17;
    block[8*7] = (a0 - b0) >> 17;
}

static void mpeg2_idct_copy_c (int16_t * block, uint8_t * dest,
                               const int stride)
{
    int i;

    for (i = 0; i < 8; i++)
        idct_row (block + 8 * i);
    for (i = 0; i < 8; i++)
        idct_col (block + i);
    do {
        dest[0] = CLIP (block[0]);
        dest[1] = CLIP (block[1]);
        dest[2] = CLIP (block[2]);
        dest[3] = CLIP (block[3]);
        dest[4] = CLIP (block[4]);
        dest[5] = CLIP (block[5]);
        dest[6] = CLIP (block[6]);
        dest[7] = CLIP (block[7]);

        ((int32_t *)block)[0] = 0;        ((int32_t *)block)[1] = 0;
        ((int32_t *)block)[2] = 0;        ((int32_t *)block)[3] = 0;

        dest += stride;
        block += 8;
    } while (--i);
}

static void mpeg2_idct_add_c (const int last, int16_t * block,
                              uint8_t * dest, const int stride)
{
    int i;

    if (last != 129 || (block[0] & (7 << 4)) == (4 << 4)) {
        for (i = 0; i < 8; i++)
            idct_row (block + 8 * i);
        for (i = 0; i < 8; i++)
            idct_col (block + i);
        do {
            dest[0] = CLIP (block[0] + dest[0]);
            dest[1] = CLIP (block[1] + dest[1]);
            dest[2] = CLIP (block[2] + dest[2]);
            dest[3] = CLIP (block[3] + dest[3]);
            dest[4] = CLIP (block[4] + dest[4]);
            dest[5] = CLIP (block[5] + dest[5]);
            dest[6] = CLIP (block[6] + dest[6]);
            dest[7] = CLIP (block[7] + dest[7]);

            ((int32_t *)block)[0] = 0;        ((int32_t *)block)[1] = 0;
            ((int32_t *)block)[2] = 0;        ((int32_t *)block)[3] = 0;

            dest += stride;
            block += 8;
        } while (--i);
    } else {
        int DC;

        DC = (block[0] + 64) >> 7;
        block[0] = block[63] = 0;
        i = 8;
        do {
            dest[0] = CLIP (DC + dest[0]);
            dest[1] = CLIP (DC + dest[1]);
            dest[2] = CLIP (DC + dest[2]);
            dest[3] = CLIP (DC + dest[3]);
            dest[4] = CLIP (DC + dest[4]);
            dest[5] = CLIP (DC + dest[5]);
            dest[6] = CLIP (DC + dest[6]);
            dest[7] = CLIP (DC + dest[7]);
            dest += stride;
        } while (--i);
    }
}

void mpeg2_idct_init (void)
{
    extern uint8_t default_mpeg2_scan_norm[64];
    extern uint8_t default_mpeg2_scan_alt[64];
    extern uint8_t mpeg2_scan_norm[64];
    extern uint8_t mpeg2_scan_alt[64];
    int i, j;

    mpeg2_idct_copy = mpeg2_idct_copy_c;
    mpeg2_idct_add = mpeg2_idct_add_c;

#if !defined(CPU_COLDFIRE) && !defined(CPU_ARM)
    for (i = -3840; i < 3840 + 256; i++)
        CLIP(i) = (i < 0) ? 0 : ((i > 255) ? 255 : i);
#endif

    for (i = 0; i < 64; i++)
    {
        j = default_mpeg2_scan_norm[i];
        mpeg2_scan_norm[i] = ((j & 0x36) >> 1) | ((j & 0x09) << 2);

        j = default_mpeg2_scan_alt[i];
        mpeg2_scan_alt[i] = ((j & 0x36) >> 1) | ((j & 0x09) << 2);
    }
}