sdl2_frt/src/render/SDL_yuv_sw.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2017 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "../SDL_internal.h"

/* This is the software implementation of the YUV texture support */

/* This code was derived from code carrying the following copyright notices:

 * Copyright (c) 1995 The Regents of the University of California.
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement is
 * hereby granted, provided that the above copyright notice and the following
 * two paragraphs appear in all copies of this software.
 *
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 * Copyright (c) 1995 Erik Corry
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement is
 * hereby granted, provided that the above copyright notice and the following
 * two paragraphs appear in all copies of this software.
 *
 * IN NO EVENT SHALL ERIK CORRY BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
 * SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF
 * THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF ERIK CORRY HAS BEEN ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * ERIK CORRY SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
 * BASIS, AND ERIK CORRY HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT,
 * UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 * Portions of this software Copyright (c) 1995 Brown University.
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement
 * is hereby granted, provided that the above copyright notice and the
 * following two paragraphs appear in all copies of this software.
 *
 * IN NO EVENT SHALL BROWN UNIVERSITY BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF BROWN
 * UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * BROWN UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
 * BASIS, AND BROWN UNIVERSITY HAS NO OBLIGATION TO PROVIDE MAINTENANCE,
 * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

#include "SDL_assert.h"
#include "SDL_video.h"
#include "SDL_cpuinfo.h"
#include "SDL_yuv_sw_c.h"
#include "SDL_yuv_mmx_c.h"


/* The colorspace conversion functions */

#ifdef USE_MMX_ASSEMBLY
extern void Color565DitherYV12MMX1X(int *colortab, Uint32 * rgb_2_pix,
                                    unsigned char *lum, unsigned char *cr,
                                    unsigned char *cb, unsigned char *out,
                                    int rows, int cols, int mod);
extern void ColorRGBDitherYV12MMX1X(int *colortab, Uint32 * rgb_2_pix,
                                    unsigned char *lum, unsigned char *cr,
                                    unsigned char *cb, unsigned char *out,
                                    int rows, int cols, int mod);
#endif

static void
Color16DitherYV12Mod1X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned short *row1;
    unsigned short *row2;
    unsigned char *lum2;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;

    row1 = (unsigned short *) out;
    row2 = row1 + cols + mod;
    lum2 = lum + cols;

    mod += cols + mod;

    y = rows / 2;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            ++cr;
            ++cb;

            L = *lum++;
            *row1++ = (unsigned short) (rgb_2_pix[L + cr_r] |
                                        rgb_2_pix[L + crb_g] |
                                        rgb_2_pix[L + cb_b]);

            L = *lum++;
            *row1++ = (unsigned short) (rgb_2_pix[L + cr_r] |
                                        rgb_2_pix[L + crb_g] |
                                        rgb_2_pix[L + cb_b]);


            /* Now, do second row.  */

            L = *lum2++;
            *row2++ = (unsigned short) (rgb_2_pix[L + cr_r] |
                                        rgb_2_pix[L + crb_g] |
                                        rgb_2_pix[L + cb_b]);

            L = *lum2++;
            *row2++ = (unsigned short) (rgb_2_pix[L + cr_r] |
                                        rgb_2_pix[L + crb_g] |
                                        rgb_2_pix[L + cb_b]);
        }

        /*
         * These values are at the start of the next line, (due
         * to the ++'s above),but they need to be at the start
         * of the line after that.
         */
        lum += cols;
        lum2 += cols;
        row1 += mod;
        row2 += mod;
    }
}

static void
Color24DitherYV12Mod1X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int value;
    unsigned char *row1;
    unsigned char *row2;
    unsigned char *lum2;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;

    row1 = out;
    row2 = row1 + cols * 3 + mod * 3;
    lum2 = lum + cols;

    mod += cols + mod;
    mod *= 3;

    y = rows / 2;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            ++cr;
            ++cb;

            L = *lum++;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            *row1++ = (value) & 0xFF;
            *row1++ = (value >> 8) & 0xFF;
            *row1++ = (value >> 16) & 0xFF;

            L = *lum++;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            *row1++ = (value) & 0xFF;
            *row1++ = (value >> 8) & 0xFF;
            *row1++ = (value >> 16) & 0xFF;


            /* Now, do second row.  */

            L = *lum2++;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            *row2++ = (value) & 0xFF;
            *row2++ = (value >> 8) & 0xFF;
            *row2++ = (value >> 16) & 0xFF;

            L = *lum2++;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            *row2++ = (value) & 0xFF;
            *row2++ = (value >> 8) & 0xFF;
            *row2++ = (value >> 16) & 0xFF;
        }

        /*
         * These values are at the start of the next line, (due
         * to the ++'s above),but they need to be at the start
         * of the line after that.
         */
        lum += cols;
        lum2 += cols;
        row1 += mod;
        row2 += mod;
    }
}

static void
Color32DitherYV12Mod1X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int *row1;
    unsigned int *row2;
    unsigned char *lum2;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = (cols + 1) / 2;
    /* not even dimensions */
    int skip_last_col = 0;
    int skip_last_row = 0;

    if ( (cols & 0x1) ) {
        skip_last_col = 1;
    }

    if ( (rows & 0x1) ) {
        skip_last_row = 1;
    }

    row1 = (unsigned int *) out;
    row2 = row1 + cols + mod;
    lum2 = lum + cols;

    mod += cols + mod;

    y = (rows + 1) / 2;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            ++cr;
            ++cb;

            L = *lum++;
            *row1++ = (rgb_2_pix[L + cr_r] |
                       rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);

            if (!(x == 0 && skip_last_col)) {
            L = *lum++;
            *row1++ = (rgb_2_pix[L + cr_r] |
                       rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            } /* skip col */


            if (!(y == 0 && skip_last_row)) {

            /* Now, do second row.  */

            L = *lum2++;
            *row2++ = (rgb_2_pix[L + cr_r] |
                       rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);

            if (!(x == 1 && skip_last_col)) {
            L = *lum2++;
            *row2++ = (rgb_2_pix[L + cr_r] |
                       rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            } /* skip col */
            } /* skip row */
        }

        /*
         * These values are at the start of the next line, (due
         * to the ++'s above),but they need to be at the start
         * of the line after that.
         */
        lum += cols;
        lum2 += cols;
        row1 += mod;
        row2 += mod;
    }
}

/*
 * In this function I make use of a nasty trick. The tables have the lower
 * 16 bits replicated in the upper 16. This means I can write ints and get
 * the horisontal doubling for free (almost).
 */
static void
Color16DitherYV12Mod2X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int *row1 = (unsigned int *) out;
    const int next_row = cols + (mod / 2);
    unsigned int *row2 = row1 + 2 * next_row;
    unsigned char *lum2;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;

    lum2 = lum + cols;

    mod = (next_row * 3) + (mod / 2);

    y = rows / 2;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            ++cr;
            ++cb;

            L = *lum++;
            row1[0] = row1[next_row] = (rgb_2_pix[L + cr_r] |
                                        rgb_2_pix[L + crb_g] |
                                        rgb_2_pix[L + cb_b]);
            row1++;

            L = *lum++;
            row1[0] = row1[next_row] = (rgb_2_pix[L + cr_r] |
                                        rgb_2_pix[L + crb_g] |
                                        rgb_2_pix[L + cb_b]);
            row1++;


            /* Now, do second row. */

            L = *lum2++;
            row2[0] = row2[next_row] = (rgb_2_pix[L + cr_r] |
                                        rgb_2_pix[L + crb_g] |
                                        rgb_2_pix[L + cb_b]);
            row2++;

            L = *lum2++;
            row2[0] = row2[next_row] = (rgb_2_pix[L + cr_r] |
                                        rgb_2_pix[L + crb_g] |
                                        rgb_2_pix[L + cb_b]);
            row2++;
        }

        /*
         * These values are at the start of the next line, (due
         * to the ++'s above),but they need to be at the start
         * of the line after that.
         */
        lum += cols;
        lum2 += cols;
        row1 += mod;
        row2 += mod;
    }
}

static void
Color24DitherYV12Mod2X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int value;
    unsigned char *row1 = out;
    const int next_row = (cols * 2 + mod) * 3;
    unsigned char *row2 = row1 + 2 * next_row;
    unsigned char *lum2;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;

    lum2 = lum + cols;

    mod = next_row * 3 + mod * 3;

    y = rows / 2;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            ++cr;
            ++cb;

            L = *lum++;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row1[0 + 0] = row1[3 + 0] = row1[next_row + 0] =
                row1[next_row + 3 + 0] = (value) & 0xFF;
            row1[0 + 1] = row1[3 + 1] = row1[next_row + 1] =
                row1[next_row + 3 + 1] = (value >> 8) & 0xFF;
            row1[0 + 2] = row1[3 + 2] = row1[next_row + 2] =
                row1[next_row + 3 + 2] = (value >> 16) & 0xFF;
            row1 += 2 * 3;

            L = *lum++;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row1[0 + 0] = row1[3 + 0] = row1[next_row + 0] =
                row1[next_row + 3 + 0] = (value) & 0xFF;
            row1[0 + 1] = row1[3 + 1] = row1[next_row + 1] =
                row1[next_row + 3 + 1] = (value >> 8) & 0xFF;
            row1[0 + 2] = row1[3 + 2] = row1[next_row + 2] =
                row1[next_row + 3 + 2] = (value >> 16) & 0xFF;
            row1 += 2 * 3;


            /* Now, do second row. */

            L = *lum2++;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row2[0 + 0] = row2[3 + 0] = row2[next_row + 0] =
                row2[next_row + 3 + 0] = (value) & 0xFF;
            row2[0 + 1] = row2[3 + 1] = row2[next_row + 1] =
                row2[next_row + 3 + 1] = (value >> 8) & 0xFF;
            row2[0 + 2] = row2[3 + 2] = row2[next_row + 2] =
                row2[next_row + 3 + 2] = (value >> 16) & 0xFF;
            row2 += 2 * 3;

            L = *lum2++;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row2[0 + 0] = row2[3 + 0] = row2[next_row + 0] =
                row2[next_row + 3 + 0] = (value) & 0xFF;
            row2[0 + 1] = row2[3 + 1] = row2[next_row + 1] =
                row2[next_row + 3 + 1] = (value >> 8) & 0xFF;
            row2[0 + 2] = row2[3 + 2] = row2[next_row + 2] =
                row2[next_row + 3 + 2] = (value >> 16) & 0xFF;
            row2 += 2 * 3;
        }

        /*
         * These values are at the start of the next line, (due
         * to the ++'s above),but they need to be at the start
         * of the line after that.
         */
        lum += cols;
        lum2 += cols;
        row1 += mod;
        row2 += mod;
    }
}

static void
Color32DitherYV12Mod2X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int *row1 = (unsigned int *) out;
    const int next_row = cols * 2 + mod;
    unsigned int *row2 = row1 + 2 * next_row;
    unsigned char *lum2;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;

    lum2 = lum + cols;

    mod = (next_row * 3) + mod;

    y = rows / 2;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            ++cr;
            ++cb;

            L = *lum++;
            row1[0] = row1[1] = row1[next_row] = row1[next_row + 1] =
                (rgb_2_pix[L + cr_r] |
                 rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row1 += 2;

            L = *lum++;
            row1[0] = row1[1] = row1[next_row] = row1[next_row + 1] =
                (rgb_2_pix[L + cr_r] |
                 rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row1 += 2;


            /* Now, do second row. */

            L = *lum2++;
            row2[0] = row2[1] = row2[next_row] = row2[next_row + 1] =
                (rgb_2_pix[L + cr_r] |
                 rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row2 += 2;

            L = *lum2++;
            row2[0] = row2[1] = row2[next_row] = row2[next_row + 1] =
                (rgb_2_pix[L + cr_r] |
                 rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row2 += 2;
        }

        /*
         * These values are at the start of the next line, (due
         * to the ++'s above),but they need to be at the start
         * of the line after that.
         */
        lum += cols;
        lum2 += cols;
        row1 += mod;
        row2 += mod;
    }
}

static void
Color16DitherYUY2Mod1X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned short *row;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;

    row = (unsigned short *) out;

    y = rows;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            cr += 4;
            cb += 4;

            L = *lum;
            lum += 2;
            *row++ = (unsigned short) (rgb_2_pix[L + cr_r] |
                                       rgb_2_pix[L + crb_g] |
                                       rgb_2_pix[L + cb_b]);

            L = *lum;
            lum += 2;
            *row++ = (unsigned short) (rgb_2_pix[L + cr_r] |
                                       rgb_2_pix[L + crb_g] |
                                       rgb_2_pix[L + cb_b]);

        }

        row += mod;
    }
}

static void
Color24DitherYUY2Mod1X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int value;
    unsigned char *row;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;

    row = (unsigned char *) out;
    mod *= 3;
    y = rows;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            cr += 4;
            cb += 4;

            L = *lum;
            lum += 2;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            *row++ = (value) & 0xFF;
            *row++ = (value >> 8) & 0xFF;
            *row++ = (value >> 16) & 0xFF;

            L = *lum;
            lum += 2;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            *row++ = (value) & 0xFF;
            *row++ = (value >> 8) & 0xFF;
            *row++ = (value >> 16) & 0xFF;

        }
        row += mod;
    }
}

static void
Color32DitherYUY2Mod1X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int *row;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = (cols + 1) / 2;
    /* not even dimensions */
    int skip_last_col = 0;
    if ( (cols & 0x1) ) {
        skip_last_col = 1;
    }

    row = (unsigned int *) out;
    y = rows;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            cr += 4;
            cb += 4;

            L = *lum;
            lum += 2;
            *row++ = (rgb_2_pix[L + cr_r] |
                      rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);

            L = *lum;
            lum += 2;

            if (!(x == 0 && skip_last_col)) {
            *row++ = (rgb_2_pix[L + cr_r] |
                      rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            } /* skip col */

        }
        row += mod;
    }
}

/*
 * In this function I make use of a nasty trick. The tables have the lower
 * 16 bits replicated in the upper 16. This means I can write ints and get
 * the horisontal doubling for free (almost).
 */
static void
Color16DitherYUY2Mod2X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int *row = (unsigned int *) out;
    const int next_row = cols + (mod / 2);
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;

    y = rows;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            cr += 4;
            cb += 4;

            L = *lum;
            lum += 2;
            row[0] = row[next_row] = (rgb_2_pix[L + cr_r] |
                                      rgb_2_pix[L + crb_g] |
                                      rgb_2_pix[L + cb_b]);
            row++;

            L = *lum;
            lum += 2;
            row[0] = row[next_row] = (rgb_2_pix[L + cr_r] |
                                      rgb_2_pix[L + crb_g] |
                                      rgb_2_pix[L + cb_b]);
            row++;

        }
        row += next_row;
    }
}

static void
Color24DitherYUY2Mod2X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int value;
    unsigned char *row = out;
    const int next_row = (cols * 2 + mod) * 3;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;
    y = rows;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            cr += 4;
            cb += 4;

            L = *lum;
            lum += 2;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row[0 + 0] = row[3 + 0] = row[next_row + 0] =
                row[next_row + 3 + 0] = (value) & 0xFF;
            row[0 + 1] = row[3 + 1] = row[next_row + 1] =
                row[next_row + 3 + 1] = (value >> 8) & 0xFF;
            row[0 + 2] = row[3 + 2] = row[next_row + 2] =
                row[next_row + 3 + 2] = (value >> 16) & 0xFF;
            row += 2 * 3;

            L = *lum;
            lum += 2;
            value = (rgb_2_pix[L + cr_r] |
                     rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row[0 + 0] = row[3 + 0] = row[next_row + 0] =
                row[next_row + 3 + 0] = (value) & 0xFF;
            row[0 + 1] = row[3 + 1] = row[next_row + 1] =
                row[next_row + 3 + 1] = (value >> 8) & 0xFF;
            row[0 + 2] = row[3 + 2] = row[next_row + 2] =
                row[next_row + 3 + 2] = (value >> 16) & 0xFF;
            row += 2 * 3;

        }
        row += next_row;
    }
}

static void
Color32DitherYUY2Mod2X(int *colortab, Uint32 * rgb_2_pix,
                       unsigned char *lum, unsigned char *cr,
                       unsigned char *cb, unsigned char *out,
                       int rows, int cols, int mod)
{
    unsigned int *row = (unsigned int *) out;
    const int next_row = cols * 2 + mod;
    int x, y;
    int cr_r;
    int crb_g;
    int cb_b;
    int cols_2 = cols / 2;
    mod += mod;
    y = rows;
    while (y--) {
        x = cols_2;
        while (x--) {
            register int L;

            cr_r = 0 * 768 + 256 + colortab[*cr + 0 * 256];
            crb_g = 1 * 768 + 256 + colortab[*cr + 1 * 256]
                + colortab[*cb + 2 * 256];
            cb_b = 2 * 768 + 256 + colortab[*cb + 3 * 256];
            cr += 4;
            cb += 4;

            L = *lum;
            lum += 2;
            row[0] = row[1] = row[next_row] = row[next_row + 1] =
                (rgb_2_pix[L + cr_r] |
                 rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row += 2;

            L = *lum;
            lum += 2;
            row[0] = row[1] = row[next_row] = row[next_row + 1] =
                (rgb_2_pix[L + cr_r] |
                 rgb_2_pix[L + crb_g] | rgb_2_pix[L + cb_b]);
            row += 2;


        }

        row += next_row;
    }
}

/*
 * How many 1 bits are there in the Uint32.
 * Low performance, do not call often.
 */
static int
number_of_bits_set(Uint32 a)
{
    if (!a)
        return 0;
    if (a & 1)
        return 1 + number_of_bits_set(a >> 1);
    return (number_of_bits_set(a >> 1));
}

/*
 * How many 0 bits are there at least significant end of Uint32.
 * Low performance, do not call often.
 */
static int
free_bits_at_bottom_nonzero(Uint32 a)
{
    SDL_assert(a != 0);
    return (((Sint32) a) & 1l) ? 0 : 1 + free_bits_at_bottom_nonzero(a >> 1);
}

static SDL_INLINE int
free_bits_at_bottom(Uint32 a)
{
    return a ? free_bits_at_bottom_nonzero(a) : 32;
}

static int
SDL_SW_SetupYUVDisplay(SDL_SW_YUVTexture * swdata, Uint32 target_format)
{
    Uint32 *r_2_pix_alloc;
    Uint32 *g_2_pix_alloc;
    Uint32 *b_2_pix_alloc;
    int i;
    int bpp;
    Uint32 Rmask, Gmask, Bmask, Amask;
    int freebits;

    if (!SDL_PixelFormatEnumToMasks
        (target_format, &bpp, &Rmask, &Gmask, &Bmask, &Amask) || bpp < 15) {
        return SDL_SetError("Unsupported YUV destination format");
    }

    swdata->target_format = target_format;
    r_2_pix_alloc = &swdata->rgb_2_pix[0 * 768];
    g_2_pix_alloc = &swdata->rgb_2_pix[1 * 768];
    b_2_pix_alloc = &swdata->rgb_2_pix[2 * 768];

    /*
     * Set up entries 0-255 in rgb-to-pixel value tables.
     */
    for (i = 0; i < 256; ++i) {
        r_2_pix_alloc[i + 256] = i >> (8 - number_of_bits_set(Rmask));
        freebits = free_bits_at_bottom(Rmask);
        if (freebits < 32) {
            r_2_pix_alloc[i + 256] <<= freebits;
        }
        r_2_pix_alloc[i + 256] |= Amask;

        g_2_pix_alloc[i + 256] = i >> (8 - number_of_bits_set(Gmask));
        freebits = free_bits_at_bottom(Gmask);
        if (freebits < 32) {
            g_2_pix_alloc[i + 256] <<= freebits;
        }
        g_2_pix_alloc[i + 256] |= Amask;

        b_2_pix_alloc[i + 256] = i >> (8 - number_of_bits_set(Bmask));
        freebits = free_bits_at_bottom(Bmask);
        if (freebits < 32) {
            b_2_pix_alloc[i + 256] <<= freebits;
        }
        b_2_pix_alloc[i + 256] |= Amask;
    }

    /*
     * If we have 16-bit output depth, then we double the value
     * in the top word. This means that we can write out both
     * pixels in the pixel doubling mode with one op. It is
     * harmless in the normal case as storing a 32-bit value
     * through a short pointer will lose the top bits anyway.
     */
    if (SDL_BYTESPERPIXEL(target_format) == 2) {
        for (i = 0; i < 256; ++i) {
            r_2_pix_alloc[i + 256] |= (r_2_pix_alloc[i + 256]) << 16;
            g_2_pix_alloc[i + 256] |= (g_2_pix_alloc[i + 256]) << 16;
            b_2_pix_alloc[i + 256] |= (b_2_pix_alloc[i + 256]) << 16;
        }
    }

    /*
     * Spread out the values we have to the rest of the array so that
     * we do not need to check for overflow.
     */
    for (i = 0; i < 256; ++i) {
        r_2_pix_alloc[i] = r_2_pix_alloc[256];
        r_2_pix_alloc[i + 512] = r_2_pix_alloc[511];
        g_2_pix_alloc[i] = g_2_pix_alloc[256];
        g_2_pix_alloc[i + 512] = g_2_pix_alloc[511];
        b_2_pix_alloc[i] = b_2_pix_alloc[256];
        b_2_pix_alloc[i + 512] = b_2_pix_alloc[511];
    }

    /* You have chosen wisely... */
    switch (swdata->format) {
    case SDL_PIXELFORMAT_YV12:
    case SDL_PIXELFORMAT_IYUV:
        if (SDL_BYTESPERPIXEL(target_format) == 2) {
#ifdef USE_MMX_ASSEMBLY
            /* inline assembly functions */
            if (SDL_HasMMX() && (Rmask == 0xF800) &&
                (Gmask == 0x07E0) && (Bmask == 0x001F)
                && (swdata->w & 15) == 0) {
/* printf("Using MMX 16-bit 565 dither\n"); */
                swdata->Display1X = Color565DitherYV12MMX1X;
            } else {
/* printf("Using C 16-bit dither\n"); */
                swdata->Display1X = Color16DitherYV12Mod1X;
            }
#else
            swdata->Display1X = Color16DitherYV12Mod1X;
#endif
            swdata->Display2X = Color16DitherYV12Mod2X;
        }
        if (SDL_BYTESPERPIXEL(target_format) == 3) {
            swdata->Display1X = Color24DitherYV12Mod1X;
            swdata->Display2X = Color24DitherYV12Mod2X;
        }
        if (SDL_BYTESPERPIXEL(target_format) == 4) {
#ifdef USE_MMX_ASSEMBLY
            /* inline assembly functions */
            if (SDL_HasMMX() && (Rmask == 0x00FF0000) &&
                (Gmask == 0x0000FF00) &&
                (Bmask == 0x000000FF) && (swdata->w & 15) == 0) {
/* printf("Using MMX 32-bit dither\n"); */
                swdata->Display1X = ColorRGBDitherYV12MMX1X;
            } else {
/* printf("Using C 32-bit dither\n"); */
                swdata->Display1X = Color32DitherYV12Mod1X;
            }
#else
            swdata->Display1X = Color32DitherYV12Mod1X;
#endif
            swdata->Display2X = Color32DitherYV12Mod2X;
        }
        break;
    case SDL_PIXELFORMAT_YUY2:
    case SDL_PIXELFORMAT_UYVY:
    case SDL_PIXELFORMAT_YVYU:
        if (SDL_BYTESPERPIXEL(target_format) == 2) {
            swdata->Display1X = Color16DitherYUY2Mod1X;
            swdata->Display2X = Color16DitherYUY2Mod2X;
        }
        if (SDL_BYTESPERPIXEL(target_format) == 3) {
            swdata->Display1X = Color24DitherYUY2Mod1X;
            swdata->Display2X = Color24DitherYUY2Mod2X;
        }
        if (SDL_BYTESPERPIXEL(target_format) == 4) {
            swdata->Display1X = Color32DitherYUY2Mod1X;
            swdata->Display2X = Color32DitherYUY2Mod2X;
        }
        break;
    case SDL_PIXELFORMAT_NV21:
    case SDL_PIXELFORMAT_NV12:
        /* no Display{1,2}X function */
        swdata->Display1X = NULL;
        swdata->Display2X = NULL;
        break;

    default:
        /* We should never get here (caught above) */
        break;
    }

    SDL_FreeSurface(swdata->display);
    swdata->display = NULL;
    return 0;
}

SDL_SW_YUVTexture *
SDL_SW_CreateYUVTexture(Uint32 format, int w, int h)
{
    SDL_SW_YUVTexture *swdata;
    int *Cr_r_tab;
    int *Cr_g_tab;
    int *Cb_g_tab;
    int *Cb_b_tab;
    int i;
    int CR, CB;

    switch (format) {
    case SDL_PIXELFORMAT_YV12:
    case SDL_PIXELFORMAT_IYUV:
    case SDL_PIXELFORMAT_YUY2:
    case SDL_PIXELFORMAT_UYVY:
    case SDL_PIXELFORMAT_YVYU:
    case SDL_PIXELFORMAT_NV12:
    case SDL_PIXELFORMAT_NV21:
        break;
    default:
        SDL_SetError("Unsupported YUV format");
        return NULL;
    }

    swdata = (SDL_SW_YUVTexture *) SDL_calloc(1, sizeof(*swdata));
    if (!swdata) {
        SDL_OutOfMemory();
        return NULL;
    }

    swdata->format = format;
    swdata->target_format = SDL_PIXELFORMAT_UNKNOWN;
    swdata->w = w;
    swdata->h = h;
    {
        const int sz_plane         = w * h;
        const int sz_plane_chroma  = ((w + 1) / 2) * ((h + 1) / 2);
        const int sz_plane_packed  = ((w + 1) / 2) * h;
        int dst_size = 0;     
        switch(format) 
        {
            case SDL_PIXELFORMAT_YV12: /**< Planar mode: Y + V + U  (3 planes) */
            case SDL_PIXELFORMAT_IYUV: /**< Planar mode: Y + U + V  (3 planes) */
                dst_size = sz_plane + sz_plane_chroma + sz_plane_chroma;
                break;

            case SDL_PIXELFORMAT_YUY2: /**< Packed mode: Y0+U0+Y1+V0 (1 plane) */
            case SDL_PIXELFORMAT_UYVY: /**< Packed mode: U0+Y0+V0+Y1 (1 plane) */
            case SDL_PIXELFORMAT_YVYU: /**< Packed mode: Y0+V0+Y1+U0 (1 plane) */
                dst_size = 4 * sz_plane_packed;
                break;

            case SDL_PIXELFORMAT_NV12: /**< Planar mode: Y + U/V interleaved  (2 planes) */
            case SDL_PIXELFORMAT_NV21: /**< Planar mode: Y + V/U interleaved  (2 planes) */
                dst_size = sz_plane + sz_plane_chroma + sz_plane_chroma;
                break;

            default:
                SDL_assert(0 && "We should never get here (caught above)");
                break;
        }
        swdata->pixels = (Uint8 *) SDL_malloc(dst_size);
    }
    swdata->colortab = (int *) SDL_malloc(4 * 256 * sizeof(int));
    swdata->rgb_2_pix = (Uint32 *) SDL_malloc(3 * 768 * sizeof(Uint32));
    if (!swdata->pixels || !swdata->colortab || !swdata->rgb_2_pix) {
        SDL_SW_DestroyYUVTexture(swdata);
        SDL_OutOfMemory();
        return NULL;
    }

    /* Generate the tables for the display surface */
    Cr_r_tab = &swdata->colortab[0 * 256];
    Cr_g_tab = &swdata->colortab[1 * 256];
    Cb_g_tab = &swdata->colortab[2 * 256];
    Cb_b_tab = &swdata->colortab[3 * 256];
    for (i = 0; i < 256; i++) {
        /* Gamma correction (luminescence table) and chroma correction
           would be done here.  See the Berkeley mpeg_play sources.
         */
        CB = CR = (i - 128);
        Cr_r_tab[i] = (int) ((0.419 / 0.299) * CR);
        Cr_g_tab[i] = (int) (-(0.299 / 0.419) * CR);
        Cb_g_tab[i] = (int) (-(0.114 / 0.331) * CB);
        Cb_b_tab[i] = (int) ((0.587 / 0.331) * CB);
    }

    /* Find the pitch and offset values for the overlay */
    switch (format) {
    case SDL_PIXELFORMAT_YV12:
    case SDL_PIXELFORMAT_IYUV:
        swdata->pitches[0] = w;
        swdata->pitches[1] = (swdata->pitches[0] + 1) / 2;
        swdata->pitches[2] = (swdata->pitches[0] + 1) / 2;
        swdata->planes[0] = swdata->pixels;
        swdata->planes[1] = swdata->planes[0] + swdata->pitches[0] * h;
        swdata->planes[2] = swdata->planes[1] + swdata->pitches[1] * ((h + 1) / 2);
        break;
    case SDL_PIXELFORMAT_YUY2:
    case SDL_PIXELFORMAT_UYVY:
    case SDL_PIXELFORMAT_YVYU:
        swdata->pitches[0] = ((w + 1) / 2) * 4;
        swdata->planes[0] = swdata->pixels;
        break;

    case SDL_PIXELFORMAT_NV12:
    case SDL_PIXELFORMAT_NV21:
        swdata->pitches[0] = w;
        swdata->pitches[1] = 2 * ((swdata->pitches[0] + 1) / 2);
        swdata->planes[0] = swdata->pixels;
        swdata->planes[1] = swdata->planes[0] + swdata->pitches[0] * h;
        break;

    default:
        SDL_assert(0 && "We should never get here (caught above)");
        break;
    }

    /* We're all done.. */
    return (swdata);
}

int
SDL_SW_QueryYUVTexturePixels(SDL_SW_YUVTexture * swdata, void **pixels,
                             int *pitch)
{
    *pixels = swdata->planes[0];
    *pitch = swdata->pitches[0];
    return 0;
}

int
SDL_SW_UpdateYUVTexture(SDL_SW_YUVTexture * swdata, const SDL_Rect * rect,
                        const void *pixels, int pitch)
{
    switch (swdata->format) {
    case SDL_PIXELFORMAT_YV12:
    case SDL_PIXELFORMAT_IYUV:
        if (rect->x == 0 && rect->y == 0 &&
            rect->w == swdata->w && rect->h == swdata->h) {
                SDL_memcpy(swdata->pixels, pixels,
                           (swdata->h * swdata->w) + 2* ((swdata->h + 1) /2) * ((swdata->w + 1) / 2));
        } else {
            Uint8 *src, *dst;
            int row;
            size_t length;

            /* Copy the Y plane */
            src = (Uint8 *) pixels;
            dst = swdata->pixels + rect->y * swdata->w + rect->x;
            length = rect->w;
            for (row = 0; row < rect->h; ++row) {
                SDL_memcpy(dst, src, length);
                src += pitch;
                dst += swdata->w;
            }
            
            /* Copy the next plane */
            src = (Uint8 *) pixels + rect->h * pitch;
            dst = swdata->pixels + swdata->h * swdata->w;
            dst += rect->y/2 * ((swdata->w + 1) / 2) + rect->x/2;
            length = (rect->w + 1) / 2;
            for (row = 0; row < (rect->h + 1)/2; ++row) {
                SDL_memcpy(dst, src, length);
                src += (pitch + 1)/2;
                dst += (swdata->w + 1)/2;
            }

            /* Copy the next plane */
            src = (Uint8 *) pixels + rect->h * pitch + ((rect->h + 1) / 2) * ((pitch + 1) / 2);
            dst = swdata->pixels + swdata->h * swdata->w +
                  ((swdata->h + 1)/2) * ((swdata->w+1) / 2);
            dst += rect->y/2 * ((swdata->w + 1)/2) + rect->x/2;
            length = (rect->w + 1) / 2;
            for (row = 0; row < (rect->h + 1)/2; ++row) {
                SDL_memcpy(dst, src, length);
                src += (pitch + 1)/2;
                dst += (swdata->w + 1)/2;
            }
        }
        break;
    case SDL_PIXELFORMAT_YUY2:
    case SDL_PIXELFORMAT_UYVY:
    case SDL_PIXELFORMAT_YVYU:
        {
            Uint8 *src, *dst;
            int row;
            size_t length;

            src = (Uint8 *) pixels;
            dst =
                swdata->planes[0] + rect->y * swdata->pitches[0] +
                rect->x * 2;
            length = 4 * ((rect->w + 1) / 2);
            for (row = 0; row < rect->h; ++row) {
                SDL_memcpy(dst, src, length);
                src += pitch;
                dst += swdata->pitches[0];
            }
        }
        break;
    case SDL_PIXELFORMAT_NV12:
    case SDL_PIXELFORMAT_NV21:
        {
            if (rect->x == 0 && rect->y == 0 && rect->w == swdata->w && rect->h == swdata->h) {
                SDL_memcpy(swdata->pixels, pixels,
                        (swdata->h * swdata->w) + 2* ((swdata->h + 1) /2) * ((swdata->w + 1) / 2));
            } else {

                Uint8 *src, *dst;
                int row;
                size_t length;

                /* Copy the Y plane */
                src = (Uint8 *) pixels;
                dst = swdata->pixels + rect->y * swdata->w + rect->x;
                length = rect->w;
                for (row = 0; row < rect->h; ++row) {
                    SDL_memcpy(dst, src, length);
                    src += pitch;
                    dst += swdata->w;
                }
                
                /* Copy the next plane */
                src = (Uint8 *) pixels + rect->h * pitch;
                dst = swdata->pixels + swdata->h * swdata->w;
                dst += 2 * ((rect->y + 1)/2) * ((swdata->w + 1) / 2) + 2 * (rect->x/2);
                length = 2 * ((rect->w + 1) / 2);
                for (row = 0; row < (rect->h + 1)/2; ++row) {
                    SDL_memcpy(dst, src, length);
                    src += 2 * ((pitch + 1)/2);
                    dst += 2 * ((swdata->w + 1)/2);
                }
            }
        }
        break;

    }
    return 0;
}

int
SDL_SW_UpdateYUVTexturePlanar(SDL_SW_YUVTexture * swdata, const SDL_Rect * rect,
                              const Uint8 *Yplane, int Ypitch,
                              const Uint8 *Uplane, int Upitch,
                              const Uint8 *Vplane, int Vpitch)
{
    const Uint8 *src;
    Uint8 *dst;
    int row;
    size_t length;

    /* Copy the Y plane */
    src = Yplane;
    dst = swdata->pixels + rect->y * swdata->w + rect->x;
    length = rect->w;
    for (row = 0; row < rect->h; ++row) {
        SDL_memcpy(dst, src, length);
        src += Ypitch;
        dst += swdata->w;
    }

    /* Copy the U plane */
    src = Uplane;
    if (swdata->format == SDL_PIXELFORMAT_IYUV) {
        dst = swdata->pixels + swdata->h * swdata->w;
    } else {
        dst = swdata->pixels + swdata->h * swdata->w +
              ((swdata->h + 1) / 2) * ((swdata->w + 1) / 2);
    }
    dst += rect->y/2 * ((swdata->w + 1)/2) + rect->x/2;
    length = (rect->w + 1) / 2;
    for (row = 0; row < (rect->h + 1)/2; ++row) {
        SDL_memcpy(dst, src, length);
        src += Upitch;
        dst += (swdata->w + 1)/2;
    }

    /* Copy the V plane */
    src = Vplane;
    if (swdata->format == SDL_PIXELFORMAT_YV12) {
        dst = swdata->pixels + swdata->h * swdata->w;
    } else {
        dst = swdata->pixels + swdata->h * swdata->w +
              ((swdata->h + 1) / 2) * ((swdata->w + 1) / 2);
    }
    dst += rect->y/2 * ((swdata->w + 1)/2) + rect->x/2;
    length = (rect->w + 1) / 2;
    for (row = 0; row < (rect->h + 1)/2; ++row) {
        SDL_memcpy(dst, src, length);
        src += Vpitch;
        dst += (swdata->w + 1)/2;
    }
    return 0;
}

int
SDL_SW_LockYUVTexture(SDL_SW_YUVTexture * swdata, const SDL_Rect * rect,
                      void **pixels, int *pitch)
{
    switch (swdata->format) {
    case SDL_PIXELFORMAT_YV12:
    case SDL_PIXELFORMAT_IYUV:
    case SDL_PIXELFORMAT_NV12:
    case SDL_PIXELFORMAT_NV21:
        if (rect
            && (rect->x != 0 || rect->y != 0 || rect->w != swdata->w
                || rect->h != swdata->h)) {
            return SDL_SetError
                ("YV12, IYUV, NV12, NV21 textures only support full surface locks");
        }
        break;
    }

    if (rect) {
        *pixels = swdata->planes[0] + rect->y * swdata->pitches[0] + rect->x * 2;
    } else {
        *pixels = swdata->planes[0];
    }
    *pitch = swdata->pitches[0];
    return 0;
}

void
SDL_SW_UnlockYUVTexture(SDL_SW_YUVTexture * swdata)
{
}

int
SDL_SW_CopyYUVToRGB(SDL_SW_YUVTexture * swdata, const SDL_Rect * srcrect,
                    Uint32 target_format, int w, int h, void *pixels,
                    int pitch)
{
    const int targetbpp = SDL_BYTESPERPIXEL(target_format);
    int stretch;
    int scale_2x;
    Uint8 *lum, *Cr, *Cb;
    int mod;

    if (targetbpp == 0) {
        return SDL_SetError("Invalid target pixel format");
    }

    /* Make sure we're set up to display in the desired format */
    if (target_format != swdata->target_format) {
        if (SDL_SW_SetupYUVDisplay(swdata, target_format) < 0) {
            return -1;
        }
    }

    stretch = 0;
    scale_2x = 0;
    if (srcrect->x || srcrect->y || srcrect->w < swdata->w
        || srcrect->h < swdata->h) {
        /* The source rectangle has been clipped.
           Using a scratch surface is easier than adding clipped
           source support to all the blitters, plus that would
           slow them down in the general unclipped case.
         */
        stretch = 1;
    } else if ((srcrect->w != w) || (srcrect->h != h)) {
        if ((w == 2 * srcrect->w) && (h == 2 * srcrect->h)) {
            scale_2x = 1;
        } else {
            stretch = 1;
        }
    }
    if (stretch) {
        int bpp;
        Uint32 Rmask, Gmask, Bmask, Amask;

        if (swdata->display) {
            swdata->display->w = w;
            swdata->display->h = h;
            swdata->display->pixels = pixels;
            swdata->display->pitch = pitch;
        } else {
            /* This must have succeeded in SDL_SW_SetupYUVDisplay() earlier */
            SDL_PixelFormatEnumToMasks(target_format, &bpp, &Rmask, &Gmask,
                                       &Bmask, &Amask);
            swdata->display =
                SDL_CreateRGBSurfaceFrom(pixels, w, h, bpp, pitch, Rmask,
                                         Gmask, Bmask, Amask);
            if (!swdata->display) {
                return (-1);
            }
        }
        if (!swdata->stretch) {
            /* This must have succeeded in SDL_SW_SetupYUVDisplay() earlier */
            SDL_PixelFormatEnumToMasks(target_format, &bpp, &Rmask, &Gmask,
                                       &Bmask, &Amask);
            swdata->stretch =
                SDL_CreateRGBSurface(0, swdata->w, swdata->h, bpp, Rmask,
                                     Gmask, Bmask, Amask);
            if (!swdata->stretch) {
                return (-1);
            }
        }
        pixels = swdata->stretch->pixels;
        pitch = swdata->stretch->pitch;
    }
    switch (swdata->format) {
    case SDL_PIXELFORMAT_YV12:
        lum = swdata->planes[0];
        Cr = swdata->planes[1];
        Cb = swdata->planes[2];
        break;
    case SDL_PIXELFORMAT_IYUV:
        lum = swdata->planes[0];
        Cr = swdata->planes[2];
        Cb = swdata->planes[1];
        break;
    case SDL_PIXELFORMAT_YUY2:
        lum = swdata->planes[0];
        Cr = lum + 3;
        Cb = lum + 1;
        break;
    case SDL_PIXELFORMAT_UYVY:
        lum = swdata->planes[0] + 1;
        Cr = lum + 1;
        Cb = lum - 1;
        break;
    case SDL_PIXELFORMAT_YVYU:
        lum = swdata->planes[0];
        Cr = lum + 1;
        Cb = lum + 3;
        break;
    case SDL_PIXELFORMAT_NV12:
    case SDL_PIXELFORMAT_NV21:
        return SDL_ConvertPixels(swdata->w, swdata->h, 
                swdata->format, swdata->planes[0], swdata->pitches[0], 
                target_format, pixels, pitch);
        break;
    default:
        return SDL_SetError("Unsupported YUV format in copy");
    }
    mod = (pitch / targetbpp);

    if (scale_2x) {
        mod -= (swdata->w * 2);
        swdata->Display2X(swdata->colortab, swdata->rgb_2_pix,
                          lum, Cr, Cb, pixels, swdata->h, swdata->w, mod);
    } else {
        mod -= swdata->w;
        swdata->Display1X(swdata->colortab, swdata->rgb_2_pix,
                          lum, Cr, Cb, pixels, swdata->h, swdata->w, mod);
    }
    if (stretch) {
        SDL_Rect rect = *srcrect;
        SDL_SoftStretch(swdata->stretch, &rect, swdata->display, NULL);
    }
    return 0;
}

void
SDL_SW_DestroyYUVTexture(SDL_SW_YUVTexture * swdata)
{
    if (swdata) {
        SDL_free(swdata->pixels);
        SDL_free(swdata->colortab);
        SDL_free(swdata->rgb_2_pix);
        SDL_FreeSurface(swdata->stretch);
        SDL_FreeSurface(swdata->display);
        SDL_free(swdata);
    }
}

/* vi: set ts=4 sw=4 expandtab: */