view src/video/SDL_pixels.c @ 1982:3b4ce57c6215

First shot at new audio data types (int32 and float32). Notable changes: - Converters between types are autogenerated. Instead of making multiple passes over the data with seperate filters for endianess, size, signedness, etc, converting between data types is always one specialized filter. This simplifies SDL_BuildAudioCVT(), which otherwise had a million edge cases with the new types, and makes the actually conversions more CPU cache friendly. Left a stub for adding specific optimized versions of these routines (SSE/MMX/Altivec, assembler, etc) - Autogenerated converters are built by SDL/src/audio/sdlgenaudiocvt.pl. This does not need to be run unless tweaking the code, and thus doesn't need integration into the build system. - Went through all the drivers and tried to weed out all the "Uint16" references that are better specified with the new SDL_AudioFormat typedef. - Cleaned out a bunch of hardcoded bitwise magic numbers and replaced them with new SDL_AUDIO_* macros. - Added initial float32 and int32 support code. Theoretically, existing drivers will push these through converters to get the data they want to feed to the hardware. Still TODO: - Optimize and debug new converters. - Update the CoreAudio backend to accept float32 data directly. - Other backends, too? - SDL_LoadWAV() needs to be updated to support int32 and float32 .wav files (both of which exist and can be generated by 'sox' for testing purposes). - Update the mixer to handle new datatypes. - Optionally update SDL_sound and SDL_mixer, etc.
author Ryan C. Gordon <icculus@icculus.org>
date Thu, 24 Aug 2006 12:10:46 +0000
parents a788656ca29a
children 0975e24a3670
line wrap: on
line source

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

/* General (mostly internal) pixel/color manipulation routines for SDL */

#include "SDL_endian.h"
#include "SDL_video.h"
#include "SDL_sysvideo.h"
#include "SDL_blit.h"
#include "SDL_pixels_c.h"
#include "SDL_RLEaccel_c.h"

/* Helper functions */

SDL_bool
SDL_PixelFormatEnumToMasks(Uint32 format, int *bpp, Uint32 * Rmask,
                           Uint32 * Gmask, Uint32 * Bmask, Uint32 * Amask)
{
    Uint32 masks[4];

    /* Initialize the values here */
    if (SDL_BITSPERPIXEL(format) == 24) {
        *bpp = SDL_BYTESPERPIXEL(format) * 8;
    } else {
        *bpp = SDL_BITSPERPIXEL(format);
    }
    *Rmask = *Gmask = *Bmask = *Amask = 0;

    if (SDL_PIXELTYPE(format) != SDL_PIXELTYPE_PACKED8 &&
        SDL_PIXELTYPE(format) != SDL_PIXELTYPE_PACKED16 &&
        SDL_PIXELTYPE(format) != SDL_PIXELTYPE_PACKED32) {
        /* Not a format that uses masks */
        return SDL_TRUE;
    }

    switch (SDL_PIXELLAYOUT(format)) {
    case SDL_PACKEDLAYOUT_332:
        masks[0] = 0x00000000;
        masks[1] = 0x000000E0;
        masks[2] = 0x0000001C;
        masks[3] = 0x00000003;
        break;
    case SDL_PACKEDLAYOUT_4444:
        masks[0] = 0x0000F000;
        masks[1] = 0x00000F00;
        masks[2] = 0x000000F0;
        masks[3] = 0x0000000F;
        break;
    case SDL_PACKEDLAYOUT_1555:
        masks[0] = 0x00008000;
        masks[1] = 0x00007C00;
        masks[2] = 0x000003E0;
        masks[3] = 0x0000001F;
        break;
    case SDL_PACKEDLAYOUT_565:
        masks[0] = 0x00000000;
        masks[1] = 0x0000F800;
        masks[2] = 0x000007E0;
        masks[3] = 0x0000001F;
        break;
    case SDL_PACKEDLAYOUT_8888:
        masks[0] = 0xFF000000;
        masks[1] = 0x00FF0000;
        masks[2] = 0x0000FF00;
        masks[3] = 0x000000FF;
        break;
    case SDL_PACKEDLAYOUT_2101010:
        masks[0] = 0xC0000000;
        masks[1] = 0x3FF00000;
        masks[2] = 0x000FFC00;
        masks[3] = 0x000003FF;
        break;
    default:
        /* Unknown layout */
        return SDL_FALSE;
    }

    switch (SDL_PIXELORDER(format)) {
    case SDL_PACKEDORDER_XRGB:
        *Rmask = masks[1];
        *Gmask = masks[2];
        *Bmask = masks[3];
        break;
    case SDL_PACKEDORDER_RGBX:
        *Rmask = masks[0];
        *Gmask = masks[1];
        *Bmask = masks[2];
        break;
    case SDL_PACKEDORDER_ARGB:
        *Amask = masks[0];
        *Rmask = masks[1];
        *Gmask = masks[2];
        *Bmask = masks[3];
        break;
    case SDL_PACKEDORDER_RGBA:
        *Rmask = masks[0];
        *Gmask = masks[1];
        *Bmask = masks[2];
        *Amask = masks[3];
        break;
    case SDL_PACKEDORDER_XBGR:
        *Bmask = masks[1];
        *Gmask = masks[2];
        *Rmask = masks[3];
        break;
    case SDL_PACKEDORDER_BGRX:
        *Bmask = masks[0];
        *Gmask = masks[1];
        *Rmask = masks[2];
        break;
    case SDL_PACKEDORDER_BGRA:
        *Bmask = masks[0];
        *Gmask = masks[1];
        *Rmask = masks[2];
        *Amask = masks[3];
        break;
    case SDL_PACKEDORDER_ABGR:
        *Amask = masks[0];
        *Bmask = masks[1];
        *Gmask = masks[2];
        *Rmask = masks[3];
        break;
    default:
        /* Unknown order */
        return SDL_FALSE;
    }
    return SDL_TRUE;
}

Uint32
SDL_MasksToPixelFormatEnum(int bpp, Uint32 Rmask, Uint32 Gmask, Uint32 Bmask,
                           Uint32 Amask)
{
    switch (bpp) {
    case 8:
        switch (Rmask) {
        case 0:
            return SDL_PIXELFORMAT_INDEX8;
        case 0xE0:
            return SDL_PIXELFORMAT_RGB332;
        }
        break;
    case 12:
        switch (Rmask) {
        case 0x0F00:
            return SDL_PIXELFORMAT_RGB444;
        }
        break;
    case 15:
        switch (Rmask) {
        case 0x7C00:
            return SDL_PIXELFORMAT_RGB555;
        }
        break;
    case 16:
        switch (Rmask) {
        case 0x0F00:
            return SDL_PIXELFORMAT_ARGB4444;
        case 0x7C00:
            return SDL_PIXELFORMAT_ARGB1555;
        case 0xF800:
            return SDL_PIXELFORMAT_RGB565;
        }
        break;
    case 32:
        switch (Rmask) {
        case 0xFF000000:
            if (Amask == 0x000000FF) {
                return SDL_PIXELFORMAT_RGBA8888;
            }
            break;
        case 0x00FF0000:
            if (Amask == 0xFF000000) {
                return SDL_PIXELFORMAT_ARGB8888;
            } else {
                return SDL_PIXELFORMAT_RGB888;
            }
            break;
        case 0x0000FF00:
            if (Amask == 0x000000FF) {
                return SDL_PIXELFORMAT_BGRA8888;
            }
            break;
        case 0x000000FF:
            if (Amask == 0xFF000000) {
                return SDL_PIXELFORMAT_ABGR8888;
            } else {
                return SDL_PIXELFORMAT_BGR888;
            }
            break;
        case 0x3FF00000:
            return SDL_PIXELFORMAT_ARGB2101010;
        }
    }
    return SDL_PIXELFORMAT_UNKNOWN;
}


SDL_Palette *
SDL_AllocPalette(int ncolors)
{
    SDL_Palette *palette;

    palette = (SDL_Palette *) SDL_malloc(sizeof(*palette));
    if (!palette) {
        SDL_OutOfMemory();
        return NULL;
    }
    palette->colors =
        (SDL_Color *) SDL_malloc(ncolors * sizeof(*palette->colors));
    if (!palette->colors) {
        SDL_free(palette);
        return NULL;
    }
    palette->ncolors = ncolors;
    palette->watch = NULL;
    palette->refcount = 1;

    SDL_memset(palette->colors, 0xFF, ncolors * sizeof(*palette->colors));

    return palette;
}

int
SDL_AddPaletteWatch(SDL_Palette * palette, SDL_PaletteChangedFunc callback,
                    void *userdata)
{
    SDL_PaletteWatch *watch;

    if (!palette) {
        return -1;
    }

    watch = (SDL_PaletteWatch *) SDL_malloc(sizeof(*watch));
    if (!watch) {
        SDL_OutOfMemory();
        return -1;
    }

    watch->callback = callback;
    watch->userdata = userdata;
    watch->next = palette->watch;
    palette->watch = watch;
    ++palette->refcount;
    return 0;
}

void
SDL_DelPaletteWatch(SDL_Palette * palette, SDL_PaletteChangedFunc callback,
                    void *userdata)
{
    SDL_PaletteWatch *prev, *watch;

    if (!palette) {
        return;
    }

    for (prev = NULL, watch = palette->watch; watch;
         prev = watch, watch = watch->next) {
        if (watch->callback == callback && watch->userdata == userdata) {
            if (prev) {
                prev->next = watch->next;
            } else {
                palette->watch = watch->next;
            }
            SDL_free(watch);
            SDL_FreePalette(palette);
            return;
        }
    }
}

int
SDL_SetPaletteColors(SDL_Palette * palette, const SDL_Color * colors,
                     int firstcolor, int ncolors)
{
    SDL_PaletteWatch *watch;
    int status = 0;

    /* Verify the parameters */
    if (!palette) {
        return -1;
    }
    if (ncolors > (palette->ncolors - firstcolor)) {
        ncolors = (palette->ncolors - firstcolor);
        status = -1;
    }

    if (colors != (palette->colors + firstcolor)) {
        SDL_memcpy(palette->colors + firstcolor, colors,
                   ncolors * sizeof(*colors));
    }

    for (watch = palette->watch; watch; watch = watch->next) {
        if (watch->callback(watch->userdata, palette) < 0) {
            status = -1;
        }
    }

    return status;
}

void
SDL_FreePalette(SDL_Palette * palette)
{
    if (!palette) {
        return;
    }
    if (--palette->refcount > 0) {
        return;
    }
    if (palette->colors) {
        SDL_free(palette->colors);
    }
    SDL_free(palette);
}

/*
 * Allocate a pixel format structure and fill it according to the given info.
 */
SDL_PixelFormat *
SDL_AllocFormat(int bpp,
                Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
{
    SDL_PixelFormat *format;
    Uint32 mask;

    /* Allocate an empty pixel format structure */
    format = SDL_calloc(1, sizeof(*format));
    if (format == NULL) {
        SDL_OutOfMemory();
        return (NULL);
    }
    format->alpha = SDL_ALPHA_OPAQUE;

    /* Set up the format */
    format->BitsPerPixel = bpp;
    format->BytesPerPixel = (bpp + 7) / 8;
    if (Rmask || Bmask || Gmask) {      /* Packed pixels with custom mask */
        format->Rshift = 0;
        format->Rloss = 8;
        if (Rmask) {
            for (mask = Rmask; !(mask & 0x01); mask >>= 1)
                ++format->Rshift;
            for (; (mask & 0x01); mask >>= 1)
                --format->Rloss;
        }
        format->Gshift = 0;
        format->Gloss = 8;
        if (Gmask) {
            for (mask = Gmask; !(mask & 0x01); mask >>= 1)
                ++format->Gshift;
            for (; (mask & 0x01); mask >>= 1)
                --format->Gloss;
        }
        format->Bshift = 0;
        format->Bloss = 8;
        if (Bmask) {
            for (mask = Bmask; !(mask & 0x01); mask >>= 1)
                ++format->Bshift;
            for (; (mask & 0x01); mask >>= 1)
                --format->Bloss;
        }
        format->Ashift = 0;
        format->Aloss = 8;
        if (Amask) {
            for (mask = Amask; !(mask & 0x01); mask >>= 1)
                ++format->Ashift;
            for (; (mask & 0x01); mask >>= 1)
                --format->Aloss;
        }
        format->Rmask = Rmask;
        format->Gmask = Gmask;
        format->Bmask = Bmask;
        format->Amask = Amask;
    } else if (bpp > 8) {       /* Packed pixels with standard mask */
        /* R-G-B */
        if (bpp > 24)
            bpp = 24;
        format->Rloss = 8 - (bpp / 3);
        format->Gloss = 8 - (bpp / 3) - (bpp % 3);
        format->Bloss = 8 - (bpp / 3);
        format->Rshift = ((bpp / 3) + (bpp % 3)) + (bpp / 3);
        format->Gshift = (bpp / 3);
        format->Bshift = 0;
        format->Rmask = ((0xFF >> format->Rloss) << format->Rshift);
        format->Gmask = ((0xFF >> format->Gloss) << format->Gshift);
        format->Bmask = ((0xFF >> format->Bloss) << format->Bshift);
    } else {
        /* Palettized formats have no mask info */
        format->Rloss = 8;
        format->Gloss = 8;
        format->Bloss = 8;
        format->Aloss = 8;
        format->Rshift = 0;
        format->Gshift = 0;
        format->Bshift = 0;
        format->Ashift = 0;
        format->Rmask = 0;
        format->Gmask = 0;
        format->Bmask = 0;
        format->Amask = 0;
    }
    format->palette = NULL;

    return (format);
}

/*
 * Change any previous mappings from/to the new surface format
 */
void
SDL_FormatChanged(SDL_Surface * surface)
{
    static int format_version = 0;
    ++format_version;
    if (format_version < 0) {   /* It wrapped... */
        format_version = 1;
    }
    surface->format_version = format_version;
    SDL_InvalidateMap(surface->map);
}

/*
 * Free a previously allocated format structure
 */
void
SDL_FreeFormat(SDL_PixelFormat * format)
{
    if (!format) {
        return;
    }
    SDL_free(format);
}

/*
 * Calculate an 8-bit (3 red, 3 green, 2 blue) dithered palette of colors
 */
void
SDL_DitherColors(SDL_Color * colors, int bpp)
{
    int i;
    if (bpp != 8)
        return;                 /* only 8bpp supported right now */

    for (i = 0; i < 256; i++) {
        int r, g, b;
        /* map each bit field to the full [0, 255] interval,
           so 0 is mapped to (0, 0, 0) and 255 to (255, 255, 255) */
        r = i & 0xe0;
        r |= r >> 3 | r >> 6;
        colors[i].r = r;
        g = (i << 3) & 0xe0;
        g |= g >> 3 | g >> 6;
        colors[i].g = g;
        b = i & 0x3;
        b |= b << 2;
        b |= b << 4;
        colors[i].b = b;
        colors[i].unused = SDL_ALPHA_OPAQUE;
    }
}

/* 
 * Calculate the pad-aligned scanline width of a surface
 */
int
SDL_CalculatePitch(SDL_Surface * surface)
{
    int pitch;

    /* Surface should be 4-byte aligned for speed */
    pitch = surface->w * surface->format->BytesPerPixel;
    switch (surface->format->BitsPerPixel) {
    case 1:
        pitch = (pitch + 7) / 8;
        break;
    case 4:
        pitch = (pitch + 1) / 2;
        break;
    default:
        break;
    }
    pitch = (pitch + 3) & ~3;   /* 4-byte aligning */
    return (pitch);
}

/*
 * Match an RGB value to a particular palette index
 */
Uint8
SDL_FindColor(SDL_Palette * pal, Uint8 r, Uint8 g, Uint8 b)
{
    /* Do colorspace distance matching */
    unsigned int smallest;
    unsigned int distance;
    int rd, gd, bd;
    int i;
    Uint8 pixel = 0;

    smallest = ~0;
    for (i = 0; i < pal->ncolors; ++i) {
        rd = pal->colors[i].r - r;
        gd = pal->colors[i].g - g;
        bd = pal->colors[i].b - b;
        distance = (rd * rd) + (gd * gd) + (bd * bd);
        if (distance < smallest) {
            pixel = i;
            if (distance == 0) {        /* Perfect match! */
                break;
            }
            smallest = distance;
        }
    }
    return (pixel);
}

/* Find the opaque pixel value corresponding to an RGB triple */
Uint32
SDL_MapRGB(SDL_PixelFormat * format, Uint8 r, Uint8 g, Uint8 b)
{
    if (format->palette == NULL) {
        return (r >> format->Rloss) << format->Rshift
            | (g >> format->Gloss) << format->Gshift
            | (b >> format->Bloss) << format->Bshift | format->Amask;
    } else {
        return SDL_FindColor(format->palette, r, g, b);
    }
}

/* Find the pixel value corresponding to an RGBA quadruple */
Uint32
SDL_MapRGBA(SDL_PixelFormat * format, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
    if (format->palette == NULL) {
        return (r >> format->Rloss) << format->Rshift
            | (g >> format->Gloss) << format->Gshift
            | (b >> format->Bloss) << format->Bshift
            | ((a >> format->Aloss) << format->Ashift & format->Amask);
    } else {
        return SDL_FindColor(format->palette, r, g, b);
    }
}

void
SDL_GetRGBA(Uint32 pixel, SDL_PixelFormat * fmt,
            Uint8 * r, Uint8 * g, Uint8 * b, Uint8 * a)
{
    if (fmt->palette == NULL) {
        /*
         * This makes sure that the result is mapped to the
         * interval [0..255], and the maximum value for each
         * component is 255. This is important to make sure
         * that white is indeed reported as (255, 255, 255),
         * and that opaque alpha is 255.
         * This only works for RGB bit fields at least 4 bit
         * wide, which is almost always the case.
         */
        unsigned v;
        v = (pixel & fmt->Rmask) >> fmt->Rshift;
        *r = (v << fmt->Rloss) + (v >> (8 - (fmt->Rloss << 1)));
        v = (pixel & fmt->Gmask) >> fmt->Gshift;
        *g = (v << fmt->Gloss) + (v >> (8 - (fmt->Gloss << 1)));
        v = (pixel & fmt->Bmask) >> fmt->Bshift;
        *b = (v << fmt->Bloss) + (v >> (8 - (fmt->Bloss << 1)));
        if (fmt->Amask) {
            v = (pixel & fmt->Amask) >> fmt->Ashift;
            *a = (v << fmt->Aloss) + (v >> (8 - (fmt->Aloss << 1)));
        } else {
            *a = SDL_ALPHA_OPAQUE;
        }
    } else {
        *r = fmt->palette->colors[pixel].r;
        *g = fmt->palette->colors[pixel].g;
        *b = fmt->palette->colors[pixel].b;
        *a = SDL_ALPHA_OPAQUE;
    }
}

void
SDL_GetRGB(Uint32 pixel, SDL_PixelFormat * fmt, Uint8 * r, Uint8 * g,
           Uint8 * b)
{
    if (fmt->palette == NULL) {
        /* the note for SDL_GetRGBA above applies here too */
        unsigned v;
        v = (pixel & fmt->Rmask) >> fmt->Rshift;
        *r = (v << fmt->Rloss) + (v >> (8 - (fmt->Rloss << 1)));
        v = (pixel & fmt->Gmask) >> fmt->Gshift;
        *g = (v << fmt->Gloss) + (v >> (8 - (fmt->Gloss << 1)));
        v = (pixel & fmt->Bmask) >> fmt->Bshift;
        *b = (v << fmt->Bloss) + (v >> (8 - (fmt->Bloss << 1)));
    } else {
        *r = fmt->palette->colors[pixel].r;
        *g = fmt->palette->colors[pixel].g;
        *b = fmt->palette->colors[pixel].b;
    }
}

/* Apply gamma to a set of colors - this is easy. :) */
void
SDL_ApplyGamma(Uint16 * gamma, SDL_Color * colors, SDL_Color * output,
               int ncolors)
{
    int i;

    for (i = 0; i < ncolors; ++i) {
        output[i].r = gamma[0 * 256 + colors[i].r] >> 8;
        output[i].g = gamma[1 * 256 + colors[i].g] >> 8;
        output[i].b = gamma[2 * 256 + colors[i].b] >> 8;
    }
}

/* Map from Palette to Palette */
static Uint8 *
Map1to1(SDL_Palette * src, SDL_Palette * dst, int *identical)
{
    Uint8 *map;
    int i;

    if (identical) {
        if (src->ncolors <= dst->ncolors) {
            /* If an identical palette, no need to map */
            if (src == dst
                ||
                (SDL_memcmp
                 (src->colors, dst->colors,
                  src->ncolors * sizeof(SDL_Color)) == 0)) {
                *identical = 1;
                return (NULL);
            }
        }
        *identical = 0;
    }
    map = (Uint8 *) SDL_malloc(src->ncolors);
    if (map == NULL) {
        SDL_OutOfMemory();
        return (NULL);
    }
    for (i = 0; i < src->ncolors; ++i) {
        map[i] = SDL_FindColor(dst,
                               src->colors[i].r, src->colors[i].g,
                               src->colors[i].b);
    }
    return (map);
}

/* Map from Palette to BitField */
static Uint8 *
Map1toN(SDL_PixelFormat * src, SDL_PixelFormat * dst)
{
    Uint8 *map;
    int i;
    int bpp;
    unsigned alpha;
    SDL_Palette *pal = src->palette;

    bpp = ((dst->BytesPerPixel == 3) ? 4 : dst->BytesPerPixel);
    map = (Uint8 *) SDL_malloc(pal->ncolors * bpp);
    if (map == NULL) {
        SDL_OutOfMemory();
        return (NULL);
    }

    alpha = dst->Amask ? src->alpha : 0;
    /* We memory copy to the pixel map so the endianness is preserved */
    for (i = 0; i < pal->ncolors; ++i) {
        ASSEMBLE_RGBA(&map[i * bpp], dst->BytesPerPixel, dst,
                      pal->colors[i].r, pal->colors[i].g,
                      pal->colors[i].b, alpha);
    }
    return (map);
}

/* Map from BitField to Dithered-Palette to Palette */
static Uint8 *
MapNto1(SDL_PixelFormat * src, SDL_PixelFormat * dst, int *identical)
{
    /* Generate a 256 color dither palette */
    SDL_Palette dithered;
    SDL_Color colors[256];
    SDL_Palette *pal = dst->palette;

    dithered.ncolors = 256;
    SDL_DitherColors(colors, 8);
    dithered.colors = colors;
    return (Map1to1(&dithered, pal, identical));
}

SDL_BlitMap *
SDL_AllocBlitMap(void)
{
    SDL_BlitMap *map;

    /* Allocate the empty map */
    map = (SDL_BlitMap *) SDL_calloc(1, sizeof(*map));
    if (map == NULL) {
        SDL_OutOfMemory();
        return (NULL);
    }

    /* Allocate the software blit data */
    map->sw_data =
        (struct private_swaccel *) SDL_calloc(1, sizeof(*map->sw_data));
    if (map->sw_data == NULL) {
        SDL_FreeBlitMap(map);
        SDL_OutOfMemory();
        return (NULL);
    }

    /* It's ready to go */
    return (map);
}

void
SDL_InvalidateMap(SDL_BlitMap * map)
{
    if (!map) {
        return;
    }
    map->dst = NULL;
    map->format_version = (unsigned int) -1;
    if (map->table) {
        SDL_free(map->table);
        map->table = NULL;
    }
}
int
SDL_MapSurface(SDL_Surface * src, SDL_Surface * dst)
{
    SDL_PixelFormat *srcfmt;
    SDL_PixelFormat *dstfmt;
    SDL_BlitMap *map;

    /* Clear out any previous mapping */
    map = src->map;
    if ((src->flags & SDL_RLEACCEL) == SDL_RLEACCEL) {
        SDL_UnRLESurface(src, 1);
    }
    SDL_InvalidateMap(map);

    /* Figure out what kind of mapping we're doing */
    map->identity = 0;
    srcfmt = src->format;
    dstfmt = dst->format;
    switch (srcfmt->BytesPerPixel) {
    case 1:
        switch (dstfmt->BytesPerPixel) {
        case 1:
            /* Palette --> Palette */
            map->table =
                Map1to1(srcfmt->palette, dstfmt->palette, &map->identity);
            if (!map->identity) {
                if (map->table == NULL) {
                    return (-1);
                }
            }
            if (srcfmt->BitsPerPixel != dstfmt->BitsPerPixel)
                map->identity = 0;
            break;

        default:
            /* Palette --> BitField */
            map->table = Map1toN(srcfmt, dstfmt);
            if (map->table == NULL) {
                return (-1);
            }
            break;
        }
        break;
    default:
        switch (dstfmt->BytesPerPixel) {
        case 1:
            /* BitField --> Palette */
            map->table = MapNto1(srcfmt, dstfmt, &map->identity);
            if (!map->identity) {
                if (map->table == NULL) {
                    return (-1);
                }
            }
            map->identity = 0;  /* Don't optimize to copy */
            break;
        default:
            /* BitField --> BitField */
            if (FORMAT_EQUAL(srcfmt, dstfmt))
                map->identity = 1;
            break;
        }
        break;
    }

    map->dst = dst;
    map->format_version = dst->format_version;

    /* Choose your blitters wisely */
    return (SDL_CalculateBlit(src));
}

void
SDL_FreeBlitMap(SDL_BlitMap * map)
{
    if (map) {
        SDL_InvalidateMap(map);
        if (map->sw_data != NULL) {
            SDL_free(map->sw_data);
        }
        SDL_free(map);
    }
}

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