/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2009 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"

#include "SDL_video.h"

#include "SDL_compat.h"

#include "SDL_sysvideo.h"

#include "SDL_blit.h"

#include "SDL_RLEaccel_c.h"

#include "SDL_pixels_c.h"

#include "SDL_leaks.h"

/* Public routines */

/*

 * Create an empty RGB surface of the appropriate depth

 */

SDL_Surface *

SDL_CreateRGBSurface(Uint32 flags,

                     int width, int height, int depth,

                     Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)

{

    SDL_Surface *surface;

    /* The flags are no longer used, make the compiler happy */

    flags;

    /* Allocate the surface */

    surface = (SDL_Surface *) SDL_calloc(1, sizeof(*surface));

    if (surface == NULL) {

        SDL_OutOfMemory();

        return NULL;

    }

    surface->format = SDL_AllocFormat(depth, Rmask, Gmask, Bmask, Amask);

    if (!surface->format) {

        SDL_FreeSurface(surface);

        return NULL;

    }

    surface->w = width;

    surface->h = height;

    surface->pitch = SDL_CalculatePitch(surface);

    SDL_SetClipRect(surface, NULL);

    if (surface->format->BitsPerPixel <= 8) {

        SDL_Palette *palette =

            SDL_AllocPalette((1 << surface->format->BitsPerPixel));

        if (!palette) {

            SDL_FreeSurface(surface);

            return NULL;

        }

        if (Rmask || Bmask || Gmask) {

            const SDL_PixelFormat *format = surface->format;

            /* create palette according to masks */

            int i;

            int Rm = 0, Gm = 0, Bm = 0;

            int Rw = 0, Gw = 0, Bw = 0;

            if (Rmask) {

                Rw = 8 - format->Rloss;

                for (i = format->Rloss; i > 0; i -= Rw)

                    Rm |= 1 << i;

            }

            if (Gmask) {

                Gw = 8 - format->Gloss;

                for (i = format->Gloss; i > 0; i -= Gw)

                    Gm |= 1 << i;

            }

            if (Bmask) {

                Bw = 8 - format->Bloss;

                for (i = format->Bloss; i > 0; i -= Bw)

                    Bm |= 1 << i;

            }

            for (i = 0; i < palette->ncolors; ++i) {

                int r, g, b;

                r = (i & Rmask) >> format->Rshift;

                r = (r << format->Rloss) | ((r * Rm) >> Rw);

                palette->colors[i].r = r;

                g = (i & Gmask) >> format->Gshift;

                g = (g << format->Gloss) | ((g * Gm) >> Gw);

                palette->colors[i].g = g;

                b = (i & Bmask) >> format->Bshift;

                b = (b << format->Bloss) | ((b * Bm) >> Bw);

                palette->colors[i].b = b;

            }

        } else if (palette->ncolors == 2) {

            /* Create a black and white bitmap palette */

            palette->colors[0].r = 0xFF;

            palette->colors[0].g = 0xFF;

            palette->colors[0].b = 0xFF;

            palette->colors[1].r = 0x00;

            palette->colors[1].g = 0x00;

            palette->colors[1].b = 0x00;

        }

        SDL_SetSurfacePalette(surface, palette);

        SDL_FreePalette(palette);

    }

    /* Get the pixels */

    if (surface->w && surface->h) {

        surface->pixels = SDL_malloc(surface->h * surface->pitch);

        if (!surface->pixels) {

            SDL_FreeSurface(surface);

            SDL_OutOfMemory();

            return NULL;

        }

        /* This is important for bitmaps */

        SDL_memset(surface->pixels, 0, surface->h * surface->pitch);

    }

    /* Allocate an empty mapping */

    surface->map = SDL_AllocBlitMap();

    if (!surface->map) {

        SDL_FreeSurface(surface);

        return NULL;

    }

    SDL_FormatChanged(surface);

    /* By default surface with an alpha mask are set up for blending */

    if (Amask) {

        SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_BLEND);

    }

    /* The surface is ready to go */

    surface->refcount = 1;

#ifdef CHECK_LEAKS

    ++surfaces_allocated;

#endif

    return surface;

}

/*

 * Create an RGB surface from an existing memory buffer

 */

SDL_Surface *

SDL_CreateRGBSurfaceFrom(void *pixels,

                         int width, int height, int depth, int pitch,

                         Uint32 Rmask, Uint32 Gmask, Uint32 Bmask,

                         Uint32 Amask)

{

    SDL_Surface *surface;

    surface =

        SDL_CreateRGBSurface(0, 0, 0, depth, Rmask, Gmask, Bmask, Amask);

    if (surface != NULL) {

        surface->flags |= SDL_PREALLOC;

        surface->pixels = pixels;

        surface->w = width;

        surface->h = height;

        surface->pitch = pitch;

        SDL_SetClipRect(surface, NULL);

    }

    return surface;

}

static int

SDL_SurfacePaletteChanged(void *userdata, SDL_Palette * palette)

{

    SDL_Surface *surface = (SDL_Surface *) userdata;

    SDL_FormatChanged(surface);

    return 0;

}

int

SDL_SetSurfacePalette(SDL_Surface * surface, SDL_Palette * palette)

{

    if (!surface || !surface->format) {

        SDL_SetError("SDL_SetSurfacePalette() passed a NULL surface");

        return -1;

    }

    if (palette && palette->ncolors != (1 << surface->format->BitsPerPixel)) {

        SDL_SetError

            ("SDL_SetSurfacePalette() passed a palette that doesn't match the surface format");

        return -1;

    }

    if (surface->format->palette == palette) {

        return 0;

    }

    if (surface->format->palette) {

        SDL_DelPaletteWatch(surface->format->palette,

                            SDL_SurfacePaletteChanged, surface);

    }

    surface->format->palette = palette;

    if (surface->format->palette) {

        SDL_AddPaletteWatch(surface->format->palette,

                            SDL_SurfacePaletteChanged, surface);

    }

    return 0;

}

int

SDL_SetSurfaceRLE(SDL_Surface * surface, int flag)

{

    int flags;

    if (!surface) {

        return -1;

    }

    flags = surface->map->info.flags;

    if (flag) {

        surface->map->info.flags |= SDL_COPY_RLE_DESIRED;

    } else {

        surface->map->info.flags &= ~SDL_COPY_RLE_DESIRED;

    }

    if (surface->map->info.flags != flags) {

        SDL_InvalidateMap(surface->map);

    }

    return 0;

}

int

SDL_SetColorKey(SDL_Surface * surface, Uint32 flag, Uint32 key)

{

    int flags;

    if (!surface) {

        return -1;

    }

    if (flag & SDL_RLEACCEL) {

        SDL_SetSurfaceRLE(surface, 1);

    }

    flags = surface->map->info.flags;

    if (flag) {

        surface->map->info.flags |= SDL_COPY_COLORKEY;

        surface->map->info.colorkey = key;

    } else {

        surface->map->info.flags &= ~SDL_COPY_COLORKEY;

    }

    if (surface->map->info.flags != flags) {

        SDL_InvalidateMap(surface->map);

    }

    /* Compatibility mode */

    if (surface->map->info.flags & SDL_COPY_COLORKEY) {

        surface->flags |= SDL_SRCCOLORKEY;

    } else {

        surface->flags &= ~SDL_SRCCOLORKEY;

    }

    return 0;

}

int

SDL_GetColorKey(SDL_Surface * surface, Uint32 * key)

{

    if (!surface) {

        return -1;

    }

    if (!(surface->map->info.flags & SDL_COPY_COLORKEY)) {

        return -1;

    }

    if (key) {

        *key = surface->map->info.colorkey;

    }

    return 0;

}

/* This is a fairly slow function to switch from colorkey to alpha */

static void

SDL_ConvertColorkeyToAlpha(SDL_Surface * surface)

{

    int x, y;

    if (!surface) {

        return;

    }

    if (!(surface->map->info.flags & SDL_COPY_COLORKEY) ||

        !surface->format->Amask) {

        return;

    }

    SDL_LockSurface(surface);

    switch (surface->format->BytesPerPixel) {

    case 2:

        {

            Uint16 *row, *spot;

            Uint16 ckey = (Uint16) surface->map->info.colorkey;

            Uint16 mask = (Uint16) (~surface->format->Amask);

            row = (Uint16 *) surface->pixels;

            for (y = surface->h; y--;) {

                spot = row;

                for (x = surface->w; x--;) {

                    if (*spot == ckey) {

                        *spot &= mask;

                    }

                    ++spot;

                }

                row += surface->pitch / 2;

            }

        }

        break;

    case 3:

        /* FIXME */

        break;

    case 4:

        {

            Uint32 *row, *spot;

            Uint32 ckey = surface->map->info.colorkey;

            Uint32 mask = ~surface->format->Amask;

            row = (Uint32 *) surface->pixels;

            for (y = surface->h; y--;) {

                spot = row;

                for (x = surface->w; x--;) {

                    if (*spot == ckey) {

                        *spot &= mask;

                    }

                    ++spot;

                }

                row += surface->pitch / 4;

            }

        }

        break;

    }

    SDL_UnlockSurface(surface);

    SDL_SetColorKey(surface, 0, 0);

    SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_BLEND);

}

int

SDL_SetSurfaceColorMod(SDL_Surface * surface, Uint8 r, Uint8 g, Uint8 b)

{

    int flags;

    if (!surface) {

        return -1;

    }

    surface->map->info.r = r;

    surface->map->info.g = g;

    surface->map->info.b = b;

    flags = surface->map->info.flags;

    if (r != 0xFF || g != 0xFF || b != 0xFF) {

        surface->map->info.flags |= SDL_COPY_MODULATE_COLOR;

    } else {

        surface->map->info.flags &= ~SDL_COPY_MODULATE_COLOR;

    }

    if (surface->map->info.flags != flags) {

        SDL_InvalidateMap(surface->map);

    }

    return 0;

}

int

SDL_GetSurfaceColorMod(SDL_Surface * surface, Uint8 * r, Uint8 * g, Uint8 * b)

{

    if (!surface) {

        return -1;

    }

    if (r) {

        *r = surface->map->info.r;

    }

    if (g) {

        *g = surface->map->info.g;

    }

    if (b) {

        *b = surface->map->info.b;

    }

    return 0;

}

int

SDL_SetSurfaceAlphaMod(SDL_Surface * surface, Uint8 alpha)

{

    int flags;

    if (!surface) {

        return -1;

    }

    surface->map->info.a = alpha;

    flags = surface->map->info.flags;

    if (alpha != 0xFF) {

        surface->map->info.flags |= SDL_COPY_MODULATE_ALPHA;

    } else {

        surface->map->info.flags &= ~SDL_COPY_MODULATE_ALPHA;

    }

    if (surface->map->info.flags != flags) {

        SDL_InvalidateMap(surface->map);

    }

    return 0;

}

int

SDL_GetSurfaceAlphaMod(SDL_Surface * surface, Uint8 * alpha)

{

    if (!surface) {

        return -1;

    }

    if (alpha) {

        *alpha = surface->map->info.a;

    }

    return 0;

}

int

SDL_SetSurfaceBlendMode(SDL_Surface * surface, int blendMode)

{

    int flags, status;

    if (!surface) {

        return -1;

    }

    status = 0;

    flags = surface->map->info.flags;

    surface->map->info.flags &=

        ~(SDL_COPY_MASK | SDL_COPY_BLEND | SDL_COPY_ADD | SDL_COPY_MOD);

    switch (blendMode) {

    case SDL_BLENDMODE_NONE:

        break;

    case SDL_BLENDMODE_MASK:

        surface->map->info.flags |= SDL_COPY_MASK;

        break;

    case SDL_BLENDMODE_BLEND:

        surface->map->info.flags |= SDL_COPY_BLEND;

        break;

    case SDL_BLENDMODE_ADD:

        surface->map->info.flags |= SDL_COPY_ADD;

        break;

    case SDL_BLENDMODE_MOD:

        surface->map->info.flags |= SDL_COPY_MOD;

        break;

    default:

        SDL_Unsupported();

        status = -1;

        break;

    }

    if (surface->map->info.flags != flags) {

        SDL_InvalidateMap(surface->map);

    }

    /* Compatibility mode */

    if (surface->map->info.flags & SDL_COPY_BLEND) {

        surface->flags |= SDL_SRCALPHA;

    } else {

        surface->flags &= ~SDL_SRCALPHA;

    }

    return status;

}

int

SDL_GetSurfaceBlendMode(SDL_Surface * surface, int *blendMode)

{

    if (!surface) {

        return -1;

    }

    if (!blendMode) {

        return 0;

    }

    switch (surface->map->

            info.flags & (SDL_COPY_MASK | SDL_COPY_BLEND | SDL_COPY_ADD |

                          SDL_COPY_MOD)) {

    case SDL_COPY_MASK:

        *blendMode = SDL_BLENDMODE_MASK;

        break;

    case SDL_COPY_BLEND:

        *blendMode = SDL_BLENDMODE_BLEND;

        break;

    case SDL_COPY_ADD:

        *blendMode = SDL_BLENDMODE_ADD;

        break;

    case SDL_COPY_MOD:

        *blendMode = SDL_BLENDMODE_MOD;

        break;

    default:

        *blendMode = SDL_BLENDMODE_NONE;

        break;

    }

    return 0;

}

int

SDL_SetSurfaceScaleMode(SDL_Surface * surface, int scaleMode)

{

    int flags, status;

    if (!surface) {

        return -1;

    }

    status = 0;

    flags = surface->map->info.flags;

    surface->map->info.flags &= ~(SDL_COPY_NEAREST);

    switch (scaleMode) {

    case SDL_TEXTURESCALEMODE_NONE:

        break;

    case SDL_TEXTURESCALEMODE_FAST:

        surface->map->info.flags |= SDL_COPY_NEAREST;

        break;

    case SDL_TEXTURESCALEMODE_SLOW:

    case SDL_TEXTURESCALEMODE_BEST:

        SDL_Unsupported();

        surface->map->info.flags |= SDL_COPY_NEAREST;

        status = -1;

        break;

    default:

        SDL_Unsupported();

        status = -1;

        break;

    }

    if (surface->map->info.flags != flags) {

        SDL_InvalidateMap(surface->map);

    }

    return status;

}

int

SDL_GetSurfaceScaleMode(SDL_Surface * surface, int *scaleMode)

{

    if (!surface) {

        return -1;

    }

    if (!scaleMode) {

        return 0;

    }

    switch (surface->map->info.flags & SDL_COPY_NEAREST) {

    case SDL_COPY_NEAREST:

        *scaleMode = SDL_TEXTURESCALEMODE_FAST;

        break;

    default:

        *scaleMode = SDL_TEXTURESCALEMODE_NONE;

        break;

    }

    return 0;

}

SDL_bool

SDL_SetClipRect(SDL_Surface * surface, const SDL_Rect * rect)

{

    SDL_Rect full_rect;

    /* Don't do anything if there's no surface to act on */

    if (!surface) {

        return SDL_FALSE;

    }

    /* Set up the full surface rectangle */

    full_rect.x = 0;

    full_rect.y = 0;

    full_rect.w = surface->w;

    full_rect.h = surface->h;

    /* Set the clipping rectangle */

    if (!rect) {

        surface->clip_rect = full_rect;

        return 1;

    }

    return SDL_IntersectRect(rect, &full_rect, &surface->clip_rect);

}

void

SDL_GetClipRect(SDL_Surface * surface, SDL_Rect * rect)

{

    if (surface && rect) {

        *rect = surface->clip_rect;

    }

}

/* 

 * Set up a blit between two surfaces -- split into three parts:

 * The upper part, SDL_UpperBlit(), performs clipping and rectangle 

 * verification.  The lower part is a pointer to a low level

 * accelerated blitting function.

 *

 * These parts are separated out and each used internally by this 

 * library in the optimimum places.  They are exported so that if

 * you know exactly what you are doing, you can optimize your code

 * by calling the one(s) you need.

 */

int

SDL_LowerBlit(SDL_Surface * src, SDL_Rect * srcrect,

              SDL_Surface * dst, SDL_Rect * dstrect)

{

    /* Check to make sure the blit mapping is valid */

    if ((src->map->dst != dst) ||

        (src->map->dst->format_version != src->map->format_version)) {

        if (SDL_MapSurface(src, dst) < 0) {

            return (-1);

        }

        /* just here for debugging */

/*         printf */

/*             ("src = 0x%08X src->flags = %08X src->map->info.flags = %08x\ndst = 0x%08X dst->flags = %08X dst->map->info.flags = %08X\nsrc->map->blit = 0x%08x\n", */

/*              src, dst->flags, src->map->info.flags, dst, dst->flags, */

/*              dst->map->info.flags, src->map->blit); */

    }

    return (src->map->blit(src, srcrect, dst, dstrect));

}

int

SDL_UpperBlit(SDL_Surface * src, SDL_Rect * srcrect,

              SDL_Surface * dst, SDL_Rect * dstrect)

{

    SDL_Rect fulldst;

    int srcx, srcy, w, h;

    /* Make sure the surfaces aren't locked */

    if (!src || !dst) {

        SDL_SetError("SDL_UpperBlit: passed a NULL surface");

        return (-1);

    }

    if (src->locked || dst->locked) {

        SDL_SetError("Surfaces must not be locked during blit");

        return (-1);

    }

    /* If the destination rectangle is NULL, use the entire dest surface */

    if (dstrect == NULL) {

        fulldst.x = fulldst.y = 0;

        dstrect = &fulldst;

    }

    /* clip the source rectangle to the source surface */

    if (srcrect) {

        int maxw, maxh;

        srcx = srcrect->x;

        w = srcrect->w;

        if (srcx < 0) {

            w += srcx;

            dstrect->x -= srcx;

            srcx = 0;

        }

        maxw = src->w - srcx;

        if (maxw < w)

            w = maxw;

        srcy = srcrect->y;

        h = srcrect->h;

        if (srcy < 0) {

            h += srcy;

            dstrect->y -= srcy;

            srcy = 0;

        }

        maxh = src->h - srcy;

        if (maxh < h)

            h = maxh;

    } else {

        srcx = srcy = 0;

        w = src->w;

        h = src->h;

    }

    /* clip the destination rectangle against the clip rectangle */

    {

        SDL_Rect *clip = &dst->clip_rect;

        int dx, dy;

        dx = clip->x - dstrect->x;

        if (dx > 0) {

            w -= dx;

            dstrect->x += dx;

            srcx += dx;

        }

        dx = dstrect->x + w - clip->x - clip->w;

        if (dx > 0)

            w -= dx;

        dy = clip->y - dstrect->y;

        if (dy > 0) {

            h -= dy;

            dstrect->y += dy;

            srcy += dy;

        }

        dy = dstrect->y + h - clip->y - clip->h;

        if (dy > 0)

            h -= dy;

    }

    if (w > 0 && h > 0) {

        SDL_Rect sr;

        sr.x = srcx;

        sr.y = srcy;

        sr.w = dstrect->w = w;

        sr.h = dstrect->h = h;

        return SDL_LowerBlit(src, &sr, dst, dstrect);

    }

    dstrect->w = dstrect->h = 0;

    return 0;

}

/*

 * Lock a surface to directly access the pixels

 */

int

SDL_LockSurface(SDL_Surface * surface)

{

    if (!surface->locked) {

        /* Perform the lock */

        if (surface->flags & SDL_RLEACCEL) {

            SDL_UnRLESurface(surface, 1);

            surface->flags |= SDL_RLEACCEL;     /* save accel'd state */

        }

    }

    /* Increment the surface lock count, for recursive locks */

    ++surface->locked;

    /* Ready to go.. */

    return (0);

}

/*

 * Unlock a previously locked surface

 */

void

SDL_UnlockSurface(SDL_Surface * surface)

{

    /* Only perform an unlock if we are locked */

    if (!surface->locked || (--surface->locked > 0)) {

        return;

    }

    /* Update RLE encoded surface with new data */

    if ((surface->flags & SDL_RLEACCEL) == SDL_RLEACCEL) {

        surface->flags &= ~SDL_RLEACCEL;        /* stop lying */

        SDL_RLESurface(surface);

    }

}

/* 

 * Convert a surface into the specified pixel format.

 */

SDL_Surface *

SDL_ConvertSurface(SDL_Surface * surface, SDL_PixelFormat * format,

                   Uint32 flags)

{

    SDL_Surface *convert;

    Uint32 copy_flags;

    SDL_Rect bounds;

    /* Check for empty destination palette! (results in empty image) */

    if (format->palette != NULL) {

        int i;

        for (i = 0; i < format->palette->ncolors; ++i) {

            if ((format->palette->colors[i].r != 0xFF) ||

                (format->palette->colors[i].g != 0xFF) ||

                (format->palette->colors[i].b != 0xFF))

                break;

        }

        if (i == format->palette->ncolors) {

            SDL_SetError("Empty destination palette");

            return (NULL);

        }

    }

    /* Create a new surface with the desired format */

    convert = SDL_CreateRGBSurface(flags, surface->w, surface->h,

                                   format->BitsPerPixel, format->Rmask,

                                   format->Gmask, format->Bmask,

                                   format->Amask);

    if (convert == NULL) {

        return (NULL);

    }

    /* Copy the palette if any */

    if (format->palette && convert->format->palette) {

        SDL_memcpy(convert->format->palette->colors,

                   format->palette->colors,

                   format->palette->ncolors * sizeof(SDL_Color));

        convert->format->palette->ncolors = format->palette->ncolors;

    }

    /* Save the original copy flags */

    copy_flags = surface->map->info.flags;

    surface->map->info.flags = 0;

    /* Copy over the image data */

    bounds.x = 0;

    bounds.y = 0;

    bounds.w = surface->w;

    bounds.h = surface->h;

    SDL_LowerBlit(surface, &bounds, convert, &bounds);

    /* Clean up the original surface, and update converted surface */

    convert->map->info.r = surface->map->info.r;

    convert->map->info.g = surface->map->info.g;

    convert->map->info.b = surface->map->info.b;

    convert->map->info.a = surface->map->info.a;

    convert->map->info.flags =

        (copy_flags &

         ~(SDL_COPY_COLORKEY | SDL_COPY_BLEND

           | SDL_COPY_RLE_DESIRED | SDL_COPY_RLE_COLORKEY |

           SDL_COPY_RLE_ALPHAKEY));

    surface->map->info.flags = copy_flags;

    if (copy_flags & SDL_COPY_COLORKEY) {

        Uint8 keyR, keyG, keyB, keyA;

        SDL_GetRGBA(surface->map->info.colorkey, surface->format, &keyR,

                    &keyG, &keyB, &keyA);

        SDL_SetColorKey(convert, 1,

                        SDL_MapRGBA(convert->format, keyR, keyG, keyB, keyA));

        /* This is needed when converting for 3D texture upload */

        SDL_ConvertColorkeyToAlpha(convert);

    }

    SDL_SetClipRect(convert, &surface->clip_rect);

    /* Enable alpha blending by default if the new surface has an

     * alpha channel or alpha modulation */

    if ((surface->format->Amask && format->Amask) ||

        (copy_flags & SDL_COPY_MODULATE_ALPHA)) {

        SDL_SetSurfaceBlendMode(convert, SDL_BLENDMODE_BLEND);

    }

    if ((copy_flags & SDL_COPY_RLE_DESIRED) || (flags & SDL_RLEACCEL)) {

        SDL_SetSurfaceRLE(convert, SDL_RLEACCEL);

    }

    /* We're ready to go! */

    return (convert);

}

/*

 * Create a surface on the stack for quick blit operations

 */

static __inline__ SDL_bool

SDL_CreateSurfaceOnStack(int width, int height, Uint32 pixel_format,

                         void * pixels, int pitch, SDL_Surface * surface, 

                         SDL_PixelFormat * format, SDL_BlitMap * blitmap)

{

    int bpp;

    Uint32 Rmask, Gmask, Bmask, Amask;

    if (!SDL_PixelFormatEnumToMasks(pixel_format,

                                    &bpp, &Rmask, &Gmask, &Bmask, &Amask)) {

        return SDL_FALSE;

    }

    if (bpp <= 8) {

        SDL_SetError("Indexed pixel formats not supported");

        return SDL_FALSE;

    }

    SDL_zerop(surface);

    surface->flags = SDL_PREALLOC;

    surface->format = SDL_InitFormat(format, bpp, Rmask, Gmask, Bmask, Amask);

    surface->pixels = pixels;

    surface->w = width;

    surface->h = height;

    surface->pitch = pitch;

    /* We don't actually need to set up the clip rect for our purposes */

    /*SDL_SetClipRect(surface, NULL);*/

    /* Allocate an empty mapping */

    SDL_zerop(blitmap);

    blitmap->info.r = 0xFF;

    blitmap->info.g = 0xFF;

    blitmap->info.b = 0xFF;

    blitmap->info.a = 0xFF;

    surface->map = blitmap;

    SDL_FormatChanged(surface);

    /* The surface is ready to go */

    surface->refcount = 1;

    return SDL_TRUE;

}

/*

 * Copy a block of pixels of one format to another format

 */

int SDL_ConvertPixels(int width, int height,

                      Uint32 src_format, const void * src, int src_pitch,

                      Uint32 dst_format, void * dst, int dst_pitch)

{

    SDL_Surface src_surface, dst_surface;

    SDL_PixelFormat src_fmt, dst_fmt;

    SDL_BlitMap src_blitmap, dst_blitmap;

    SDL_Rect rect;

    /* Fast path for same format copy */

    if (src_format == dst_format) {

        int bpp;

        if (SDL_ISPIXELFORMAT_FOURCC(src_format)) {

            switch (src_format) {

            case SDL_PIXELFORMAT_YV12:

            case SDL_PIXELFORMAT_IYUV:

            case SDL_PIXELFORMAT_YUY2:

            case SDL_PIXELFORMAT_UYVY:

            case SDL_PIXELFORMAT_YVYU:

                bpp = 2;

            default:

                SDL_SetError("Unknown FOURCC pixel format");

                return -1;

            }

        } else {

            bpp = SDL_BYTESPERPIXEL(src_format);

        }

        width *= bpp;

        while (height-- > 0) {

            SDL_memcpy(dst, src, width);

            src = (Uint8*)src + src_pitch;

            dst = (Uint8*)dst + dst_pitch;

        }

        return SDL_TRUE;

    }

    if (!SDL_CreateSurfaceOnStack(width, height, src_format, (void*)src,

                                  src_pitch,

                                  &src_surface, &src_fmt, &src_blitmap)) {

        return -1;

    }

    if (!SDL_CreateSurfaceOnStack(width, height, dst_format, dst, dst_pitch,

                                  &dst_surface, &dst_fmt, &dst_blitmap)) {

        return -1;

    }

    /* Set up the rect and go! */

    rect.x = 0;

    rect.y = 0;

    rect.w = width;

    rect.h = height;

    return SDL_LowerBlit(&src_surface, &rect, &dst_surface, &rect);

}

/*

 * Free a surface created by the above function.

 */

void

SDL_FreeSurface(SDL_Surface * surface)

{

    if (surface == NULL) {

        return;

    }

    if (--surface->refcount > 0) {

        return;

    }

    while (surface->locked > 0) {

        SDL_UnlockSurface(surface);

    }

    if (surface->flags & SDL_RLEACCEL) {

        SDL_UnRLESurface(surface, 0);

    }

    if (surface->format) {

        SDL_SetSurfacePalette(surface, NULL);

        SDL_FreeFormat(surface->format);

        surface->format = NULL;

    }

    if (surface->map != NULL) {

        SDL_FreeBlitMap(surface->map);

        surface->map = NULL;