sdl3-src 3.4.4

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2026 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"

#ifdef SDL_HAVE_BLIT_0

#include "SDL_surface_c.h"

// Functions to blit from bitmaps to other surfaces

SDL_FORCE_INLINE void BlitBto1(SDL_BlitInfo *info, const Uint32 srcbpp)
{
    const Uint32 mask = (1 << srcbpp) - 1;
    const Uint32 align = (8 / srcbpp) - 1;

    int c;
    int width, height;
    Uint8 *src, *map, *dst;
    int srcskip, dstskip;

    // Set up some basic variables
    width = info->dst_w;
    height = info->dst_h;
    src = info->src;
    srcskip = info->src_skip;
    dst = info->dst;
    dstskip = info->dst_skip;
    map = info->table;

    width += info->leading_skip;

    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;

    if (map) {
        if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
            while (height--) {
                Uint8 byte = 0, bit;
                for (c = 0; c < info->leading_skip; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    byte >>= srcbpp;
                }
                for (; c < width; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    bit = (byte & mask);
                    if (1) {
                        *dst = map[bit];
                    }
                    dst++;
                    byte >>= srcbpp;
                }
                src += srcskip;
                dst += dstskip;
            }
        } else {
            while (height--) {
                Uint8 byte = 0, bit;
                for (c = 0; c < info->leading_skip; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    byte <<= srcbpp;
                }
                for (; c < width; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    bit = (byte >> (8 - srcbpp)) & mask;
                    if (1) {
                        *dst = map[bit];
                    }
                    dst++;
                    byte <<= srcbpp;
                }
                src += srcskip;
                dst += dstskip;
            }
        }
    } else {
        if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
            while (height--) {
                Uint8 byte = 0, bit;
                for (c = 0; c < info->leading_skip; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    byte >>= srcbpp;
                }
                for (; c < width; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    bit = (byte & mask);
                    if (1) {
                        *dst = bit;
                    }
                    dst++;
                    byte >>= srcbpp;
                }
                src += srcskip;
                dst += dstskip;
            }
        } else {
            while (height--) {
                Uint8 byte = 0, bit;
                for (c = 0; c < info->leading_skip; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    byte <<= srcbpp;
                }
                for (; c < width; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    bit = (byte >> (8 - srcbpp)) & mask;
                    if (1) {
                        *dst = bit;
                    }
                    dst++;
                    byte <<= srcbpp;
                }
                src += srcskip;
                dst += dstskip;
            }
        }
    }
}

SDL_FORCE_INLINE void BlitBto2(SDL_BlitInfo *info, const Uint32 srcbpp)
{
    const Uint32 mask = (1 << srcbpp) - 1;
    const Uint32 align = (8 / srcbpp) - 1;

    int c;
    int width, height;
    Uint8 *src;
    Uint16 *map, *dst;
    int srcskip, dstskip;

    // Set up some basic variables
    width = info->dst_w;
    height = info->dst_h;
    src = info->src;
    srcskip = info->src_skip;
    dst = (Uint16 *)info->dst;
    dstskip = info->dst_skip / 2;
    map = (Uint16 *)info->table;

    width += info->leading_skip;

    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;

    if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte >>= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte & mask);
                if (1) {
                    *dst = map[bit];
                }
                byte >>= srcbpp;
                dst++;
            }
            src += srcskip;
            dst += dstskip;
        }
    } else {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte <<= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte >> (8 - srcbpp)) & mask;
                if (1) {
                    *dst = map[bit];
                }
                byte <<= srcbpp;
                dst++;
            }
            src += srcskip;
            dst += dstskip;
        }
    }
}

SDL_FORCE_INLINE void BlitBto3(SDL_BlitInfo *info, const Uint32 srcbpp)
{
    const Uint32 mask = (1 << srcbpp) - 1;
    const Uint32 align = (8 / srcbpp) - 1;

    int c, o;
    int width, height;
    Uint8 *src, *map, *dst;
    int srcskip, dstskip;

    // Set up some basic variables
    width = info->dst_w;
    height = info->dst_h;
    src = info->src;
    srcskip = info->src_skip;
    dst = info->dst;
    dstskip = info->dst_skip;
    map = info->table;

    width += info->leading_skip;

    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;

    if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte >>= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte & mask);
                if (1) {
                    o = bit * 4;
                    dst[0] = map[o++];
                    dst[1] = map[o++];
                    dst[2] = map[o++];
                }
                byte >>= srcbpp;
                dst += 3;
            }
            src += srcskip;
            dst += dstskip;
        }
    } else {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte <<= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte >> (8 - srcbpp)) & mask;
                if (1) {
                    o = bit * 4;
                    dst[0] = map[o++];
                    dst[1] = map[o++];
                    dst[2] = map[o++];
                }
                byte <<= srcbpp;
                dst += 3;
            }
            src += srcskip;
            dst += dstskip;
        }
    }
}

SDL_FORCE_INLINE void BlitBto4(SDL_BlitInfo *info, const Uint32 srcbpp)
{
    const Uint32 mask = (1 << srcbpp) - 1;
    const Uint32 align = (8 / srcbpp) - 1;

    int width, height;
    Uint8 *src;
    Uint32 *map, *dst;
    int srcskip, dstskip;
    int c;

    // Set up some basic variables
    width = info->dst_w;
    height = info->dst_h;
    src = info->src;
    srcskip = info->src_skip;
    dst = (Uint32 *)info->dst;
    dstskip = info->dst_skip / 4;
    map = (Uint32 *)info->table;

    width += info->leading_skip;

    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;

    if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte >>= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte & mask);
                if (1) {
                    *dst = map[bit];
                }
                byte >>= srcbpp;
                dst++;
            }
            src += srcskip;
            dst += dstskip;
        }
    } else {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte <<= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte >> (8 - srcbpp)) & mask;
                if (1) {
                    *dst = map[bit];
                }
                byte <<= srcbpp;
                dst++;
            }
            src += srcskip;
            dst += dstskip;
        }
    }
}

SDL_FORCE_INLINE void BlitBto1Key(SDL_BlitInfo *info, const Uint32 srcbpp)
{
    const Uint32 mask = (1 << srcbpp) - 1;
    const Uint32 align = (8 / srcbpp) - 1;

    int width = info->dst_w;
    int height = info->dst_h;
    Uint8 *src = info->src;
    Uint8 *dst = info->dst;
    int srcskip = info->src_skip;
    int dstskip = info->dst_skip;
    Uint32 ckey = info->colorkey;
    Uint8 *palmap = info->table;
    int c;

    width += info->leading_skip;

    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;

    if (palmap) {
        if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
            while (height--) {
                Uint8 byte = 0, bit;
                for (c = 0; c < info->leading_skip; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    byte >>= srcbpp;
                }
                for (; c < width; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    bit = (byte & mask);
                    if (bit != ckey) {
                        *dst = palmap[bit];
                    }
                    dst++;
                    byte >>= srcbpp;
                }
                src += srcskip;
                dst += dstskip;
            }
        } else {
            while (height--) {
                Uint8 byte = 0, bit;
                for (c = 0; c < info->leading_skip; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    byte <<= srcbpp;
                }
                for (; c < width; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    bit = (byte >> (8 - srcbpp)) & mask;
                    if (bit != ckey) {
                        *dst = palmap[bit];
                    }
                    dst++;
                    byte <<= srcbpp;
                }
                src += srcskip;
                dst += dstskip;
            }
        }
    } else {
        if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
            while (height--) {
                Uint8 byte = 0, bit;
                for (c = 0; c < info->leading_skip; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    byte >>= srcbpp;
                }
                for (; c < width; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    bit = (byte & mask);
                    if (bit != ckey) {
                        *dst = bit;
                    }
                    dst++;
                    byte >>= srcbpp;
                }
                src += srcskip;
                dst += dstskip;
            }
        } else {
            while (height--) {
                Uint8 byte = 0, bit;
                for (c = 0; c < info->leading_skip; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    byte <<= srcbpp;
                }
                for (; c < width; ++c) {
                    if (!(c & align)) {
                        byte = *src++;
                    }
                    bit = (byte >> (8 - srcbpp)) & mask;
                    if (bit != ckey) {
                        *dst = bit;
                    }
                    dst++;
                    byte <<= srcbpp;
                }
                src += srcskip;
                dst += dstskip;
            }
        }
    }
}

SDL_FORCE_INLINE void BlitBto2Key(SDL_BlitInfo *info, const Uint32 srcbpp)
{
    const Uint32 mask = (1 << srcbpp) - 1;
    const Uint32 align = (8 / srcbpp) - 1;

    int width = info->dst_w;
    int height = info->dst_h;
    Uint8 *src = info->src;
    Uint16 *dstp = (Uint16 *)info->dst;
    int srcskip = info->src_skip;
    int dstskip = info->dst_skip;
    Uint32 ckey = info->colorkey;
    Uint8 *palmap = info->table;
    int c;

    width += info->leading_skip;

    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;
    dstskip /= 2;

    if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte >>= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte & mask);
                if (bit != ckey) {
                    *dstp = ((Uint16 *)palmap)[bit];
                }
                byte >>= srcbpp;
                dstp++;
            }
            src += srcskip;
            dstp += dstskip;
        }
    } else {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte <<= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte >> (8 - srcbpp)) & mask;
                if (bit != ckey) {
                    *dstp = ((Uint16 *)palmap)[bit];
                }
                byte <<= srcbpp;
                dstp++;
            }
            src += srcskip;
            dstp += dstskip;
        }
    }
}

SDL_FORCE_INLINE void BlitBto3Key(SDL_BlitInfo *info, const Uint32 srcbpp)
{
    const Uint32 mask = (1 << srcbpp) - 1;
    const Uint32 align = (8 / srcbpp) - 1;

    int width = info->dst_w;
    int height = info->dst_h;
    Uint8 *src = info->src;
    Uint8 *dst = info->dst;
    int srcskip = info->src_skip;
    int dstskip = info->dst_skip;
    Uint32 ckey = info->colorkey;
    Uint8 *palmap = info->table;
    int c;

    width += info->leading_skip;

    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;

    if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte >>= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte & mask);
                if (bit != ckey) {
                    SDL_memcpy(dst, &palmap[bit * 4], 3);
                }
                byte >>= srcbpp;
                dst += 3;
            }
            src += srcskip;
            dst += dstskip;
        }
    } else {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte <<= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte >> (8 - srcbpp)) & mask;
                if (bit != ckey) {
                    SDL_memcpy(dst, &palmap[bit * 4], 3);
                }
                byte <<= srcbpp;
                dst += 3;
            }
            src += srcskip;
            dst += dstskip;
        }
    }
}

SDL_FORCE_INLINE void BlitBto4Key(SDL_BlitInfo *info, const Uint32 srcbpp)
{
    const Uint32 mask = (1 << srcbpp) - 1;
    const Uint32 align = (8 / srcbpp) - 1;

    int width = info->dst_w;
    int height = info->dst_h;
    Uint8 *src = info->src;
    Uint32 *dstp = (Uint32 *)info->dst;
    int srcskip = info->src_skip;
    int dstskip = info->dst_skip;
    Uint32 ckey = info->colorkey;
    Uint8 *palmap = info->table;
    int c;

    width += info->leading_skip;

    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;
    dstskip /= 4;

    if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte >>= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte & mask);
                if (bit != ckey) {
                    *dstp = ((Uint32 *)palmap)[bit];
                }
                byte >>= srcbpp;
                dstp++;
            }
            src += srcskip;
            dstp += dstskip;
        }
    } else {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte <<= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte >> (8 - srcbpp)) & mask;
                if (bit != ckey) {
                    *dstp = ((Uint32 *)palmap)[bit];
                }
                byte <<= srcbpp;
                dstp++;
            }
            src += srcskip;
            dstp += dstskip;
        }
    }
}

static void BlitBtoNAlpha(SDL_BlitInfo *info)
{
    int width = info->dst_w;
    int height = info->dst_h;
    Uint8 *src = info->src;
    Uint8 *dst = info->dst;
    int srcskip = info->src_skip;
    int dstskip = info->dst_skip;
    const SDL_Color *srcpal = info->src_pal->colors;
    const SDL_PixelFormatDetails *srcfmt = info->src_fmt;
    const SDL_PixelFormatDetails *dstfmt = info->dst_fmt;
    int srcbpp, dstbpp;
    int c;
    Uint32 pixelvalue, mask, align;
    unsigned sR, sG, sB;
    unsigned dR, dG, dB, dA;
    const unsigned A = info->a;

    width += info->leading_skip;

    srcbpp = srcfmt->bytes_per_pixel;
    dstbpp = dstfmt->bytes_per_pixel;
    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;
    mask = (1 << srcbpp) - 1;
    align = (8 / srcbpp) - 1;

    if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte >>= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte & mask);
                if (1) {
                    sR = srcpal[bit].r;
                    sG = srcpal[bit].g;
                    sB = srcpal[bit].b;
                    DISEMBLE_RGBA(dst, dstbpp, dstfmt, pixelvalue, dR, dG, dB, dA);
                    ALPHA_BLEND_RGBA(sR, sG, sB, A, dR, dG, dB, dA);
                    ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
                }
                byte >>= srcbpp;
                dst += dstbpp;
            }
            src += srcskip;
            dst += dstskip;
        }
    } else {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte <<= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte >> (8 - srcbpp)) & mask;
                if (1) {
                    sR = srcpal[bit].r;
                    sG = srcpal[bit].g;
                    sB = srcpal[bit].b;
                    DISEMBLE_RGBA(dst, dstbpp, dstfmt, pixelvalue, dR, dG, dB, dA);
                    ALPHA_BLEND_RGBA(sR, sG, sB, A, dR, dG, dB, dA);
                    ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
                }
                byte <<= srcbpp;
                dst += dstbpp;
            }
            src += srcskip;
            dst += dstskip;
        }
    }
}

static void BlitBtoNAlphaKey(SDL_BlitInfo *info)
{
    int width = info->dst_w;
    int height = info->dst_h;
    Uint8 *src = info->src;
    Uint8 *dst = info->dst;
    int srcskip = info->src_skip;
    int dstskip = info->dst_skip;
    const SDL_PixelFormatDetails *srcfmt = info->src_fmt;
    const SDL_PixelFormatDetails *dstfmt = info->dst_fmt;
    const SDL_Color *srcpal = info->src_pal->colors;
    int srcbpp, dstbpp;
    int c;
    Uint32 pixelvalue, mask, align;
    unsigned sR, sG, sB;
    unsigned dR, dG, dB, dA;
    const unsigned A = info->a;
    Uint32 ckey = info->colorkey;

    width += info->leading_skip;

    srcbpp = srcfmt->bytes_per_pixel;
    dstbpp = dstfmt->bytes_per_pixel;
    if (srcbpp == 4)
        srcskip += width - (width + 1) / 2;
    else if (srcbpp == 2)
        srcskip += width - (width + 3) / 4;
    else if (srcbpp == 1)
        srcskip += width - (width + 7) / 8;
    mask = (1 << srcbpp) - 1;
    align = (8 / srcbpp) - 1;

    if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte >>= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte & mask);
                if (bit != ckey) {
                    sR = srcpal[bit].r;
                    sG = srcpal[bit].g;
                    sB = srcpal[bit].b;
                    DISEMBLE_RGBA(dst, dstbpp, dstfmt, pixelvalue, dR, dG, dB, dA);
                    ALPHA_BLEND_RGBA(sR, sG, sB, A, dR, dG, dB, dA);
                    ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
                }
                byte >>= srcbpp;
                dst += dstbpp;
            }
            src += srcskip;
            dst += dstskip;
        }
    } else {
        while (height--) {
            Uint8 byte = 0, bit;
            for (c = 0; c < info->leading_skip; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                byte <<= srcbpp;
            }
            for (; c < width; ++c) {
                if (!(c & align)) {
                    byte = *src++;
                }
                bit = (byte >> (8 - srcbpp)) & mask;
                if (bit != ckey) {
                    sR = srcpal[bit].r;
                    sG = srcpal[bit].g;
                    sB = srcpal[bit].b;
                    DISEMBLE_RGBA(dst, dstbpp, dstfmt, pixelvalue, dR, dG, dB, dA);
                    ALPHA_BLEND_RGBA(sR, sG, sB, A, dR, dG, dB, dA);
                    ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
                }
                byte <<= srcbpp;
                dst += dstbpp;
            }
            src += srcskip;
            dst += dstskip;
        }
    }
}



static void Blit1bto1(SDL_BlitInfo *info) {
    BlitBto1(info, 1);
}

static void Blit1bto2(SDL_BlitInfo *info) {
    BlitBto2(info, 1);
}

static void Blit1bto3(SDL_BlitInfo *info) {
    BlitBto3(info, 1);
}

static void Blit1bto4(SDL_BlitInfo *info) {
    BlitBto4(info, 1);
}

static const SDL_BlitFunc bitmap_blit_1b[] = {
    (SDL_BlitFunc)NULL, Blit1bto1, Blit1bto2, Blit1bto3, Blit1bto4
};

static void Blit1bto1Key(SDL_BlitInfo *info) {
    BlitBto1Key(info, 1);
}

static void Blit1bto2Key(SDL_BlitInfo *info) {
    BlitBto2Key(info, 1);
}

static void Blit1bto3Key(SDL_BlitInfo *info) {
    BlitBto3Key(info, 1);
}

static void Blit1bto4Key(SDL_BlitInfo *info) {
    BlitBto4Key(info, 1);
}

static const SDL_BlitFunc colorkey_blit_1b[] = {
    (SDL_BlitFunc)NULL, Blit1bto1Key, Blit1bto2Key, Blit1bto3Key, Blit1bto4Key
};



static void Blit2bto1(SDL_BlitInfo *info) {
    BlitBto1(info, 2);
}

static void Blit2bto2(SDL_BlitInfo *info) {
    BlitBto2(info, 2);
}

static void Blit2bto3(SDL_BlitInfo *info) {
    BlitBto3(info, 2);
}

static void Blit2bto4(SDL_BlitInfo *info) {
    BlitBto4(info, 2);
}

static const SDL_BlitFunc bitmap_blit_2b[] = {
    (SDL_BlitFunc)NULL, Blit2bto1, Blit2bto2, Blit2bto3, Blit2bto4
};

static void Blit2bto1Key(SDL_BlitInfo *info) {
    BlitBto1Key(info, 2);
}

static void Blit2bto2Key(SDL_BlitInfo *info) {
    BlitBto2Key(info, 2);
}

static void Blit2bto3Key(SDL_BlitInfo *info) {
    BlitBto3Key(info, 2);
}

static void Blit2bto4Key(SDL_BlitInfo *info) {
    BlitBto4Key(info, 2);
}

static const SDL_BlitFunc colorkey_blit_2b[] = {
    (SDL_BlitFunc)NULL, Blit2bto1Key, Blit2bto2Key, Blit2bto3Key, Blit2bto4Key
};



static void Blit4bto1(SDL_BlitInfo *info) {
    BlitBto1(info, 4);
}

static void Blit4bto2(SDL_BlitInfo *info) {
    BlitBto2(info, 4);
}

static void Blit4bto3(SDL_BlitInfo *info) {
    BlitBto3(info, 4);
}

static void Blit4bto4(SDL_BlitInfo *info) {
    BlitBto4(info, 4);
}

static const SDL_BlitFunc bitmap_blit_4b[] = {
    (SDL_BlitFunc)NULL, Blit4bto1, Blit4bto2, Blit4bto3, Blit4bto4
};

static void Blit4bto1Key(SDL_BlitInfo *info) {
    BlitBto1Key(info, 4);
}

static void Blit4bto2Key(SDL_BlitInfo *info) {
    BlitBto2Key(info, 4);
}

static void Blit4bto3Key(SDL_BlitInfo *info) {
    BlitBto3Key(info, 4);
}

static void Blit4bto4Key(SDL_BlitInfo *info) {
    BlitBto4Key(info, 4);
}

static const SDL_BlitFunc colorkey_blit_4b[] = {
    (SDL_BlitFunc)NULL, Blit4bto1Key, Blit4bto2Key, Blit4bto3Key, Blit4bto4Key
};



SDL_BlitFunc SDL_CalculateBlit0(SDL_Surface *surface)
{
    int which;

    if (SDL_BITSPERPIXEL(surface->map.info.dst_fmt->format) < 8) {
        which = 0;
    } else {
        which = SDL_BYTESPERPIXEL(surface->map.info.dst_fmt->format);
    }

    if (SDL_PIXELTYPE(surface->format) == SDL_PIXELTYPE_INDEX1) {
        switch (surface->map.info.flags & ~SDL_COPY_RLE_MASK) {
        case 0:
            if (which < SDL_arraysize(bitmap_blit_1b)) {
                return bitmap_blit_1b[which];
            }
            break;

        case SDL_COPY_COLORKEY:
            if (which < SDL_arraysize(colorkey_blit_1b)) {
                return colorkey_blit_1b[which];
            }
            break;

        case SDL_COPY_MODULATE_ALPHA | SDL_COPY_BLEND:
            return which >= 2 ? BlitBtoNAlpha : (SDL_BlitFunc)NULL;

        case SDL_COPY_COLORKEY | SDL_COPY_MODULATE_ALPHA | SDL_COPY_BLEND:
            return which >= 2 ? BlitBtoNAlphaKey : (SDL_BlitFunc)NULL;
        }
        return NULL;
    }

    if (SDL_PIXELTYPE(surface->format) == SDL_PIXELTYPE_INDEX2) {
        switch (surface->map.info.flags & ~SDL_COPY_RLE_MASK) {
        case 0:
            if (which < SDL_arraysize(bitmap_blit_2b)) {
                return bitmap_blit_2b[which];
            }
            break;

        case SDL_COPY_COLORKEY:
            if (which < SDL_arraysize(colorkey_blit_2b)) {
                return colorkey_blit_2b[which];
            }
            break;

        case SDL_COPY_MODULATE_ALPHA | SDL_COPY_BLEND:
            return which >= 2 ? BlitBtoNAlpha : (SDL_BlitFunc)NULL;

        case SDL_COPY_COLORKEY | SDL_COPY_MODULATE_ALPHA | SDL_COPY_BLEND:
            return which >= 2 ? BlitBtoNAlphaKey : (SDL_BlitFunc)NULL;
        }
        return NULL;
    }

    if (SDL_PIXELTYPE(surface->format) == SDL_PIXELTYPE_INDEX4) {
        switch (surface->map.info.flags & ~SDL_COPY_RLE_MASK) {
        case 0:
            if (which < SDL_arraysize(bitmap_blit_4b)) {
                return bitmap_blit_4b[which];
            }
            break;

        case SDL_COPY_COLORKEY:
            if (which < SDL_arraysize(colorkey_blit_4b)) {
                return colorkey_blit_4b[which];
            }
            break;

        case SDL_COPY_MODULATE_ALPHA | SDL_COPY_BLEND:
            return which >= 2 ? BlitBtoNAlpha : (SDL_BlitFunc)NULL;

        case SDL_COPY_COLORKEY | SDL_COPY_MODULATE_ALPHA | SDL_COPY_BLEND:
            return which >= 2 ? BlitBtoNAlphaKey : (SDL_BlitFunc)NULL;
        }
        return NULL;
    }

    return NULL;
}

#endif // SDL_HAVE_BLIT_0