src/video/SDL_blit_1.c
author Sam Lantinga <slouken@libsdl.org>
Tue, 23 Jul 2013 08:06:49 -0700
changeset 7502 6ff02ff3cf06
parent 6967 adc80d085ddf
child 8093 b43765095a6f
permissions -rw-r--r--
Updated blend semantics so blending uses the following formula:
dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA))
dstA = srcA + (dstA * (1-srcA))
This allows proper compositing semantics without requiring premultiplied alpha.

Needs full unit test coverage and bug fixes!
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/*
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  Simple DirectMedia Layer
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  Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>
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  This software is provided 'as-is', without any express or implied
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  warranty.  In no event will the authors be held liable for any damages
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  arising from the use of this software.
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  Permission is granted to anyone to use this software for any purpose,
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  including commercial applications, and to alter it and redistribute it
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  freely, subject to the following restrictions:
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  1. The origin of this software must not be misrepresented; you must not
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     claim that you wrote the original software. If you use this software
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     in a product, an acknowledgment in the product documentation would be
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     appreciated but is not required.
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  2. Altered source versions must be plainly marked as such, and must not be
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     misrepresented as being the original software.
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  3. This notice may not be removed or altered from any source distribution.
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*/
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#include "SDL_config.h"
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#include "SDL_video.h"
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#include "SDL_blit.h"
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#include "SDL_sysvideo.h"
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#include "SDL_endian.h"
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/* Functions to blit from 8-bit surfaces to other surfaces */
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static void
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Blit1to1(SDL_BlitInfo * info)
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{
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#ifndef USE_DUFFS_LOOP
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    int c;
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#endif
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    int width, height;
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    Uint8 *src, *map, *dst;
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    int srcskip, dstskip;
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    /* Set up some basic variables */
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    width = info->dst_w;
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    height = info->dst_h;
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    src = info->src;
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    srcskip = info->src_skip;
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    dst = info->dst;
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    dstskip = info->dst_skip;
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    map = info->table;
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    while (height--) {
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#ifdef USE_DUFFS_LOOP
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        /* *INDENT-OFF* */
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		DUFFS_LOOP(
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			{
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			  *dst = map[*src];
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			}
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			dst++;
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			src++;
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		, width);
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        /* *INDENT-ON* */
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#else
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        for (c = width; c; --c) {
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            *dst = map[*src];
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            dst++;
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            src++;
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        }
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#endif
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        src += srcskip;
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        dst += dstskip;
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    }
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}
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/* This is now endian dependent */
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#if ( SDL_BYTEORDER == SDL_LIL_ENDIAN )
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#define HI	1
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#define LO	0
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#else /* ( SDL_BYTEORDER == SDL_BIG_ENDIAN ) */
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#define HI	0
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#define LO	1
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#endif
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static void
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Blit1to2(SDL_BlitInfo * info)
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{
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#ifndef USE_DUFFS_LOOP
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    int c;
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#endif
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    int width, height;
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    Uint8 *src, *dst;
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    Uint16 *map;
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    int srcskip, dstskip;
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    /* Set up some basic variables */
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    width = info->dst_w;
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    height = info->dst_h;
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    src = info->src;
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    srcskip = info->src_skip;
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    dst = info->dst;
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    dstskip = info->dst_skip;
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    map = (Uint16 *) info->table;
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#ifdef USE_DUFFS_LOOP
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    while (height--) {
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		/* *INDENT-OFF* */
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		DUFFS_LOOP(
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		{
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			*(Uint16 *)dst = map[*src++];
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			dst += 2;
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		},
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		width);
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		/* *INDENT-ON* */
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        src += srcskip;
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        dst += dstskip;
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    }
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#else
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    /* Memory align at 4-byte boundary, if necessary */
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    if ((long) dst & 0x03) {
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        /* Don't do anything if width is 0 */
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        if (width == 0) {
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            return;
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        }
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        --width;
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        while (height--) {
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            /* Perform copy alignment */
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            *(Uint16 *) dst = map[*src++];
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            dst += 2;
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            /* Copy in 4 pixel chunks */
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            for (c = width / 4; c; --c) {
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                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
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                src += 2;
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                dst += 4;
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                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
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                src += 2;
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                dst += 4;
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            }
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            /* Get any leftovers */
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            switch (width & 3) {
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            case 3:
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                *(Uint16 *) dst = map[*src++];
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                dst += 2;
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            case 2:
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                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
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                src += 2;
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                dst += 4;
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                break;
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            case 1:
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                *(Uint16 *) dst = map[*src++];
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                dst += 2;
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                break;
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            }
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            src += srcskip;
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            dst += dstskip;
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        }
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    } else {
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        while (height--) {
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            /* Copy in 4 pixel chunks */
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            for (c = width / 4; c; --c) {
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                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
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                src += 2;
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                dst += 4;
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                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
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                src += 2;
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                dst += 4;
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            }
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            /* Get any leftovers */
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            switch (width & 3) {
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            case 3:
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                *(Uint16 *) dst = map[*src++];
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                dst += 2;
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            case 2:
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                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
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                src += 2;
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                dst += 4;
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                break;
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            case 1:
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                *(Uint16 *) dst = map[*src++];
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                dst += 2;
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                break;
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            }
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            src += srcskip;
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            dst += dstskip;
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        }
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    }
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#endif /* USE_DUFFS_LOOP */
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}
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static void
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Blit1to3(SDL_BlitInfo * info)
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{
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#ifndef USE_DUFFS_LOOP
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    int c;
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#endif
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    int o;
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    int width, height;
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    Uint8 *src, *map, *dst;
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    int srcskip, dstskip;
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    /* Set up some basic variables */
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    width = info->dst_w;
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    height = info->dst_h;
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    src = info->src;
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    srcskip = info->src_skip;
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    dst = info->dst;
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    dstskip = info->dst_skip;
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    map = info->table;
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    while (height--) {
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#ifdef USE_DUFFS_LOOP
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		/* *INDENT-OFF* */
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		DUFFS_LOOP(
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			{
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				o = *src * 4;
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				dst[0] = map[o++];
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				dst[1] = map[o++];
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				dst[2] = map[o++];
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			}
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			src++;
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			dst += 3;
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		, width);
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		/* *INDENT-ON* */
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#else
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        for (c = width; c; --c) {
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            o = *src * 4;
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            dst[0] = map[o++];
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            dst[1] = map[o++];
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            dst[2] = map[o++];
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            src++;
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            dst += 3;
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        }
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#endif /* USE_DUFFS_LOOP */
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        src += srcskip;
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        dst += dstskip;
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    }
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}
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static void
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Blit1to4(SDL_BlitInfo * info)
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{
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#ifndef USE_DUFFS_LOOP
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    int c;
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#endif
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    int width, height;
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    Uint8 *src;
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    Uint32 *map, *dst;
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    int srcskip, dstskip;
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    /* Set up some basic variables */
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    width = info->dst_w;
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    height = info->dst_h;
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    src = info->src;
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    srcskip = info->src_skip;
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    dst = (Uint32 *) info->dst;
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    dstskip = info->dst_skip / 4;
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    map = (Uint32 *) info->table;
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    while (height--) {
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#ifdef USE_DUFFS_LOOP
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		/* *INDENT-OFF* */
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		DUFFS_LOOP(
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			*dst++ = map[*src++];
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		, width);
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		/* *INDENT-ON* */
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#else
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        for (c = width / 4; c; --c) {
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            *dst++ = map[*src++];
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            *dst++ = map[*src++];
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            *dst++ = map[*src++];
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            *dst++ = map[*src++];
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        }
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        switch (width & 3) {
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        case 3:
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            *dst++ = map[*src++];
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        case 2:
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            *dst++ = map[*src++];
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        case 1:
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            *dst++ = map[*src++];
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        }
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#endif /* USE_DUFFS_LOOP */
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        src += srcskip;
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        dst += dstskip;
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    }
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}
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static void
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Blit1to1Key(SDL_BlitInfo * info)
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{
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    int width = info->dst_w;
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    int height = info->dst_h;
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    Uint8 *src = info->src;
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    int srcskip = info->src_skip;
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    Uint8 *dst = info->dst;
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    int dstskip = info->dst_skip;
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    Uint8 *palmap = info->table;
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    Uint32 ckey = info->colorkey;
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    if (palmap) {
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        while (height--) {
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			/* *INDENT-OFF* */
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			DUFFS_LOOP(
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			{
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				if ( *src != ckey ) {
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				  *dst = palmap[*src];
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				}
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				dst++;
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				src++;
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			},
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			width);
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			/* *INDENT-ON* */
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            src += srcskip;
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            dst += dstskip;
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        }
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    } else {
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        while (height--) {
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			/* *INDENT-OFF* */
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			DUFFS_LOOP(
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			{
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				if ( *src != ckey ) {
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				  *dst = *src;
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				}
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				dst++;
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				src++;
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			},
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			width);
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			/* *INDENT-ON* */
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            src += srcskip;
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            dst += dstskip;
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        }
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    }
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}
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static void
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Blit1to2Key(SDL_BlitInfo * info)
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{
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    int width = info->dst_w;
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    int height = info->dst_h;
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    Uint8 *src = info->src;
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    int srcskip = info->src_skip;
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    Uint16 *dstp = (Uint16 *) info->dst;
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    int dstskip = info->dst_skip;
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    Uint16 *palmap = (Uint16 *) info->table;
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    Uint32 ckey = info->colorkey;
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    /* Set up some basic variables */
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    dstskip /= 2;
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    while (height--) {
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		/* *INDENT-OFF* */
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		DUFFS_LOOP(
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		{
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			if ( *src != ckey ) {
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				*dstp=palmap[*src];
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   352
			}
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			src++;
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			dstp++;
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		},
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		width);
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		/* *INDENT-ON* */
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        src += srcskip;
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        dstp += dstskip;
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    }
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}
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static void
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Blit1to3Key(SDL_BlitInfo * info)
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   365
{
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    int width = info->dst_w;
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    int height = info->dst_h;
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   368
    Uint8 *src = info->src;
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    int srcskip = info->src_skip;
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    Uint8 *dst = info->dst;
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   371
    int dstskip = info->dst_skip;
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   372
    Uint8 *palmap = info->table;
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   373
    Uint32 ckey = info->colorkey;
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   374
    int o;
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   375
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   376
    while (height--) {
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		/* *INDENT-OFF* */
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   378
		DUFFS_LOOP(
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   379
		{
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   380
			if ( *src != ckey ) {
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   381
				o = *src * 4;
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   382
				dst[0] = palmap[o++];
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   383
				dst[1] = palmap[o++];
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   384
				dst[2] = palmap[o++];
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   385
			}
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   386
			src++;
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   387
			dst += 3;
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   388
		},
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   389
		width);
slouken@1895
   390
		/* *INDENT-ON* */
slouken@1895
   391
        src += srcskip;
slouken@1895
   392
        dst += dstskip;
slouken@1895
   393
    }
slouken@0
   394
}
slouken@0
   395
slouken@1895
   396
static void
slouken@1895
   397
Blit1to4Key(SDL_BlitInfo * info)
slouken@0
   398
{
slouken@2262
   399
    int width = info->dst_w;
slouken@2262
   400
    int height = info->dst_h;
slouken@2262
   401
    Uint8 *src = info->src;
slouken@2267
   402
    int srcskip = info->src_skip;
slouken@2262
   403
    Uint32 *dstp = (Uint32 *) info->dst;
slouken@2267
   404
    int dstskip = info->dst_skip;
slouken@1895
   405
    Uint32 *palmap = (Uint32 *) info->table;
slouken@2267
   406
    Uint32 ckey = info->colorkey;
slouken@0
   407
slouken@1895
   408
    /* Set up some basic variables */
slouken@1895
   409
    dstskip /= 4;
slouken@0
   410
slouken@1895
   411
    while (height--) {
slouken@1895
   412
		/* *INDENT-OFF* */
slouken@0
   413
		DUFFS_LOOP(
slouken@0
   414
		{
slouken@0
   415
			if ( *src != ckey ) {
slouken@0
   416
				*dstp = palmap[*src];
slouken@0
   417
			}
slouken@0
   418
			src++;
slouken@0
   419
			dstp++;
slouken@0
   420
		},
slouken@0
   421
		width);
slouken@1895
   422
		/* *INDENT-ON* */
slouken@1895
   423
        src += srcskip;
slouken@1895
   424
        dstp += dstskip;
slouken@1895
   425
    }
slouken@0
   426
}
slouken@0
   427
slouken@1895
   428
static void
slouken@1895
   429
Blit1toNAlpha(SDL_BlitInfo * info)
slouken@0
   430
{
slouken@2262
   431
    int width = info->dst_w;
slouken@2262
   432
    int height = info->dst_h;
slouken@2262
   433
    Uint8 *src = info->src;
slouken@2267
   434
    int srcskip = info->src_skip;
slouken@2262
   435
    Uint8 *dst = info->dst;
slouken@2267
   436
    int dstskip = info->dst_skip;
slouken@2267
   437
    SDL_PixelFormat *dstfmt = info->dst_fmt;
slouken@2267
   438
    const SDL_Color *srcpal = info->src_fmt->palette->colors;
slouken@1895
   439
    int dstbpp;
slouken@7502
   440
    Uint32 pixel;
slouken@7502
   441
    unsigned sR, sG, sB;
slouken@7502
   442
    unsigned dR, dG, dB, dA;
slouken@7502
   443
    const unsigned A = info->a;
slouken@0
   444
slouken@1895
   445
    /* Set up some basic variables */
slouken@1895
   446
    dstbpp = dstfmt->BytesPerPixel;
slouken@0
   447
slouken@1895
   448
    while (height--) {
slouken@7502
   449
        /* *INDENT-OFF* */
slouken@7502
   450
        DUFFS_LOOP4(
slouken@7502
   451
        {
slouken@7502
   452
            sR = srcpal[*src].r;
slouken@7502
   453
            sG = srcpal[*src].g;
slouken@7502
   454
            sB = srcpal[*src].b;
slouken@7502
   455
            DISEMBLE_RGBA(dst, dstbpp, dstfmt, pixel, dR, dG, dB, dA);
slouken@7502
   456
            ALPHA_BLEND_RGBA(sR, sG, sB, A, dR, dG, dB, dA);
slouken@7502
   457
            ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
slouken@7502
   458
            src++;
slouken@7502
   459
            dst += dstbpp;
slouken@7502
   460
        },
slouken@7502
   461
        width);
slouken@7502
   462
        /* *INDENT-ON* */
slouken@1895
   463
        src += srcskip;
slouken@1895
   464
        dst += dstskip;
slouken@1895
   465
    }
slouken@0
   466
}
slouken@0
   467
slouken@1895
   468
static void
slouken@1895
   469
Blit1toNAlphaKey(SDL_BlitInfo * info)
slouken@0
   470
{
slouken@2262
   471
    int width = info->dst_w;
slouken@2262
   472
    int height = info->dst_h;
slouken@2262
   473
    Uint8 *src = info->src;
slouken@2267
   474
    int srcskip = info->src_skip;
slouken@2262
   475
    Uint8 *dst = info->dst;
slouken@2267
   476
    int dstskip = info->dst_skip;
slouken@2267
   477
    SDL_PixelFormat *dstfmt = info->dst_fmt;
slouken@2267
   478
    const SDL_Color *srcpal = info->src_fmt->palette->colors;
slouken@2267
   479
    Uint32 ckey = info->colorkey;
slouken@1895
   480
    int dstbpp;
slouken@7502
   481
    Uint32 pixel;
slouken@7502
   482
    unsigned sR, sG, sB;
slouken@7502
   483
    unsigned dR, dG, dB, dA;
slouken@7502
   484
    const unsigned A = info->a;
slouken@0
   485
slouken@1895
   486
    /* Set up some basic variables */
slouken@1895
   487
    dstbpp = dstfmt->BytesPerPixel;
slouken@0
   488
slouken@1895
   489
    while (height--) {
slouken@1895
   490
		/* *INDENT-OFF* */
slouken@0
   491
		DUFFS_LOOP(
slouken@0
   492
		{
slouken@0
   493
			if ( *src != ckey ) {
slouken@0
   494
				sR = srcpal[*src].r;
slouken@0
   495
				sG = srcpal[*src].g;
slouken@0
   496
				sB = srcpal[*src].b;
slouken@7502
   497
				DISEMBLE_RGBA(dst, dstbpp, dstfmt, pixel, dR, dG, dB, dA);
slouken@7502
   498
				ALPHA_BLEND_RGBA(sR, sG, sB, A, dR, dG, dB, dA);
slouken@7502
   499
			  	ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
slouken@0
   500
			}
slouken@0
   501
			src++;
slouken@0
   502
			dst += dstbpp;
slouken@0
   503
		},
slouken@0
   504
		width);
slouken@1895
   505
		/* *INDENT-ON* */
slouken@1895
   506
        src += srcskip;
slouken@1895
   507
        dst += dstskip;
slouken@1895
   508
    }
slouken@0
   509
}
slouken@0
   510
slouken@3162
   511
static const SDL_BlitFunc one_blit[] = {
eviltypeguy@6967
   512
    (SDL_BlitFunc) NULL, Blit1to1, Blit1to2, Blit1to3, Blit1to4
slouken@0
   513
};
slouken@0
   514
slouken@3162
   515
static const SDL_BlitFunc one_blitkey[] = {
eviltypeguy@6967
   516
    (SDL_BlitFunc) NULL, Blit1to1Key, Blit1to2Key, Blit1to3Key, Blit1to4Key
slouken@0
   517
};
slouken@0
   518
slouken@2267
   519
SDL_BlitFunc
slouken@2267
   520
SDL_CalculateBlit1(SDL_Surface * surface)
slouken@0
   521
{
slouken@1895
   522
    int which;
slouken@1895
   523
    SDL_PixelFormat *dstfmt;
slouken@0
   524
slouken@1895
   525
    dstfmt = surface->map->dst->format;
slouken@1895
   526
    if (dstfmt->BitsPerPixel < 8) {
slouken@1895
   527
        which = 0;
slouken@1895
   528
    } else {
slouken@1895
   529
        which = dstfmt->BytesPerPixel;
slouken@1895
   530
    }
slouken@2853
   531
    switch (surface->map->info.flags & ~SDL_COPY_RLE_MASK) {
slouken@2267
   532
    case 0:
slouken@1895
   533
        return one_blit[which];
slouken@0
   534
slouken@2267
   535
    case SDL_COPY_COLORKEY:
slouken@1895
   536
        return one_blitkey[which];
slouken@0
   537
slouken@2267
   538
    case SDL_COPY_MODULATE_ALPHA | SDL_COPY_BLEND:
slouken@1895
   539
        /* Supporting 8bpp->8bpp alpha is doable but requires lots of
slouken@1895
   540
           tables which consume space and takes time to precompute,
slouken@1895
   541
           so is better left to the user */
eviltypeguy@6967
   542
        return which >= 2 ? Blit1toNAlpha : (SDL_BlitFunc) NULL;
slouken@0
   543
slouken@2267
   544
    case SDL_COPY_COLORKEY | SDL_COPY_MODULATE_ALPHA | SDL_COPY_BLEND:
eviltypeguy@6967
   545
        return which >= 2 ? Blit1toNAlphaKey : (SDL_BlitFunc) NULL;
slouken@1895
   546
    }
eviltypeguy@6967
   547
    return (SDL_BlitFunc) NULL;
slouken@0
   548
}
slouken@1895
   549
slouken@1895
   550
/* vi: set ts=4 sw=4 expandtab: */