src/video/SDL_blit.c
author Sam Lantinga <slouken@libsdl.org>
Fri, 11 Oct 2002 07:56:36 +0000
changeset 526 4314a501d7be
parent 310 c97c1d3b3b5c
child 689 5bb080d35049
permissions -rw-r--r--
Fixed a crash blitting RLE surfaces to RLE surfaces
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/*
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    SDL - Simple DirectMedia Layer
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    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  Sam Lantinga
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    This library is free software; you can redistribute it and/or
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    modify it under the terms of the GNU Library General Public
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    License as published by the Free Software Foundation; either
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    version 2 of the License, or (at your option) any later version.
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    This library is distributed in the hope that it will be useful,
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
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    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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    Library General Public License for more details.
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    You should have received a copy of the GNU Library General Public
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    License along with this library; if not, write to the Free
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    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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    Sam Lantinga
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    slouken@libsdl.org
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*/
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#ifdef SAVE_RCSID
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static char rcsid =
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 "@(#) $Id$";
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "SDL_error.h"
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#include "SDL_video.h"
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#include "SDL_sysvideo.h"
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#include "SDL_blit.h"
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#include "SDL_RLEaccel_c.h"
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#include "SDL_pixels_c.h"
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#include "SDL_memops.h"
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/* The general purpose software blit routine */
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static int SDL_SoftBlit(SDL_Surface *src, SDL_Rect *srcrect,
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			SDL_Surface *dst, SDL_Rect *dstrect)
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{
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	int okay;
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	int src_locked;
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	int dst_locked;
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	/* Everything is okay at the beginning...  */
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	okay = 1;
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	/* Lock the destination if it's in hardware */
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	dst_locked = 0;
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	if ( SDL_MUSTLOCK(dst) ) {
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		if ( SDL_LockSurface(dst) < 0 ) {
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			okay = 0;
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		} else {
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			dst_locked = 1;
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		}
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	}
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	/* Lock the source if it's in hardware */
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	src_locked = 0;
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	if ( SDL_MUSTLOCK(src) ) {
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		if ( SDL_LockSurface(src) < 0 ) {
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			okay = 0;
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		} else {
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			src_locked = 1;
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		}
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	}
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	/* Set up source and destination buffer pointers, and BLIT! */
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	if ( okay  && srcrect->w && srcrect->h ) {
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		SDL_BlitInfo info;
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		SDL_loblit RunBlit;
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		/* Set up the blit information */
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		info.s_pixels = (Uint8 *)src->pixels +
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				(Uint16)srcrect->y*src->pitch +
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				(Uint16)srcrect->x*src->format->BytesPerPixel;
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		info.s_width = srcrect->w;
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		info.s_height = srcrect->h;
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		info.s_skip=src->pitch-info.s_width*src->format->BytesPerPixel;
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		info.d_pixels = (Uint8 *)dst->pixels +
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				(Uint16)dstrect->y*dst->pitch +
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				(Uint16)dstrect->x*dst->format->BytesPerPixel;
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		info.d_width = dstrect->w;
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		info.d_height = dstrect->h;
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		info.d_skip=dst->pitch-info.d_width*dst->format->BytesPerPixel;
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		info.aux_data = src->map->sw_data->aux_data;
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		info.src = src->format;
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		info.table = src->map->table;
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		info.dst = dst->format;
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		RunBlit = src->map->sw_data->blit;
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		/* Run the actual software blit */
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		RunBlit(&info);
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	}
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	/* We need to unlock the surfaces if they're locked */
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	if ( dst_locked ) {
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		SDL_UnlockSurface(dst);
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	}
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	if ( src_locked ) {
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		SDL_UnlockSurface(src);
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	}
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	/* Blit is done! */
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	return(okay ? 0 : -1);
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}
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static void SDL_BlitCopy(SDL_BlitInfo *info)
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{
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	Uint8 *src, *dst;
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	int w, h;
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	int srcskip, dstskip;
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	w = info->d_width*info->dst->BytesPerPixel;
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	h = info->d_height;
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	src = info->s_pixels;
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	dst = info->d_pixels;
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	srcskip = w+info->s_skip;
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	dstskip = w+info->d_skip;
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	while ( h-- ) {
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		SDL_memcpy(dst, src, w);
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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 SDL_BlitCopyOverlap(SDL_BlitInfo *info)
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{
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	Uint8 *src, *dst;
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	int w, h;
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	int srcskip, dstskip;
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	w = info->d_width*info->dst->BytesPerPixel;
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	h = info->d_height;
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	src = info->s_pixels;
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	dst = info->d_pixels;
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	srcskip = w+info->s_skip;
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	dstskip = w+info->d_skip;
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	if ( dst < src ) {
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		while ( h-- ) {
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			SDL_memcpy(dst, src, w);
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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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		src += ((h-1) * srcskip);
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		dst += ((h-1) * dstskip);
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		while ( h-- ) {
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			SDL_revcpy(dst, src, w);
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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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/* Figure out which of many blit routines to set up on a surface */
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int SDL_CalculateBlit(SDL_Surface *surface)
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{
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	int blit_index;
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	/* Clean everything out to start */
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	if ( (surface->flags & SDL_RLEACCEL) == SDL_RLEACCEL ) {
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		SDL_UnRLESurface(surface, 1);
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	}
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	surface->map->sw_blit = NULL;
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	/* Figure out if an accelerated hardware blit is possible */
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	surface->flags &= ~SDL_HWACCEL;
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	if ( surface->map->identity ) {
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		int hw_blit_ok;
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		if ( (surface->flags & SDL_HWSURFACE) == SDL_HWSURFACE ) {
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			/* We only support accelerated blitting to hardware */
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			if ( surface->map->dst->flags & SDL_HWSURFACE ) {
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				hw_blit_ok = current_video->info.blit_hw;
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			} else {
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				hw_blit_ok = 0;
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			}
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			if (hw_blit_ok && (surface->flags & SDL_SRCCOLORKEY)) {
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				hw_blit_ok = current_video->info.blit_hw_CC;
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			}
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			if ( hw_blit_ok && (surface->flags & SDL_SRCALPHA) ) {
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				hw_blit_ok = current_video->info.blit_hw_A;
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			}
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		} else {
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			/* We only support accelerated blitting to hardware */
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			if ( surface->map->dst->flags & SDL_HWSURFACE ) {
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				hw_blit_ok = current_video->info.blit_sw;
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			} else {
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				hw_blit_ok = 0;
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			}
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			if (hw_blit_ok && (surface->flags & SDL_SRCCOLORKEY)) {
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				hw_blit_ok = current_video->info.blit_sw_CC;
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			}
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			if ( hw_blit_ok && (surface->flags & SDL_SRCALPHA) ) {
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				hw_blit_ok = current_video->info.blit_sw_A;
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			}
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		}
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		if ( hw_blit_ok ) {
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			SDL_VideoDevice *video = current_video;
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			SDL_VideoDevice *this  = current_video;
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			video->CheckHWBlit(this, surface, surface->map->dst);
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		}
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	}
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	/* Get the blit function index, based on surface mode */
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	/* { 0 = nothing, 1 = colorkey, 2 = alpha, 3 = colorkey+alpha } */
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	blit_index = 0;
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	blit_index |= (!!(surface->flags & SDL_SRCCOLORKEY))      << 0;
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	if ( surface->flags & SDL_SRCALPHA
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	     && (surface->format->alpha != SDL_ALPHA_OPAQUE
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		 || surface->format->Amask) ) {
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	        blit_index |= 2;
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	}
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	/* Check for special "identity" case -- copy blit */
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	if ( surface->map->identity && blit_index == 0 ) {
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	        surface->map->sw_data->blit = SDL_BlitCopy;
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		/* Handle overlapping blits on the same surface */
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		if ( surface == surface->map->dst ) {
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		        surface->map->sw_data->blit = SDL_BlitCopyOverlap;
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		}
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	} else {
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		if ( surface->format->BitsPerPixel < 8 ) {
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			surface->map->sw_data->blit =
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			    SDL_CalculateBlit0(surface, blit_index);
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		} else {
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			switch ( surface->format->BytesPerPixel ) {
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			    case 1:
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				surface->map->sw_data->blit =
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				    SDL_CalculateBlit1(surface, blit_index);
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				break;
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			    case 2:
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			    case 3:
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			    case 4:
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				surface->map->sw_data->blit =
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				    SDL_CalculateBlitN(surface, blit_index);
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				break;
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			    default:
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				surface->map->sw_data->blit = NULL;
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				break;
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			}
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		}
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	}
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	/* Make sure we have a blit function */
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	if ( surface->map->sw_data->blit == NULL ) {
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		SDL_InvalidateMap(surface->map);
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		SDL_SetError("Blit combination not supported");
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		return(-1);
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	}
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	/* Choose software blitting function */
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	if(surface->flags & SDL_RLEACCELOK
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	   && (surface->flags & SDL_HWACCEL) != SDL_HWACCEL) {
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	        if(surface->map->identity
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		   && (blit_index == 1
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		       || (blit_index == 3 && !surface->format->Amask))) {
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		        if ( SDL_RLESurface(surface) == 0 )
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			        surface->map->sw_blit = SDL_RLEBlit;
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		} else if(blit_index == 2 && surface->format->Amask) {
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		        if ( SDL_RLESurface(surface) == 0 )
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			        surface->map->sw_blit = SDL_RLEAlphaBlit;
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		}
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	}
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	if ( surface->map->sw_blit == NULL ) {
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		surface->map->sw_blit = SDL_SoftBlit;
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	}
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	return(0);
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}
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