IMG_pcx.c
author Sam Lantinga <slouken@libsdl.org>
Sun, 04 Jan 2004 22:04:38 +0000
changeset 98 9f94c4674cc9
parent 97 e1161bd417c4
child 117 e613cf987897
permissions -rw-r--r--
Added checks for NULL data sources to individual loaders.
Apps shouldn't be calling them, but they do. Naughty naughty! :)
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/*
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    SDL_image:  An example image loading library for use with SDL
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    Copyright (C) 1999-2004 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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/* $Id$ */
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/*
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 * PCX file reader:
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 * Supports:
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 *  1..4 bits/pixel in multiplanar format (1 bit/plane/pixel)
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 *  8 bits/pixel in single-planar format (8 bits/plane/pixel)
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 *  24 bits/pixel in 3-plane format (8 bits/plane/pixel)
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 *
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 * (The <8bpp formats are expanded to 8bpp surfaces)
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 *
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 * Doesn't support:
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 *  single-planar packed-pixel formats other than 8bpp
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 *  4-plane 32bpp format with a fourth "intensity" plane
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 */
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#include <stdio.h>
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#include <stdlib.h>
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#include "SDL_endian.h"
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#include "SDL_image.h"
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#ifdef LOAD_PCX
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struct PCXheader {
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	Uint8 Manufacturer;
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	Uint8 Version;
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	Uint8 Encoding;
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	Uint8 BitsPerPixel;
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	Sint16 Xmin, Ymin, Xmax, Ymax;
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	Sint16 HDpi, VDpi;
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	Uint8 Colormap[48];
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	Uint8 Reserved;
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	Uint8 NPlanes;
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	Sint16 BytesPerLine;
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	Sint16 PaletteInfo;
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	Sint16 HscreenSize;
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	Sint16 VscreenSize;
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	Uint8 Filler[54];
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};
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/* See if an image is contained in a data source */
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int IMG_isPCX(SDL_RWops *src)
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{
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	int is_PCX;
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	const int ZSoft_Manufacturer = 10;
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	const int PC_Paintbrush_Version = 5;
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	const int PCX_RunLength_Encoding = 1;
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	struct PCXheader pcxh;
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	is_PCX = 0;
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	if ( SDL_RWread(src, &pcxh, sizeof(pcxh), 1) == 1 ) {
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		if ( (pcxh.Manufacturer == ZSoft_Manufacturer) &&
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		     (pcxh.Version == PC_Paintbrush_Version) &&
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		     (pcxh.Encoding == PCX_RunLength_Encoding) ) {
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			is_PCX = 1;
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		}
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	}
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	return(is_PCX);
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}
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/* Load a PCX type image from an SDL datasource */
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SDL_Surface *IMG_LoadPCX_RW(SDL_RWops *src)
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{
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	struct PCXheader pcxh;
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	Uint32 Rmask;
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	Uint32 Gmask;
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	Uint32 Bmask;
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	Uint32 Amask;
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	SDL_Surface *surface = NULL;
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	int width, height;
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	int y, bpl;
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	Uint8 *row, *buf = NULL;
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	char *error = NULL;
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	int bits, src_bits;
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	if ( !src ) {
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		/* The error message has been set in SDL_RWFromFile */
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		return NULL;
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	}
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	if ( ! SDL_RWread(src, &pcxh, sizeof(pcxh), 1) ) {
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		error = "file truncated";
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		goto done;
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	}
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	pcxh.Xmin = SDL_SwapLE16(pcxh.Xmin);
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	pcxh.Ymin = SDL_SwapLE16(pcxh.Ymin);
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	pcxh.Xmax = SDL_SwapLE16(pcxh.Xmax);
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	pcxh.Ymax = SDL_SwapLE16(pcxh.Ymax);
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	pcxh.BytesPerLine = SDL_SwapLE16(pcxh.BytesPerLine);
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	/* Create the surface of the appropriate type */
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	width = (pcxh.Xmax - pcxh.Xmin) + 1;
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	height = (pcxh.Ymax - pcxh.Ymin) + 1;
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	Rmask = Gmask = Bmask = Amask = 0;
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	src_bits = pcxh.BitsPerPixel * pcxh.NPlanes;
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	if((pcxh.BitsPerPixel == 1 && pcxh.NPlanes >= 1 && pcxh.NPlanes <= 4)
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	   || (pcxh.BitsPerPixel == 8 && pcxh.NPlanes == 1)) {
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		bits = 8;
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	} else if(pcxh.BitsPerPixel == 8 && pcxh.NPlanes == 3) {
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		bits = 24;
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		if ( SDL_BYTEORDER == SDL_LIL_ENDIAN ) {
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			Rmask = 0x000000FF;
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			Gmask = 0x0000FF00;
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			Bmask = 0x00FF0000;
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		} else {
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			Rmask = 0xFF0000;
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			Gmask = 0x00FF00;
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			Bmask = 0x0000FF;
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		}
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	} else {
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		error = "unsupported PCX format";
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		goto done;
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	}
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	surface = SDL_AllocSurface(SDL_SWSURFACE, width, height,
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				   bits, Rmask, Gmask, Bmask, Amask);
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	if ( surface == NULL )
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		goto done;
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	bpl = pcxh.NPlanes * pcxh.BytesPerLine;
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	buf = malloc(bpl);
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	row = surface->pixels;
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	for ( y=0; y<surface->h; ++y ) {
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		/* decode a scan line to a temporary buffer first */
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		int i, count = 0;
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		Uint8 ch;
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		Uint8 *dst = (src_bits == 8) ? row : buf;
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		for(i = 0; i < bpl; i++) {
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			if(!count) {
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				if(!SDL_RWread(src, &ch, 1, 1)) {
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					error = "file truncated";
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					goto done;
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				}
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				if( (ch & 0xc0) == 0xc0) {
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					count = ch & 0x3f;
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					if(!SDL_RWread(src, &ch, 1, 1)) {
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						error = "file truncated";
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						goto done;
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					}
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				} else
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					count = 1;
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			}
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			dst[i] = ch;
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			count--;
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		}
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		if(src_bits <= 4) {
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			/* expand planes to 1 byte/pixel */
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			Uint8 *src = buf;
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			int plane;
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			for(plane = 0; plane < pcxh.NPlanes; plane++) {
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				int i, j, x = 0;
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				for(i = 0; i < pcxh.BytesPerLine; i++) {
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					Uint8 byte = *src++;
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					for(j = 7; j >= 0; j--) {
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						unsigned bit = (byte >> j) & 1;
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						/* skip padding bits */
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						if (i * 8 + j >= width)
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							continue;
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						row[x++] |= bit << plane;
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					}
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				}
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			}
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 		} else if(src_bits == 24) {
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			/* de-interlace planes */
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			Uint8 *src = buf;
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			int plane;
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			for(plane = 0; plane < pcxh.NPlanes; plane++) {
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				int x;
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				dst = row + plane;
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				for(x = 0; x < width; x++) {
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					*dst = *src++;
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					dst += pcxh.NPlanes;
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				}
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			}
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		}
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		row += surface->pitch;
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	}
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	if(bits == 8) {
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		SDL_Color *colors = surface->format->palette->colors;
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		int nc = 1 << src_bits;
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		int i;
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		surface->format->palette->ncolors = nc;
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		if(src_bits == 8) {
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			Uint8 ch;
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			/* look for a 256-colour palette */
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			do {
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				if ( !SDL_RWread(src, &ch, 1, 1)) {
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					error = "file truncated";
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					goto done;
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				}
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			} while ( ch != 12 );
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			for(i = 0; i < 256; i++) {
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				SDL_RWread(src, &colors[i].r, 1, 1);
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				SDL_RWread(src, &colors[i].g, 1, 1);
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				SDL_RWread(src, &colors[i].b, 1, 1);
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			}
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		} else {
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			for(i = 0; i < nc; i++) {
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				colors[i].r = pcxh.Colormap[i * 3];
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				colors[i].g = pcxh.Colormap[i * 3 + 1];
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				colors[i].b = pcxh.Colormap[i * 3 + 2];
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			}
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		}
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	}
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done:
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	free(buf);
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	if ( error ) {
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		SDL_FreeSurface(surface);
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		IMG_SetError(error);
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		surface = NULL;
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	}
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	return(surface);
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}
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#else
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/* See if an image is contained in a data source */
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int IMG_isPCX(SDL_RWops *src)
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{
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	return(0);
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}
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/* Load a PCX type image from an SDL datasource */
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SDL_Surface *IMG_LoadPCX_RW(SDL_RWops *src)
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{
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	return(NULL);
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}
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#endif /* LOAD_PCX */