IMG_lbm.c
author Sam Lantinga <slouken@libsdl.org>
Sun, 04 Jan 2004 17:41:55 +0000
changeset 97 e1161bd417c4
parent 96 cada40fddd77
child 98 9f94c4674cc9
permissions -rw-r--r--
Updated copyright information for 2004 (Happy New Year!)
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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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/* This is a ILBM image file loading framework
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   Load IFF pictures, PBM & ILBM packing methods, with or without stencil
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   Written by Daniel Morais ( Daniel@Morais.com ) in September 2001.
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   24 bits ILBM files support added by Marc Le Douarain (mavati AT club-internet
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   POINT fr) in December 2002.
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   EHB and HAM (specific Amiga graphic chip modes) support added by Marc Le Douarain
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   (mavati AT club-internet POINT fr) in December 2003.
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*/
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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_endian.h"
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#include "SDL_image.h"
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#ifdef LOAD_LBM
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#define MAXCOLORS 256
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/* Structure for an IFF picture ( BMHD = Bitmap Header ) */
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typedef struct
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{
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    Uint16 w, h;		/* width & height of the bitmap in pixels */
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    Sint16 x, y;		/* screen coordinates of the bitmap */
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    Uint8 planes;		/* number of planes of the bitmap */
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    Uint8 mask;			/* mask type ( 0 => no mask ) */
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    Uint8 tcomp;		/* compression type */
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    Uint8 pad1;			/* dummy value, for padding */
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    Uint16 tcolor;		/* transparent color */
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    Uint8 xAspect,		/* pixel aspect ratio */
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         yAspect;
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    Sint16  Lpage;		/* width of the screen in pixels */
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    Sint16  Hpage;		/* height of the screen in pixels */
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} BMHD;
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int IMG_isLBM( SDL_RWops *src )
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{
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	int   is_LBM;
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	Uint8 magic[4+4+4];
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	is_LBM = 0;
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	if ( SDL_RWread( src, magic, 4+4+4, 1 ) )
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	{
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		if ( !memcmp( magic, "FORM", 4 ) &&
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			( !memcmp( magic + 8, "PBM ", 4 ) ||
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			  !memcmp( magic + 8, "ILBM", 4 ) ) )
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		{
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			is_LBM = 1;
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		}
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	}
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	return( is_LBM );
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}
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SDL_Surface *IMG_LoadLBM_RW( SDL_RWops *src )
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{
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	SDL_Surface *Image;
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	Uint8       id[4], pbm, colormap[MAXCOLORS*3], *MiniBuf, *ptr, count, color, msk;
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	Uint32      size, bytesloaded, nbcolors;
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	Uint32      i, j, bytesperline, nbplanes, plane, h;
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	Uint32      remainingbytes;
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	Uint32      width;
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	BMHD	      bmhd;
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	char        *error;
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	Uint8       flagHAM,flagEHB;
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	Image   = NULL;
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	error   = NULL;
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	MiniBuf = NULL;
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	if ( !SDL_RWread( src, id, 4, 1 ) )
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	{
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		error="error reading IFF chunk";
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		goto done;
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	}
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	/* Should be the size of the file minus 4+4 ( 'FORM'+size ) */
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	if ( !SDL_RWread( src, &size, 4, 1 ) )
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	{
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		error="error reading IFF chunk size";
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		goto done;
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	}
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	/* As size is not used here, no need to swap it */
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	if ( memcmp( id, "FORM", 4 ) != 0 )
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	{
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		error="not a IFF file";
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		goto done;
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	}
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	if ( !SDL_RWread( src, id, 4, 1 ) )
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	{
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		error="error reading IFF chunk";
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		goto done;
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	}
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	pbm = 0;
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	/* File format : PBM=Packed Bitmap, ILBM=Interleaved Bitmap */
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	if ( !memcmp( id, "PBM ", 4 ) ) pbm = 1;
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	else if ( memcmp( id, "ILBM", 4 ) )
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	{
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		error="not a IFF picture";
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		goto done;
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	}
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	nbcolors = 0;
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	memset( &bmhd, 0, sizeof( BMHD ) );
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	flagHAM = 0;
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	flagEHB = 0;
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	while ( memcmp( id, "BODY", 4 ) != 0 )
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	{
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		if ( !SDL_RWread( src, id, 4, 1 ) ) 
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		{
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			error="error reading IFF chunk";
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			goto done;
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		}
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		if ( !SDL_RWread( src, &size, 4, 1 ) )
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		{
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			error="error reading IFF chunk size";
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			goto done;
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		}
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		bytesloaded = 0;
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		size = SDL_SwapBE32( size );
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		if ( !memcmp( id, "BMHD", 4 ) ) /* Bitmap header */
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		{
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			if ( !SDL_RWread( src, &bmhd, sizeof( BMHD ), 1 ) )
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			{
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				error="error reading BMHD chunk";
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				goto done;
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			}
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			bytesloaded = sizeof( BMHD );
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			bmhd.w 		= SDL_SwapBE16( bmhd.w );
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			bmhd.h 		= SDL_SwapBE16( bmhd.h );
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			bmhd.x 		= SDL_SwapBE16( bmhd.x );
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			bmhd.y 		= SDL_SwapBE16( bmhd.y );
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			bmhd.tcolor = SDL_SwapBE16( bmhd.tcolor );
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			bmhd.Lpage 	= SDL_SwapBE16( bmhd.Lpage );
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			bmhd.Hpage 	= SDL_SwapBE16( bmhd.Hpage );
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		}
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		if ( !memcmp( id, "CMAP", 4 ) ) /* palette ( Color Map ) */
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		{
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			if ( !SDL_RWread( src, &colormap, size, 1 ) )
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			{
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				error="error reading CMAP chunk";
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				goto done;
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			}
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			bytesloaded = size;
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			nbcolors = size / 3;
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		}
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		if ( !memcmp( id, "CAMG", 4 ) ) /* Amiga ViewMode  */
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		{
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			Uint32 viewmodes;
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			if ( !SDL_RWread( src, &viewmodes, sizeof(viewmodes), 1 ) )
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			{
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				error="error reading CAMG chunk";
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				goto done;
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			}
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			bytesloaded = size;
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			viewmodes = SDL_SwapBE32( viewmodes );
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			if ( viewmodes & 0x0800 )
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				flagHAM = 1;
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			if ( viewmodes & 0x0080 )
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				flagEHB = 1;
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		}
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		if ( memcmp( id, "BODY", 4 ) )
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		{
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			if ( size & 1 )	++size;  	/* padding ! */
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			size -= bytesloaded;
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			/* skip the remaining bytes of this chunk */
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			if ( size )	SDL_RWseek( src, size, SEEK_CUR );
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		}
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	}
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	/* compute some usefull values, based on the bitmap header */
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	width = ( bmhd.w + 15 ) & 0xFFFFFFF0;  /* Width in pixels modulo 16 */
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	bytesperline = ( ( bmhd.w + 15 ) / 16 ) * 2;
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	nbplanes = bmhd.planes;
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	if ( pbm )                         /* File format : 'Packed Bitmap' */
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	{
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		bytesperline *= 8;
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		nbplanes = 1;
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	}
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	if ( bmhd.mask ) ++nbplanes;       /* There is a mask ( 'stencil' ) */
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	/* Allocate memory for a temporary buffer ( used for
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           decompression/deinterleaving ) */
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	if ( ( MiniBuf = (void *)malloc( bytesperline * nbplanes ) ) == NULL )
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	{
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		error="no enough memory for temporary buffer";
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		goto done;
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	}
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	if ( ( Image = SDL_CreateRGBSurface( SDL_SWSURFACE, width, bmhd.h, (bmhd.planes==24 || flagHAM==1)?24:8, 0, 0, 0, 0 ) ) == NULL )
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	   goto done;
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	/* Update palette informations */
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	/* There is no palette in 24 bits ILBM file */
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	if ( nbcolors>0 && flagHAM==0 )
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	{
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		Image->format->palette->ncolors = nbcolors;
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		ptr = &colormap[0];
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		for ( i=0; i<nbcolors; i++ )
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		{
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			Image->format->palette->colors[i].r = *ptr++;
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			Image->format->palette->colors[i].g = *ptr++;
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			Image->format->palette->colors[i].b = *ptr++;
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		}
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		/* Amiga EHB mode (Extra-Half-Bright) */
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		/* 6 bitplanes mode with a 32 colors palette */
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		/* The 32 last colors are the same but divided by 2 */
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		/* Some Amiga pictures save 64 colors with 32 last wrong colors,
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		/* they shouldn't !, and here we overwrite these 32 bad colors. */
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		if ( (nbcolors==32 || flagEHB ) && (1<<bmhd.planes)==64 )
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		{
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   266
			Image->format->palette->ncolors = 64;
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			ptr = &colormap[0];
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			for ( i=32; i<64; i++ )
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			{
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				Image->format->palette->colors[i].r = (*ptr++)/2;
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				Image->format->palette->colors[i].g = (*ptr++)/2;
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				Image->format->palette->colors[i].b = (*ptr++)/2;
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   273
			}
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   274
		}
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	}
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   276
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   277
	/* Get the bitmap */
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   278
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   279
	for ( h=0; h < bmhd.h; h++ )
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	{
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   281
		/* uncompress the datas of each planes */
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		for ( plane=0; plane < nbplanes; plane++ )
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		{
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			ptr = MiniBuf + ( plane * bytesperline );
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   287
			remainingbytes = bytesperline;
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   288
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   289
			if ( bmhd.tcomp == 1 )	    /* Datas are compressed */
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   290
			{
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   291
				do
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				{
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   293
					if ( !SDL_RWread( src, &count, 1, 1 ) )
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					{
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						error="error reading BODY chunk";
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   296
						goto done;
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					}
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   298
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   299
					if ( count & 0x80 )
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					{
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   301
						count ^= 0xFF;
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						count += 2; /* now it */
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   303
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   304
						if ( !SDL_RWread( src, &color, 1, 1 ) )
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   305
						{
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   306
						   error="error reading BODY chunk";
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   307
							goto done;
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   308
						}
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   309
						memset( ptr, color, count );
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   310
					}
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   311
					else
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   312
					{
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   313
						++count;
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   314
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   315
						if ( !SDL_RWread( src, ptr, count, 1 ) )
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   316
						{
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   317
						   error="error reading BODY chunk";
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   318
							goto done;
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   319
						}
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   320
					}
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   321
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   322
					ptr += count;
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   323
					remainingbytes -= count;
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   324
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   325
				} while ( remainingbytes > 0 );
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   326
			}
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   327
			else
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   328
			{
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   329
				if ( !SDL_RWread( src, ptr, bytesperline, 1 ) )
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   330
				{
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   331
					error="error reading BODY chunk";
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   332
					goto done;
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   333
				}
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   334
			}
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   335
		}
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   336
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   337
		/* One line has been read, store it ! */
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   338
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   339
		ptr = Image->pixels;
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   340
		if ( nbplanes==24 || flagHAM==1 )
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   341
			ptr += h * width * 3;
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   342
		else
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   343
			ptr += h * width;
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   344
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   345
		if ( pbm )                 /* File format : 'Packed Bitmap' */
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   346
		{
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   347
		   memcpy( ptr, MiniBuf, width );
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   348
		}
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   349
		else		/* We have to un-interlace the bits ! */
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   350
		{
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   351
			if ( nbplanes!=24 && flagHAM==0 )
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   352
			{
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   353
				size = ( width + 7 ) / 8;
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   354
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   355
				for ( i=0; i < size; i++ )
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   356
				{
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   357
					memset( ptr, 0, 8 );
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   358
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   359
					for ( plane=0; plane < nbplanes; plane++ )
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   360
					{
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   361
						color = *( MiniBuf + i + ( plane * bytesperline ) );
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   362
						msk = 0x80;
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   363
slouken@74
   364
						for ( j=0; j<8; j++ )
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   365
						{
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   366
							if ( ( plane + j ) <= 7 ) ptr[j] |= (Uint8)( color & msk ) >> ( 7 - plane - j );
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   367
							else 	                    ptr[j] |= (Uint8)( color & msk ) << ( plane + j - 7 );
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   368
slouken@74
   369
							msk >>= 1;
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   370
						}
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   371
					}
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   372
					ptr += 8;
slouken@74
   373
				}
slouken@74
   374
			}
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   375
			else
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   376
			{
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   377
				Uint32 finalcolor = 0;
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   378
				size = ( width + 7 ) / 8;
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   379
				/* 24 bitplanes ILBM : R0...R7,G0...G7,B0...B7 */
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   380
				/* or HAM (6 bitplanes) or HAM8 (8 bitplanes) modes */
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   381
				for ( i=0; i<width; i=i+8 )
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   382
				{
slouken@74
   383
					Uint8 maskBit = 0x80;
slouken@45
   384
					for ( j=0; j<8; j++ )
slouken@45
   385
					{
slouken@96
   386
						Uint32 pixelcolor = 0;
slouken@96
   387
						Uint32 maskColor = 1;
slouken@74
   388
						Uint8 dataBody;
slouken@74
   389
						for ( plane=0; plane < nbplanes; plane++ )
slouken@74
   390
						{
slouken@74
   391
							dataBody = MiniBuf[ plane*size+i/8 ];
slouken@74
   392
							if ( dataBody&maskBit )
slouken@96
   393
								pixelcolor = pixelcolor | maskColor;
slouken@96
   394
							maskColor = maskColor<<1;
slouken@96
   395
						}
slouken@96
   396
						/* HAM : 12 bits RGB image (4 bits per color component) */
slouken@96
   397
						/* HAM8 : 18 bits RGB image (6 bits per color component) */
slouken@96
   398
						if ( flagHAM )
slouken@96
   399
						{
slouken@96
   400
							switch( pixelcolor>>(nbplanes-2) )
slouken@96
   401
							{
slouken@96
   402
								case 0: /* take direct color from palette */
slouken@96
   403
									finalcolor = colormap[ pixelcolor*3 ] + (colormap[ pixelcolor*3+1 ]<<8) + (colormap[ pixelcolor*3+2 ]<<16);
slouken@96
   404
									break;
slouken@96
   405
								case 1: /* modify only blue component */
slouken@96
   406
									finalcolor = finalcolor&0x00FFFF;
slouken@96
   407
									finalcolor = finalcolor | (pixelcolor<<(16+(10-nbplanes)));
slouken@96
   408
									break;
slouken@96
   409
								case 2: /* modify only red component */
slouken@96
   410
									finalcolor = finalcolor&0xFFFF00;
slouken@96
   411
									finalcolor = finalcolor | pixelcolor<<(10-nbplanes);
slouken@96
   412
									break;
slouken@96
   413
								case 3: /* modify only green component */
slouken@96
   414
									finalcolor = finalcolor&0xFF00FF;
slouken@96
   415
									finalcolor = finalcolor | (pixelcolor<<(8+(10-nbplanes)));
slouken@96
   416
									break;
slouken@96
   417
							}
slouken@96
   418
						}
slouken@96
   419
						else
slouken@96
   420
						{
slouken@96
   421
							finalcolor = pixelcolor;
slouken@74
   422
						}
slouken@74
   423
						if ( SDL_BYTEORDER == SDL_LIL_ENDIAN )
slouken@74
   424
						{
slouken@96
   425
							*ptr++ = finalcolor>>16;
slouken@96
   426
							*ptr++ = finalcolor>>8;
slouken@96
   427
							*ptr++ = finalcolor;
slouken@74
   428
						}
slouken@74
   429
						else
slouken@74
   430
						{
slouken@96
   431
							*ptr++ = finalcolor;
slouken@96
   432
							*ptr++ = finalcolor>>8;
slouken@96
   433
							*ptr++ = finalcolor>>16;
slouken@74
   434
						}
slouken@74
   435
slouken@74
   436
						maskBit = maskBit>>1;
slouken@45
   437
					}
slouken@45
   438
				}
slouken@45
   439
			}
slouken@45
   440
		}
slouken@45
   441
	}
slouken@45
   442
slouken@45
   443
done:
slouken@45
   444
slouken@45
   445
	if ( MiniBuf ) free( MiniBuf );
slouken@45
   446
slouken@74
   447
	if ( error )
slouken@45
   448
	{
slouken@45
   449
		IMG_SetError( error );
slouken@74
   450
		SDL_FreeSurface( Image );
slouken@45
   451
		Image = NULL;
slouken@45
   452
	}
slouken@45
   453
slouken@45
   454
	return( Image );
slouken@45
   455
}
slouken@45
   456
slouken@45
   457
#else /* LOAD_LBM */
slouken@45
   458
slouken@45
   459
/* See if an image is contained in a data source */
slouken@45
   460
int IMG_isLBM(SDL_RWops *src)
slouken@45
   461
{
slouken@45
   462
	return(0);
slouken@45
   463
}
slouken@45
   464
slouken@45
   465
/* Load an IFF type image from an SDL datasource */
slouken@45
   466
SDL_Surface *IMG_LoadLBM_RW(SDL_RWops *src)
slouken@45
   467
{
slouken@45
   468
	return(NULL);
slouken@45
   469
}
slouken@45
   470
slouken@45
   471
#endif /* LOAD_LBM */