turbojpegl.c - third_party/libjpeg-turbo - Git at Google

 /* Copyright (C)2004 Landmark Graphics Corporation
  * Copyright (C)2005 Sun Microsystems, Inc.
  * Copyright (C)2009 D. R. Commander
  *
  * This library is free software and may be redistributed and/or modified under
  * the terms of the wxWindows Library License, Version 3.1 or (at your option)
  * any later version.  The full license is in the LICENSE.txt file included
  * with this distribution.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * wxWindows Library License for more details.
  */

 // This implements a JPEG compressor/decompressor using the libjpeg API

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <jpeglib.h>
 #include <jerror.h>
 #include <setjmp.h>
 #include "./turbojpeg.h"


 // Error handling

 static char lasterror[JMSG_LENGTH_MAX]="No error";

 typedef struct _error_mgr
 {
 	struct jpeg_error_mgr pub;
 	jmp_buf jb;
 } error_mgr;

 static void my_error_exit(j_common_ptr cinfo)
 {
 	error_mgr *myerr = (error_mgr *)cinfo->err;
 	(*cinfo->err->output_message)(cinfo);
 	longjmp(myerr->jb, 1);
 }

 static void my_output_message(j_common_ptr cinfo)
 {
 	(*cinfo->err->format_message)(cinfo, lasterror);
 }


 // Global structures, macros, etc.

 typedef struct _jpgstruct
 {
 	struct jpeg_compress_struct cinfo;
 	struct jpeg_decompress_struct dinfo;
 	struct jpeg_destination_mgr jdms;
 	struct jpeg_source_mgr jsms;
 	error_mgr jerr;
 	int initc, initd;
 } jpgstruct;

 static const int hsampfactor[NUMSUBOPT]={1, 2, 2, 1};
 static const int vsampfactor[NUMSUBOPT]={1, 1, 2, 1};

 #define _throw(c) {sprintf(lasterror, "%s", c);  return -1;}
 #define _catch(f) {if((f)==-1) return -1;}
 #define checkhandle(h) jpgstruct *j=(jpgstruct *)h; \
 	if(!j) _throw("Invalid handle");


 // CO

 static boolean empty_output_buffer(struct jpeg_compress_struct *cinfo)
 {
 	ERREXIT(cinfo, JERR_BUFFER_SIZE);
 	return TRUE;
 }

 static void destination_noop(struct jpeg_compress_struct *cinfo)
 {
 }

 DLLEXPORT tjhandle DLLCALL tjInitCompress(void)
 {
 	jpgstruct *j=NULL;
 	if((j=(jpgstruct *)malloc(sizeof(jpgstruct)))==NULL)
 		{sprintf(lasterror, "Memory allocation failure");  return NULL;}
 	memset(j, 0, sizeof(jpgstruct));
 	j->cinfo.err=jpeg_std_error(&j->jerr.pub);
 	j->jerr.pub.error_exit=my_error_exit;
 	j->jerr.pub.output_message=my_output_message;

 	if(setjmp(j->jerr.jb))
 	{ // this will execute if LIBJPEG has an error
 		if(j) free(j);  return NULL;
   }

 	jpeg_create_compress(&j->cinfo);
 	j->cinfo.dest=&j->jdms;
 	j->jdms.init_destination=destination_noop;
 	j->jdms.empty_output_buffer=empty_output_buffer;
 	j->jdms.term_destination=destination_noop;

 	j->initc=1;
 	return (tjhandle)j;
 }

 DLLEXPORT unsigned long DLLCALL TJBUFSIZE(int width, int height)
 {
 	// This allows enough room in case the image doesn't compress
 	return ((width+15)&(~15)) * ((height+15)&(~15)) * 6 + 2048;
 }

 DLLEXPORT int DLLCALL tjCompress(tjhandle h,
 	unsigned char *srcbuf, int width, int pitch, int height, int ps,
 	unsigned char *dstbuf, unsigned long *size,
 	int jpegsub, int qual, int flags)
 {
 	int i;  JSAMPROW *row_pointer=NULL;

 	checkhandle(h);

 	if(srcbuf==NULL || width<=0 || pitch<0 || height<=0
 		|| dstbuf==NULL || size==NULL
 		|| jpegsub<0 || jpegsub>=NUMSUBOPT || qual<0 || qual>100)
 		_throw("Invalid argument in tjCompress()");
 	if(ps!=3 && ps!=4) _throw("This compressor can only take 24-bit or 32-bit RGB input");
 	if(!j->initc) _throw("Instance has not been initialized for compression");

 	if(pitch==0) pitch=width*ps;

 	j->cinfo.image_width = width;
 	j->cinfo.image_height = height;
 	j->cinfo.input_components = ps;

 	#if JCS_EXTENSIONS==1
 	j->cinfo.in_color_space = JCS_EXT_RGB;
 	if(ps==3 && (flags&TJ_BGR))
 		j->cinfo.in_color_space = JCS_EXT_BGR;
 	else if(ps==4 && !(flags&TJ_BGR) && !(flags&TJ_ALPHAFIRST))
 		j->cinfo.in_color_space = JCS_EXT_RGBX;
 	else if(ps==4 && (flags&TJ_BGR) && !(flags&TJ_ALPHAFIRST))
 		j->cinfo.in_color_space = JCS_EXT_BGRX;
 	else if(ps==4 && (flags&TJ_BGR) && (flags&TJ_ALPHAFIRST))
 		j->cinfo.in_color_space = JCS_EXT_XBGR;
 	else if(ps==4 && !(flags&TJ_BGR) && (flags&TJ_ALPHAFIRST))
 		j->cinfo.in_color_space = JCS_EXT_XRGB;
 	#else
 	#error "TurboJPEG requires JPEG colorspace extensions"
 	#endif

 	if(flags&TJ_FORCEMMX) putenv("JSIMD_FORCEMMX=1");
 	else if(flags&TJ_FORCESSE) putenv("JSIMD_FORCESSE=1");
 	else if(flags&TJ_FORCESSE2) putenv("JSIMD_FORCESSE2=1");

 	if(setjmp(j->jerr.jb))
 	{  // this will execute if LIBJPEG has an error
 		if(row_pointer) free(row_pointer);
 		return -1;
   }

 	jpeg_set_defaults(&j->cinfo);

 	jpeg_set_quality(&j->cinfo, qual, TRUE);
 	if(jpegsub==TJ_GRAYSCALE)
 		jpeg_set_colorspace(&j->cinfo, JCS_GRAYSCALE);
 	else
 		jpeg_set_colorspace(&j->cinfo, JCS_YCbCr);
 	if(qual>=96) j->cinfo.dct_method=JDCT_ISLOW;
 	else j->cinfo.dct_method=JDCT_FASTEST;

 	j->cinfo.comp_info[0].h_samp_factor=hsampfactor[jpegsub];
 	j->cinfo.comp_info[1].h_samp_factor=1;
 	j->cinfo.comp_info[2].h_samp_factor=1;
 	j->cinfo.comp_info[0].v_samp_factor=vsampfactor[jpegsub];
 	j->cinfo.comp_info[1].v_samp_factor=1;
 	j->cinfo.comp_info[2].v_samp_factor=1;

 	j->jdms.next_output_byte = dstbuf;
 	j->jdms.free_in_buffer = TJBUFSIZE(j->cinfo.image_width, j->cinfo.image_height);

 	if((row_pointer=(JSAMPROW *)malloc(sizeof(JSAMPROW)*height))==NULL)
 		_throw("Memory allocation failed in tjInitCompress()");
 	for(i=0; i<height; i++)
 	{
 		if(flags&TJ_BOTTOMUP) row_pointer[i]= &srcbuf[(height-i-1)*pitch];
 		else row_pointer[i]= &srcbuf[i*pitch];
 	}
 	jpeg_start_compress(&j->cinfo, TRUE);
 	while(j->cinfo.next_scanline<j->cinfo.image_height)
 	{
 		jpeg_write_scanlines(&j->cinfo, &row_pointer[j->cinfo.next_scanline],
 			j->cinfo.image_height-j->cinfo.next_scanline);
 	}
 	jpeg_finish_compress(&j->cinfo);
 	*size=TJBUFSIZE(j->cinfo.image_width, j->cinfo.image_height)
 		-(unsigned long)(j->jdms.free_in_buffer);

 	if(row_pointer) free(row_pointer);
 	return 0;
 }


 // DEC

 static boolean fill_input_buffer (struct jpeg_decompress_struct *dinfo)
 {
 	ERREXIT(dinfo, JERR_BUFFER_SIZE);
 	return TRUE;
 }

 static void skip_input_data (struct jpeg_decompress_struct *dinfo, long num_bytes)
 {
 	dinfo->src->next_input_byte += (size_t) num_bytes;
 	dinfo->src->bytes_in_buffer -= (size_t) num_bytes;
 }

 static void source_noop (struct jpeg_decompress_struct *dinfo)
 {
 }

 DLLEXPORT tjhandle DLLCALL tjInitDecompress(void)
 {
 	jpgstruct *j;
 	if((j=(jpgstruct *)malloc(sizeof(jpgstruct)))==NULL)
 		{sprintf(lasterror, "Memory allocation failure");  return NULL;}
 	memset(j, 0, sizeof(jpgstruct));
 	j->dinfo.err=jpeg_std_error(&j->jerr.pub);
 	j->jerr.pub.error_exit=my_error_exit;
 	j->jerr.pub.output_message=my_output_message;

 	if(setjmp(j->jerr.jb))
 	{ // this will execute if LIBJPEG has an error
 		free(j);  return NULL;
   }

 	jpeg_create_decompress(&j->dinfo);
 	j->dinfo.src=&j->jsms;
 	j->jsms.init_source=source_noop;
 	j->jsms.fill_input_buffer = fill_input_buffer;
 	j->jsms.skip_input_data = skip_input_data;
 	j->jsms.resync_to_restart = jpeg_resync_to_restart;
 	j->jsms.term_source = source_noop;

 	j->initd=1;
 	return (tjhandle)j;
 }


 DLLEXPORT int DLLCALL tjDecompressHeader(tjhandle h,
 	unsigned char *srcbuf, unsigned long size,
 	int *width, int *height)
 {
 	checkhandle(h);

 	if(srcbuf==NULL || size<=0 || width==NULL || height==NULL)
 		_throw("Invalid argument in tjDecompressHeader()");
 	if(!j->initd) _throw("Instance has not been initialized for decompression");

 	if(setjmp(j->jerr.jb))
 	{  // this will execute if LIBJPEG has an error
 		return -1;
 	}

 	j->jsms.bytes_in_buffer = size;
 	j->jsms.next_input_byte = srcbuf;

 	jpeg_read_header(&j->dinfo, TRUE);

 	*width=j->dinfo.image_width;  *height=j->dinfo.image_height;

 	jpeg_abort_decompress(&j->dinfo);

 	if(*width<1 || *height<1) _throw("Invalid data returned in header");
 	return 0;
 }


 DLLEXPORT int DLLCALL tjDecompress(tjhandle h,
 	unsigned char *srcbuf, unsigned long size,
 	unsigned char *dstbuf, int width, int pitch, int height, int ps,
 	int flags)
 {
 	int i;  JSAMPROW *row_pointer=NULL;

 	checkhandle(h);

 	if(srcbuf==NULL || size<=0
 		|| dstbuf==NULL || width<=0 || pitch<0 || height<=0)
 		_throw("Invalid argument in tjDecompress()");
 	if(ps!=3 && ps!=4) _throw("This compressor can only take 24-bit or 32-bit RGB input");
 	if(!j->initd) _throw("Instance has not been initialized for decompression");

 	if(pitch==0) pitch=width*ps;

 	if(flags&TJ_FORCEMMX) putenv("JSIMD_FORCEMMX=1");
 	else if(flags&TJ_FORCESSE) putenv("JSIMD_FORCESSE=1");
 	else if(flags&TJ_FORCESSE2) putenv("JSIMD_FORCESSE2=1");

 	if(setjmp(j->jerr.jb))
 	{  // this will execute if LIBJPEG has an error
 		if(row_pointer) free(row_pointer);
 		return -1;
   }

 	j->jsms.bytes_in_buffer = size;
 	j->jsms.next_input_byte = srcbuf;

 	jpeg_read_header(&j->dinfo, TRUE);

 	if((row_pointer=(JSAMPROW *)malloc(sizeof(JSAMPROW)*height))==NULL)
 		_throw("Memory allocation failed in tjInitDecompress()");
 	for(i=0; i<height; i++)
 	{
 		if(flags&TJ_BOTTOMUP) row_pointer[i]= &dstbuf[(height-i-1)*pitch];
 		else row_pointer[i]= &dstbuf[i*pitch];
 	}

 	#if JCS_EXTENSIONS==1
 	j->dinfo.out_color_space = JCS_EXT_RGB;
 	if(ps==3 && (flags&TJ_BGR))
 		j->dinfo.out_color_space = JCS_EXT_BGR;
 	else if(ps==4 && !(flags&TJ_BGR) && !(flags&TJ_ALPHAFIRST))
 		j->dinfo.out_color_space = JCS_EXT_RGBX;
 	else if(ps==4 && (flags&TJ_BGR) && !(flags&TJ_ALPHAFIRST))
 		j->dinfo.out_color_space = JCS_EXT_BGRX;
 	else if(ps==4 && (flags&TJ_BGR) && (flags&TJ_ALPHAFIRST))
 		j->dinfo.out_color_space = JCS_EXT_XBGR;
 	else if(ps==4 && !(flags&TJ_BGR) && (flags&TJ_ALPHAFIRST))
 		j->dinfo.out_color_space = JCS_EXT_XRGB;
 	#else
 	#error "TurboJPEG requires JPEG colorspace extensions"
 	#endif
 	if(flags&TJ_FASTUPSAMPLE) j->dinfo.do_fancy_upsampling=FALSE;

 	jpeg_start_decompress(&j->dinfo);
 	while(j->dinfo.output_scanline<j->dinfo.output_height)
 	{
 		jpeg_read_scanlines(&j->dinfo, &row_pointer[j->dinfo.output_scanline],
 			j->dinfo.output_height-j->dinfo.output_scanline);
 	}
 	jpeg_finish_decompress(&j->dinfo);

 	if(row_pointer) free(row_pointer);
 	return 0;
 }


 // General

 DLLEXPORT char* DLLCALL tjGetErrorStr(void)
 {
 	return lasterror;
 }

 DLLEXPORT int DLLCALL tjDestroy(tjhandle h)
 {
 	checkhandle(h);
 	if(setjmp(j->jerr.jb)) return -1;
 	if(j->initc) jpeg_destroy_compress(&j->cinfo);
 	if(j->initd) jpeg_destroy_decompress(&j->dinfo);
 	free(j);
 	return 0;
 }
	/* Copyright (C)2004 Landmark Graphics Corporation
	* Copyright (C)2005 Sun Microsystems, Inc.
	* Copyright (C)2009 D. R. Commander
	*
	* This library is free software and may be redistributed and/or modified under
	* the terms of the wxWindows Library License, Version 3.1 or (at your option)
	* any later version. The full license is in the LICENSE.txt file included
	* with this distribution.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* wxWindows Library License for more details.
	*/

	// This implements a JPEG compressor/decompressor using the libjpeg API

	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <jpeglib.h>
	#include <jerror.h>
	#include <setjmp.h>
	#include "./turbojpeg.h"


	// Error handling

	static char lasterror[JMSG_LENGTH_MAX]="No error";

	typedef struct _error_mgr
	{
	struct jpeg_error_mgr pub;
	jmp_buf jb;
	} error_mgr;

	static void my_error_exit(j_common_ptr cinfo)
	{
	error_mgr myerr = (error_mgr )cinfo->err;
	(*cinfo->err->output_message)(cinfo);
	longjmp(myerr->jb, 1);
	}

	static void my_output_message(j_common_ptr cinfo)
	{
	(*cinfo->err->format_message)(cinfo, lasterror);
	}


	// Global structures, macros, etc.

	typedef struct _jpgstruct
	{
	struct jpeg_compress_struct cinfo;
	struct jpeg_decompress_struct dinfo;
	struct jpeg_destination_mgr jdms;
	struct jpeg_source_mgr jsms;
	error_mgr jerr;
	int initc, initd;
	} jpgstruct;

	static const int hsampfactor[NUMSUBOPT]={1, 2, 2, 1};
	static const int vsampfactor[NUMSUBOPT]={1, 1, 2, 1};

	#define _throw(c) {sprintf(lasterror, "%s", c); return -1;}
	#define _catch(f) {if((f)==-1) return -1;}
	#define checkhandle(h) jpgstruct j=(jpgstruct )h; \
	if(!j) _throw("Invalid handle");


	// CO

	static boolean empty_output_buffer(struct jpeg_compress_struct *cinfo)
	{
	ERREXIT(cinfo, JERR_BUFFER_SIZE);
	return TRUE;
	}

	static void destination_noop(struct jpeg_compress_struct *cinfo)
	{
	}

	DLLEXPORT tjhandle DLLCALL tjInitCompress(void)
	{
	jpgstruct *j=NULL;
	if((j=(jpgstruct *)malloc(sizeof(jpgstruct)))==NULL)
	{sprintf(lasterror, "Memory allocation failure"); return NULL;}
	memset(j, 0, sizeof(jpgstruct));
	j->cinfo.err=jpeg_std_error(&j->jerr.pub);
	j->jerr.pub.error_exit=my_error_exit;
	j->jerr.pub.output_message=my_output_message;

	if(setjmp(j->jerr.jb))
	{ // this will execute if LIBJPEG has an error
	if(j) free(j); return NULL;
	}

	jpeg_create_compress(&j->cinfo);
	j->cinfo.dest=&j->jdms;
	j->jdms.init_destination=destination_noop;
	j->jdms.empty_output_buffer=empty_output_buffer;
	j->jdms.term_destination=destination_noop;

	j->initc=1;
	return (tjhandle)j;
	}

	DLLEXPORT unsigned long DLLCALL TJBUFSIZE(int width, int height)
	{
	// This allows enough room in case the image doesn't compress
	return ((width+15)&(~15)) * ((height+15)&(~15)) * 6 + 2048;
	}

	DLLEXPORT int DLLCALL tjCompress(tjhandle h,
	unsigned char *srcbuf, int width, int pitch, int height, int ps,
	unsigned char dstbuf, unsigned long size,
	int jpegsub, int qual, int flags)
	{
	int i; JSAMPROW *row_pointer=NULL;

	checkhandle(h);

	if(srcbuf==NULL \|\| width<=0 \|\| pitch<0 \|\| height<=0
	\|\| dstbuf==NULL \|\| size==NULL
	\|\| jpegsub<0 \|\| jpegsub>=NUMSUBOPT \|\| qual<0 \|\| qual>100)
	_throw("Invalid argument in tjCompress()");
	if(ps!=3 && ps!=4) _throw("This compressor can only take 24-bit or 32-bit RGB input");
	if(!j->initc) _throw("Instance has not been initialized for compression");

	if(pitch==0) pitch=width*ps;

	j->cinfo.image_width = width;
	j->cinfo.image_height = height;
	j->cinfo.input_components = ps;

	#if JCS_EXTENSIONS==1
	j->cinfo.in_color_space = JCS_EXT_RGB;
	if(ps==3 && (flags&TJ_BGR))
	j->cinfo.in_color_space = JCS_EXT_BGR;
	else if(ps==4 && !(flags&TJ_BGR) && !(flags&TJ_ALPHAFIRST))
	j->cinfo.in_color_space = JCS_EXT_RGBX;
	else if(ps==4 && (flags&TJ_BGR) && !(flags&TJ_ALPHAFIRST))
	j->cinfo.in_color_space = JCS_EXT_BGRX;
	else if(ps==4 && (flags&TJ_BGR) && (flags&TJ_ALPHAFIRST))
	j->cinfo.in_color_space = JCS_EXT_XBGR;
	else if(ps==4 && !(flags&TJ_BGR) && (flags&TJ_ALPHAFIRST))
	j->cinfo.in_color_space = JCS_EXT_XRGB;
	#else
	#error "TurboJPEG requires JPEG colorspace extensions"
	#endif

	if(flags&TJ_FORCEMMX) putenv("JSIMD_FORCEMMX=1");
	else if(flags&TJ_FORCESSE) putenv("JSIMD_FORCESSE=1");
	else if(flags&TJ_FORCESSE2) putenv("JSIMD_FORCESSE2=1");

	if(setjmp(j->jerr.jb))
	{ // this will execute if LIBJPEG has an error
	if(row_pointer) free(row_pointer);
	return -1;
	}

	jpeg_set_defaults(&j->cinfo);

	jpeg_set_quality(&j->cinfo, qual, TRUE);
	if(jpegsub==TJ_GRAYSCALE)
	jpeg_set_colorspace(&j->cinfo, JCS_GRAYSCALE);
	else
	jpeg_set_colorspace(&j->cinfo, JCS_YCbCr);
	if(qual>=96) j->cinfo.dct_method=JDCT_ISLOW;
	else j->cinfo.dct_method=JDCT_FASTEST;

	j->cinfo.comp_info[0].h_samp_factor=hsampfactor[jpegsub];
	j->cinfo.comp_info[1].h_samp_factor=1;
	j->cinfo.comp_info[2].h_samp_factor=1;
	j->cinfo.comp_info[0].v_samp_factor=vsampfactor[jpegsub];
	j->cinfo.comp_info[1].v_samp_factor=1;
	j->cinfo.comp_info[2].v_samp_factor=1;

	j->jdms.next_output_byte = dstbuf;
	j->jdms.free_in_buffer = TJBUFSIZE(j->cinfo.image_width, j->cinfo.image_height);

	if((row_pointer=(JSAMPROW )malloc(sizeof(JSAMPROW)height))==NULL)
	_throw("Memory allocation failed in tjInitCompress()");
	for(i=0; i<height; i++)
	{
	if(flags&TJ_BOTTOMUP) row_pointer[i]= &srcbuf[(height-i-1)*pitch];
	else row_pointer[i]= &srcbuf[i*pitch];
	}
	jpeg_start_compress(&j->cinfo, TRUE);
	while(j->cinfo.next_scanline<j->cinfo.image_height)
	{
	jpeg_write_scanlines(&j->cinfo, &row_pointer[j->cinfo.next_scanline],
	j->cinfo.image_height-j->cinfo.next_scanline);
	}
	jpeg_finish_compress(&j->cinfo);
	*size=TJBUFSIZE(j->cinfo.image_width, j->cinfo.image_height)
	-(unsigned long)(j->jdms.free_in_buffer);

	if(row_pointer) free(row_pointer);
	return 0;
	}


	// DEC

	static boolean fill_input_buffer (struct jpeg_decompress_struct *dinfo)
	{
	ERREXIT(dinfo, JERR_BUFFER_SIZE);
	return TRUE;
	}

	static void skip_input_data (struct jpeg_decompress_struct *dinfo, long num_bytes)
	{
	dinfo->src->next_input_byte += (size_t) num_bytes;
	dinfo->src->bytes_in_buffer -= (size_t) num_bytes;
	}

	static void source_noop (struct jpeg_decompress_struct *dinfo)
	{
	}

	DLLEXPORT tjhandle DLLCALL tjInitDecompress(void)
	{
	jpgstruct *j;
	if((j=(jpgstruct *)malloc(sizeof(jpgstruct)))==NULL)
	{sprintf(lasterror, "Memory allocation failure"); return NULL;}
	memset(j, 0, sizeof(jpgstruct));
	j->dinfo.err=jpeg_std_error(&j->jerr.pub);
	j->jerr.pub.error_exit=my_error_exit;
	j->jerr.pub.output_message=my_output_message;

	if(setjmp(j->jerr.jb))
	{ // this will execute if LIBJPEG has an error
	free(j); return NULL;
	}

	jpeg_create_decompress(&j->dinfo);
	j->dinfo.src=&j->jsms;
	j->jsms.init_source=source_noop;
	j->jsms.fill_input_buffer = fill_input_buffer;
	j->jsms.skip_input_data = skip_input_data;
	j->jsms.resync_to_restart = jpeg_resync_to_restart;
	j->jsms.term_source = source_noop;

	j->initd=1;
	return (tjhandle)j;
	}


	DLLEXPORT int DLLCALL tjDecompressHeader(tjhandle h,
	unsigned char *srcbuf, unsigned long size,
	int width, int height)
	{
	checkhandle(h);

	if(srcbuf==NULL \|\| size<=0 \|\| width==NULL \|\| height==NULL)
	_throw("Invalid argument in tjDecompressHeader()");
	if(!j->initd) _throw("Instance has not been initialized for decompression");

	if(setjmp(j->jerr.jb))
	{ // this will execute if LIBJPEG has an error
	return -1;
	}

	j->jsms.bytes_in_buffer = size;
	j->jsms.next_input_byte = srcbuf;

	jpeg_read_header(&j->dinfo, TRUE);

	width=j->dinfo.image_width; height=j->dinfo.image_height;

	jpeg_abort_decompress(&j->dinfo);

	if(width<1 \|\| height<1) _throw("Invalid data returned in header");
	return 0;
	}


	DLLEXPORT int DLLCALL tjDecompress(tjhandle h,
	unsigned char *srcbuf, unsigned long size,
	unsigned char *dstbuf, int width, int pitch, int height, int ps,
	int flags)
	{
	int i; JSAMPROW *row_pointer=NULL;

	checkhandle(h);

	if(srcbuf==NULL \|\| size<=0
	\|\| dstbuf==NULL \|\| width<=0 \|\| pitch<0 \|\| height<=0)
	_throw("Invalid argument in tjDecompress()");
	if(ps!=3 && ps!=4) _throw("This compressor can only take 24-bit or 32-bit RGB input");
	if(!j->initd) _throw("Instance has not been initialized for decompression");

	if(pitch==0) pitch=width*ps;

	if(flags&TJ_FORCEMMX) putenv("JSIMD_FORCEMMX=1");
	else if(flags&TJ_FORCESSE) putenv("JSIMD_FORCESSE=1");
	else if(flags&TJ_FORCESSE2) putenv("JSIMD_FORCESSE2=1");

	if(setjmp(j->jerr.jb))
	{ // this will execute if LIBJPEG has an error
	if(row_pointer) free(row_pointer);
	return -1;
	}

	j->jsms.bytes_in_buffer = size;
	j->jsms.next_input_byte = srcbuf;

	jpeg_read_header(&j->dinfo, TRUE);

	if((row_pointer=(JSAMPROW )malloc(sizeof(JSAMPROW)height))==NULL)
	_throw("Memory allocation failed in tjInitDecompress()");
	for(i=0; i<height; i++)
	{
	if(flags&TJ_BOTTOMUP) row_pointer[i]= &dstbuf[(height-i-1)*pitch];
	else row_pointer[i]= &dstbuf[i*pitch];
	}

	#if JCS_EXTENSIONS==1
	j->dinfo.out_color_space = JCS_EXT_RGB;
	if(ps==3 && (flags&TJ_BGR))
	j->dinfo.out_color_space = JCS_EXT_BGR;
	else if(ps==4 && !(flags&TJ_BGR) && !(flags&TJ_ALPHAFIRST))
	j->dinfo.out_color_space = JCS_EXT_RGBX;
	else if(ps==4 && (flags&TJ_BGR) && !(flags&TJ_ALPHAFIRST))
	j->dinfo.out_color_space = JCS_EXT_BGRX;
	else if(ps==4 && (flags&TJ_BGR) && (flags&TJ_ALPHAFIRST))
	j->dinfo.out_color_space = JCS_EXT_XBGR;
	else if(ps==4 && !(flags&TJ_BGR) && (flags&TJ_ALPHAFIRST))
	j->dinfo.out_color_space = JCS_EXT_XRGB;
	#else
	#error "TurboJPEG requires JPEG colorspace extensions"
	#endif
	if(flags&TJ_FASTUPSAMPLE) j->dinfo.do_fancy_upsampling=FALSE;

	jpeg_start_decompress(&j->dinfo);
	while(j->dinfo.output_scanline<j->dinfo.output_height)
	{
	jpeg_read_scanlines(&j->dinfo, &row_pointer[j->dinfo.output_scanline],
	j->dinfo.output_height-j->dinfo.output_scanline);
	}
	jpeg_finish_decompress(&j->dinfo);

	if(row_pointer) free(row_pointer);
	return 0;
	}


	// General

	DLLEXPORT char* DLLCALL tjGetErrorStr(void)
	{
	return lasterror;
	}

	DLLEXPORT int DLLCALL tjDestroy(tjhandle h)
	{
	checkhandle(h);
	if(setjmp(j->jerr.jb)) return -1;
	if(j->initc) jpeg_destroy_compress(&j->cinfo);
	if(j->initd) jpeg_destroy_decompress(&j->dinfo);
	free(j);
	return 0;
	}