Source/FreeImage/FreeImageIO.cpp

// ==========================================================
// Input/Output functions
//
// Design and implementation by
// - Floris van den Berg (flvdberg@wxs.nl)
//
// This file is part of FreeImage 3
//
// COVERED CODE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES
// THAT THE COVERED CODE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE
// OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE COVERED
// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT
// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY
// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL
// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER
// THIS DISCLAIMER.
//
// Use at your own risk!
// ==========================================================

#include "FreeImage.h"
#include "Utilities.h"
#include "FreeImageIO.h"

// ----------------------------------------------------------

unsigned DLL_CALLCONV 
_ReadProc(void *buffer, unsigned size, unsigned count, fi_handle handle) {
	return (unsigned)fread(buffer, size, count, (FILE *)handle);
}

unsigned DLL_CALLCONV 
_WriteProc(void *buffer, unsigned size, unsigned count, fi_handle handle) {
	return (unsigned)fwrite(buffer, size, count, (FILE *)handle);
}

int DLL_CALLCONV
_SeekProc(fi_handle handle, long offset, int origin) {
	return fseek((FILE *)handle, offset, origin);
}

long DLL_CALLCONV
_TellProc(fi_handle handle) {
	return ftell((FILE *)handle);
}

// ----------------------------------------------------------

void
SetDefaultIO(FreeImageIO *io) {
	io->read_proc  = _ReadProc;
	io->seek_proc  = _SeekProc;
	io->tell_proc  = _TellProc;
	io->write_proc = _WriteProc;
}

// =====================================================================
// Memory IO functions
// =====================================================================

unsigned DLL_CALLCONV 
_MemoryReadProc(void *buffer, unsigned size, unsigned count, fi_handle handle) {
	unsigned x;

	FIMEMORYHEADER *mem_header = (FIMEMORYHEADER*)(((FIMEMORY*)handle)->data);

	for(x = 0; x < count; x++) {
		//if there isnt size bytes left to read, set pos to eof and return a short count
		if( (mem_header->filelen - mem_header->curpos) < (long)size ) {
			mem_header->curpos = mem_header->filelen;
			break;
		}
		//copy size bytes count times
		memcpy( buffer, (char *)mem_header->data + mem_header->curpos, size );
		mem_header->curpos += size;
		buffer = (char *)buffer + size;
	}
	return x;
}

unsigned DLL_CALLCONV 
_MemoryWriteProc(void *buffer, unsigned size, unsigned count, fi_handle handle) {
	void *newdata;
	long newdatalen;

	FIMEMORYHEADER *mem_header = (FIMEMORYHEADER*)(((FIMEMORY*)handle)->data);

	//double the data block size if we need to
	while( (mem_header->curpos + (long)(size*count)) >= mem_header->datalen ) {
		//if we are at or above 1G, we cant double without going negative
		if( mem_header->datalen & 0x40000000 ) {
			//max 2G
			if( mem_header->datalen == 0x7FFFFFFF ) {
				return 0;
			}
			newdatalen = 0x7FFFFFFF;
		} else if( mem_header->datalen == 0 ) {
			//default to 4K if nothing yet
			newdatalen = 4096;
		} else {
			//double size
			newdatalen = mem_header->datalen << 1;
		}
		newdata = realloc( mem_header->data, newdatalen );
		if( !newdata ) {
			return 0;
		}
		mem_header->data = newdata;
		mem_header->datalen = newdatalen;
	}
	memcpy( (char *)mem_header->data + mem_header->curpos, buffer, size*count );
	mem_header->curpos += size*count;
	if( mem_header->curpos > mem_header->filelen ) {
		mem_header->filelen = mem_header->curpos;
	}
	return count;
}

int DLL_CALLCONV 
_MemorySeekProc(fi_handle handle, long offset, int origin) {
	FIMEMORYHEADER *mem_header = (FIMEMORYHEADER*)(((FIMEMORY*)handle)->data);

	switch(origin) { //0 to filelen-1 are 'inside' the file
		default:
		case SEEK_SET: //can fseek() to 0-7FFFFFFF always
			if( offset >= 0 ) {
				mem_header->curpos = offset;
				return 0;
			}
			break;

		case SEEK_CUR:
			if( mem_header->curpos + offset >= 0 ) {
				mem_header->curpos += offset;
				return 0;
			}
			break;

		case SEEK_END:
			if( mem_header->filelen + offset >= 0 ) {
				mem_header->curpos = mem_header->filelen + offset;
				return 0;
			}
			break;
	}

	return -1;
}

long DLL_CALLCONV 
_MemoryTellProc(fi_handle handle) {
	FIMEMORYHEADER *mem_header = (FIMEMORYHEADER*)(((FIMEMORY*)handle)->data);

	return mem_header->curpos;
}

// ----------------------------------------------------------

void
SetMemoryIO(FreeImageIO *io) {
	io->read_proc  = _MemoryReadProc;
	io->seek_proc  = _MemorySeekProc;
	io->tell_proc  = _MemoryTellProc;
	io->write_proc = _MemoryWriteProc;
}