mirror of
https://github.com/dborth/vbagx.git
synced 2024-12-27 11:11:50 +01:00
133 lines
4.1 KiB
C++
133 lines
4.1 KiB
C++
/****************************************************************************
|
|
* Memory-based replacement for standard C file functions
|
|
* This allows standard file calls to be replaced by memory based ones
|
|
* With little modification required to the code
|
|
*
|
|
* Written By: Daryl Borth, October 2008
|
|
*
|
|
* This code is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2, or (at your option)
|
|
* any later version.
|
|
***************************************************************************/
|
|
#include <string.h>
|
|
#include <stdlib.h>
|
|
|
|
#include "memfile.h"
|
|
|
|
/****************************************************************************
|
|
* memfopen
|
|
* memory replacement for fopen
|
|
*
|
|
* Creates a memory-based file
|
|
***************************************************************************/
|
|
MFILE * memfopen(char * buffer, int size)
|
|
{
|
|
MFILE *f = (MFILE *)malloc(sizeof(MFILE));
|
|
|
|
f->buffer = buffer;
|
|
f->offset = 0;
|
|
f->size = size;
|
|
|
|
return f;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* memfclose
|
|
* memory replacement for fclose
|
|
*
|
|
* 'Closes' the memory file specified
|
|
***************************************************************************/
|
|
int memfclose(MFILE * src)
|
|
{
|
|
free(src);
|
|
return 0;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* memfseek
|
|
* memory replacement for fseek
|
|
*
|
|
* Sets the position indicator associated with the stream to a new position
|
|
* defined by adding offset to a reference position specified by origin.
|
|
***************************************************************************/
|
|
int memfseek ( MFILE * m, long int offset, int origin )
|
|
{
|
|
int success = 0; // 0 indicates success
|
|
|
|
switch(origin)
|
|
{
|
|
case MSEEK_SET:
|
|
if(offset >= 0 && offset <= m->size)
|
|
m->offset = offset;
|
|
else
|
|
success = 1; // failure
|
|
break;
|
|
case MSEEK_CUR:
|
|
if((m->offset + offset) >= 0 && (m->offset + offset) <= m->size)
|
|
m->offset += offset;
|
|
else
|
|
success = 1; // failure
|
|
break;
|
|
case MSEEK_END:
|
|
if((m->size + offset) >= 0 && (m->size + offset) <= m->size)
|
|
m->offset = m->size + offset;
|
|
else
|
|
success = 1; // failure
|
|
break;
|
|
}
|
|
return success;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* memftell
|
|
* memory replacement for ftell
|
|
*
|
|
* Get current position in stream (offset + 1)
|
|
***************************************************************************/
|
|
long int memftell (MFILE * stream)
|
|
{
|
|
return stream->offset; // to emulate ftell behavior
|
|
}
|
|
|
|
/****************************************************************************
|
|
* memfread
|
|
* memory replacement for fread
|
|
*
|
|
* Reads an array of count elements, each one with a size of size bytes, from
|
|
* the buffer and stores them in the block of memory specified by ptr. The
|
|
* postion indicator of the buffer is advanced by the total amount of bytes
|
|
* read. The total amount of bytes read if successful is (size * count).
|
|
***************************************************************************/
|
|
size_t memfread(void * dst, size_t size, size_t count, MFILE * src)
|
|
{
|
|
if(src->offset >= src->size) // reached end of buffer
|
|
return 0;
|
|
|
|
int numbytes = size*count;
|
|
|
|
if((src->offset + numbytes) > src->size) // can't read full # requested
|
|
numbytes = src->size - src->offset; // do a partial read
|
|
|
|
if(numbytes > 0)
|
|
memcpy(dst, src->buffer+src->offset, numbytes);
|
|
|
|
src->offset += numbytes;
|
|
return numbytes;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* memfgetc
|
|
* memory replacement for fgetc
|
|
*
|
|
* Returns the next character in the buffer specified, and advances the
|
|
* postion indicator of the buffer by 1.
|
|
***************************************************************************/
|
|
int memfgetc(MFILE * src)
|
|
{
|
|
if(src->offset >= src->size) // reached end of buffer
|
|
return MEOF;
|
|
else
|
|
return src->buffer[src->offset++];
|
|
}
|