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