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//
// Copyright(C) 1993-1996 Id Software, Inc.
// Copyright(C) 2005-2014 Simon Howard
//
// This program 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
// of the License, or (at your option) any later version.
//
// This program 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
// GNU General Public License for more details.
//
// Emulates the IO functions in C stdio.h reading and writing to
// memory.
//
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "memio.h"
#include "z_zone.h"
typedef enum {
MODE_READ,
MODE_WRITE,
} memfile_mode_t;
struct _MEMFILE {
unsigned char *buf;
size_t buflen;
size_t alloced;
unsigned int position;
memfile_mode_t mode;
};
// Open a memory area for reading
MEMFILE *mem_fopen_read(void *buf, size_t buflen)
{
MEMFILE *file;
file = Z_Malloc(sizeof(MEMFILE), PU_STATIC, 0);
file->buf = (unsigned char *) buf;
file->buflen = buflen;
file->position = 0;
file->mode = MODE_READ;
return file;
}
// Read bytes
size_t mem_fread(void *buf, size_t size, size_t nmemb, MEMFILE *stream)
{
size_t items;
if (stream->mode != MODE_READ)
{
printf("not a read stream\n");
return -1;
}
// Trying to read more bytes than we have left?
items = nmemb;
if (items * size > stream->buflen - stream->position)
{
items = (stream->buflen - stream->position) / size;
}
// Copy bytes to buffer
memcpy(buf, stream->buf + stream->position, items * size);
// Update position
stream->position += items * size;
return items;
}
// Open a memory area for writing
MEMFILE *mem_fopen_write(void)
{
MEMFILE *file;
file = Z_Malloc(sizeof(MEMFILE), PU_STATIC, 0);
file->alloced = 1024;
file->buf = Z_Malloc(file->alloced, PU_STATIC, 0);
file->buflen = 0;
file->position = 0;
file->mode = MODE_WRITE;
return file;
}
// Write bytes to stream
size_t mem_fwrite(const void *ptr, size_t size, size_t nmemb, MEMFILE *stream)
{
size_t bytes;
if (stream->mode != MODE_WRITE)
{
return -1;
}
// More bytes than can fit in the buffer?
// If so, reallocate bigger.
bytes = size * nmemb;
while (bytes > stream->alloced - stream->position)
{
unsigned char *newbuf;
newbuf = Z_Malloc(stream->alloced * 2, PU_STATIC, 0);
memcpy(newbuf, stream->buf, stream->alloced);
Z_Free(stream->buf);
stream->buf = newbuf;
stream->alloced *= 2;
}
// Copy into buffer
memcpy(stream->buf + stream->position, ptr, bytes);
stream->position += bytes;
if (stream->position > stream->buflen)
stream->buflen = stream->position;
return nmemb;
}
void mem_get_buf(MEMFILE *stream, void **buf, size_t *buflen)
{
*buf = stream->buf;
*buflen = stream->buflen;
}
void mem_fclose(MEMFILE *stream)
{
if (stream->mode == MODE_WRITE)
{
Z_Free(stream->buf);
}
Z_Free(stream);
}
long mem_ftell(MEMFILE *stream)
{
return stream->position;
}
int mem_fseek(MEMFILE *stream, signed long position, mem_rel_t whence)
{
unsigned int newpos;
switch (whence)
{
case MEM_SEEK_SET:
newpos = (int) position;
break;
case MEM_SEEK_CUR:
newpos = (int) (stream->position + position);
break;
case MEM_SEEK_END:
newpos = (int) (stream->buflen + position);
break;
default:
return -1;
}
if (newpos < stream->buflen)
{
stream->position = newpos;
return 0;
}
else
{
printf("Error seeking to %i\n", newpos);
return -1;
}
}
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