134 lines
2.7 KiB
C
134 lines
2.7 KiB
C
#include <stdio.h>
|
|
#include <stdint.h>
|
|
#include <stdlib.h>
|
|
#include <stddef.h>
|
|
#include <string.h>
|
|
#include "memstream.h"
|
|
|
|
static uint8_t *g_buffer = NULL;
|
|
static size_t g_size = 0;
|
|
static size_t g_last_file_size = 0;
|
|
|
|
struct memstream
|
|
{
|
|
uint8_t *m_buf;
|
|
size_t m_size;
|
|
size_t m_ptr;
|
|
size_t m_max_ptr;
|
|
unsigned writing;
|
|
};
|
|
|
|
static void memstream_update_ptr(memstream_t *stream)
|
|
{
|
|
if (stream->m_ptr > stream->m_max_ptr)
|
|
stream->m_max_ptr = stream->m_ptr;
|
|
}
|
|
|
|
static void memstream_init(memstream_t *stream, uint8_t *buffer, size_t max_size, unsigned writing)
|
|
{
|
|
stream->m_buf = buffer;
|
|
stream->m_size = max_size;
|
|
stream->m_ptr = 0;
|
|
stream->m_max_ptr = 0;
|
|
stream->writing = writing;
|
|
}
|
|
|
|
void memstream_set_buffer(uint8_t *buffer, size_t size)
|
|
{
|
|
g_buffer = buffer;
|
|
g_size = size;
|
|
}
|
|
|
|
size_t memstream_get_last_size(void)
|
|
{
|
|
return g_last_file_size;
|
|
}
|
|
|
|
memstream_t *memstream_open(unsigned writing)
|
|
{
|
|
memstream_t *stream;
|
|
if (!g_buffer || !g_size)
|
|
return NULL;
|
|
|
|
stream = (memstream_t*)calloc(1, sizeof(*stream));
|
|
memstream_init(stream, g_buffer, g_size, writing);
|
|
g_buffer = NULL;
|
|
g_size = 0;
|
|
return stream;
|
|
}
|
|
|
|
void memstream_close(memstream_t *stream)
|
|
{
|
|
g_last_file_size = stream->writing ? stream->m_max_ptr : stream->m_size;
|
|
free(stream);
|
|
}
|
|
|
|
size_t memstream_read(memstream_t *stream, void *data, size_t bytes)
|
|
{
|
|
size_t avail = stream->m_size - stream->m_ptr;
|
|
if (bytes > avail)
|
|
bytes = avail;
|
|
|
|
memcpy(data, stream->m_buf + stream->m_ptr, bytes);
|
|
stream->m_ptr += bytes;
|
|
memstream_update_ptr(stream);
|
|
return bytes;
|
|
}
|
|
|
|
size_t memstream_write(memstream_t *stream, const void *data, size_t bytes)
|
|
{
|
|
size_t avail = stream->m_size - stream->m_ptr;
|
|
if (bytes > avail)
|
|
bytes = avail;
|
|
|
|
memcpy(stream->m_buf + stream->m_ptr, data, bytes);
|
|
stream->m_ptr += bytes;
|
|
memstream_update_ptr(stream);
|
|
return bytes;
|
|
}
|
|
|
|
int memstream_seek(memstream_t *stream, int offset, int whence)
|
|
{
|
|
size_t ptr;
|
|
if (whence == SEEK_SET)
|
|
ptr = offset;
|
|
else if (whence == SEEK_CUR)
|
|
ptr = stream->m_ptr + offset;
|
|
else if (whence == SEEK_END)
|
|
ptr = (stream->writing ? stream->m_max_ptr : stream->m_size) + offset;
|
|
else
|
|
return -1;
|
|
|
|
if (ptr <= stream->m_size)
|
|
{
|
|
stream->m_ptr = ptr;
|
|
return 0;
|
|
}
|
|
else
|
|
return -1;
|
|
}
|
|
|
|
size_t memstream_pos(memstream_t *stream)
|
|
{
|
|
return stream->m_ptr;
|
|
}
|
|
|
|
int memstream_getc(memstream_t *stream)
|
|
{
|
|
if (stream->m_ptr >= stream->m_size)
|
|
return EOF;
|
|
else
|
|
return stream->m_buf[stream->m_ptr++];
|
|
|
|
memstream_update_ptr(stream);
|
|
}
|
|
|
|
void memstream_putc(memstream_t *stream, int c)
|
|
{
|
|
if (stream->m_ptr < stream->m_size)
|
|
stream->m_buf[stream->m_ptr++] = c;
|
|
|
|
memstream_update_ptr(stream);
|
|
}
|
|
|