Memory source for libjpeg-turbo

jpeg_memory_src.c

#include "jpeg_memory_src.h"

/// JPEG source manager
struct jpeg_source_t
{
    struct jpeg_source_mgr _pub;

    const char *_begin;
    const char *_end;
};

/// Initialize JPEG source
METHODDEF(void) init_source(j_decompress_ptr cinfo)
{
}

/// Fill image buffer
METHODDEF(boolean) fill_input_buffer(j_decompress_ptr cinfo)
{
    struct jpeg_source_t *src=(struct jpeg_source_t *)cinfo->src;

    src->_pub.next_input_byte=(const JOCTET *)src->_begin;
    src->_pub.bytes_in_buffer=src->_end-src->_begin;

    return TRUE;
}


/// Skip data in buffer
METHODDEF(void)skip_input_data(j_decompress_ptr cinfo, long num_bytes)
{
    struct jpeg_source_t *src=(struct jpeg_source_t *)cinfo->src;

    src->_pub.next_input_byte+=(size_t)num_bytes;
    src->_pub.bytes_in_buffer-=(size_t)num_bytes;
}


/// Close buffer
METHODDEF(void)term_source(j_decompress_ptr cinfo)
{
}


/// Initialize memory source
void jpeg_memory_src(j_decompress_ptr cinfo, const char *begin, const char *end)
{
    cinfo->src=(struct jpeg_source_mgr *)(*cinfo->mem->alloc_small)((j_common_ptr)cinfo, JPOOL_PERMANENT, sizeof(struct jpeg_source_t));
    struct jpeg_source_t *src=(struct jpeg_source_t *)cinfo->src;

    src->_pub.init_source=init_source;
    src->_pub.fill_input_buffer=fill_input_buffer;
    src->_pub.skip_input_data=skip_input_data;
    src->_pub.resync_to_restart=jpeg_resync_to_restart;
    src->_pub.term_source=term_source;
    src->_pub.bytes_in_buffer=0;
    src->_pub.next_input_byte=NULL;
    src->_begin=begin;
    src->_end=end;
}

jpeg_memory_src.h

#ifndef jpegtest_jpeg_memory_src_h
#define jpegtest_jpeg_memory_src_h

#include <stdio.h>
#include <jpeglib.h>

extern void jpeg_memory_src(j_decompress_ptr cinfo, const char *begin, const char *end);

#endif