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94 lines
3 KiB
C++
94 lines
3 KiB
C++
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/*
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* Copyright (C) 1994-1996, Thomas G. Lane.
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* Modified 2009-2010 by Guido Vollbeding.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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* This file contains decompression data source routines for the case of
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* reading JPEG data from memory or from a file (or any stdio stream).
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* While these routines are sufficient for most applications,
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* some will want to use a different source manager.
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* IMPORTANT: we assume that fread() will correctly transcribe an array of
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* JOCTETs from 8-bit-wide elements on external storage. If char is wider
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* than 8 bits on your machine, you may need to do some tweaking.
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*/
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#include "sys/platform.h"
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#include "renderer/jpeg_memory_src.h"
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#ifdef HAVE_JPEG_MEM_SRC
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void jpeg_memory_src(j_decompress_ptr cinfo, unsigned char *inbuffer, unsigned long insize) {
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jpeg_mem_src(cinfo, inbuffer, insize);
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}
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#else
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static void init_mem_source(j_decompress_ptr cinfo) {
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/* no work necessary here */
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}
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static boolean fill_mem_input_buffer(j_decompress_ptr cinfo) {
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static JOCTET mybuffer[4];
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/* The whole JPEG data is expected to reside in the supplied memory
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* buffer, so any request for more data beyond the given buffer size
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* is treated as an error.
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*/
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WARNMS(cinfo, JWRN_JPEG_EOF);
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/* Insert a fake EOI marker */
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mybuffer[0] = (JOCTET) 0xFF;
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mybuffer[1] = (JOCTET) JPEG_EOI;
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cinfo->src->next_input_byte = mybuffer;
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cinfo->src->bytes_in_buffer = 2;
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return TRUE;
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}
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static void skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
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struct jpeg_source_mgr *src = cinfo->src;
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if (num_bytes > 0) {
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while (num_bytes > (long)src->bytes_in_buffer) {
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num_bytes -= (long)src->bytes_in_buffer;
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(void)(*src->fill_input_buffer) (cinfo);
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/* note we assume that fill_input_buffer will never return FALSE,
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* so suspension need not be handled.
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*/
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}
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src->next_input_byte += (size_t)num_bytes;
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src->bytes_in_buffer -= (size_t)num_bytes;
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}
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}
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static void term_source(j_decompress_ptr cinfo)
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{
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/* no work necessary here */
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}
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void jpeg_memory_src(j_decompress_ptr cinfo, unsigned char *inbuffer, unsigned long insize) {
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struct jpeg_source_mgr *src;
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if (inbuffer == NULL || insize == 0) /* Treat empty input as fatal error */
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ERREXIT(cinfo, JERR_INPUT_EMPTY);
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/* The source object is made permanent so that a series of JPEG images
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* can be read from the same buffer by calling jpeg_mem_src only before
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* the first one.
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*/
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if (cinfo->src == NULL) { /* first time for this JPEG object? */
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cinfo->src = (struct jpeg_source_mgr *)
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(*cinfo->mem->alloc_small)((j_common_ptr)cinfo, JPOOL_PERMANENT,
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sizeof(struct jpeg_source_mgr));
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}
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src = cinfo->src;
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src->init_source = init_mem_source;
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src->fill_input_buffer = fill_mem_input_buffer;
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src->skip_input_data = skip_input_data;
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src->resync_to_restart = jpeg_resync_to_restart; /* use default method */
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src->term_source = term_source;
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src->bytes_in_buffer = (size_t)insize;
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src->next_input_byte = (JOCTET *)inbuffer;
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}
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#endif
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