+++ /dev/null
-/*
- * jdatasrc.c
- *
- * Copyright (C) 1994, Thomas G. Lane.
- * This file is part of the Independent JPEG Group's software.
- * For conditions of distribution and use, see the accompanying README file.
- *
- * This file contains decompression data source routines for the case of
- * reading JPEG data from a file (or any stdio stream). While these routines
- * are sufficient for most applications, some will want to use a different
- * source manager.
- * IMPORTANT: we assume that fread() will correctly transcribe an array of
- * JOCTETs from 8-bit-wide elements on external storage. If char is wider
- * than 8 bits on your machine, you may need to do some tweaking.
- */
-
-/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
-#include "jinclude.h"
-#include "radiant_jpeglib.h"
-#include "jerror.h"
-//extern int leo_buf_size; // FIXME ? merged in from Alpha - replaced by my_source_mgr->src_size
-/* Expanded data source object for stdio input */
-typedef struct {
- struct jpeg_source_mgr pub; /* public fields */
- int src_size; // FIXME ? merged from Alpha
- unsigned char *infile; /* source stream */
- JOCTET * buffer; /* start of buffer */
- boolean start_of_file; /* have we gotten any data yet? */
-} my_source_mgr;
-typedef my_source_mgr * my_src_ptr;
-#define INPUT_BUF_SIZE 4096 /* choose an efficiently fread'able size */
-
-/*
- * Initialize source --- called by jpeg_read_header
- * before any data is actually read.
- */
-METHODDEF void
-init_source (j_decompress_ptr cinfo)
-{
- my_src_ptr src = (my_src_ptr) cinfo->src;
- /* We reset the empty-input-file flag for each image,
- * but we don't clear the input buffer.
- * This is correct behavior for reading a series of images from one source.
- */
- src->start_of_file = TRUE;
-}
-
-/*
- * Fill the input buffer --- called whenever buffer is emptied.
- *
- * In typical applications, this should read fresh data into the buffer
- * (ignoring the current state of next_input_byte & bytes_in_buffer),
- * reset the pointer & count to the start of the buffer, and return TRUE
- * indicating that the buffer has been reloaded. It is not necessary to
- * fill the buffer entirely, only to obtain at least one more byte.
- *
- * There is no such thing as an EOF return. If the end of the file has been
- * reached, the routine has a choice of ERREXIT() or inserting fake data into
- * the buffer. In most cases, generating a warning message and inserting a
- * fake EOI marker is the best course of action --- this will allow the
- * decompressor to output however much of the image is there. However,
- * the resulting error message is misleading if the real problem is an empty
- * input file, so we handle that case specially.
- *
- * In applications that need to be able to suspend compression due to input
- * not being available yet, a FALSE return indicates that no more data can be
- * obtained right now, but more may be forthcoming later. In this situation,
- * the decompressor will return to its caller (with an indication of the
- * number of scanlines it has read, if any). The application should resume
- * decompression after it has loaded more data into the input buffer. Note
- * that there are substantial restrictions on the use of suspension --- see
- * the documentation.
- *
- * When suspending, the decompressor will back up to a convenient restart point
- * (typically the start of the current MCU). next_input_byte & bytes_in_buffer
- * indicate where the restart point will be if the current call returns FALSE.
- * Data beyond this point must be rescanned after resumption, so move it to
- * the front of the buffer rather than discarding it.
- */
-METHODDEF boolean
-// FIXME ? merged in from Alpha
-fill_input_buffer (j_decompress_ptr cinfo)
-{
- my_src_ptr src = (my_src_ptr) cinfo->src;
- size_t nbytes;
-
- if (src->src_size > INPUT_BUF_SIZE)
- nbytes = INPUT_BUF_SIZE;
- else
- nbytes = src->src_size;
- memcpy (src->buffer, src->infile, nbytes);
- src->infile += nbytes;
- src->src_size -= nbytes;
- src->pub.next_input_byte = src->buffer;
- src->pub.bytes_in_buffer = nbytes;
- src->start_of_file = FALSE;
- return TRUE;
-}
-
-/*
- * Skip data --- used to skip over a potentially large amount of
- * uninteresting data (such as an APPn marker).
- *
- * Writers of suspendable-input applications must note that skip_input_data
- * is not granted the right to give a suspension return. If the skip extends
- * beyond the data currently in the buffer, the buffer can be marked empty so
- * that the next read will cause a fill_input_buffer call that can suspend.
- * Arranging for additional bytes to be discarded before reloading the input
- * buffer is the application writer's problem.
- */
-METHODDEF void
-skip_input_data (j_decompress_ptr cinfo, long num_bytes)
-{
- my_src_ptr src = (my_src_ptr) cinfo->src;
- /* Just a dumb implementation for now. Could use fseek() except
- * it doesn't work on pipes. Not clear that being smart is worth
- * any trouble anyway --- large skips are infrequent.
- */
- if (num_bytes > 0) {
- while (num_bytes > (long) src->pub.bytes_in_buffer) {
- num_bytes -= (long) src->pub.bytes_in_buffer;
- (void) fill_input_buffer(cinfo);
- /* note we assume that fill_input_buffer will never return FALSE,
- * so suspension need not be handled.
- */
- }
- src->pub.next_input_byte += (size_t) num_bytes;
- src->pub.bytes_in_buffer -= (size_t) num_bytes;
- }
-}
-
-/*
- * An additional method that can be provided by data source modules is the
- * resync_to_restart method for error recovery in the presence of RST markers.
- * For the moment, this source module just uses the default resync method
- * provided by the JPEG library. That method assumes that no backtracking
- * is possible.
- */
-
-/*
- * Terminate source --- called by jpeg_finish_decompress
- * after all data has been read. Often a no-op.
- *
- * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
- * application must deal with any cleanup that should happen even
- * for error exit.
- */
-METHODDEF void
-term_source (j_decompress_ptr cinfo)
-{
- /* no work necessary here */
-}
-
-/*
- * Prepare for input from a stdio stream.
- * The caller must have already opened the stream, and is responsible
- * for closing it after finishing decompression.
- */
-GLOBAL void
-jpeg_stdio_src (j_decompress_ptr cinfo, unsigned char *infile, int bufsize)
-{
- my_src_ptr src;
- /* The source object and input buffer are made permanent so that a series
- * of JPEG images can be read from the same file by calling jpeg_stdio_src
- * only before the first one. (If we discarded the buffer at the end of
- * one image, we'd likely lose the start of the next one.)
- * This makes it unsafe to use this manager and a different source
- * manager serially with the same JPEG object. Caveat programmer.
- */
- if (cinfo->src == NULL) { /* first time for this JPEG object? */
- cinfo->src = (struct jpeg_source_mgr *)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
- SIZEOF(my_source_mgr));
- src = (my_src_ptr) cinfo->src;
- src->buffer = (JOCTET *)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
- INPUT_BUF_SIZE * SIZEOF(JOCTET));
- }
- src = (my_src_ptr) 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; /* use default method */
- src->pub.term_source = term_source;
- src->infile = infile;
- src->src_size = bufsize; // FIXME ? merged from Alpha
- src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
- src->pub.next_input_byte = NULL; /* until buffer loaded */
-}
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