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Diffstat (limited to 'libjpegtwrp/jdatasrc.c')
| -rw-r--r-- | libjpegtwrp/jdatasrc.c | 212 |
1 files changed, 0 insertions, 212 deletions
diff --git a/libjpegtwrp/jdatasrc.c b/libjpegtwrp/jdatasrc.c deleted file mode 100644 index edc752bf5..000000000 --- a/libjpegtwrp/jdatasrc.c +++ /dev/null @@ -1,212 +0,0 @@ -/* - * jdatasrc.c - * - * Copyright (C) 1994-1996, 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 "jpeglib.h" -#include "jerror.h" - - -/* Expanded data source object for stdio input */ - -typedef struct { - struct jpeg_source_mgr pub; /* public fields */ - - FILE * 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) -fill_input_buffer (j_decompress_ptr cinfo) -{ - my_src_ptr src = (my_src_ptr) cinfo->src; - size_t nbytes; - - nbytes = JFREAD(src->infile, src->buffer, INPUT_BUF_SIZE); - - if (nbytes <= 0) { - if (src->start_of_file) /* Treat empty input file as fatal error */ - ERREXIT(cinfo, JERR_INPUT_EMPTY); - WARNMS(cinfo, JWRN_JPEG_EOF); - /* Insert a fake EOI marker */ - src->buffer[0] = (JOCTET) 0xFF; - src->buffer[1] = (JOCTET) JPEG_EOI; - nbytes = 2; - } - - 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, FILE * infile) -{ - 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->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */ - src->pub.next_input_byte = NULL; /* until buffer loaded */ -} |