--- /dev/null
+/*
+ * jdapistd.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 application interface code for the decompression half
+ * of the JPEG library. These are the "standard" API routines that are
+ * used in the normal full-decompression case. They are not used by a
+ * transcoding-only application. Note that if an application links in
+ * jpeg_start_decompress, it will end up linking in the entire decompressor.
+ * We thus must separate this file from jdapimin.c to avoid linking the
+ * whole decompression library into a transcoder.
+ */
+
+#define JPEG_INTERNALS
+#include "jinclude.h"
+#include "jpeglib.h"
+
+
+/* Forward declarations */
+LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
+
+
+/*
+ * Decompression initialization.
+ * jpeg_read_header must be completed before calling this.
+ *
+ * If a multipass operating mode was selected, this will do all but the
+ * last pass, and thus may take a great deal of time.
+ *
+ * Returns FALSE if suspended. The return value need be inspected only if
+ * a suspending data source is used.
+ */
+
+GLOBAL(boolean)
+jpeg_start_decompress (j_decompress_ptr cinfo)
+{
+ if (cinfo->global_state == DSTATE_READY) {
+ /* First call: initialize master control, select active modules */
+ jinit_master_decompress(cinfo);
+ if (cinfo->buffered_image) {
+ /* No more work here; expecting jpeg_start_output next */
+ cinfo->global_state = DSTATE_BUFIMAGE;
+ return TRUE;
+ }
+ cinfo->global_state = DSTATE_PRELOAD;
+ }
+ if (cinfo->global_state == DSTATE_PRELOAD) {
+ /* If file has multiple scans, absorb them all into the coef buffer */
+ if (cinfo->inputctl->has_multiple_scans) {
+#ifdef D_MULTISCAN_FILES_SUPPORTED
+ for (;;) {
+ int retcode;
+ /* Call progress monitor hook if present */
+ if (cinfo->progress != NULL)
+ (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
+ /* Absorb some more input */
+ retcode = (*cinfo->inputctl->consume_input) (cinfo);
+ if (retcode == JPEG_SUSPENDED)
+ return FALSE;
+ if (retcode == JPEG_REACHED_EOI)
+ break;
+ /* Advance progress counter if appropriate */
+ if (cinfo->progress != NULL &&
+ (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
+ if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
+ /* jdmaster underestimated number of scans; ratchet up one scan */
+ cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
+ }
+ }
+ }
+#else
+ ERREXIT(cinfo, JERR_NOT_COMPILED);
+#endif /* D_MULTISCAN_FILES_SUPPORTED */
+ }
+ cinfo->output_scan_number = cinfo->input_scan_number;
+ } else if (cinfo->global_state != DSTATE_PRESCAN)
+ ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
+ /* Perform any dummy output passes, and set up for the final pass */
+ return output_pass_setup(cinfo);
+}
+
+
+/*
+ * Set up for an output pass, and perform any dummy pass(es) needed.
+ * Common subroutine for jpeg_start_decompress and jpeg_start_output.
+ * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
+ * Exit: If done, returns TRUE and sets global_state for proper output mode.
+ * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
+ */
+
+LOCAL(boolean)
+output_pass_setup (j_decompress_ptr cinfo)
+{
+ if (cinfo->global_state != DSTATE_PRESCAN) {
+ /* First call: do pass setup */
+ (*cinfo->master->prepare_for_output_pass) (cinfo);
+ cinfo->output_scanline = 0;
+ cinfo->global_state = DSTATE_PRESCAN;
+ }
+ /* Loop over any required dummy passes */
+ while (cinfo->master->is_dummy_pass) {
+#ifdef QUANT_2PASS_SUPPORTED
+ /* Crank through the dummy pass */
+ while (cinfo->output_scanline < cinfo->output_height) {
+ JDIMENSION last_scanline;
+ /* Call progress monitor hook if present */
+ if (cinfo->progress != NULL) {
+ cinfo->progress->pass_counter = (long) cinfo->output_scanline;
+ cinfo->progress->pass_limit = (long) cinfo->output_height;
+ (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
+ }
+ /* Process some data */
+ last_scanline = cinfo->output_scanline;
+ (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
+ &cinfo->output_scanline, (JDIMENSION) 0);
+ if (cinfo->output_scanline == last_scanline)
+ return FALSE; /* No progress made, must suspend */
+ }
+ /* Finish up dummy pass, and set up for another one */
+ (*cinfo->master->finish_output_pass) (cinfo);
+ (*cinfo->master->prepare_for_output_pass) (cinfo);
+ cinfo->output_scanline = 0;
+#else
+ ERREXIT(cinfo, JERR_NOT_COMPILED);
+#endif /* QUANT_2PASS_SUPPORTED */
+ }
+ /* Ready for application to drive output pass through
+ * jpeg_read_scanlines or jpeg_read_raw_data.
+ */
+ cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
+ return TRUE;
+}
+
+
+/*
+ * Read some scanlines of data from the JPEG decompressor.
+ *
+ * The return value will be the number of lines actually read.
+ * This may be less than the number requested in several cases,
+ * including bottom of image, data source suspension, and operating
+ * modes that emit multiple scanlines at a time.
+ *
+ * Note: we warn about excess calls to jpeg_read_scanlines() since
+ * this likely signals an application programmer error. However,
+ * an oversize buffer (max_lines > scanlines remaining) is not an error.
+ */
+
+GLOBAL(JDIMENSION)
+jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
+ JDIMENSION max_lines)
+{
+ JDIMENSION row_ctr;
+
+ if (cinfo->global_state != DSTATE_SCANNING)
+ ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
+ if (cinfo->output_scanline >= cinfo->output_height) {
+ WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
+ return 0;
+ }
+
+ /* Call progress monitor hook if present */
+ if (cinfo->progress != NULL) {
+ cinfo->progress->pass_counter = (long) cinfo->output_scanline;
+ cinfo->progress->pass_limit = (long) cinfo->output_height;
+ (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
+ }
+
+ /* Process some data */
+ row_ctr = 0;
+ (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
+ cinfo->output_scanline += row_ctr;
+ return row_ctr;
+}
+
+
+/*
+ * Alternate entry point to read raw data.
+ * Processes exactly one iMCU row per call, unless suspended.
+ */
+
+GLOBAL(JDIMENSION)
+jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
+ JDIMENSION max_lines)
+{
+ JDIMENSION lines_per_iMCU_row;
+
+ if (cinfo->global_state != DSTATE_RAW_OK)
+ ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
+ if (cinfo->output_scanline >= cinfo->output_height) {
+ WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
+ return 0;
+ }
+
+ /* Call progress monitor hook if present */
+ if (cinfo->progress != NULL) {
+ cinfo->progress->pass_counter = (long) cinfo->output_scanline;
+ cinfo->progress->pass_limit = (long) cinfo->output_height;
+ (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
+ }
+
+ /* Verify that at least one iMCU row can be returned. */
+ lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size;
+ if (max_lines < lines_per_iMCU_row)
+ ERREXIT(cinfo, JERR_BUFFER_SIZE);
+
+ /* Decompress directly into user's buffer. */
+ if (! (*cinfo->coef->decompress_data) (cinfo, data))
+ return 0; /* suspension forced, can do nothing more */
+
+ /* OK, we processed one iMCU row. */
+ cinfo->output_scanline += lines_per_iMCU_row;
+ return lines_per_iMCU_row;
+}
+
+
+/* Additional entry points for buffered-image mode. */
+
+#ifdef D_MULTISCAN_FILES_SUPPORTED
+
+/*
+ * Initialize for an output pass in buffered-image mode.
+ */
+
+GLOBAL(boolean)
+jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
+{
+ if (cinfo->global_state != DSTATE_BUFIMAGE &&
+ cinfo->global_state != DSTATE_PRESCAN)
+ ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
+ /* Limit scan number to valid range */
+ if (scan_number <= 0)
+ scan_number = 1;
+ if (cinfo->inputctl->eoi_reached &&
+ scan_number > cinfo->input_scan_number)
+ scan_number = cinfo->input_scan_number;
+ cinfo->output_scan_number = scan_number;
+ /* Perform any dummy output passes, and set up for the real pass */
+ return output_pass_setup(cinfo);
+}
+
+
+/*
+ * Finish up after an output pass in buffered-image mode.
+ *
+ * Returns FALSE if suspended. The return value need be inspected only if
+ * a suspending data source is used.
+ */
+
+GLOBAL(boolean)
+jpeg_finish_output (j_decompress_ptr cinfo)
+{
+ if ((cinfo->global_state == DSTATE_SCANNING ||
+ cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
+ /* Terminate this pass. */
+ /* We do not require the whole pass to have been completed. */
+ (*cinfo->master->finish_output_pass) (cinfo);
+ cinfo->global_state = DSTATE_BUFPOST;
+ } else if (cinfo->global_state != DSTATE_BUFPOST) {
+ /* BUFPOST = repeat call after a suspension, anything else is error */
+ ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
+ }
+ /* Read markers looking for SOS or EOI */
+ while (cinfo->input_scan_number <= cinfo->output_scan_number &&
+ ! cinfo->inputctl->eoi_reached) {
+ if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
+ return FALSE; /* Suspend, come back later */
+ }
+ cinfo->global_state = DSTATE_BUFIMAGE;
+ return TRUE;
+}
+
+#endif /* D_MULTISCAN_FILES_SUPPORTED */
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