| 1 | /*
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| 2 | * jdapistd.c
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| 3 | *
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| 4 | * Copyright (C) 1994-1996, Thomas G. Lane.
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| 5 | * This file is part of the Independent JPEG Group's software.
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| 6 | * For conditions of distribution and use, see the accompanying README file.
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| 7 | *
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| 8 | * This file contains application interface code for the decompression half
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| 9 | * of the JPEG library. These are the "standard" API routines that are
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| 10 | * used in the normal full-decompression case. They are not used by a
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| 11 | * transcoding-only application. Note that if an application links in
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| 12 | * jpeg_start_decompress, it will end up linking in the entire decompressor.
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| 13 | * We thus must separate this file from jdapimin.c to avoid linking the
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| 14 | * whole decompression library into a transcoder.
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| 15 | */
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| 16 |
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| 17 | #define JPEG_INTERNALS
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| 18 | #include "jinclude.h"
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| 19 | #include "jpeglib.h"
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| 20 |
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| 21 |
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| 22 | /* Forward declarations */
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| 23 | LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
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| 24 |
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| 25 |
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| 26 | /*
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| 27 | * Decompression initialization.
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| 28 | * jpeg_read_header must be completed before calling this.
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| 29 | *
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| 30 | * If a multipass operating mode was selected, this will do all but the
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| 31 | * last pass, and thus may take a great deal of time.
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| 32 | *
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| 33 | * Returns FALSE if suspended. The return value need be inspected only if
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| 34 | * a suspending data source is used.
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| 35 | */
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| 36 |
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| 37 | GLOBAL(boolean)
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| 38 | jpeg_start_decompress (j_decompress_ptr cinfo)
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| 39 | {
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| 40 | if (cinfo->global_state == DSTATE_READY) {
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| 41 | /* First call: initialize master control, select active modules */
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| 42 | jinit_master_decompress(cinfo);
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| 43 | if (cinfo->buffered_image) {
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| 44 | /* No more work here; expecting jpeg_start_output next */
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| 45 | cinfo->global_state = DSTATE_BUFIMAGE;
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| 46 | return TRUE;
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| 47 | }
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| 48 | cinfo->global_state = DSTATE_PRELOAD;
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| 49 | }
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| 50 | if (cinfo->global_state == DSTATE_PRELOAD) {
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| 51 | /* If file has multiple scans, absorb them all into the coef buffer */
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| 52 | if (cinfo->inputctl->has_multiple_scans) {
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| 53 | #ifdef D_MULTISCAN_FILES_SUPPORTED
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| 54 | for (;;) {
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| 55 | int retcode;
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| 56 | /* Call progress monitor hook if present */
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| 57 | if (cinfo->progress != NULL)
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| 58 | (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
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| 59 | /* Absorb some more input */
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| 60 | retcode = (*cinfo->inputctl->consume_input) (cinfo);
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| 61 | if (retcode == JPEG_SUSPENDED)
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| 62 | return FALSE;
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| 63 | if (retcode == JPEG_REACHED_EOI)
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| 64 | break;
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| 65 | /* Advance progress counter if appropriate */
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| 66 | if (cinfo->progress != NULL &&
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| 67 | (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
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| 68 | if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
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| 69 | /* jdmaster underestimated number of scans; ratchet up one scan */
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| 70 | cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
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| 71 | }
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| 72 | }
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| 73 | }
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| 74 | #else
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| 75 | ERREXIT(cinfo, JERR_NOT_COMPILED);
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| 76 | #endif /* D_MULTISCAN_FILES_SUPPORTED */
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| 77 | }
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| 78 | cinfo->output_scan_number = cinfo->input_scan_number;
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| 79 | } else if (cinfo->global_state != DSTATE_PRESCAN)
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| 80 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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| 81 | /* Perform any dummy output passes, and set up for the final pass */
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| 82 | return output_pass_setup(cinfo);
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| 83 | }
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| 84 |
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| 85 |
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| 86 | /*
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| 87 | * Set up for an output pass, and perform any dummy pass(es) needed.
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| 88 | * Common subroutine for jpeg_start_decompress and jpeg_start_output.
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| 89 | * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
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| 90 | * Exit: If done, returns TRUE and sets global_state for proper output mode.
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| 91 | * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
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| 92 | */
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| 93 |
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| 94 | LOCAL(boolean)
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| 95 | output_pass_setup (j_decompress_ptr cinfo)
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| 96 | {
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| 97 | if (cinfo->global_state != DSTATE_PRESCAN) {
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| 98 | /* First call: do pass setup */
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| 99 | (*cinfo->master->prepare_for_output_pass) (cinfo);
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