7 * Copyright (C) 1994-1995, Thomas G. Lane.
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9 * This file is part of the Independent JPEG Group's software.
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11 * For conditions of distribution and use, see the accompanying README file.
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15 * This file contains application interface code for the decompression half
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17 * of the JPEG library. These are the "minimum" API routines that may be
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19 * needed in either the normal full-decompression case or the
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21 * transcoding-only case.
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25 * Most of the routines intended to be called directly by an application
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27 * are in this file or in jdapistd.c. But also see jcomapi.c for routines
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29 * shared by compression and decompression, and jdtrans.c for the transcoding
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37 #define JPEG_INTERNALS
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39 #include "jinclude.h"
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41 #include "radiant_jpeglib.h"
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49 * Initialization of a JPEG decompression object.
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51 * The error manager must already be set up (in case memory manager fails).
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59 jpeg_create_decompress (j_decompress_ptr cinfo)
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67 /* For debugging purposes, zero the whole master structure.
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69 * But error manager pointer is already there, so save and restore it.
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75 struct jpeg_error_mgr * err = cinfo->err;
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77 i = sizeof(struct jpeg_decompress_struct);
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79 i = SIZEOF(struct jpeg_decompress_struct);
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81 MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
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87 cinfo->is_decompressor = TRUE;
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91 /* Initialize a memory manager instance for this object */
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93 jinit_memory_mgr((j_common_ptr) cinfo);
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97 /* Zero out pointers to permanent structures. */
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99 cinfo->progress = NULL;
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105 for (i = 0; i < NUM_QUANT_TBLS; i++)
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107 cinfo->quant_tbl_ptrs[i] = NULL;
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111 for (i = 0; i < NUM_HUFF_TBLS; i++) {
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113 cinfo->dc_huff_tbl_ptrs[i] = NULL;
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115 cinfo->ac_huff_tbl_ptrs[i] = NULL;
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121 /* Initialize marker processor so application can override methods
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123 * for COM, APPn markers before calling jpeg_read_header.
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127 jinit_marker_reader(cinfo);
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131 /* And initialize the overall input controller. */
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133 jinit_input_controller(cinfo);
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137 /* OK, I'm ready */
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139 cinfo->global_state = DSTATE_START;
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149 * Destruction of a JPEG decompression object
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157 jpeg_destroy_decompress (j_decompress_ptr cinfo)
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161 jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
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171 * Abort processing of a JPEG decompression operation,
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173 * but don't destroy the object itself.
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181 jpeg_abort_decompress (j_decompress_ptr cinfo)
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185 jpeg_abort((j_common_ptr) cinfo); /* use common routine */
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195 * Install a special processing method for COM or APPn markers.
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203 jpeg_set_marker_processor (j_decompress_ptr cinfo, int marker_code,
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205 jpeg_marker_parser_method routine)
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209 if (marker_code == JPEG_COM)
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211 cinfo->marker->process_COM = routine;
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213 else if (marker_code >= JPEG_APP0 && marker_code <= JPEG_APP0+15)
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215 cinfo->marker->process_APPn[marker_code-JPEG_APP0] = routine;
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219 ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
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229 * Set default decompression parameters.
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237 default_decompress_parms (j_decompress_ptr cinfo)
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241 /* Guess the input colorspace, and set output colorspace accordingly. */
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243 /* (Wish JPEG committee had provided a real way to specify this...) */
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245 /* Note application may override our guesses. */
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247 switch (cinfo->num_components) {
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251 cinfo->jpeg_color_space = JCS_GRAYSCALE;
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253 cinfo->out_color_space = JCS_GRAYSCALE;
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261 if (cinfo->saw_JFIF_marker) {
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263 cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */
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265 } else if (cinfo->saw_Adobe_marker) {
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267 switch (cinfo->Adobe_transform) {
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271 cinfo->jpeg_color_space = JCS_RGB;
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277 cinfo->jpeg_color_space = JCS_YCbCr;
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283 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
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285 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
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293 /* Saw no special markers, try to guess from the component IDs */
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295 int cid0 = cinfo->comp_info[0].component_id;
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297 int cid1 = cinfo->comp_info[1].component_id;
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299 int cid2 = cinfo->comp_info[2].component_id;
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303 if (cid0 == 1 && cid1 == 2 && cid2 == 3)
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305 cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */
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307 else if (cid0 == 82 && cid1 == 71 && cid2 == 66)
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309 cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
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313 TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
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315 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
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321 /* Always guess RGB is proper output colorspace. */
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323 cinfo->out_color_space = JCS_RGB;
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331 if (cinfo->saw_Adobe_marker) {
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333 switch (cinfo->Adobe_transform) {
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337 cinfo->jpeg_color_space = JCS_CMYK;
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343 cinfo->jpeg_color_space = JCS_YCCK;
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349 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
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351 cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
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359 /* No special markers, assume straight CMYK. */
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361 cinfo->jpeg_color_space = JCS_CMYK;
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365 cinfo->out_color_space = JCS_CMYK;
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373 cinfo->jpeg_color_space = JCS_UNKNOWN;
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375 cinfo->out_color_space = JCS_UNKNOWN;
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383 /* Set defaults for other decompression parameters. */
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385 cinfo->scale_num = 1; /* 1:1 scaling */
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387 cinfo->scale_denom = 1;
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389 cinfo->output_gamma = 1.0;
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391 cinfo->buffered_image = FALSE;
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393 cinfo->raw_data_out = FALSE;
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395 cinfo->dct_method = JDCT_DEFAULT;
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397 cinfo->do_fancy_upsampling = TRUE;
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399 cinfo->do_block_smoothing = TRUE;
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401 cinfo->quantize_colors = FALSE;
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403 /* We set these in case application only sets quantize_colors. */
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405 cinfo->dither_mode = JDITHER_FS;
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407 #ifdef QUANT_2PASS_SUPPORTED
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409 cinfo->two_pass_quantize = TRUE;
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413 cinfo->two_pass_quantize = FALSE;
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417 cinfo->desired_number_of_colors = 256;
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419 cinfo->colormap = NULL;
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421 /* Initialize for no mode change in buffered-image mode. */
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423 cinfo->enable_1pass_quant = FALSE;
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425 cinfo->enable_external_quant = FALSE;
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427 cinfo->enable_2pass_quant = FALSE;
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437 * Decompression startup: read start of JPEG datastream to see what's there.
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439 * Need only initialize JPEG object and supply a data source before calling.
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443 * This routine will read as far as the first SOS marker (ie, actual start of
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445 * compressed data), and will save all tables and parameters in the JPEG
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447 * object. It will also initialize the decompression parameters to default
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449 * values, and finally return JPEG_HEADER_OK. On return, the application may
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451 * adjust the decompression parameters and then call jpeg_start_decompress.
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453 * (Or, if the application only wanted to determine the image parameters,
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455 * the data need not be decompressed. In that case, call jpeg_abort or
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457 * jpeg_destroy to release any temporary space.)
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459 * If an abbreviated (tables only) datastream is presented, the routine will
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461 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI. The application may then
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463 * re-use the JPEG object to read the abbreviated image datastream(s).
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465 * It is unnecessary (but OK) to call jpeg_abort in this case.
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467 * The JPEG_SUSPENDED return code only occurs if the data source module
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469 * requests suspension of the decompressor. In this case the application
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471 * should load more source data and then re-call jpeg_read_header to resume
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475 * If a non-suspending data source is used and require_image is TRUE, then the
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477 * return code need not be inspected since only JPEG_HEADER_OK is possible.
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481 * This routine is now just a front end to jpeg_consume_input, with some
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483 * extra error checking.
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491 jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
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499 if (cinfo->global_state != DSTATE_START &&
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501 cinfo->global_state != DSTATE_INHEADER)
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503 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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507 retcode = jpeg_consume_input(cinfo);
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513 case JPEG_REACHED_SOS:
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515 retcode = JPEG_HEADER_OK;
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519 case JPEG_REACHED_EOI:
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521 if (require_image) /* Complain if application wanted an image */
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523 ERREXIT(cinfo, JERR_NO_IMAGE);
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525 /* Reset to start state; it would be safer to require the application to
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527 * call jpeg_abort, but we can't change it now for compatibility reasons.
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529 * A side effect is to free any temporary memory (there shouldn't be any).
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533 jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */
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535 retcode = JPEG_HEADER_TABLES_ONLY;
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539 case JPEG_SUSPENDED:
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559 * Consume data in advance of what the decompressor requires.
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561 * This can be called at any time once the decompressor object has
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563 * been created and a data source has been set up.
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567 * This routine is essentially a state machine that handles a couple
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569 * of critical state-transition actions, namely initial setup and
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571 * transition from header scanning to ready-for-start_decompress.
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573 * All the actual input is done via the input controller's consume_input
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583 jpeg_consume_input (j_decompress_ptr cinfo)
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587 int retcode = JPEG_SUSPENDED;
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591 /* NB: every possible DSTATE value should be listed in this switch */
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593 switch (cinfo->global_state) {
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597 /* Start-of-datastream actions: reset appropriate modules */
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599 (*cinfo->inputctl->reset_input_controller) (cinfo);
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601 /* Initialize application's data source module */
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603 (*cinfo->src->init_source) (cinfo);
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605 cinfo->global_state = DSTATE_INHEADER;
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609 case DSTATE_INHEADER:
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611 retcode = (*cinfo->inputctl->consume_input) (cinfo);
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613 if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
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615 /* Set up default parameters based on header data */
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617 default_decompress_parms(cinfo);
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619 /* Set global state: ready for start_decompress */
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621 cinfo->global_state = DSTATE_READY;
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629 /* Can't advance past first SOS until start_decompress is called */
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631 retcode = JPEG_REACHED_SOS;
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635 case DSTATE_PRELOAD:
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637 case DSTATE_PRESCAN:
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639 case DSTATE_SCANNING:
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641 case DSTATE_RAW_OK:
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643 case DSTATE_BUFIMAGE:
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645 case DSTATE_BUFPOST:
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647 case DSTATE_STOPPING:
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649 retcode = (*cinfo->inputctl->consume_input) (cinfo);
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655 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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669 * Have we finished reading the input file?
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677 jpeg_input_complete (j_decompress_ptr cinfo)
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681 /* Check for valid jpeg object */
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683 if (cinfo->global_state < DSTATE_START ||
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685 cinfo->global_state > DSTATE_STOPPING)
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687 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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689 return cinfo->inputctl->eoi_reached;
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699 * Is there more than one scan?
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707 jpeg_has_multiple_scans (j_decompress_ptr cinfo)
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711 /* Only valid after jpeg_read_header completes */
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713 if (cinfo->global_state < DSTATE_READY ||
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715 cinfo->global_state > DSTATE_STOPPING)
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717 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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719 return cinfo->inputctl->has_multiple_scans;
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729 * Finish JPEG decompression.
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733 * This will normally just verify the file trailer and release temp storage.
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737 * Returns FALSE if suspended. The return value need be inspected only if
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739 * a suspending data source is used.
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747 jpeg_finish_decompress (j_decompress_ptr cinfo)
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751 if ((cinfo->global_state == DSTATE_SCANNING ||
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753 cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {
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755 /* Terminate final pass of non-buffered mode */
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757 if (cinfo->output_scanline < cinfo->output_height)
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759 ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
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761 (*cinfo->master->finish_output_pass) (cinfo);
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763 cinfo->global_state = DSTATE_STOPPING;
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765 } else if (cinfo->global_state == DSTATE_BUFIMAGE) {
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767 /* Finishing after a buffered-image operation */
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769 cinfo->global_state = DSTATE_STOPPING;
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771 } else if (cinfo->global_state != DSTATE_STOPPING) {
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773 /* STOPPING = repeat call after a suspension, anything else is error */
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775 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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779 /* Read until EOI */
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781 while (! cinfo->inputctl->eoi_reached) {
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783 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
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785 return FALSE; /* Suspend, come back later */
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789 /* Do final cleanup */
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791 (*cinfo->src->term_source) (cinfo);
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793 /* We can use jpeg_abort to release memory and reset global_state */
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795 jpeg_abort((j_common_ptr) cinfo);
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