2 * CDE - Common Desktop Environment
4 * Copyright (c) 1993-2012, The Open Group. All rights reserved.
6 * These libraries and programs are free software; you can
7 * redistribute them and/or modify them under the terms of the GNU
8 * Lesser General Public License as published by the Free Software
9 * Foundation; either version 2 of the License, or (at your option)
12 * These libraries and programs are distributed in the hope that
13 * they will be useful, but WITHOUT ANY WARRANTY; without even the
14 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
15 * PURPOSE. See the GNU Lesser General Public License for more
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with these librararies and programs; if not, write
20 * to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
21 * Floor, Boston, MA 02110-1301 USA
23 /* $XConsortium: jdinput.c /main/2 1996/05/09 03:48:17 drk $ */
27 * Copyright (C) 1991-1996, Thomas G. Lane.
28 * This file is part of the Independent JPEG Group's software.
29 * For conditions of distribution and use, see the accompanying README file.
31 * This file contains input control logic for the JPEG decompressor.
32 * These routines are concerned with controlling the decompressor's input
33 * processing (marker reading and coefficient decoding). The actual input
34 * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
37 #define JPEG_INTERNALS
45 struct jpeg_input_controller pub; /* public fields */
47 boolean inheaders; /* TRUE until first SOS is reached */
48 } my_input_controller;
50 typedef my_input_controller * my_inputctl_ptr;
53 /* Forward declarations */
54 METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
58 * Routines to calculate various quantities related to the size of the image.
62 initial_setup (j_decompress_ptr cinfo)
63 /* Called once, when first SOS marker is reached */
66 jpeg_component_info *compptr;
68 /* Make sure image isn't bigger than I can handle */
69 if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
70 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
71 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
73 /* For now, precision must match compiled-in value... */
74 if (cinfo->data_precision != BITS_IN_JSAMPLE)
75 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
77 /* Check that number of components won't exceed internal array sizes */
78 if (cinfo->num_components > MAX_COMPONENTS)
79 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
82 /* Compute maximum sampling factors; check factor validity */
83 cinfo->max_h_samp_factor = 1;
84 cinfo->max_v_samp_factor = 1;
85 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
87 if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
88 compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
89 ERREXIT(cinfo, JERR_BAD_SAMPLING);
90 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
91 compptr->h_samp_factor);
92 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
93 compptr->v_samp_factor);
96 /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
97 * In the full decompressor, this will be overridden by jdmaster.c;
98 * but in the transcoder, jdmaster.c is not used, so we must do it here.
100 cinfo->min_DCT_scaled_size = DCTSIZE;
102 /* Compute dimensions of components */
103 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
105 compptr->DCT_scaled_size = DCTSIZE;
106 /* Size in DCT blocks */
107 compptr->width_in_blocks = (JDIMENSION)
108 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
109 (long) (cinfo->max_h_samp_factor * DCTSIZE));
110 compptr->height_in_blocks = (JDIMENSION)
111 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
112 (long) (cinfo->max_v_samp_factor * DCTSIZE));
113 /* downsampled_width and downsampled_height will also be overridden by
114 * jdmaster.c if we are doing full decompression. The transcoder library
115 * doesn't use these values, but the calling application might.
117 /* Size in samples */
118 compptr->downsampled_width = (JDIMENSION)
119 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
120 (long) cinfo->max_h_samp_factor);
121 compptr->downsampled_height = (JDIMENSION)
122 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
123 (long) cinfo->max_v_samp_factor);
124 /* Mark component needed, until color conversion says otherwise */
125 compptr->component_needed = TRUE;
126 /* Mark no quantization table yet saved for component */
127 compptr->quant_table = NULL;
130 /* Compute number of fully interleaved MCU rows. */
131 cinfo->total_iMCU_rows = (JDIMENSION)
132 jdiv_round_up((long) cinfo->image_height,
133 (long) (cinfo->max_v_samp_factor*DCTSIZE));
135 /* Decide whether file contains multiple scans */
136 if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
137 cinfo->inputctl->has_multiple_scans = TRUE;
139 cinfo->inputctl->has_multiple_scans = FALSE;
144 per_scan_setup (j_decompress_ptr cinfo)
145 /* Do computations that are needed before processing a JPEG scan */
146 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
148 int ci, mcublks, tmp;
149 jpeg_component_info *compptr;
151 if (cinfo->comps_in_scan == 1) {
153 /* Noninterleaved (single-component) scan */
154 compptr = cinfo->cur_comp_info[0];
156 /* Overall image size in MCUs */
157 cinfo->MCUs_per_row = compptr->width_in_blocks;
158 cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
160 /* For noninterleaved scan, always one block per MCU */
161 compptr->MCU_width = 1;
162 compptr->MCU_height = 1;
163 compptr->MCU_blocks = 1;
164 compptr->MCU_sample_width = compptr->DCT_scaled_size;
165 compptr->last_col_width = 1;
166 /* For noninterleaved scans, it is convenient to define last_row_height
167 * as the number of block rows present in the last iMCU row.
169 tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
170 if (tmp == 0) tmp = compptr->v_samp_factor;
171 compptr->last_row_height = tmp;
173 /* Prepare array describing MCU composition */
174 cinfo->blocks_in_MCU = 1;
175 cinfo->MCU_membership[0] = 0;
179 /* Interleaved (multi-component) scan */
180 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
181 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
184 /* Overall image size in MCUs */
185 cinfo->MCUs_per_row = (JDIMENSION)
186 jdiv_round_up((long) cinfo->image_width,
187 (long) (cinfo->max_h_samp_factor*DCTSIZE));
188 cinfo->MCU_rows_in_scan = (JDIMENSION)
189 jdiv_round_up((long) cinfo->image_height,
190 (long) (cinfo->max_v_samp_factor*DCTSIZE));
192 cinfo->blocks_in_MCU = 0;
194 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
195 compptr = cinfo->cur_comp_info[ci];
196 /* Sampling factors give # of blocks of component in each MCU */
197 compptr->MCU_width = compptr->h_samp_factor;
198 compptr->MCU_height = compptr->v_samp_factor;
199 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
200 compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
201 /* Figure number of non-dummy blocks in last MCU column & row */
202 tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
203 if (tmp == 0) tmp = compptr->MCU_width;
204 compptr->last_col_width = tmp;
205 tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
206 if (tmp == 0) tmp = compptr->MCU_height;
207 compptr->last_row_height = tmp;
208 /* Prepare array describing MCU composition */
209 mcublks = compptr->MCU_blocks;
210 if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
211 ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
212 while (mcublks-- > 0) {
213 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
222 * Save away a copy of the Q-table referenced by each component present
223 * in the current scan, unless already saved during a prior scan.
225 * In a multiple-scan JPEG file, the encoder could assign different components
226 * the same Q-table slot number, but change table definitions between scans
227 * so that each component uses a different Q-table. (The IJG encoder is not
228 * currently capable of doing this, but other encoders might.) Since we want
229 * to be able to dequantize all the components at the end of the file, this
230 * means that we have to save away the table actually used for each component.
231 * We do this by copying the table at the start of the first scan containing
233 * The JPEG spec prohibits the encoder from changing the contents of a Q-table
234 * slot between scans of a component using that slot. If the encoder does so
235 * anyway, this decoder will simply use the Q-table values that were current
236 * at the start of the first scan for the component.
238 * The decompressor output side looks only at the saved quant tables,
239 * not at the current Q-table slots.
243 latch_quant_tables (j_decompress_ptr cinfo)
246 jpeg_component_info *compptr;
249 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
250 compptr = cinfo->cur_comp_info[ci];
251 /* No work if we already saved Q-table for this component */
252 if (compptr->quant_table != NULL)
254 /* Make sure specified quantization table is present */
255 qtblno = compptr->quant_tbl_no;
256 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
257 cinfo->quant_tbl_ptrs[qtblno] == NULL)
258 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
259 /* OK, save away the quantization table */
260 qtbl = (JQUANT_TBL *)
261 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
263 MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
264 compptr->quant_table = qtbl;
270 * Initialize the input modules to read a scan of compressed data.
271 * The first call to this is done by jdmaster.c after initializing
272 * the entire decompressor (during jpeg_start_decompress).
273 * Subsequent calls come from consume_markers, below.
277 start_input_pass (j_decompress_ptr cinfo)
279 per_scan_setup(cinfo);
280 latch_quant_tables(cinfo);
281 (*cinfo->entropy->start_pass) (cinfo);
282 (*cinfo->coef->start_input_pass) (cinfo);
283 cinfo->inputctl->consume_input = cinfo->coef->consume_data;
288 * Finish up after inputting a compressed-data scan.
289 * This is called by the coefficient controller after it's read all
290 * the expected data of the scan.
294 finish_input_pass (j_decompress_ptr cinfo)
296 cinfo->inputctl->consume_input = consume_markers;
301 * Read JPEG markers before, between, or after compressed-data scans.
302 * Change state as necessary when a new scan is reached.
303 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
305 * The consume_input method pointer points either here or to the
306 * coefficient controller's consume_data routine, depending on whether
307 * we are reading a compressed data segment or inter-segment markers.
311 consume_markers (j_decompress_ptr cinfo)
313 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
316 if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
317 return JPEG_REACHED_EOI;
319 val = (*cinfo->marker->read_markers) (cinfo);
322 case JPEG_REACHED_SOS: /* Found SOS */
323 if (inputctl->inheaders) { /* 1st SOS */
324 initial_setup(cinfo);
325 inputctl->inheaders = FALSE;
326 /* Note: start_input_pass must be called by jdmaster.c
327 * before any more input can be consumed. jdapi.c is
328 * responsible for enforcing this sequencing.
330 } else { /* 2nd or later SOS marker */
331 if (! inputctl->pub.has_multiple_scans)
332 ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
333 start_input_pass(cinfo);
336 case JPEG_REACHED_EOI: /* Found EOI */
337 inputctl->pub.eoi_reached = TRUE;
338 if (inputctl->inheaders) { /* Tables-only datastream, apparently */
339 if (cinfo->marker->saw_SOF)
340 ERREXIT(cinfo, JERR_SOF_NO_SOS);
342 /* Prevent infinite loop in coef ctlr's decompress_data routine
343 * if user set output_scan_number larger than number of scans.
345 if (cinfo->output_scan_number > cinfo->input_scan_number)
346 cinfo->output_scan_number = cinfo->input_scan_number;
358 * Reset state to begin a fresh datastream.
362 reset_input_controller (j_decompress_ptr cinfo)
364 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
366 inputctl->pub.consume_input = consume_markers;
367 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
368 inputctl->pub.eoi_reached = FALSE;
369 inputctl->inheaders = TRUE;
370 /* Reset other modules */
371 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
372 (*cinfo->marker->reset_marker_reader) (cinfo);
373 /* Reset progression state -- would be cleaner if entropy decoder did this */
374 cinfo->coef_bits = NULL;
379 * Initialize the input controller module.
380 * This is called only once, when the decompression object is created.
384 jinit_input_controller (j_decompress_ptr cinfo)
386 my_inputctl_ptr inputctl;
388 /* Create subobject in permanent pool */
389 inputctl = (my_inputctl_ptr)
390 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
391 SIZEOF(my_input_controller));
392 cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
393 /* Initialize method pointers */
394 inputctl->pub.consume_input = consume_markers;
395 inputctl->pub.reset_input_controller = reset_input_controller;
396 inputctl->pub.start_input_pass = start_input_pass;
397 inputctl->pub.finish_input_pass = finish_input_pass;
398 /* Initialize state: can't use reset_input_controller since we don't
399 * want to try to reset other modules yet.
401 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
402 inputctl->pub.eoi_reached = FALSE;
403 inputctl->inheaders = TRUE;