4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1991-1997, Thomas G. Lane.
6 * Lossless JPEG Modifications:
7 * Copyright (C) 1999, Ken Murchison.
8 * libjpeg-turbo Modifications:
9 * Copyright (C) 2010, 2016, 2018, 2022, D. R. Commander.
10 * Copyright (C) 2015, Google, Inc.
11 * For conditions of distribution and use, see the accompanying README.ijg
14 * This file contains input control logic for the JPEG decompressor.
15 * These routines are concerned with controlling the decompressor's input
16 * processing (marker reading and coefficient/difference decoding).
17 * The actual input reading is done in jdmarker.c, jdhuff.c, jdphuff.c,
21 #define JPEG_INTERNALS
24 #include "jpegapicomp.h"
30 struct jpeg_input_controller pub; /* public fields */
32 boolean inheaders; /* TRUE until first SOS is reached */
33 } my_input_controller;
35 typedef my_input_controller *my_inputctl_ptr;
38 /* Forward declarations */
39 METHODDEF(int) consume_markers(j_decompress_ptr cinfo);
43 * Routines to calculate various quantities related to the size of the image.
47 initial_setup(j_decompress_ptr cinfo)
48 /* Called once, when first SOS marker is reached */
51 jpeg_component_info *compptr;
52 int data_unit = cinfo->master->lossless ? 1 : DCTSIZE;
54 /* Make sure image isn't bigger than I can handle */
55 if ((long)cinfo->image_height > (long)JPEG_MAX_DIMENSION ||
56 (long)cinfo->image_width > (long)JPEG_MAX_DIMENSION)
57 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int)JPEG_MAX_DIMENSION);
59 /* For now, precision must match compiled-in value... */
60 #ifdef D_LOSSLESS_SUPPORTED
61 if (cinfo->data_precision != 8 && cinfo->data_precision != 12 &&
62 cinfo->data_precision != 16)
64 if (cinfo->data_precision != 8 && cinfo->data_precision != 12)
66 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
68 /* Check that number of components won't exceed internal array sizes */
69 if (cinfo->num_components > MAX_COMPONENTS)
70 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
73 /* Compute maximum sampling factors; check factor validity */
74 cinfo->max_h_samp_factor = 1;
75 cinfo->max_v_samp_factor = 1;
76 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
78 if (compptr->h_samp_factor <= 0 ||
79 compptr->h_samp_factor > MAX_SAMP_FACTOR ||
80 compptr->v_samp_factor <= 0 ||
81 compptr->v_samp_factor > MAX_SAMP_FACTOR)
82 ERREXIT(cinfo, JERR_BAD_SAMPLING);
83 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
84 compptr->h_samp_factor);
85 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
86 compptr->v_samp_factor);
89 #if JPEG_LIB_VERSION >= 80
90 cinfo->block_size = data_unit;
91 cinfo->natural_order = jpeg_natural_order;
92 cinfo->lim_Se = DCTSIZE2 - 1;
95 /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE in lossy
96 * mode. In the full decompressor, this will be overridden by jdmaster.c;
97 * but in the transcoder, jdmaster.c is not used, so we must do it here.
99 #if JPEG_LIB_VERSION >= 70
100 cinfo->min_DCT_h_scaled_size = cinfo->min_DCT_v_scaled_size = data_unit;
102 cinfo->min_DCT_scaled_size = data_unit;
105 /* Compute dimensions of components */
106 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
108 #if JPEG_LIB_VERSION >= 70
109 compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = data_unit;
111 compptr->DCT_scaled_size = data_unit;
113 /* Size in data units */
114 compptr->width_in_blocks = (JDIMENSION)
115 jdiv_round_up((long)cinfo->image_width * (long)compptr->h_samp_factor,
116 (long)(cinfo->max_h_samp_factor * data_unit));
117 compptr->height_in_blocks = (JDIMENSION)
118 jdiv_round_up((long)cinfo->image_height * (long)compptr->v_samp_factor,
119 (long)(cinfo->max_v_samp_factor * data_unit));
120 /* Set the first and last MCU columns to decompress from multi-scan images.
121 * By default, decompress all of the MCU columns.
123 cinfo->master->first_MCU_col[ci] = 0;
124 cinfo->master->last_MCU_col[ci] = compptr->width_in_blocks - 1;
125 /* downsampled_width and downsampled_height will also be overridden by
126 * jdmaster.c if we are doing full decompression. The transcoder library
127 * doesn't use these values, but the calling application might.
129 /* Size in samples */
130 compptr->downsampled_width = (JDIMENSION)
131 jdiv_round_up((long)cinfo->image_width * (long)compptr->h_samp_factor,
132 (long)cinfo->max_h_samp_factor);
133 compptr->downsampled_height = (JDIMENSION)
134 jdiv_round_up((long)cinfo->image_height * (long)compptr->v_samp_factor,
135 (long)cinfo->max_v_samp_factor);
136 /* Mark component needed, until color conversion says otherwise */
137 compptr->component_needed = TRUE;
138 /* Mark no quantization table yet saved for component */
139 compptr->quant_table = NULL;
142 /* Compute number of fully interleaved MCU rows. */
143 cinfo->total_iMCU_rows = (JDIMENSION)
144 jdiv_round_up((long)cinfo->image_height,
145 (long)(cinfo->max_v_samp_factor * data_unit));
147 /* Decide whether file contains multiple scans */
148 if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
149 cinfo->inputctl->has_multiple_scans = TRUE;
151 cinfo->inputctl->has_multiple_scans = FALSE;
156 per_scan_setup(j_decompress_ptr cinfo)
157 /* Do computations that are needed before processing a JPEG scan */
158 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
160 int ci, mcublks, tmp;
161 jpeg_component_info *compptr;
162 int data_unit = cinfo->master->lossless ? 1 : DCTSIZE;
164 if (cinfo->comps_in_scan == 1) {
166 /* Noninterleaved (single-component) scan */
167 compptr = cinfo->cur_comp_info[0];
169 /* Overall image size in MCUs */
170 cinfo->MCUs_per_row = compptr->width_in_blocks;
171 cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
173 /* For noninterleaved scan, always one data unit per MCU */
174 compptr->MCU_width = 1;
175 compptr->MCU_height = 1;
176 compptr->MCU_blocks = 1;
177 compptr->MCU_sample_width = compptr->_DCT_scaled_size;
178 compptr->last_col_width = 1;
179 /* For noninterleaved scans, it is convenient to define last_row_height
180 * as the number of data unit rows present in the last iMCU row.
182 tmp = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
183 if (tmp == 0) tmp = compptr->v_samp_factor;
184 compptr->last_row_height = tmp;
186 /* Prepare array describing MCU composition */
187 cinfo->blocks_in_MCU = 1;
188 cinfo->MCU_membership[0] = 0;
192 /* Interleaved (multi-component) scan */
193 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
194 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
197 /* Overall image size in MCUs */
198 cinfo->MCUs_per_row = (JDIMENSION)
199 jdiv_round_up((long)cinfo->image_width,
200 (long)(cinfo->max_h_samp_factor * data_unit));
201 cinfo->MCU_rows_in_scan = (JDIMENSION)
202 jdiv_round_up((long)cinfo->image_height,
203 (long)(cinfo->max_v_samp_factor * data_unit));
205 cinfo->blocks_in_MCU = 0;
207 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
208 compptr = cinfo->cur_comp_info[ci];
209 /* Sampling factors give # of data units of component in each MCU */
210 compptr->MCU_width = compptr->h_samp_factor;
211 compptr->MCU_height = compptr->v_samp_factor;
212 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
213 compptr->MCU_sample_width = compptr->MCU_width *
214 compptr->_DCT_scaled_size;
215 /* Figure number of non-dummy data units in last MCU column & row */
216 tmp = (int)(compptr->width_in_blocks % compptr->MCU_width);
217 if (tmp == 0) tmp = compptr->MCU_width;
218 compptr->last_col_width = tmp;
219 tmp = (int)(compptr->height_in_blocks % compptr->MCU_height);
220 if (tmp == 0) tmp = compptr->MCU_height;
221 compptr->last_row_height = tmp;
222 /* Prepare array describing MCU composition */
223 mcublks = compptr->MCU_blocks;
224 if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
225 ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
226 while (mcublks-- > 0) {
227 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
236 * Save away a copy of the Q-table referenced by each component present
237 * in the current scan, unless already saved during a prior scan.
239 * In a multiple-scan JPEG file, the encoder could assign different components
240 * the same Q-table slot number, but change table definitions between scans
241 * so that each component uses a different Q-table. (The IJG encoder is not
242 * currently capable of doing this, but other encoders might.) Since we want
243 * to be able to dequantize all the components at the end of the file, this
244 * means that we have to save away the table actually used for each component.
245 * We do this by copying the table at the start of the first scan containing
247 * Rec. ITU-T T.81 | ISO/IEC 10918-1 prohibits the encoder from changing the
248 * contents of a Q-table slot between scans of a component using that slot. If
249 * the encoder does so anyway, this decoder will simply use the Q-table values
250 * that were current at the start of the first scan for the component.
252 * The decompressor output side looks only at the saved quant tables,
253 * not at the current Q-table slots.
257 latch_quant_tables(j_decompress_ptr cinfo)
260 jpeg_component_info *compptr;
263 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
264 compptr = cinfo->cur_comp_info[ci];
265 /* No work if we already saved Q-table for this component */
266 if (compptr->quant_table != NULL)
268 /* Make sure specified quantization table is present */
269 qtblno = compptr->quant_tbl_no;
270 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
271 cinfo->quant_tbl_ptrs[qtblno] == NULL)
272 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
273 /* OK, save away the quantization table */
274 qtbl = (JQUANT_TBL *)
275 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
277 memcpy(qtbl, cinfo->quant_tbl_ptrs[qtblno], sizeof(JQUANT_TBL));
278 compptr->quant_table = qtbl;
284 * Initialize the input modules to read a scan of compressed data.
285 * The first call to this is done by jdmaster.c after initializing
286 * the entire decompressor (during jpeg_start_decompress).
287 * Subsequent calls come from consume_markers, below.
291 start_input_pass(j_decompress_ptr cinfo)
293 per_scan_setup(cinfo);
294 if (!cinfo->master->lossless)
295 latch_quant_tables(cinfo);
296 (*cinfo->entropy->start_pass) (cinfo);
297 (*cinfo->coef->start_input_pass) (cinfo);
298 cinfo->inputctl->consume_input = cinfo->coef->consume_data;
303 * Finish up after inputting a compressed-data scan.
304 * This is called by the coefficient or difference controller after it's read
305 * all the expected data of the scan.
309 finish_input_pass(j_decompress_ptr cinfo)
311 cinfo->inputctl->consume_input = consume_markers;
316 * Read JPEG markers before, between, or after compressed-data scans.
317 * Change state as necessary when a new scan is reached.
318 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
320 * The consume_input method pointer points either here or to the
321 * coefficient or difference controller's consume_data routine, depending on
322 * whether we are reading a compressed data segment or inter-segment markers.
326 consume_markers(j_decompress_ptr cinfo)
328 my_inputctl_ptr inputctl = (my_inputctl_ptr)cinfo->inputctl;
331 if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
332 return JPEG_REACHED_EOI;
334 val = (*cinfo->marker->read_markers) (cinfo);
337 case JPEG_REACHED_SOS: /* Found SOS */
338 if (inputctl->inheaders) { /* 1st SOS */
339 initial_setup(cinfo);
340 inputctl->inheaders = FALSE;
341 /* Note: start_input_pass must be called by jdmaster.c
342 * before any more input can be consumed. jdapimin.c is
343 * responsible for enforcing this sequencing.
345 } else { /* 2nd or later SOS marker */
346 if (!inputctl->pub.has_multiple_scans)
347 ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
348 start_input_pass(cinfo);
351 case JPEG_REACHED_EOI: /* Found EOI */
352 inputctl->pub.eoi_reached = TRUE;
353 if (inputctl->inheaders) { /* Tables-only datastream, apparently */
354 if (cinfo->marker->saw_SOF)
355 ERREXIT(cinfo, JERR_SOF_NO_SOS);
357 /* Prevent infinite loop in coef ctlr's decompress_data routine
358 * if user set output_scan_number larger than number of scans.
360 if (cinfo->output_scan_number > cinfo->input_scan_number)
361 cinfo->output_scan_number = cinfo->input_scan_number;
373 * Reset state to begin a fresh datastream.
377 reset_input_controller(j_decompress_ptr cinfo)
379 my_inputctl_ptr inputctl = (my_inputctl_ptr)cinfo->inputctl;
381 inputctl->pub.consume_input = consume_markers;
382 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
383 inputctl->pub.eoi_reached = FALSE;
384 inputctl->inheaders = TRUE;
385 /* Reset other modules */
386 (*cinfo->err->reset_error_mgr) ((j_common_ptr)cinfo);
387 (*cinfo->marker->reset_marker_reader) (cinfo);
388 /* Reset progression state -- would be cleaner if entropy decoder did this */
389 cinfo->coef_bits = NULL;
394 * Initialize the input controller module.
395 * This is called only once, when the decompression object is created.
399 jinit_input_controller(j_decompress_ptr cinfo)
401 my_inputctl_ptr inputctl;
403 /* Create subobject in permanent pool */
404 inputctl = (my_inputctl_ptr)
405 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT,
406 sizeof(my_input_controller));
407 cinfo->inputctl = (struct jpeg_input_controller *)inputctl;
408 /* Initialize method pointers */
409 inputctl->pub.consume_input = consume_markers;
410 inputctl->pub.reset_input_controller = reset_input_controller;
411 inputctl->pub.start_input_pass = start_input_pass;
412 inputctl->pub.finish_input_pass = finish_input_pass;
413 /* Initialize state: can't use reset_input_controller since we don't
414 * want to try to reset other modules yet.
416 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
417 inputctl->pub.eoi_reached = FALSE;
418 inputctl->inheaders = TRUE;