1/* 2 * reserved comment block 3 * DO NOT REMOVE OR ALTER! 4 */ 5/* 6 * jdinput.c 7 * 8 * Copyright (C) 1991-1997, Thomas G. Lane. 9 * This file is part of the Independent JPEG Group's software. 10 * For conditions of distribution and use, see the accompanying README file. 11 * 12 * This file contains input control logic for the JPEG decompressor. 13 * These routines are concerned with controlling the decompressor's input 14 * processing (marker reading and coefficient decoding). The actual input 15 * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c. 16 */ 17 18#define JPEG_INTERNALS 19#include "jinclude.h" 20#include "jpeglib.h" 21 22 23/* Private state */ 24 25typedef struct { 26 struct jpeg_input_controller pub; /* public fields */ 27 28 boolean inheaders; /* TRUE until first SOS is reached */ 29} my_input_controller; 30 31typedef my_input_controller * my_inputctl_ptr; 32 33 34/* Forward declarations */ 35METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo)); 36 37 38/* 39 * Routines to calculate various quantities related to the size of the image. 40 */ 41 42LOCAL(void) 43initial_setup (j_decompress_ptr cinfo) 44/* Called once, when first SOS marker is reached */ 45{ 46 int ci; 47 jpeg_component_info *compptr; 48 49 /* Make sure image isn't bigger than I can handle */ 50 if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION || 51 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION) 52 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION); 53 54 /* For now, precision must match compiled-in value... */ 55 if (cinfo->data_precision != BITS_IN_JSAMPLE) 56 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision); 57 58 /* Check that number of components won't exceed internal array sizes */ 59 if (cinfo->num_components > MAX_COMPONENTS) 60 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components, 61 MAX_COMPONENTS); 62 63 /* Compute maximum sampling factors; check factor validity */ 64 cinfo->max_h_samp_factor = 1; 65 cinfo->max_v_samp_factor = 1; 66 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 67 ci++, compptr++) { 68 if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR || 69 compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR) 70 ERREXIT(cinfo, JERR_BAD_SAMPLING); 71 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor, 72 compptr->h_samp_factor); 73 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor, 74 compptr->v_samp_factor); 75 } 76 77 /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE. 78 * In the full decompressor, this will be overridden by jdmaster.c; 79 * but in the transcoder, jdmaster.c is not used, so we must do it here. 80 */ 81 cinfo->min_DCT_scaled_size = DCTSIZE; 82 83 /* Compute dimensions of components */ 84 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 85 ci++, compptr++) { 86 compptr->DCT_scaled_size = DCTSIZE; 87 /* Size in DCT blocks */ 88 compptr->width_in_blocks = (JDIMENSION) 89 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 90 (long) (cinfo->max_h_samp_factor * DCTSIZE)); 91 compptr->height_in_blocks = (JDIMENSION) 92 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 93 (long) (cinfo->max_v_samp_factor * DCTSIZE)); 94 /* downsampled_width and downsampled_height will also be overridden by 95 * jdmaster.c if we are doing full decompression. The transcoder library 96 * doesn't use these values, but the calling application might. 97 */ 98 /* Size in samples */ 99 compptr->downsampled_width = (JDIMENSION) 100 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 101 (long) cinfo->max_h_samp_factor); 102 compptr->downsampled_height = (JDIMENSION) 103 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 104 (long) cinfo->max_v_samp_factor); 105 /* Mark component needed, until color conversion says otherwise */ 106 compptr->component_needed = TRUE; 107 /* Mark no quantization table yet saved for component */ 108 compptr->quant_table = NULL; 109 } 110 111 /* Compute number of fully interleaved MCU rows. */ 112 cinfo->total_iMCU_rows = (JDIMENSION) 113 jdiv_round_up((long) cinfo->image_height, 114 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 115 116 /* Decide whether file contains multiple scans */ 117 if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode) 118 cinfo->inputctl->has_multiple_scans = TRUE; 119 else 120 cinfo->inputctl->has_multiple_scans = FALSE; 121} 122 123 124LOCAL(void) 125per_scan_setup (j_decompress_ptr cinfo) 126/* Do computations that are needed before processing a JPEG scan */ 127/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */ 128{ 129 int ci, mcublks, tmp; 130 jpeg_component_info *compptr; 131 132 if (cinfo->comps_in_scan == 1) { 133 134 /* Noninterleaved (single-component) scan */ 135 compptr = cinfo->cur_comp_info[0]; 136 137 /* Overall image size in MCUs */ 138 cinfo->MCUs_per_row = compptr->width_in_blocks; 139 cinfo->MCU_rows_in_scan = compptr->height_in_blocks; 140 141 /* For noninterleaved scan, always one block per MCU */ 142 compptr->MCU_width = 1; 143 compptr->MCU_height = 1; 144 compptr->MCU_blocks = 1; 145 compptr->MCU_sample_width = compptr->DCT_scaled_size; 146 compptr->last_col_width = 1; 147 /* For noninterleaved scans, it is convenient to define last_row_height 148 * as the number of block rows present in the last iMCU row. 149 */ 150 tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 151 if (tmp == 0) tmp = compptr->v_samp_factor; 152 compptr->last_row_height = tmp; 153 154 /* Prepare array describing MCU composition */ 155 cinfo->blocks_in_MCU = 1; 156 cinfo->MCU_membership[0] = 0; 157 158 } else { 159 160 /* Interleaved (multi-component) scan */ 161 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN) 162 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan, 163 MAX_COMPS_IN_SCAN); 164 165 /* Overall image size in MCUs */ 166 cinfo->MCUs_per_row = (JDIMENSION) 167 jdiv_round_up((long) cinfo->image_width, 168 (long) (cinfo->max_h_samp_factor*DCTSIZE)); 169 cinfo->MCU_rows_in_scan = (JDIMENSION) 170 jdiv_round_up((long) cinfo->image_height, 171 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 172 173 cinfo->blocks_in_MCU = 0; 174 175 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 176 compptr = cinfo->cur_comp_info[ci]; 177 /* Sampling factors give # of blocks of component in each MCU */ 178 compptr->MCU_width = compptr->h_samp_factor; 179 compptr->MCU_height = compptr->v_samp_factor; 180 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height; 181 compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size; 182 /* Figure number of non-dummy blocks in last MCU column & row */ 183 tmp = (int) (compptr->width_in_blocks % compptr->MCU_width); 184 if (tmp == 0) tmp = compptr->MCU_width; 185 compptr->last_col_width = tmp; 186 tmp = (int) (compptr->height_in_blocks % compptr->MCU_height); 187 if (tmp == 0) tmp = compptr->MCU_height; 188 compptr->last_row_height = tmp; 189 /* Prepare array describing MCU composition */ 190 mcublks = compptr->MCU_blocks; 191 if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU) 192 ERREXIT(cinfo, JERR_BAD_MCU_SIZE); 193 while (mcublks-- > 0) { 194 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci; 195 } 196 } 197 198 } 199} 200 201 202/* 203 * Save away a copy of the Q-table referenced by each component present 204 * in the current scan, unless already saved during a prior scan. 205 * 206 * In a multiple-scan JPEG file, the encoder could assign different components 207 * the same Q-table slot number, but change table definitions between scans 208 * so that each component uses a different Q-table. (The IJG encoder is not 209 * currently capable of doing this, but other encoders might.) Since we want 210 * to be able to dequantize all the components at the end of the file, this 211 * means that we have to save away the table actually used for each component. 212 * We do this by copying the table at the start of the first scan containing 213 * the component. 214 * The JPEG spec prohibits the encoder from changing the contents of a Q-table 215 * slot between scans of a component using that slot. If the encoder does so 216 * anyway, this decoder will simply use the Q-table values that were current 217 * at the start of the first scan for the component. 218 * 219 * The decompressor output side looks only at the saved quant tables, 220 * not at the current Q-table slots. 221 */ 222 223LOCAL(void) 224latch_quant_tables (j_decompress_ptr cinfo) 225{ 226 int ci, qtblno; 227 jpeg_component_info *compptr; 228 JQUANT_TBL * qtbl; 229 230 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 231 compptr = cinfo->cur_comp_info[ci]; 232 /* No work if we already saved Q-table for this component */ 233 if (compptr->quant_table != NULL) 234 continue; 235 /* Make sure specified quantization table is present */ 236 qtblno = compptr->quant_tbl_no; 237 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || 238 cinfo->quant_tbl_ptrs[qtblno] == NULL) 239 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno); 240 /* OK, save away the quantization table */ 241 qtbl = (JQUANT_TBL *) 242 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 243 SIZEOF(JQUANT_TBL)); 244 MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL)); 245 compptr->quant_table = qtbl; 246 } 247} 248 249 250/* 251 * Initialize the input modules to read a scan of compressed data. 252 * The first call to this is done by jdmaster.c after initializing 253 * the entire decompressor (during jpeg_start_decompress). 254 * Subsequent calls come from consume_markers, below. 255 */ 256 257METHODDEF(void) 258start_input_pass (j_decompress_ptr cinfo) 259{ 260 per_scan_setup(cinfo); 261 latch_quant_tables(cinfo); 262 (*cinfo->entropy->start_pass) (cinfo); 263 (*cinfo->coef->start_input_pass) (cinfo); 264 cinfo->inputctl->consume_input = cinfo->coef->consume_data; 265} 266 267 268/* 269 * Finish up after inputting a compressed-data scan. 270 * This is called by the coefficient controller after it's read all 271 * the expected data of the scan. 272 */ 273 274METHODDEF(void) 275finish_input_pass (j_decompress_ptr cinfo) 276{ 277 cinfo->inputctl->consume_input = consume_markers; 278} 279 280 281/* 282 * Read JPEG markers before, between, or after compressed-data scans. 283 * Change state as necessary when a new scan is reached. 284 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI. 285 * 286 * The consume_input method pointer points either here or to the 287 * coefficient controller's consume_data routine, depending on whether 288 * we are reading a compressed data segment or inter-segment markers. 289 */ 290 291METHODDEF(int) 292consume_markers (j_decompress_ptr cinfo) 293{ 294 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; 295 int val; 296 297 if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */ 298 return JPEG_REACHED_EOI; 299 300 val = (*cinfo->marker->read_markers) (cinfo); 301 302 switch (val) { 303 case JPEG_REACHED_SOS: /* Found SOS */ 304 if (inputctl->inheaders) { /* 1st SOS */ 305 initial_setup(cinfo); 306 inputctl->inheaders = FALSE; 307 /* Note: start_input_pass must be called by jdmaster.c 308 * before any more input can be consumed. jdapimin.c is 309 * responsible for enforcing this sequencing. 310 */ 311 } else { /* 2nd or later SOS marker */ 312 if (! inputctl->pub.has_multiple_scans) 313 ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */ 314 start_input_pass(cinfo); 315 } 316 break; 317 case JPEG_REACHED_EOI: /* Found EOI */ 318 inputctl->pub.eoi_reached = TRUE; 319 if (inputctl->inheaders) { /* Tables-only datastream, apparently */ 320 if (cinfo->marker->saw_SOF) 321 ERREXIT(cinfo, JERR_SOF_NO_SOS); 322 } else { 323 /* Prevent infinite loop in coef ctlr's decompress_data routine 324 * if user set output_scan_number larger than number of scans. 325 */ 326 if (cinfo->output_scan_number > cinfo->input_scan_number) 327 cinfo->output_scan_number = cinfo->input_scan_number; 328 } 329 break; 330 case JPEG_SUSPENDED: 331 break; 332 } 333 334 return val; 335} 336 337 338/* 339 * Reset state to begin a fresh datastream. 340 */ 341 342METHODDEF(void) 343reset_input_controller (j_decompress_ptr cinfo) 344{ 345 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; 346 347 inputctl->pub.consume_input = consume_markers; 348 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ 349 inputctl->pub.eoi_reached = FALSE; 350 inputctl->inheaders = TRUE; 351 /* Reset other modules */ 352 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); 353 (*cinfo->marker->reset_marker_reader) (cinfo); 354 /* Reset progression state -- would be cleaner if entropy decoder did this */ 355 cinfo->coef_bits = NULL; 356} 357 358 359/* 360 * Initialize the input controller module. 361 * This is called only once, when the decompression object is created. 362 */ 363 364GLOBAL(void) 365jinit_input_controller (j_decompress_ptr cinfo) 366{ 367 my_inputctl_ptr inputctl; 368 369 /* Create subobject in permanent pool */ 370 inputctl = (my_inputctl_ptr) 371 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, 372 SIZEOF(my_input_controller)); 373 cinfo->inputctl = (struct jpeg_input_controller *) inputctl; 374 /* Initialize method pointers */ 375 inputctl->pub.consume_input = consume_markers; 376 inputctl->pub.reset_input_controller = reset_input_controller; 377 inputctl->pub.start_input_pass = start_input_pass; 378 inputctl->pub.finish_input_pass = finish_input_pass; 379 /* Initialize state: can't use reset_input_controller since we don't 380 * want to try to reset other modules yet. 381 */ 382 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ 383 inputctl->pub.eoi_reached = FALSE; 384 inputctl->inheaders = TRUE; 385} 386