1/* 2 * jdinput.c 3 * 4 * Copyright (C) 1991-1997, Thomas G. Lane. 5 * This file is part of the Independent JPEG Group's software. 6 * For conditions of distribution and use, see the accompanying README file. 7 * 8 * This file contains input control logic for the JPEG decompressor. 9 * These routines are concerned with controlling the decompressor's input 10 * processing (marker reading and coefficient decoding). The actual input 11 * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c. 12 */ 13 14#define JPEG_INTERNALS 15#include "jinclude.h" 16#include "jpeglib.h" 17 18/* Private state */ 19 20typedef struct { 21 struct jpeg_input_controller pub; /* public fields */ 22 23 wxjpeg_boolean inheaders; /* TRUE until first SOS is reached */ 24} my_input_controller; 25 26typedef my_input_controller * my_inputctl_ptr; 27 28 29/* Forward declarations */ 30METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo)); 31 32 33/* 34 * Routines to calculate various quantities related to the size of the image. 35 */ 36 37LOCAL(void) 38initial_setup (j_decompress_ptr cinfo) 39/* Called once, when first SOS marker is reached */ 40{ 41 int ci; 42 jpeg_component_info *compptr; 43 44 /* Make sure image isn't bigger than I can handle */ 45 if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION || 46 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION) 47 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION); 48 49 /* For now, precision must match compiled-in value... */ 50 if (cinfo->data_precision != BITS_IN_JSAMPLE) 51 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision); 52 53 /* Check that number of components won't exceed internal array sizes */ 54 if (cinfo->num_components > MAX_COMPONENTS) 55 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components, 56 MAX_COMPONENTS); 57 58 /* Compute maximum sampling factors; check factor validity */ 59 cinfo->max_h_samp_factor = 1; 60 cinfo->max_v_samp_factor = 1; 61 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 62 ci++, compptr++) { 63 if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR || 64 compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR) 65 ERREXIT(cinfo, JERR_BAD_SAMPLING); 66 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor, 67 compptr->h_samp_factor); 68 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor, 69 compptr->v_samp_factor); 70 } 71 72 /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE. 73 * In the full decompressor, this will be overridden by jdmaster.c; 74 * but in the transcoder, jdmaster.c is not used, so we must do it here. 75 */ 76 cinfo->min_DCT_scaled_size = DCTSIZE; 77 78 /* Compute dimensions of components */ 79 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 80 ci++, compptr++) { 81 compptr->DCT_scaled_size = DCTSIZE; 82 /* Size in DCT blocks */ 83 compptr->width_in_blocks = (JDIMENSION) 84 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 85 (long) (cinfo->max_h_samp_factor * DCTSIZE)); 86 compptr->height_in_blocks = (JDIMENSION) 87 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 88 (long) (cinfo->max_v_samp_factor * DCTSIZE)); 89 /* downsampled_width and downsampled_height will also be overridden by 90 * jdmaster.c if we are doing full decompression. The transcoder library 91 * doesn't use these values, but the calling application might. 92 */ 93 /* Size in samples */ 94 compptr->downsampled_width = (JDIMENSION) 95 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 96 (long) cinfo->max_h_samp_factor); 97 compptr->downsampled_height = (JDIMENSION) 98 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 99 (long) cinfo->max_v_samp_factor); 100 /* Mark component needed, until color conversion says otherwise */ 101 compptr->component_needed = TRUE; 102 /* Mark no quantization table yet saved for component */ 103 compptr->quant_table = NULL; 104 } 105 106 /* Compute number of fully interleaved MCU rows. */ 107 cinfo->total_iMCU_rows = (JDIMENSION) 108 jdiv_round_up((long) cinfo->image_height, 109 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 110 111 /* Decide whether file contains multiple scans */ 112 if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode) 113 cinfo->inputctl->has_multiple_scans = TRUE; 114 else 115 cinfo->inputctl->has_multiple_scans = FALSE; 116} 117 118 119LOCAL(void) 120per_scan_setup (j_decompress_ptr cinfo) 121/* Do computations that are needed before processing a JPEG scan */ 122/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */ 123{ 124 int ci, mcublks, tmp; 125 jpeg_component_info *compptr; 126 127 if (cinfo->comps_in_scan == 1) { 128 129 /* Noninterleaved (single-component) scan */ 130 compptr = cinfo->cur_comp_info[0]; 131 132 /* Overall image size in MCUs */ 133 cinfo->MCUs_per_row = compptr->width_in_blocks; 134 cinfo->MCU_rows_in_scan = compptr->height_in_blocks; 135 136 /* For noninterleaved scan, always one block per MCU */ 137 compptr->MCU_width = 1; 138 compptr->MCU_height = 1; 139 compptr->MCU_blocks = 1; 140 compptr->MCU_sample_width = compptr->DCT_scaled_size; 141 compptr->last_col_width = 1; 142 /* For noninterleaved scans, it is convenient to define last_row_height 143 * as the number of block rows present in the last iMCU row. 144 */ 145 tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 146 if (tmp == 0) tmp = compptr->v_samp_factor; 147 compptr->last_row_height = tmp; 148 149 /* Prepare array describing MCU composition */ 150 cinfo->blocks_in_MCU = 1; 151 cinfo->MCU_membership[0] = 0; 152 153 } else { 154 155 /* Interleaved (multi-component) scan */ 156 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN) 157 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan, 158 MAX_COMPS_IN_SCAN); 159 160 /* Overall image size in MCUs */ 161 cinfo->MCUs_per_row = (JDIMENSION) 162 jdiv_round_up((long) cinfo->image_width, 163 (long) (cinfo->max_h_samp_factor*DCTSIZE)); 164 cinfo->MCU_rows_in_scan = (JDIMENSION) 165 jdiv_round_up((long) cinfo->image_height, 166 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 167 168 cinfo->blocks_in_MCU = 0; 169 170 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 171 compptr = cinfo->cur_comp_info[ci]; 172 /* Sampling factors give # of blocks of component in each MCU */ 173 compptr->MCU_width = compptr->h_samp_factor; 174 compptr->MCU_height = compptr->v_samp_factor; 175 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height; 176 compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size; 177 /* Figure number of non-dummy blocks in last MCU column & row */ 178 tmp = (int) (compptr->width_in_blocks % compptr->MCU_width); 179 if (tmp == 0) tmp = compptr->MCU_width; 180 compptr->last_col_width = tmp; 181 tmp = (int) (compptr->height_in_blocks % compptr->MCU_height); 182 if (tmp == 0) tmp = compptr->MCU_height; 183 compptr->last_row_height = tmp; 184 /* Prepare array describing MCU composition */ 185 mcublks = compptr->MCU_blocks; 186 if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU) 187 ERREXIT(cinfo, JERR_BAD_MCU_SIZE); 188 while (mcublks-- > 0) { 189 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci; 190 } 191 } 192 193 } 194} 195 196 197/* 198 * Save away a copy of the Q-table referenced by each component present 199 * in the current scan, unless already saved during a prior scan. 200 * 201 * In a multiple-scan JPEG file, the encoder could assign different components 202 * the same Q-table slot number, but change table definitions between scans 203 * so that each component uses a different Q-table. (The IJG encoder is not 204 * currently capable of doing this, but other encoders might.) Since we want 205 * to be able to dequantize all the components at the end of the file, this 206 * means that we have to save away the table actually used for each component. 207 * We do this by copying the table at the start of the first scan containing 208 * the component. 209 * The JPEG spec prohibits the encoder from changing the contents of a Q-table 210 * slot between scans of a component using that slot. If the encoder does so 211 * anyway, this decoder will simply use the Q-table values that were current 212 * at the start of the first scan for the component. 213 * 214 * The decompressor output side looks only at the saved quant tables, 215 * not at the current Q-table slots. 216 */ 217 218LOCAL(void) 219latch_quant_tables (j_decompress_ptr cinfo) 220{ 221 int ci, qtblno; 222 jpeg_component_info *compptr; 223 JQUANT_TBL * qtbl; 224 225 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 226 compptr = cinfo->cur_comp_info[ci]; 227 /* No work if we already saved Q-table for this component */ 228 if (compptr->quant_table != NULL) 229 continue; 230 /* Make sure specified quantization table is present */ 231 qtblno = compptr->quant_tbl_no; 232 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || 233 cinfo->quant_tbl_ptrs[qtblno] == NULL) 234 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno); 235 /* OK, save away the quantization table */ 236 qtbl = (JQUANT_TBL *) 237 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 238 SIZEOF(JQUANT_TBL)); 239 MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL)); 240 compptr->quant_table = qtbl; 241 } 242} 243 244 245/* 246 * Initialize the input modules to read a scan of compressed data. 247 * The first call to this is done by jdmaster.c after initializing 248 * the entire decompressor (during jpeg_start_decompress). 249 * Subsequent calls come from consume_markers, below. 250 */ 251 252METHODDEF(void) 253start_input_pass (j_decompress_ptr cinfo) 254{ 255 per_scan_setup(cinfo); 256 latch_quant_tables(cinfo); 257 (*cinfo->entropy->start_pass) (cinfo); 258#if defined(__VISAGECPP__) 259 (*cinfo->coef->start_input_pass2) (cinfo); 260#else 261 (*cinfo->coef->start_input_pass) (cinfo); 262#endif 263 cinfo->inputctl->consume_input = cinfo->coef->consume_data; 264} 265 266 267/* 268 * Finish up after inputting a compressed-data scan. 269 * This is called by the coefficient controller after it's read all 270 * the expected data of the scan. 271 */ 272 273METHODDEF(void) 274finish_input_pass (j_decompress_ptr cinfo) 275{ 276 cinfo->inputctl->consume_input = consume_markers; 277} 278 279 280/* 281 * Read JPEG markers before, between, or after compressed-data scans. 282 * Change state as necessary when a new scan is reached. 283 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI. 284 * 285 * The consume_input method pointer points either here or to the 286 * coefficient controller's consume_data routine, depending on whether 287 * we are reading a compressed data segment or inter-segment markers. 288 */ 289 290METHODDEF(int) 291consume_markers (j_decompress_ptr cinfo) 292{ 293 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; 294 int val; 295 296 if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */ 297 return JPEG_REACHED_EOI; 298 299 val = (*cinfo->marker->read_markers) (cinfo); 300 301 switch (val) { 302 case JPEG_REACHED_SOS: /* Found SOS */ 303 if (inputctl->inheaders) { /* 1st SOS */ 304 initial_setup(cinfo); 305 inputctl->inheaders = FALSE; 306 /* Note: start_input_pass must be called by jdmaster.c 307 * before any more input can be consumed. jdapimin.c is 308 * responsible for enforcing this sequencing. 309 */ 310 } else { /* 2nd or later SOS marker */ 311 if (! inputctl->pub.has_multiple_scans) 312 ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */ 313 start_input_pass(cinfo); 314 } 315 break; 316 case JPEG_REACHED_EOI: /* Found EOI */ 317 inputctl->pub.eoi_reached = TRUE; 318 if (inputctl->inheaders) { /* Tables-only datastream, apparently */ 319 if (cinfo->marker->saw_SOF) 320 ERREXIT(cinfo, JERR_SOF_NO_SOS); 321 } else { 322 /* Prevent infinite loop in coef ctlr's decompress_data routine 323 * if user set output_scan_number larger than number of scans. 324 */ 325 if (cinfo->output_scan_number > cinfo->input_scan_number) 326 cinfo->output_scan_number = cinfo->input_scan_number; 327 } 328 break; 329 case JPEG_SUSPENDED: 330 break; 331 } 332 333 return val; 334} 335 336 337/* 338 * Reset state to begin a fresh datastream. 339 */ 340 341METHODDEF(void) 342reset_input_controller (j_decompress_ptr cinfo) 343{ 344 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; 345 346 inputctl->pub.consume_input = consume_markers; 347 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ 348 inputctl->pub.eoi_reached = FALSE; 349 inputctl->inheaders = TRUE; 350 /* Reset other modules */ 351 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); 352 (*cinfo->marker->reset_marker_reader) (cinfo); 353 /* Reset progression state -- would be cleaner if entropy decoder did this */ 354 cinfo->coef_bits = NULL; 355} 356 357 358/* 359 * Initialize the input controller module. 360 * This is called only once, when the decompression object is created. 361 */ 362 363GLOBAL(void) 364jinit_input_controller (j_decompress_ptr cinfo) 365{ 366 my_inputctl_ptr inputctl; 367 368 /* Create subobject in permanent pool */ 369 inputctl = (my_inputctl_ptr) 370 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, 371 SIZEOF(my_input_controller)); 372 cinfo->inputctl = (struct jpeg_input_controller *) inputctl; 373 /* Initialize method pointers */ 374 inputctl->pub.consume_input = consume_markers; 375 inputctl->pub.reset_input_controller = reset_input_controller; 376 inputctl->pub.start_input_pass = start_input_pass; 377 inputctl->pub.finish_input_pass = finish_input_pass; 378 /* Initialize state: can't use reset_input_controller since we don't 379 * want to try to reset other modules yet. 380 */ 381 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ 382 inputctl->pub.eoi_reached = FALSE; 383 inputctl->inheaders = TRUE; 384} 385 386