1 /* 2 * jdinput.c 3 * 4 * Copyright (C) 1991-1997, Thomas G. Lane. 5 * Modified 2002-2009 by Guido Vollbeding. 6 * This file is part of the Independent JPEG Group's software. 7 * For conditions of distribution and use, see the accompanying README file. 8 * 9 * This file contains input control logic for the JPEG decompressor. 10 * These routines are concerned with controlling the decompressor's input 11 * processing (marker reading and coefficient decoding). The actual input 12 * reading is done in jdmarker.c, jdhuff.c, and jdarith.c. 13 */ 14 15 #define JPEG_INTERNALS 16 #include "jinclude.h" 17 #include "jpeglib.h" 18 19 20 /* Private state */ 21 22 typedef struct { 23 struct jpeg_input_controller pub; /* public fields */ 24 25 boolean inheaders; /* TRUE until first SOS is reached */ 26 } my_input_controller; 27 28 typedef my_input_controller * my_inputctl_ptr; 29 30 31 /* Forward declarations */ 32 METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo)); 33 34 35 /* 36 * Routines to calculate various quantities related to the size of the image. 37 */ 38 39 LOCAL(void) 40 initial_setup (j_decompress_ptr cinfo) 41 /* Called once, when first SOS marker is reached */ 42 { 43 int ci; 44 jpeg_component_info *compptr; 45 46 /* Make sure image isn't bigger than I can handle */ 47 if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION || 48 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION) 49 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION); 50 51 /* For now, precision must match compiled-in value... */ 52 if (cinfo->data_precision != BITS_IN_JSAMPLE) 53 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision); 54 55 /* Check that number of components won't exceed internal array sizes */ 56 if (cinfo->num_components > MAX_COMPONENTS) 57 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components, 58 MAX_COMPONENTS); 59 60 /* Compute maximum sampling factors; check factor validity */ 61 cinfo->max_h_samp_factor = 1; 62 cinfo->max_v_samp_factor = 1; 63 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 64 ci++, compptr++) { 65 if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR || 66 compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR) 67 ERREXIT(cinfo, JERR_BAD_SAMPLING); 68 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor, 69 compptr->h_samp_factor); 70 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor, 71 compptr->v_samp_factor); 72 } 73 74 /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE. 75 * In the full decompressor, this will be overridden by jdmaster.c; 76 * but in the transcoder, jdmaster.c is not used, so we must do it here. 77 */ 78 cinfo->min_DCT_h_scaled_size = DCTSIZE; 79 cinfo->min_DCT_v_scaled_size = DCTSIZE; 80 81 /* Compute dimensions of components */ 82 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 83 ci++, compptr++) { 84 compptr->DCT_h_scaled_size = DCTSIZE; 85 compptr->DCT_v_scaled_size = DCTSIZE; 86 /* Size in DCT blocks */ 87 compptr->width_in_blocks = (JDIMENSION) 88 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 89 (long) (cinfo->max_h_samp_factor * DCTSIZE)); 90 compptr->height_in_blocks = (JDIMENSION) 91 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 92 (long) (cinfo->max_v_samp_factor * DCTSIZE)); 93 /* downsampled_width and downsampled_height will also be overridden by 94 * jdmaster.c if we are doing full decompression. The transcoder library 95 * doesn't use these values, but the calling application might. 96 */ 97 /* Size in samples */ 98 compptr->downsampled_width = (JDIMENSION) 99 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 100 (long) cinfo->max_h_samp_factor); 101 compptr->downsampled_height = (JDIMENSION) 102 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 103 (long) cinfo->max_v_samp_factor); 104 /* Mark component needed, until color conversion says otherwise */ 105 compptr->component_needed = TRUE; 106 /* Mark no quantization table yet saved for component */ 107 compptr->quant_table = NULL; 108 } 109 110 /* Compute number of fully interleaved MCU rows. */ 111 cinfo->total_iMCU_rows = (JDIMENSION) 112 jdiv_round_up((long) cinfo->image_height, 113 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 114 115 /* Decide whether file contains multiple scans */ 116 if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode) 117 cinfo->inputctl->has_multiple_scans = TRUE; 118 else 119 cinfo->inputctl->has_multiple_scans = FALSE; 120 } 121 122 123 LOCAL(void) 124 per_scan_setup (j_decompress_ptr cinfo) 125 /* Do computations that are needed before processing a JPEG scan */ 126 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */ 127 { 128 int ci, mcublks, tmp; 129 jpeg_component_info *compptr; 130 131 if (cinfo->comps_in_scan == 1) { 132 133 /* Noninterleaved (single-component) scan */ 134 compptr = cinfo->cur_comp_info[0]; 135 136 /* Overall image size in MCUs */ 137 cinfo->MCUs_per_row = compptr->width_in_blocks; 138 cinfo->MCU_rows_in_scan = compptr->height_in_blocks; 139 140 /* For noninterleaved scan, always one block per MCU */ 141 compptr->MCU_width = 1; 142 compptr->MCU_height = 1; 143 compptr->MCU_blocks = 1; 144 compptr->MCU_sample_width = compptr->DCT_h_scaled_size; 145 compptr->last_col_width = 1; 146 /* For noninterleaved scans, it is convenient to define last_row_height 147 * as the number of block rows present in the last iMCU row. 148 */ 149 tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 150 if (tmp == 0) tmp = compptr->v_samp_factor; 151 compptr->last_row_height = tmp; 152 153 /* Prepare array describing MCU composition */ 154 cinfo->blocks_in_MCU = 1; 155 cinfo->MCU_membership[0] = 0; 156 157 } else { 158 159 /* Interleaved (multi-component) scan */ 160 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN) 161 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan, 162 MAX_COMPS_IN_SCAN); 163 164 /* Overall image size in MCUs */ 165 cinfo->MCUs_per_row = (JDIMENSION) 166 jdiv_round_up((long) cinfo->image_width, 167 (long) (cinfo->max_h_samp_factor*DCTSIZE)); 168 cinfo->MCU_rows_in_scan = (JDIMENSION) 169 jdiv_round_up((long) cinfo->image_height, 170 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 171 172 cinfo->blocks_in_MCU = 0; 173 174 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 175 compptr = cinfo->cur_comp_info[ci]; 176 /* Sampling factors give # of blocks of component in each MCU */ 177 compptr->MCU_width = compptr->h_samp_factor; 178 compptr->MCU_height = compptr->v_samp_factor; 179 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height; 180 compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size; 181 /* Figure number of non-dummy blocks in last MCU column & row */ 182 tmp = (int) (compptr->width_in_blocks % compptr->MCU_width); 183 if (tmp == 0) tmp = compptr->MCU_width; 184 compptr->last_col_width = tmp; 185 tmp = (int) (compptr->height_in_blocks % compptr->MCU_height); 186 if (tmp == 0) tmp = compptr->MCU_height; 187 compptr->last_row_height = tmp; 188 /* Prepare array describing MCU composition */ 189 mcublks = compptr->MCU_blocks; 190 if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU) 191 ERREXIT(cinfo, JERR_BAD_MCU_SIZE); 192 while (mcublks-- > 0) { 193 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci; 194 } 195 } 196 197 } 198 } 199 200 201 /* 202 * Save away a copy of the Q-table referenced by each component present 203 * in the current scan, unless already saved during a prior scan. 204 * 205 * In a multiple-scan JPEG file, the encoder could assign different components 206 * the same Q-table slot number, but change table definitions between scans 207 * so that each component uses a different Q-table. (The IJG encoder is not 208 * currently capable of doing this, but other encoders might.) Since we want 209 * to be able to dequantize all the components at the end of the file, this 210 * means that we have to save away the table actually used for each component. 211 * We do this by copying the table at the start of the first scan containing 212 * the component. 213 * The JPEG spec prohibits the encoder from changing the contents of a Q-table 214 * slot between scans of a component using that slot. If the encoder does so 215 * anyway, this decoder will simply use the Q-table values that were current 216 * at the start of the first scan for the component. 217 * 218 * The decompressor output side looks only at the saved quant tables, 219 * not at the current Q-table slots. 220 */ 221 222 LOCAL(void) 223 latch_quant_tables (j_decompress_ptr cinfo) 224 { 225 int ci, qtblno; 226 jpeg_component_info *compptr; 227 JQUANT_TBL * qtbl; 228 229 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 230 compptr = cinfo->cur_comp_info[ci]; 231 /* No work if we already saved Q-table for this component */ 232 if (compptr->quant_table != NULL) 233 continue; 234 /* Make sure specified quantization table is present */ 235 qtblno = compptr->quant_tbl_no; 236 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || 237 cinfo->quant_tbl_ptrs[qtblno] == NULL) 238 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno); 239 /* OK, save away the quantization table */ 240 qtbl = (JQUANT_TBL *) 241 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 242 SIZEOF(JQUANT_TBL)); 243 MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL)); 244 compptr->quant_table = qtbl; 245 } 246 } 247 248 249 /* 250 * Initialize the input modules to read a scan of compressed data. 251 * The first call to this is done by jdmaster.c after initializing 252 * the entire decompressor (during jpeg_start_decompress). 253 * Subsequent calls come from consume_markers, below. 254 */ 255 256 METHODDEF(void) 257 start_input_pass (j_decompress_ptr cinfo) 258 { 259 per_scan_setup(cinfo); 260 latch_quant_tables(cinfo); 261 (*cinfo->entropy->start_pass) (cinfo); 262 (*cinfo->coef->start_input_pass) (cinfo); 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 */ 272 273 METHODDEF(void) 274 finish_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 */ 289 290 METHODDEF(int) 291 consume_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 */ 340 341 METHODDEF(void) 342 reset_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 */ 362 363 GLOBAL(void) 364 jinit_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 }