1 /* 2 * jdinput.c 3 * 4 * This file was part of the Independent JPEG Group's software: 5 * Copyright (C) 1991-1997, Thomas G. Lane. 6 * libjpeg-turbo Modifications: 7 * Copyright (C) 2010, D. R. Commander. 8 * For conditions of distribution and use, see the accompanying README file. 9 * 10 * This file contains input control logic for the JPEG decompressor. 11 * These routines are concerned with controlling the decompressor's input 12 * processing (marker reading and coefficient decoding). The actual input 13 * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c. 14 */ 15 16 #define JPEG_INTERNALS 17 #include "jinclude.h" 18 #include "jpeglib.h" 19 #include "jpegcomp.h" 20 21 22 /* Private state */ 23 24 typedef struct { 25 struct jpeg_input_controller pub; /* public fields */ 26 27 boolean inheaders; /* TRUE until first SOS is reached */ 28 } my_input_controller; 29 30 typedef my_input_controller * my_inputctl_ptr; 31 32 33 /* Forward declarations */ 34 METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo)); 35 36 37 /* 38 * Routines to calculate various quantities related to the size of the image. 39 */ 40 41 LOCAL(void) 42 initial_setup (j_decompress_ptr cinfo) 43 /* Called once, when first SOS marker is reached */ 44 { 45 int ci; 46 jpeg_component_info *compptr; 47 48 /* Make sure image isn't bigger than I can handle */ 49 if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION || 50 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION) 51 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION); 52 53 /* For now, precision must match compiled-in value... */ 54 if (cinfo->data_precision != BITS_IN_JSAMPLE) 55 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision); 56 57 /* Check that number of components won't exceed internal array sizes */ 58 if (cinfo->num_components > MAX_COMPONENTS) 59 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components, 60 MAX_COMPONENTS); 61 62 /* Compute maximum sampling factors; check factor validity */ 63 cinfo->max_h_samp_factor = 1; 64 cinfo->max_v_samp_factor = 1; 65 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 66 ci++, compptr++) { 67 if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR || 68 compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR) 69 ERREXIT(cinfo, JERR_BAD_SAMPLING); 70 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor, 71 compptr->h_samp_factor); 72 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor, 73 compptr->v_samp_factor); 74 } 75 76 #if JPEG_LIB_VERSION >=80 77 cinfo->block_size = DCTSIZE; 78 cinfo->natural_order = jpeg_natural_order; 79 cinfo->lim_Se = DCTSIZE2-1; 80 #endif 81 82 /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE. 83 * In the full decompressor, this will be overridden by jdmaster.c; 84 * but in the transcoder, jdmaster.c is not used, so we must do it here. 85 */ 86 #if JPEG_LIB_VERSION >= 70 87 cinfo->min_DCT_h_scaled_size = cinfo->min_DCT_v_scaled_size = DCTSIZE; 88 #else 89 cinfo->min_DCT_scaled_size = DCTSIZE; 90 #endif 91 92 /* Compute dimensions of components */ 93 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 94 ci++, compptr++) { 95 #if JPEG_LIB_VERSION >= 70 96 compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = DCTSIZE; 97 #else 98 compptr->DCT_scaled_size = DCTSIZE; 99 #endif 100 /* Size in DCT blocks */ 101 compptr->width_in_blocks = (JDIMENSION) 102 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 103 (long) (cinfo->max_h_samp_factor * DCTSIZE)); 104 compptr->height_in_blocks = (JDIMENSION) 105 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 106 (long) (cinfo->max_v_samp_factor * DCTSIZE)); 107 /* downsampled_width and downsampled_height will also be overridden by 108 * jdmaster.c if we are doing full decompression. The transcoder library 109 * doesn't use these values, but the calling application might. 110 */ 111 /* Size in samples */ 112 compptr->downsampled_width = (JDIMENSION) 113 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 114 (long) cinfo->max_h_samp_factor); 115 compptr->downsampled_height = (JDIMENSION) 116 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 117 (long) cinfo->max_v_samp_factor); 118 /* Mark component needed, until color conversion says otherwise */ 119 compptr->component_needed = TRUE; 120 /* Mark no quantization table yet saved for component */ 121 compptr->quant_table = NULL; 122 } 123 124 /* Compute number of fully interleaved MCU rows. */ 125 cinfo->total_iMCU_rows = (JDIMENSION) 126 jdiv_round_up((long) cinfo->image_height, 127 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 128 129 /* Decide whether file contains multiple scans */ 130 if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode) 131 cinfo->inputctl->has_multiple_scans = TRUE; 132 else 133 cinfo->inputctl->has_multiple_scans = FALSE; 134 } 135 136 137 LOCAL(void) 138 per_scan_setup (j_decompress_ptr cinfo) 139 /* Do computations that are needed before processing a JPEG scan */ 140 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */ 141 { 142 int ci, mcublks, tmp; 143 jpeg_component_info *compptr; 144 145 if (cinfo->comps_in_scan == 1) { 146 147 /* Noninterleaved (single-component) scan */ 148 compptr = cinfo->cur_comp_info[0]; 149 150 /* Overall image size in MCUs */ 151 cinfo->MCUs_per_row = compptr->width_in_blocks; 152 cinfo->MCU_rows_in_scan = compptr->height_in_blocks; 153 154 /* For noninterleaved scan, always one block per MCU */ 155 compptr->MCU_width = 1; 156 compptr->MCU_height = 1; 157 compptr->MCU_blocks = 1; 158 compptr->MCU_sample_width = compptr->_DCT_scaled_size; 159 compptr->last_col_width = 1; 160 /* For noninterleaved scans, it is convenient to define last_row_height 161 * as the number of block rows present in the last iMCU row. 162 */ 163 tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 164 if (tmp == 0) tmp = compptr->v_samp_factor; 165 compptr->last_row_height = tmp; 166 167 /* Prepare array describing MCU composition */ 168 cinfo->blocks_in_MCU = 1; 169 cinfo->MCU_membership[0] = 0; 170 171 } else { 172 173 /* Interleaved (multi-component) scan */ 174 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN) 175 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan, 176 MAX_COMPS_IN_SCAN); 177 178 /* Overall image size in MCUs */ 179 cinfo->MCUs_per_row = (JDIMENSION) 180 jdiv_round_up((long) cinfo->image_width, 181 (long) (cinfo->max_h_samp_factor*DCTSIZE)); 182 cinfo->MCU_rows_in_scan = (JDIMENSION) 183 jdiv_round_up((long) cinfo->image_height, 184 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 185 186 cinfo->blocks_in_MCU = 0; 187 188 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 189 compptr = cinfo->cur_comp_info[ci]; 190 /* Sampling factors give # of blocks of component in each MCU */ 191 compptr->MCU_width = compptr->h_samp_factor; 192 compptr->MCU_height = compptr->v_samp_factor; 193 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height; 194 compptr->MCU_sample_width = compptr->MCU_width * compptr->_DCT_scaled_size; 195 /* Figure number of non-dummy blocks in last MCU column & row */ 196 tmp = (int) (compptr->width_in_blocks % compptr->MCU_width); 197 if (tmp == 0) tmp = compptr->MCU_width; 198 compptr->last_col_width = tmp; 199 tmp = (int) (compptr->height_in_blocks % compptr->MCU_height); 200 if (tmp == 0) tmp = compptr->MCU_height; 201 compptr->last_row_height = tmp; 202 /* Prepare array describing MCU composition */ 203 mcublks = compptr->MCU_blocks; 204 if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU) 205 ERREXIT(cinfo, JERR_BAD_MCU_SIZE); 206 while (mcublks-- > 0) { 207 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci; 208 } 209 } 210 211 } 212 } 213 214 215 /* 216 * Save away a copy of the Q-table referenced by each component present 217 * in the current scan, unless already saved during a prior scan. 218 * 219 * In a multiple-scan JPEG file, the encoder could assign different components 220 * the same Q-table slot number, but change table definitions between scans 221 * so that each component uses a different Q-table. (The IJG encoder is not 222 * currently capable of doing this, but other encoders might.) Since we want 223 * to be able to dequantize all the components at the end of the file, this 224 * means that we have to save away the table actually used for each component. 225 * We do this by copying the table at the start of the first scan containing 226 * the component. 227 * The JPEG spec prohibits the encoder from changing the contents of a Q-table 228 * slot between scans of a component using that slot. If the encoder does so 229 * anyway, this decoder will simply use the Q-table values that were current 230 * at the start of the first scan for the component. 231 * 232 * The decompressor output side looks only at the saved quant tables, 233 * not at the current Q-table slots. 234 */ 235 236 LOCAL(void) 237 latch_quant_tables (j_decompress_ptr cinfo) 238 { 239 int ci, qtblno; 240 jpeg_component_info *compptr; 241 JQUANT_TBL * qtbl; 242 243 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 244 compptr = cinfo->cur_comp_info[ci]; 245 /* No work if we already saved Q-table for this component */ 246 if (compptr->quant_table != NULL) 247 continue; 248 /* Make sure specified quantization table is present */ 249 qtblno = compptr->quant_tbl_no; 250 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || 251 cinfo->quant_tbl_ptrs[qtblno] == NULL) 252 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno); 253 /* OK, save away the quantization table */ 254 qtbl = (JQUANT_TBL *) 255 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 256 SIZEOF(JQUANT_TBL)); 257 MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL)); 258 compptr->quant_table = qtbl; 259 } 260 } 261 262 263 /* 264 * Initialize the input modules to read a scan of compressed data. 265 * The first call to this is done by jdmaster.c after initializing 266 * the entire decompressor (during jpeg_start_decompress). 267 * Subsequent calls come from consume_markers, below. 268 */ 269 270 METHODDEF(void) 271 start_input_pass (j_decompress_ptr cinfo) 272 { 273 per_scan_setup(cinfo); 274 latch_quant_tables(cinfo); 275 (*cinfo->entropy->start_pass) (cinfo); 276 (*cinfo->coef->start_input_pass) (cinfo); 277 cinfo->inputctl->consume_input = cinfo->coef->consume_data; 278 } 279 280 281 /* 282 * Finish up after inputting a compressed-data scan. 283 * This is called by the coefficient controller after it's read all 284 * the expected data of the scan. 285 */ 286 287 METHODDEF(void) 288 finish_input_pass (j_decompress_ptr cinfo) 289 { 290 cinfo->inputctl->consume_input = consume_markers; 291 } 292 293 294 /* 295 * Read JPEG markers before, between, or after compressed-data scans. 296 * Change state as necessary when a new scan is reached. 297 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI. 298 * 299 * The consume_input method pointer points either here or to the 300 * coefficient controller's consume_data routine, depending on whether 301 * we are reading a compressed data segment or inter-segment markers. 302 */ 303 304 METHODDEF(int) 305 consume_markers (j_decompress_ptr cinfo) 306 { 307 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; 308 int val; 309 310 if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */ 311 return JPEG_REACHED_EOI; 312 313 val = (*cinfo->marker->read_markers) (cinfo); 314 315 switch (val) { 316 case JPEG_REACHED_SOS: /* Found SOS */ 317 if (inputctl->inheaders) { /* 1st SOS */ 318 initial_setup(cinfo); 319 inputctl->inheaders = FALSE; 320 /* Note: start_input_pass must be called by jdmaster.c 321 * before any more input can be consumed. jdapimin.c is 322 * responsible for enforcing this sequencing. 323 */ 324 } else { /* 2nd or later SOS marker */ 325 if (! inputctl->pub.has_multiple_scans) 326 ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */ 327 start_input_pass(cinfo); 328 } 329 break; 330 case JPEG_REACHED_EOI: /* Found EOI */ 331 inputctl->pub.eoi_reached = TRUE; 332 if (inputctl->inheaders) { /* Tables-only datastream, apparently */ 333 if (cinfo->marker->saw_SOF) 334 ERREXIT(cinfo, JERR_SOF_NO_SOS); 335 } else { 336 /* Prevent infinite loop in coef ctlr's decompress_data routine 337 * if user set output_scan_number larger than number of scans. 338 */ 339 if (cinfo->output_scan_number > cinfo->input_scan_number) 340 cinfo->output_scan_number = cinfo->input_scan_number; 341 } 342 break; 343 case JPEG_SUSPENDED: 344 break; 345 } 346 347 return val; 348 } 349 350 351 /* 352 * Reset state to begin a fresh datastream. 353 */ 354 355 METHODDEF(void) 356 reset_input_controller (j_decompress_ptr cinfo) 357 { 358 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; 359 360 inputctl->pub.consume_input = consume_markers; 361 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ 362 inputctl->pub.eoi_reached = FALSE; 363 inputctl->inheaders = TRUE; 364 /* Reset other modules */ 365 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); 366 (*cinfo->marker->reset_marker_reader) (cinfo); 367 /* Reset progression state -- would be cleaner if entropy decoder did this */ 368 cinfo->coef_bits = NULL; 369 } 370 371 372 /* 373 * Initialize the input controller module. 374 * This is called only once, when the decompression object is created. 375 */ 376 377 GLOBAL(void) 378 jinit_input_controller (j_decompress_ptr cinfo) 379 { 380 my_inputctl_ptr inputctl; 381 382 /* Create subobject in permanent pool */ 383 inputctl = (my_inputctl_ptr) 384 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, 385 SIZEOF(my_input_controller)); 386 cinfo->inputctl = (struct jpeg_input_controller *) inputctl; 387 /* Initialize method pointers */ 388 inputctl->pub.consume_input = consume_markers; 389 inputctl->pub.reset_input_controller = reset_input_controller; 390 inputctl->pub.start_input_pass = start_input_pass; 391 inputctl->pub.finish_input_pass = finish_input_pass; 392 /* Initialize state: can't use reset_input_controller since we don't 393 * want to try to reset other modules yet. 394 */ 395 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ 396 inputctl->pub.eoi_reached = FALSE; 397 inputctl->inheaders = TRUE; 398 } 399