jdinput.c (13500B)
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 19 /* Private state */ 20 21 typedef struct { 22 struct jpeg_input_controller pub; /* public fields */ 23 24 boolean inheaders; /* TRUE until first SOS is reached */ 25 } my_input_controller; 26 27 typedef my_input_controller * my_inputctl_ptr; 28 29 30 /* Forward declarations */ 31 METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo)); 32 33 34 /* 35 * Routines to calculate various quantities related to the size of the image. 36 */ 37 38 LOCAL(void) 39 initial_setup (j_decompress_ptr cinfo) 40 /* Called once, when first SOS marker is reached */ 41 { 42 int ci; 43 jpeg_component_info *compptr; 44 45 /* Make sure image isn't bigger than I can handle */ 46 if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION || 47 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION) 48 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION); 49 50 /* For now, precision must match compiled-in value... */ 51 if (cinfo->data_precision != BITS_IN_JSAMPLE) 52 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision); 53 54 /* Check that number of components won't exceed internal array sizes */ 55 if (cinfo->num_components > MAX_COMPONENTS) 56 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components, 57 MAX_COMPONENTS); 58 59 /* Compute maximum sampling factors; check factor validity */ 60 cinfo->max_h_samp_factor = 1; 61 cinfo->max_v_samp_factor = 1; 62 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 63 ci++, compptr++) { 64 if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR || 65 compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR) 66 ERREXIT(cinfo, JERR_BAD_SAMPLING); 67 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor, 68 compptr->h_samp_factor); 69 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor, 70 compptr->v_samp_factor); 71 } 72 73 /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE. 74 * In the full decompressor, this will be overridden by jdmaster.c; 75 * but in the transcoder, jdmaster.c is not used, so we must do it here. 76 */ 77 cinfo->min_DCT_scaled_size = DCTSIZE; 78 79 /* Compute dimensions of components */ 80 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 81 ci++, compptr++) { 82 compptr->DCT_scaled_size = DCTSIZE; 83 /* Size in DCT blocks */ 84 compptr->width_in_blocks = (JDIMENSION) 85 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 86 (long) (cinfo->max_h_samp_factor * DCTSIZE)); 87 compptr->height_in_blocks = (JDIMENSION) 88 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 89 (long) (cinfo->max_v_samp_factor * DCTSIZE)); 90 /* downsampled_width and downsampled_height will also be overridden by 91 * jdmaster.c if we are doing full decompression. The transcoder library 92 * doesn't use these values, but the calling application might. 93 */ 94 /* Size in samples */ 95 compptr->downsampled_width = (JDIMENSION) 96 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, 97 (long) cinfo->max_h_samp_factor); 98 compptr->downsampled_height = (JDIMENSION) 99 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, 100 (long) cinfo->max_v_samp_factor); 101 /* Mark component needed, until color conversion says otherwise */ 102 compptr->component_needed = TRUE; 103 /* Mark no quantization table yet saved for component */ 104 compptr->quant_table = NULL; 105 } 106 107 /* Compute number of fully interleaved MCU rows. */ 108 cinfo->total_iMCU_rows = (JDIMENSION) 109 jdiv_round_up((long) cinfo->image_height, 110 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 111 112 /* Decide whether file contains multiple scans */ 113 if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode) 114 cinfo->inputctl->has_multiple_scans = TRUE; 115 else 116 cinfo->inputctl->has_multiple_scans = FALSE; 117 } 118 119 120 LOCAL(void) 121 per_scan_setup (j_decompress_ptr cinfo) 122 /* Do computations that are needed before processing a JPEG scan */ 123 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */ 124 { 125 int ci, mcublks, tmp; 126 jpeg_component_info *compptr; 127 128 if (cinfo->comps_in_scan == 1) { 129 130 /* Noninterleaved (single-component) scan */ 131 compptr = cinfo->cur_comp_info[0]; 132 133 /* Overall image size in MCUs */ 134 cinfo->MCUs_per_row = compptr->width_in_blocks; 135 cinfo->MCU_rows_in_scan = compptr->height_in_blocks; 136 137 /* For noninterleaved scan, always one block per MCU */ 138 compptr->MCU_width = 1; 139 compptr->MCU_height = 1; 140 compptr->MCU_blocks = 1; 141 compptr->MCU_sample_width = compptr->DCT_scaled_size; 142 compptr->last_col_width = 1; 143 /* For noninterleaved scans, it is convenient to define last_row_height 144 * as the number of block rows present in the last iMCU row. 145 */ 146 tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 147 if (tmp == 0) tmp = compptr->v_samp_factor; 148 compptr->last_row_height = tmp; 149 150 /* Prepare array describing MCU composition */ 151 cinfo->blocks_in_MCU = 1; 152 cinfo->MCU_membership[0] = 0; 153 154 } else { 155 156 /* Interleaved (multi-component) scan */ 157 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN) 158 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan, 159 MAX_COMPS_IN_SCAN); 160 161 /* Overall image size in MCUs */ 162 cinfo->MCUs_per_row = (JDIMENSION) 163 jdiv_round_up((long) cinfo->image_width, 164 (long) (cinfo->max_h_samp_factor*DCTSIZE)); 165 cinfo->MCU_rows_in_scan = (JDIMENSION) 166 jdiv_round_up((long) cinfo->image_height, 167 (long) (cinfo->max_v_samp_factor*DCTSIZE)); 168 169 cinfo->blocks_in_MCU = 0; 170 171 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 172 compptr = cinfo->cur_comp_info[ci]; 173 /* Sampling factors give # of blocks of component in each MCU */ 174 compptr->MCU_width = compptr->h_samp_factor; 175 compptr->MCU_height = compptr->v_samp_factor; 176 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height; 177 compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size; 178 /* Figure number of non-dummy blocks in last MCU column & row */ 179 tmp = (int) (compptr->width_in_blocks % compptr->MCU_width); 180 if (tmp == 0) tmp = compptr->MCU_width; 181 compptr->last_col_width = tmp; 182 tmp = (int) (compptr->height_in_blocks % compptr->MCU_height); 183 if (tmp == 0) tmp = compptr->MCU_height; 184 compptr->last_row_height = tmp; 185 /* Prepare array describing MCU composition */ 186 mcublks = compptr->MCU_blocks; 187 if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU) 188 ERREXIT(cinfo, JERR_BAD_MCU_SIZE); 189 while (mcublks-- > 0) { 190 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci; 191 } 192 } 193 194 } 195 } 196 197 198 /* 199 * Save away a copy of the Q-table referenced by each component present 200 * in the current scan, unless already saved during a prior scan. 201 * 202 * In a multiple-scan JPEG file, the encoder could assign different components 203 * the same Q-table slot number, but change table definitions between scans 204 * so that each component uses a different Q-table. (The IJG encoder is not 205 * currently capable of doing this, but other encoders might.) Since we want 206 * to be able to dequantize all the components at the end of the file, this 207 * means that we have to save away the table actually used for each component. 208 * We do this by copying the table at the start of the first scan containing 209 * the component. 210 * The JPEG spec prohibits the encoder from changing the contents of a Q-table 211 * slot between scans of a component using that slot. If the encoder does so 212 * anyway, this decoder will simply use the Q-table values that were current 213 * at the start of the first scan for the component. 214 * 215 * The decompressor output side looks only at the saved quant tables, 216 * not at the current Q-table slots. 217 */ 218 219 LOCAL(void) 220 latch_quant_tables (j_decompress_ptr cinfo) 221 { 222 int ci, qtblno; 223 jpeg_component_info *compptr; 224 JQUANT_TBL * qtbl; 225 226 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 227 compptr = cinfo->cur_comp_info[ci]; 228 /* No work if we already saved Q-table for this component */ 229 if (compptr->quant_table != NULL) 230 continue; 231 /* Make sure specified quantization table is present */ 232 qtblno = compptr->quant_tbl_no; 233 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || 234 cinfo->quant_tbl_ptrs[qtblno] == NULL) 235 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno); 236 /* OK, save away the quantization table */ 237 qtbl = (JQUANT_TBL *) 238 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 239 SIZEOF(JQUANT_TBL)); 240 MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL)); 241 compptr->quant_table = qtbl; 242 } 243 } 244 245 246 /* 247 * Initialize the input modules to read a scan of compressed data. 248 * The first call to this is done by jdmaster.c after initializing 249 * the entire decompressor (during jpeg_start_decompress). 250 * Subsequent calls come from consume_markers, below. 251 */ 252 253 METHODDEF(void) 254 start_input_pass (j_decompress_ptr cinfo) 255 { 256 per_scan_setup(cinfo); 257 latch_quant_tables(cinfo); 258 (*cinfo->entropy->start_pass) (cinfo); 259 (*cinfo->coef->start_input_pass) (cinfo); 260 cinfo->inputctl->consume_input = cinfo->coef->consume_data; 261 } 262 263 264 /* 265 * Finish up after inputting a compressed-data scan. 266 * This is called by the coefficient controller after it's read all 267 * the expected data of the scan. 268 */ 269 270 METHODDEF(void) 271 finish_input_pass (j_decompress_ptr cinfo) 272 { 273 cinfo->inputctl->consume_input = consume_markers; 274 } 275 276 277 /* 278 * Read JPEG markers before, between, or after compressed-data scans. 279 * Change state as necessary when a new scan is reached. 280 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI. 281 * 282 * The consume_input method pointer points either here or to the 283 * coefficient controller's consume_data routine, depending on whether 284 * we are reading a compressed data segment or inter-segment markers. 285 */ 286 287 METHODDEF(int) 288 consume_markers (j_decompress_ptr cinfo) 289 { 290 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; 291 int val; 292 293 if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */ 294 return JPEG_REACHED_EOI; 295 296 val = (*cinfo->marker->read_markers) (cinfo); 297 298 switch (val) { 299 case JPEG_REACHED_SOS: /* Found SOS */ 300 if (inputctl->inheaders) { /* 1st SOS */ 301 initial_setup(cinfo); 302 inputctl->inheaders = FALSE; 303 /* Note: start_input_pass must be called by jdmaster.c 304 * before any more input can be consumed. jdapimin.c is 305 * responsible for enforcing this sequencing. 306 */ 307 } else { /* 2nd or later SOS marker */ 308 if (! inputctl->pub.has_multiple_scans) 309 ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */ 310 start_input_pass(cinfo); 311 } 312 break; 313 case JPEG_REACHED_EOI: /* Found EOI */ 314 inputctl->pub.eoi_reached = TRUE; 315 if (inputctl->inheaders) { /* Tables-only datastream, apparently */ 316 if (cinfo->marker->saw_SOF) 317 ERREXIT(cinfo, JERR_SOF_NO_SOS); 318 } else { 319 /* Prevent infinite loop in coef ctlr's decompress_data routine 320 * if user set output_scan_number larger than number of scans. 321 */ 322 if (cinfo->output_scan_number > cinfo->input_scan_number) 323 cinfo->output_scan_number = cinfo->input_scan_number; 324 } 325 break; 326 case JPEG_SUSPENDED: 327 break; 328 } 329 330 return val; 331 } 332 333 334 /* 335 * Reset state to begin a fresh datastream. 336 */ 337 338 METHODDEF(void) 339 reset_input_controller (j_decompress_ptr cinfo) 340 { 341 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; 342 343 inputctl->pub.consume_input = consume_markers; 344 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ 345 inputctl->pub.eoi_reached = FALSE; 346 inputctl->inheaders = TRUE; 347 /* Reset other modules */ 348 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); 349 (*cinfo->marker->reset_marker_reader) (cinfo); 350 /* Reset progression state -- would be cleaner if entropy decoder did this */ 351 cinfo->coef_bits = NULL; 352 } 353 354 355 /* 356 * Initialize the input controller module. 357 * This is called only once, when the decompression object is created. 358 */ 359 360 GLOBAL(void) 361 jinit_input_controller (j_decompress_ptr cinfo) 362 { 363 my_inputctl_ptr inputctl; 364 365 /* Create subobject in permanent pool */ 366 inputctl = (my_inputctl_ptr) 367 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, 368 SIZEOF(my_input_controller)); 369 cinfo->inputctl = (struct jpeg_input_controller *) inputctl; 370 /* Initialize method pointers */ 371 inputctl->pub.consume_input = consume_markers; 372 inputctl->pub.reset_input_controller = reset_input_controller; 373 inputctl->pub.start_input_pass = start_input_pass; 374 inputctl->pub.finish_input_pass = finish_input_pass; 375 /* Initialize state: can't use reset_input_controller since we don't 376 * want to try to reset other modules yet. 377 */ 378 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ 379 inputctl->pub.eoi_reached = FALSE; 380 inputctl->inheaders = TRUE; 381 }