Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 1 | /* |
| 2 | * jdphuff.c |
| 3 | * |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 4 | * Copyright (C) 1995-1997, Thomas G. Lane. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 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 Huffman entropy decoding routines for progressive JPEG. |
| 9 | * |
| 10 | * Much of the complexity here has to do with supporting input suspension. |
| 11 | * If the data source module demands suspension, we want to be able to back |
| 12 | * up to the start of the current MCU. To do this, we copy state variables |
| 13 | * into local working storage, and update them back to the permanent |
| 14 | * storage only upon successful completion of an MCU. |
| 15 | */ |
| 16 | |
| 17 | #define JPEG_INTERNALS |
| 18 | #include "jinclude.h" |
| 19 | #include "jpeglib.h" |
| 20 | #include "jdhuff.h" /* Declarations shared with jdhuff.c */ |
| 21 | |
| 22 | |
| 23 | #ifdef D_PROGRESSIVE_SUPPORTED |
| 24 | |
| 25 | /* |
| 26 | * Expanded entropy decoder object for progressive Huffman decoding. |
| 27 | * |
| 28 | * The savable_state subrecord contains fields that change within an MCU, |
| 29 | * but must not be updated permanently until we complete the MCU. |
| 30 | */ |
| 31 | |
| 32 | typedef struct { |
| 33 | unsigned int EOBRUN; /* remaining EOBs in EOBRUN */ |
| 34 | int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ |
| 35 | } savable_state; |
| 36 | |
| 37 | /* This macro is to work around compilers with missing or broken |
| 38 | * structure assignment. You'll need to fix this code if you have |
| 39 | * such a compiler and you change MAX_COMPS_IN_SCAN. |
| 40 | */ |
| 41 | |
| 42 | #ifndef NO_STRUCT_ASSIGN |
| 43 | #define ASSIGN_STATE(dest,src) ((dest) = (src)) |
| 44 | #else |
| 45 | #if MAX_COMPS_IN_SCAN == 4 |
| 46 | #define ASSIGN_STATE(dest,src) \ |
| 47 | ((dest).EOBRUN = (src).EOBRUN, \ |
| 48 | (dest).last_dc_val[0] = (src).last_dc_val[0], \ |
| 49 | (dest).last_dc_val[1] = (src).last_dc_val[1], \ |
| 50 | (dest).last_dc_val[2] = (src).last_dc_val[2], \ |
| 51 | (dest).last_dc_val[3] = (src).last_dc_val[3]) |
| 52 | #endif |
| 53 | #endif |
| 54 | |
| 55 | |
| 56 | typedef struct { |
| 57 | struct jpeg_entropy_decoder pub; /* public fields */ |
| 58 | |
| 59 | /* These fields are loaded into local variables at start of each MCU. |
| 60 | * In case of suspension, we exit WITHOUT updating them. |
| 61 | */ |
| 62 | bitread_perm_state bitstate; /* Bit buffer at start of MCU */ |
| 63 | savable_state saved; /* Other state at start of MCU */ |
| 64 | |
| 65 | /* These fields are NOT loaded into local working state. */ |
| 66 | unsigned int restarts_to_go; /* MCUs left in this restart interval */ |
| 67 | |
| 68 | /* Pointers to derived tables (these workspaces have image lifespan) */ |
| 69 | d_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; |
| 70 | |
| 71 | d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */ |
| 72 | } phuff_entropy_decoder; |
| 73 | |
| 74 | typedef phuff_entropy_decoder * phuff_entropy_ptr; |
| 75 | |
| 76 | /* Forward declarations */ |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 77 | METHODDEF(boolean) decode_mcu_DC_first JPP((j_decompress_ptr cinfo, |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 78 | JBLOCKROW *MCU_data)); |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 79 | METHODDEF(boolean) decode_mcu_AC_first JPP((j_decompress_ptr cinfo, |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 80 | JBLOCKROW *MCU_data)); |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 81 | METHODDEF(boolean) decode_mcu_DC_refine JPP((j_decompress_ptr cinfo, |
| 82 | JBLOCKROW *MCU_data)); |
| 83 | METHODDEF(boolean) decode_mcu_AC_refine JPP((j_decompress_ptr cinfo, |
| 84 | JBLOCKROW *MCU_data)); |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 85 | |
| 86 | |
| 87 | /* |
| 88 | * Initialize for a Huffman-compressed scan. |
| 89 | */ |
| 90 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 91 | METHODDEF(void) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 92 | start_pass_phuff_decoder (j_decompress_ptr cinfo) |
| 93 | { |
| 94 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 95 | boolean is_DC_band, bad; |
| 96 | int ci, coefi, tbl; |
| 97 | int *coef_bit_ptr; |
| 98 | jpeg_component_info * compptr; |
| 99 | |
| 100 | is_DC_band = (cinfo->Ss == 0); |
| 101 | |
| 102 | /* Validate scan parameters */ |
| 103 | bad = FALSE; |
| 104 | if (is_DC_band) { |
| 105 | if (cinfo->Se != 0) |
| 106 | bad = TRUE; |
| 107 | } else { |
| 108 | /* need not check Ss/Se < 0 since they came from unsigned bytes */ |
| 109 | if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2) |
| 110 | bad = TRUE; |
| 111 | /* AC scans may have only one component */ |
| 112 | if (cinfo->comps_in_scan != 1) |
| 113 | bad = TRUE; |
| 114 | } |
| 115 | if (cinfo->Ah != 0) { |
| 116 | /* Successive approximation refinement scan: must have Al = Ah-1. */ |
| 117 | if (cinfo->Al != cinfo->Ah-1) |
| 118 | bad = TRUE; |
| 119 | } |
| 120 | if (cinfo->Al > 13) /* need not check for < 0 */ |
| 121 | bad = TRUE; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 122 | /* Arguably the maximum Al value should be less than 13 for 8-bit precision, |
| 123 | * but the spec doesn't say so, and we try to be liberal about what we |
| 124 | * accept. Note: large Al values could result in out-of-range DC |
| 125 | * coefficients during early scans, leading to bizarre displays due to |
| 126 | * overflows in the IDCT math. But we won't crash. |
| 127 | */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 128 | if (bad) |
| 129 | ERREXIT4(cinfo, JERR_BAD_PROGRESSION, |
| 130 | cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al); |
| 131 | /* Update progression status, and verify that scan order is legal. |
| 132 | * Note that inter-scan inconsistencies are treated as warnings |
| 133 | * not fatal errors ... not clear if this is right way to behave. |
| 134 | */ |
| 135 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
| 136 | int cindex = cinfo->cur_comp_info[ci]->component_index; |
| 137 | coef_bit_ptr = & cinfo->coef_bits[cindex][0]; |
| 138 | if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */ |
| 139 | WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0); |
| 140 | for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) { |
| 141 | int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi]; |
| 142 | if (cinfo->Ah != expected) |
| 143 | WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi); |
| 144 | coef_bit_ptr[coefi] = cinfo->Al; |
| 145 | } |
| 146 | } |
| 147 | |
| 148 | /* Select MCU decoding routine */ |
| 149 | if (cinfo->Ah == 0) { |
| 150 | if (is_DC_band) |
| 151 | entropy->pub.decode_mcu = decode_mcu_DC_first; |
| 152 | else |
| 153 | entropy->pub.decode_mcu = decode_mcu_AC_first; |
| 154 | } else { |
| 155 | if (is_DC_band) |
| 156 | entropy->pub.decode_mcu = decode_mcu_DC_refine; |
| 157 | else |
| 158 | entropy->pub.decode_mcu = decode_mcu_AC_refine; |
| 159 | } |
| 160 | |
| 161 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
| 162 | compptr = cinfo->cur_comp_info[ci]; |
| 163 | /* Make sure requested tables are present, and compute derived tables. |
| 164 | * We may build same derived table more than once, but it's not expensive. |
| 165 | */ |
| 166 | if (is_DC_band) { |
| 167 | if (cinfo->Ah == 0) { /* DC refinement needs no table */ |
| 168 | tbl = compptr->dc_tbl_no; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 169 | jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 170 | & entropy->derived_tbls[tbl]); |
| 171 | } |
| 172 | } else { |
| 173 | tbl = compptr->ac_tbl_no; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 174 | jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 175 | & entropy->derived_tbls[tbl]); |
| 176 | /* remember the single active table */ |
| 177 | entropy->ac_derived_tbl = entropy->derived_tbls[tbl]; |
| 178 | } |
| 179 | /* Initialize DC predictions to 0 */ |
| 180 | entropy->saved.last_dc_val[ci] = 0; |
| 181 | } |
| 182 | |
| 183 | /* Initialize bitread state variables */ |
| 184 | entropy->bitstate.bits_left = 0; |
| 185 | entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 186 | entropy->pub.insufficient_data = FALSE; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 187 | |
| 188 | /* Initialize private state variables */ |
| 189 | entropy->saved.EOBRUN = 0; |
| 190 | |
| 191 | /* Initialize restart counter */ |
| 192 | entropy->restarts_to_go = cinfo->restart_interval; |
| 193 | } |
| 194 | |
| 195 | |
| 196 | /* |
| 197 | * Figure F.12: extend sign bit. |
| 198 | * On some machines, a shift and add will be faster than a table lookup. |
| 199 | */ |
| 200 | |
| 201 | #ifdef AVOID_TABLES |
| 202 | |
| 203 | #define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x)) |
| 204 | |
| 205 | #else |
| 206 | |
| 207 | #define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x)) |
| 208 | |
| 209 | static const int extend_test[16] = /* entry n is 2**(n-1) */ |
| 210 | { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, |
| 211 | 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }; |
| 212 | |
| 213 | static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */ |
| 214 | { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1, |
| 215 | ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1, |
| 216 | ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1, |
| 217 | ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 }; |
| 218 | |
| 219 | #endif /* AVOID_TABLES */ |
| 220 | |
| 221 | |
| 222 | /* |
| 223 | * Check for a restart marker & resynchronize decoder. |
| 224 | * Returns FALSE if must suspend. |
| 225 | */ |
| 226 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 227 | LOCAL(boolean) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 228 | process_restart (j_decompress_ptr cinfo) |
| 229 | { |
| 230 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 231 | int ci; |
| 232 | |
| 233 | /* Throw away any unused bits remaining in bit buffer; */ |
| 234 | /* include any full bytes in next_marker's count of discarded bytes */ |
| 235 | cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8; |
| 236 | entropy->bitstate.bits_left = 0; |
| 237 | |
| 238 | /* Advance past the RSTn marker */ |
| 239 | if (! (*cinfo->marker->read_restart_marker) (cinfo)) |
| 240 | return FALSE; |
| 241 | |
| 242 | /* Re-initialize DC predictions to 0 */ |
| 243 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) |
| 244 | entropy->saved.last_dc_val[ci] = 0; |
| 245 | /* Re-init EOB run count, too */ |
| 246 | entropy->saved.EOBRUN = 0; |
| 247 | |
| 248 | /* Reset restart counter */ |
| 249 | entropy->restarts_to_go = cinfo->restart_interval; |
| 250 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 251 | /* Reset out-of-data flag, unless read_restart_marker left us smack up |
| 252 | * against a marker. In that case we will end up treating the next data |
| 253 | * segment as empty, and we can avoid producing bogus output pixels by |
| 254 | * leaving the flag set. |
| 255 | */ |
| 256 | if (cinfo->unread_marker == 0) |
| 257 | entropy->pub.insufficient_data = FALSE; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 258 | |
| 259 | return TRUE; |
| 260 | } |
| 261 | |
| 262 | |
| 263 | /* |
| 264 | * Huffman MCU decoding. |
| 265 | * Each of these routines decodes and returns one MCU's worth of |
| 266 | * Huffman-compressed coefficients. |
| 267 | * The coefficients are reordered from zigzag order into natural array order, |
| 268 | * but are not dequantized. |
| 269 | * |
| 270 | * The i'th block of the MCU is stored into the block pointed to by |
| 271 | * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER. |
| 272 | * |
| 273 | * We return FALSE if data source requested suspension. In that case no |
| 274 | * changes have been made to permanent state. (Exception: some output |
| 275 | * coefficients may already have been assigned. This is harmless for |
| 276 | * spectral selection, since we'll just re-assign them on the next call. |
| 277 | * Successive approximation AC refinement has to be more careful, however.) |
| 278 | */ |
| 279 | |
| 280 | /* |
| 281 | * MCU decoding for DC initial scan (either spectral selection, |
| 282 | * or first pass of successive approximation). |
| 283 | */ |
| 284 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 285 | METHODDEF(boolean) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 286 | decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
| 287 | { |
| 288 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 289 | int Al = cinfo->Al; |
| 290 | register int s, r; |
| 291 | int blkn, ci; |
| 292 | JBLOCKROW block; |
| 293 | BITREAD_STATE_VARS; |
| 294 | savable_state state; |
| 295 | d_derived_tbl * tbl; |
| 296 | jpeg_component_info * compptr; |
| 297 | |
| 298 | /* Process restart marker if needed; may have to suspend */ |
| 299 | if (cinfo->restart_interval) { |
| 300 | if (entropy->restarts_to_go == 0) |
| 301 | if (! process_restart(cinfo)) |
| 302 | return FALSE; |
| 303 | } |
| 304 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 305 | /* If we've run out of data, just leave the MCU set to zeroes. |
| 306 | * This way, we return uniform gray for the remainder of the segment. |
| 307 | */ |
| 308 | if (! entropy->pub.insufficient_data) { |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 309 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 310 | /* Load up working state */ |
| 311 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 312 | ASSIGN_STATE(state, entropy->saved); |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 313 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 314 | /* Outer loop handles each block in the MCU */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 315 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 316 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| 317 | block = MCU_data[blkn]; |
| 318 | ci = cinfo->MCU_membership[blkn]; |
| 319 | compptr = cinfo->cur_comp_info[ci]; |
| 320 | tbl = entropy->derived_tbls[compptr->dc_tbl_no]; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 321 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 322 | /* Decode a single block's worth of coefficients */ |
| 323 | |
| 324 | /* Section F.2.2.1: decode the DC coefficient difference */ |
| 325 | HUFF_DECODE(s, br_state, tbl, return FALSE, label1); |
| 326 | if (s) { |
| 327 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 328 | r = GET_BITS(s); |
| 329 | s = HUFF_EXTEND(r, s); |
| 330 | } |
| 331 | |
| 332 | /* Convert DC difference to actual value, update last_dc_val */ |
| 333 | s += state.last_dc_val[ci]; |
| 334 | state.last_dc_val[ci] = s; |
| 335 | /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */ |
| 336 | (*block)[0] = (JCOEF) (s << Al); |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 337 | } |
| 338 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 339 | /* Completed MCU, so update state */ |
| 340 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
| 341 | ASSIGN_STATE(entropy->saved, state); |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 342 | } |
| 343 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 344 | /* Account for restart interval (no-op if not using restarts) */ |
| 345 | entropy->restarts_to_go--; |
| 346 | |
| 347 | return TRUE; |
| 348 | } |
| 349 | |
| 350 | |
| 351 | /* |
| 352 | * MCU decoding for AC initial scan (either spectral selection, |
| 353 | * or first pass of successive approximation). |
| 354 | */ |
| 355 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 356 | METHODDEF(boolean) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 357 | decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
| 358 | { |
| 359 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 360 | int Se = cinfo->Se; |
| 361 | int Al = cinfo->Al; |
| 362 | register int s, k, r; |
| 363 | unsigned int EOBRUN; |
| 364 | JBLOCKROW block; |
| 365 | BITREAD_STATE_VARS; |
| 366 | d_derived_tbl * tbl; |
| 367 | |
| 368 | /* Process restart marker if needed; may have to suspend */ |
| 369 | if (cinfo->restart_interval) { |
| 370 | if (entropy->restarts_to_go == 0) |
| 371 | if (! process_restart(cinfo)) |
| 372 | return FALSE; |
| 373 | } |
| 374 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 375 | /* If we've run out of data, just leave the MCU set to zeroes. |
| 376 | * This way, we return uniform gray for the remainder of the segment. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 377 | */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 378 | if (! entropy->pub.insufficient_data) { |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 379 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 380 | /* Load up working state. |
| 381 | * We can avoid loading/saving bitread state if in an EOB run. |
| 382 | */ |
| 383 | EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 384 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 385 | /* There is always only one block per MCU */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 386 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 387 | if (EOBRUN > 0) /* if it's a band of zeroes... */ |
| 388 | EOBRUN--; /* ...process it now (we do nothing) */ |
| 389 | else { |
| 390 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 391 | block = MCU_data[0]; |
| 392 | tbl = entropy->ac_derived_tbl; |
| 393 | |
| 394 | for (k = cinfo->Ss; k <= Se; k++) { |
| 395 | HUFF_DECODE(s, br_state, tbl, return FALSE, label2); |
| 396 | r = s >> 4; |
| 397 | s &= 15; |
| 398 | if (s) { |
| 399 | k += r; |
| 400 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 401 | r = GET_BITS(s); |
| 402 | s = HUFF_EXTEND(r, s); |
| 403 | /* Scale and output coefficient in natural (dezigzagged) order */ |
| 404 | (*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al); |
| 405 | } else { |
| 406 | if (r == 15) { /* ZRL */ |
| 407 | k += 15; /* skip 15 zeroes in band */ |
| 408 | } else { /* EOBr, run length is 2^r + appended bits */ |
| 409 | EOBRUN = 1 << r; |
| 410 | if (r) { /* EOBr, r > 0 */ |
| 411 | CHECK_BIT_BUFFER(br_state, r, return FALSE); |
| 412 | r = GET_BITS(r); |
| 413 | EOBRUN += r; |
| 414 | } |
| 415 | EOBRUN--; /* this band is processed at this moment */ |
| 416 | break; /* force end-of-band */ |
| 417 | } |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 418 | } |
| 419 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 420 | |
| 421 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 422 | } |
| 423 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 424 | /* Completed MCU, so update state */ |
| 425 | entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 426 | } |
| 427 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 428 | /* Account for restart interval (no-op if not using restarts) */ |
| 429 | entropy->restarts_to_go--; |
| 430 | |
| 431 | return TRUE; |
| 432 | } |
| 433 | |
| 434 | |
| 435 | /* |
| 436 | * MCU decoding for DC successive approximation refinement scan. |
| 437 | * Note: we assume such scans can be multi-component, although the spec |
| 438 | * is not very clear on the point. |
| 439 | */ |
| 440 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 441 | METHODDEF(boolean) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 442 | decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
| 443 | { |
| 444 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 445 | int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ |
| 446 | int blkn; |
| 447 | JBLOCKROW block; |
| 448 | BITREAD_STATE_VARS; |
| 449 | |
| 450 | /* Process restart marker if needed; may have to suspend */ |
| 451 | if (cinfo->restart_interval) { |
| 452 | if (entropy->restarts_to_go == 0) |
| 453 | if (! process_restart(cinfo)) |
| 454 | return FALSE; |
| 455 | } |
| 456 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 457 | /* Not worth the cycles to check insufficient_data here, |
| 458 | * since we will not change the data anyway if we read zeroes. |
| 459 | */ |
| 460 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 461 | /* Load up working state */ |
| 462 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 463 | |
| 464 | /* Outer loop handles each block in the MCU */ |
| 465 | |
| 466 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| 467 | block = MCU_data[blkn]; |
| 468 | |
| 469 | /* Encoded data is simply the next bit of the two's-complement DC value */ |
| 470 | CHECK_BIT_BUFFER(br_state, 1, return FALSE); |
| 471 | if (GET_BITS(1)) |
| 472 | (*block)[0] |= p1; |
| 473 | /* Note: since we use |=, repeating the assignment later is safe */ |
| 474 | } |
| 475 | |
| 476 | /* Completed MCU, so update state */ |
| 477 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
| 478 | |
| 479 | /* Account for restart interval (no-op if not using restarts) */ |
| 480 | entropy->restarts_to_go--; |
| 481 | |
| 482 | return TRUE; |
| 483 | } |
| 484 | |
| 485 | |
| 486 | /* |
| 487 | * MCU decoding for AC successive approximation refinement scan. |
| 488 | */ |
| 489 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 490 | METHODDEF(boolean) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 491 | decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
| 492 | { |
| 493 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 494 | int Se = cinfo->Se; |
| 495 | int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ |
| 496 | int m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */ |
| 497 | register int s, k, r; |
| 498 | unsigned int EOBRUN; |
| 499 | JBLOCKROW block; |
| 500 | JCOEFPTR thiscoef; |
| 501 | BITREAD_STATE_VARS; |
| 502 | d_derived_tbl * tbl; |
| 503 | int num_newnz; |
| 504 | int newnz_pos[DCTSIZE2]; |
| 505 | |
| 506 | /* Process restart marker if needed; may have to suspend */ |
| 507 | if (cinfo->restart_interval) { |
| 508 | if (entropy->restarts_to_go == 0) |
| 509 | if (! process_restart(cinfo)) |
| 510 | return FALSE; |
| 511 | } |
| 512 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 513 | /* If we've run out of data, don't modify the MCU. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 514 | */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 515 | if (! entropy->pub.insufficient_data) { |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 516 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 517 | /* Load up working state */ |
| 518 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 519 | EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 520 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 521 | /* There is always only one block per MCU */ |
| 522 | block = MCU_data[0]; |
| 523 | tbl = entropy->ac_derived_tbl; |
| 524 | |
| 525 | /* If we are forced to suspend, we must undo the assignments to any newly |
| 526 | * nonzero coefficients in the block, because otherwise we'd get confused |
| 527 | * next time about which coefficients were already nonzero. |
| 528 | * But we need not undo addition of bits to already-nonzero coefficients; |
| 529 | * instead, we can test the current bit to see if we already did it. |
| 530 | */ |
| 531 | num_newnz = 0; |
| 532 | |
| 533 | /* initialize coefficient loop counter to start of band */ |
| 534 | k = cinfo->Ss; |
| 535 | |
| 536 | if (EOBRUN == 0) { |
| 537 | for (; k <= Se; k++) { |
| 538 | HUFF_DECODE(s, br_state, tbl, goto undoit, label3); |
| 539 | r = s >> 4; |
| 540 | s &= 15; |
| 541 | if (s) { |
| 542 | if (s != 1) /* size of new coef should always be 1 */ |
| 543 | WARNMS(cinfo, JWRN_HUFF_BAD_CODE); |
| 544 | CHECK_BIT_BUFFER(br_state, 1, goto undoit); |
| 545 | if (GET_BITS(1)) |
| 546 | s = p1; /* newly nonzero coef is positive */ |
| 547 | else |
| 548 | s = m1; /* newly nonzero coef is negative */ |
| 549 | } else { |
| 550 | if (r != 15) { |
| 551 | EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */ |
| 552 | if (r) { |
| 553 | CHECK_BIT_BUFFER(br_state, r, goto undoit); |
| 554 | r = GET_BITS(r); |
| 555 | EOBRUN += r; |
| 556 | } |
| 557 | break; /* rest of block is handled by EOB logic */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 558 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 559 | /* note s = 0 for processing ZRL */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 560 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 561 | /* Advance over already-nonzero coefs and r still-zero coefs, |
| 562 | * appending correction bits to the nonzeroes. A correction bit is 1 |
| 563 | * if the absolute value of the coefficient must be increased. |
| 564 | */ |
| 565 | do { |
| 566 | thiscoef = *block + jpeg_natural_order[k]; |
| 567 | if (*thiscoef != 0) { |
| 568 | CHECK_BIT_BUFFER(br_state, 1, goto undoit); |
| 569 | if (GET_BITS(1)) { |
| 570 | if ((*thiscoef & p1) == 0) { /* do nothing if already set it */ |
| 571 | if (*thiscoef >= 0) |
| 572 | *thiscoef += p1; |
| 573 | else |
| 574 | *thiscoef += m1; |
| 575 | } |
| 576 | } |
| 577 | } else { |
| 578 | if (--r < 0) |
| 579 | break; /* reached target zero coefficient */ |
| 580 | } |
| 581 | k++; |
| 582 | } while (k <= Se); |
| 583 | if (s) { |
| 584 | int pos = jpeg_natural_order[k]; |
| 585 | /* Output newly nonzero coefficient */ |
| 586 | (*block)[pos] = (JCOEF) s; |
| 587 | /* Remember its position in case we have to suspend */ |
| 588 | newnz_pos[num_newnz++] = pos; |
| 589 | } |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 590 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 591 | } |
| 592 | |
| 593 | if (EOBRUN > 0) { |
| 594 | /* Scan any remaining coefficient positions after the end-of-band |
| 595 | * (the last newly nonzero coefficient, if any). Append a correction |
| 596 | * bit to each already-nonzero coefficient. A correction bit is 1 |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 597 | * if the absolute value of the coefficient must be increased. |
| 598 | */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 599 | for (; k <= Se; k++) { |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 600 | thiscoef = *block + jpeg_natural_order[k]; |
| 601 | if (*thiscoef != 0) { |
| 602 | CHECK_BIT_BUFFER(br_state, 1, goto undoit); |
| 603 | if (GET_BITS(1)) { |
| 604 | if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */ |
| 605 | if (*thiscoef >= 0) |
| 606 | *thiscoef += p1; |
| 607 | else |
| 608 | *thiscoef += m1; |
| 609 | } |
| 610 | } |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 611 | } |
| 612 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 613 | /* Count one block completed in EOB run */ |
| 614 | EOBRUN--; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 615 | } |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 616 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 617 | /* Completed MCU, so update state */ |
| 618 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
| 619 | entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ |
| 620 | } |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 621 | |
| 622 | /* Account for restart interval (no-op if not using restarts) */ |
| 623 | entropy->restarts_to_go--; |
| 624 | |
| 625 | return TRUE; |
| 626 | |
| 627 | undoit: |
| 628 | /* Re-zero any output coefficients that we made newly nonzero */ |
| 629 | while (num_newnz > 0) |
| 630 | (*block)[newnz_pos[--num_newnz]] = 0; |
| 631 | |
| 632 | return FALSE; |
| 633 | } |
| 634 | |
| 635 | |
| 636 | /* |
| 637 | * Module initialization routine for progressive Huffman entropy decoding. |
| 638 | */ |
| 639 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 640 | GLOBAL(void) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 641 | jinit_phuff_decoder (j_decompress_ptr cinfo) |
| 642 | { |
| 643 | phuff_entropy_ptr entropy; |
| 644 | int *coef_bit_ptr; |
| 645 | int ci, i; |
| 646 | |
| 647 | entropy = (phuff_entropy_ptr) |
| 648 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 649 | SIZEOF(phuff_entropy_decoder)); |
| 650 | cinfo->entropy = (struct jpeg_entropy_decoder *) entropy; |
| 651 | entropy->pub.start_pass = start_pass_phuff_decoder; |
| 652 | |
| 653 | /* Mark derived tables unallocated */ |
| 654 | for (i = 0; i < NUM_HUFF_TBLS; i++) { |
| 655 | entropy->derived_tbls[i] = NULL; |
| 656 | } |
| 657 | |
| 658 | /* Create progression status table */ |
| 659 | cinfo->coef_bits = (int (*)[DCTSIZE2]) |
| 660 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 661 | cinfo->num_components*DCTSIZE2*SIZEOF(int)); |
| 662 | coef_bit_ptr = & cinfo->coef_bits[0][0]; |
| 663 | for (ci = 0; ci < cinfo->num_components; ci++) |
| 664 | for (i = 0; i < DCTSIZE2; i++) |
| 665 | *coef_bit_ptr++ = -1; |
| 666 | } |
| 667 | |
| 668 | #endif /* D_PROGRESSIVE_SUPPORTED */ |