Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1 | /* |
| 2 | * jdhuff.c |
| 3 | * |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 4 | * Copyright (C) 1991-1997, Thomas G. Lane. |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 5 | * Modified 2006-2012 by Guido Vollbeding. |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 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 Huffman entropy decoding routines. |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 10 | * Both sequential and progressive modes are supported in this single module. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 11 | * |
| 12 | * Much of the complexity here has to do with supporting input suspension. |
| 13 | * If the data source module demands suspension, we want to be able to back |
| 14 | * up to the start of the current MCU. To do this, we copy state variables |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 15 | * into local working storage, and update them back to the permanent |
| 16 | * storage only upon successful completion of an MCU. |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 17 | */ |
| 18 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 19 | #define JPEG_INTERNALS |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 20 | #include "jinclude.h" |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 21 | #include "jpeglib.h" |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 22 | |
| 23 | |
| 24 | /* Derived data constructed for each Huffman table */ |
| 25 | |
| 26 | #define HUFF_LOOKAHEAD 8 /* # of bits of lookahead */ |
| 27 | |
| 28 | typedef struct { |
| 29 | /* Basic tables: (element [0] of each array is unused) */ |
| 30 | INT32 maxcode[18]; /* largest code of length k (-1 if none) */ |
| 31 | /* (maxcode[17] is a sentinel to ensure jpeg_huff_decode terminates) */ |
| 32 | INT32 valoffset[17]; /* huffval[] offset for codes of length k */ |
| 33 | /* valoffset[k] = huffval[] index of 1st symbol of code length k, less |
| 34 | * the smallest code of length k; so given a code of length k, the |
| 35 | * corresponding symbol is huffval[code + valoffset[k]] |
| 36 | */ |
| 37 | |
| 38 | /* Link to public Huffman table (needed only in jpeg_huff_decode) */ |
| 39 | JHUFF_TBL *pub; |
| 40 | |
| 41 | /* Lookahead tables: indexed by the next HUFF_LOOKAHEAD bits of |
| 42 | * the input data stream. If the next Huffman code is no more |
| 43 | * than HUFF_LOOKAHEAD bits long, we can obtain its length and |
| 44 | * the corresponding symbol directly from these tables. |
| 45 | */ |
| 46 | int look_nbits[1<<HUFF_LOOKAHEAD]; /* # bits, or 0 if too long */ |
| 47 | UINT8 look_sym[1<<HUFF_LOOKAHEAD]; /* symbol, or unused */ |
| 48 | } d_derived_tbl; |
| 49 | |
| 50 | |
| 51 | /* |
| 52 | * Fetching the next N bits from the input stream is a time-critical operation |
| 53 | * for the Huffman decoders. We implement it with a combination of inline |
| 54 | * macros and out-of-line subroutines. Note that N (the number of bits |
| 55 | * demanded at one time) never exceeds 15 for JPEG use. |
| 56 | * |
| 57 | * We read source bytes into get_buffer and dole out bits as needed. |
| 58 | * If get_buffer already contains enough bits, they are fetched in-line |
| 59 | * by the macros CHECK_BIT_BUFFER and GET_BITS. When there aren't enough |
| 60 | * bits, jpeg_fill_bit_buffer is called; it will attempt to fill get_buffer |
| 61 | * as full as possible (not just to the number of bits needed; this |
| 62 | * prefetching reduces the overhead cost of calling jpeg_fill_bit_buffer). |
| 63 | * Note that jpeg_fill_bit_buffer may return FALSE to indicate suspension. |
| 64 | * On TRUE return, jpeg_fill_bit_buffer guarantees that get_buffer contains |
| 65 | * at least the requested number of bits --- dummy zeroes are inserted if |
| 66 | * necessary. |
| 67 | */ |
| 68 | |
| 69 | typedef INT32 bit_buf_type; /* type of bit-extraction buffer */ |
| 70 | #define BIT_BUF_SIZE 32 /* size of buffer in bits */ |
| 71 | |
| 72 | /* If long is > 32 bits on your machine, and shifting/masking longs is |
| 73 | * reasonably fast, making bit_buf_type be long and setting BIT_BUF_SIZE |
| 74 | * appropriately should be a win. Unfortunately we can't define the size |
| 75 | * with something like #define BIT_BUF_SIZE (sizeof(bit_buf_type)*8) |
| 76 | * because not all machines measure sizeof in 8-bit bytes. |
| 77 | */ |
| 78 | |
| 79 | typedef struct { /* Bitreading state saved across MCUs */ |
| 80 | bit_buf_type get_buffer; /* current bit-extraction buffer */ |
| 81 | int bits_left; /* # of unused bits in it */ |
| 82 | } bitread_perm_state; |
| 83 | |
| 84 | typedef struct { /* Bitreading working state within an MCU */ |
| 85 | /* Current data source location */ |
| 86 | /* We need a copy, rather than munging the original, in case of suspension */ |
| 87 | const JOCTET * next_input_byte; /* => next byte to read from source */ |
| 88 | size_t bytes_in_buffer; /* # of bytes remaining in source buffer */ |
| 89 | /* Bit input buffer --- note these values are kept in register variables, |
| 90 | * not in this struct, inside the inner loops. |
| 91 | */ |
| 92 | bit_buf_type get_buffer; /* current bit-extraction buffer */ |
| 93 | int bits_left; /* # of unused bits in it */ |
| 94 | /* Pointer needed by jpeg_fill_bit_buffer. */ |
| 95 | j_decompress_ptr cinfo; /* back link to decompress master record */ |
| 96 | } bitread_working_state; |
| 97 | |
| 98 | /* Macros to declare and load/save bitread local variables. */ |
| 99 | #define BITREAD_STATE_VARS \ |
| 100 | register bit_buf_type get_buffer; \ |
| 101 | register int bits_left; \ |
| 102 | bitread_working_state br_state |
| 103 | |
| 104 | #define BITREAD_LOAD_STATE(cinfop,permstate) \ |
| 105 | br_state.cinfo = cinfop; \ |
| 106 | br_state.next_input_byte = cinfop->src->next_input_byte; \ |
| 107 | br_state.bytes_in_buffer = cinfop->src->bytes_in_buffer; \ |
| 108 | get_buffer = permstate.get_buffer; \ |
| 109 | bits_left = permstate.bits_left; |
| 110 | |
| 111 | #define BITREAD_SAVE_STATE(cinfop,permstate) \ |
| 112 | cinfop->src->next_input_byte = br_state.next_input_byte; \ |
| 113 | cinfop->src->bytes_in_buffer = br_state.bytes_in_buffer; \ |
| 114 | permstate.get_buffer = get_buffer; \ |
| 115 | permstate.bits_left = bits_left |
| 116 | |
| 117 | /* |
| 118 | * These macros provide the in-line portion of bit fetching. |
| 119 | * Use CHECK_BIT_BUFFER to ensure there are N bits in get_buffer |
| 120 | * before using GET_BITS, PEEK_BITS, or DROP_BITS. |
| 121 | * The variables get_buffer and bits_left are assumed to be locals, |
| 122 | * but the state struct might not be (jpeg_huff_decode needs this). |
| 123 | * CHECK_BIT_BUFFER(state,n,action); |
| 124 | * Ensure there are N bits in get_buffer; if suspend, take action. |
| 125 | * val = GET_BITS(n); |
| 126 | * Fetch next N bits. |
| 127 | * val = PEEK_BITS(n); |
| 128 | * Fetch next N bits without removing them from the buffer. |
| 129 | * DROP_BITS(n); |
| 130 | * Discard next N bits. |
| 131 | * The value N should be a simple variable, not an expression, because it |
| 132 | * is evaluated multiple times. |
| 133 | */ |
| 134 | |
| 135 | #define CHECK_BIT_BUFFER(state,nbits,action) \ |
| 136 | { if (bits_left < (nbits)) { \ |
| 137 | if (! jpeg_fill_bit_buffer(&(state),get_buffer,bits_left,nbits)) \ |
| 138 | { action; } \ |
| 139 | get_buffer = (state).get_buffer; bits_left = (state).bits_left; } } |
| 140 | |
| 141 | #define GET_BITS(nbits) \ |
| 142 | (((int) (get_buffer >> (bits_left -= (nbits)))) & BIT_MASK(nbits)) |
| 143 | |
| 144 | #define PEEK_BITS(nbits) \ |
| 145 | (((int) (get_buffer >> (bits_left - (nbits)))) & BIT_MASK(nbits)) |
| 146 | |
| 147 | #define DROP_BITS(nbits) \ |
| 148 | (bits_left -= (nbits)) |
| 149 | |
| 150 | |
| 151 | /* |
| 152 | * Code for extracting next Huffman-coded symbol from input bit stream. |
| 153 | * Again, this is time-critical and we make the main paths be macros. |
| 154 | * |
| 155 | * We use a lookahead table to process codes of up to HUFF_LOOKAHEAD bits |
| 156 | * without looping. Usually, more than 95% of the Huffman codes will be 8 |
| 157 | * or fewer bits long. The few overlength codes are handled with a loop, |
| 158 | * which need not be inline code. |
| 159 | * |
| 160 | * Notes about the HUFF_DECODE macro: |
| 161 | * 1. Near the end of the data segment, we may fail to get enough bits |
| 162 | * for a lookahead. In that case, we do it the hard way. |
| 163 | * 2. If the lookahead table contains no entry, the next code must be |
| 164 | * more than HUFF_LOOKAHEAD bits long. |
| 165 | * 3. jpeg_huff_decode returns -1 if forced to suspend. |
| 166 | */ |
| 167 | |
| 168 | #define HUFF_DECODE(result,state,htbl,failaction,slowlabel) \ |
| 169 | { register int nb, look; \ |
| 170 | if (bits_left < HUFF_LOOKAHEAD) { \ |
| 171 | if (! jpeg_fill_bit_buffer(&state,get_buffer,bits_left, 0)) {failaction;} \ |
| 172 | get_buffer = state.get_buffer; bits_left = state.bits_left; \ |
| 173 | if (bits_left < HUFF_LOOKAHEAD) { \ |
| 174 | nb = 1; goto slowlabel; \ |
| 175 | } \ |
| 176 | } \ |
| 177 | look = PEEK_BITS(HUFF_LOOKAHEAD); \ |
| 178 | if ((nb = htbl->look_nbits[look]) != 0) { \ |
| 179 | DROP_BITS(nb); \ |
| 180 | result = htbl->look_sym[look]; \ |
| 181 | } else { \ |
| 182 | nb = HUFF_LOOKAHEAD+1; \ |
| 183 | slowlabel: \ |
| 184 | if ((result=jpeg_huff_decode(&state,get_buffer,bits_left,htbl,nb)) < 0) \ |
| 185 | { failaction; } \ |
| 186 | get_buffer = state.get_buffer; bits_left = state.bits_left; \ |
| 187 | } \ |
| 188 | } |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 189 | |
| 190 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 191 | /* |
| 192 | * Expanded entropy decoder object for Huffman decoding. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 193 | * |
| 194 | * The savable_state subrecord contains fields that change within an MCU, |
| 195 | * but must not be updated permanently until we complete the MCU. |
| 196 | */ |
| 197 | |
| 198 | typedef struct { |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 199 | unsigned int EOBRUN; /* remaining EOBs in EOBRUN */ |
| 200 | int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 201 | } savable_state; |
| 202 | |
| 203 | /* This macro is to work around compilers with missing or broken |
| 204 | * structure assignment. You'll need to fix this code if you have |
| 205 | * such a compiler and you change MAX_COMPS_IN_SCAN. |
| 206 | */ |
| 207 | |
| 208 | #ifndef NO_STRUCT_ASSIGN |
| 209 | #define ASSIGN_STATE(dest,src) ((dest) = (src)) |
| 210 | #else |
| 211 | #if MAX_COMPS_IN_SCAN == 4 |
| 212 | #define ASSIGN_STATE(dest,src) \ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 213 | ((dest).EOBRUN = (src).EOBRUN, \ |
| 214 | (dest).last_dc_val[0] = (src).last_dc_val[0], \ |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 215 | (dest).last_dc_val[1] = (src).last_dc_val[1], \ |
| 216 | (dest).last_dc_val[2] = (src).last_dc_val[2], \ |
| 217 | (dest).last_dc_val[3] = (src).last_dc_val[3]) |
| 218 | #endif |
| 219 | #endif |
| 220 | |
| 221 | |
| 222 | typedef struct { |
| 223 | struct jpeg_entropy_decoder pub; /* public fields */ |
| 224 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 225 | /* These fields are loaded into local variables at start of each MCU. |
| 226 | * In case of suspension, we exit WITHOUT updating them. |
| 227 | */ |
| 228 | bitread_perm_state bitstate; /* Bit buffer at start of MCU */ |
| 229 | savable_state saved; /* Other state at start of MCU */ |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 230 | |
| 231 | /* These fields are NOT loaded into local working state. */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 232 | boolean insufficient_data; /* set TRUE after emitting warning */ |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 233 | unsigned int restarts_to_go; /* MCUs left in this restart interval */ |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 234 | |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 235 | /* Following two fields used only in progressive mode */ |
| 236 | |
| 237 | /* Pointers to derived tables (these workspaces have image lifespan) */ |
| 238 | d_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; |
| 239 | |
| 240 | d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */ |
| 241 | |
| 242 | /* Following fields used only in sequential mode */ |
| 243 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 244 | /* Pointers to derived tables (these workspaces have image lifespan) */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 245 | d_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS]; |
| 246 | d_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS]; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 247 | |
| 248 | /* Precalculated info set up by start_pass for use in decode_mcu: */ |
| 249 | |
| 250 | /* Pointers to derived tables to be used for each block within an MCU */ |
| 251 | d_derived_tbl * dc_cur_tbls[D_MAX_BLOCKS_IN_MCU]; |
| 252 | d_derived_tbl * ac_cur_tbls[D_MAX_BLOCKS_IN_MCU]; |
| 253 | /* Whether we care about the DC and AC coefficient values for each block */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 254 | int coef_limit[D_MAX_BLOCKS_IN_MCU]; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 255 | } huff_entropy_decoder; |
| 256 | |
| 257 | typedef huff_entropy_decoder * huff_entropy_ptr; |
| 258 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 259 | |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 260 | static const int jpeg_zigzag_order[8][8] = { |
| 261 | { 0, 1, 5, 6, 14, 15, 27, 28 }, |
| 262 | { 2, 4, 7, 13, 16, 26, 29, 42 }, |
| 263 | { 3, 8, 12, 17, 25, 30, 41, 43 }, |
| 264 | { 9, 11, 18, 24, 31, 40, 44, 53 }, |
| 265 | { 10, 19, 23, 32, 39, 45, 52, 54 }, |
| 266 | { 20, 22, 33, 38, 46, 51, 55, 60 }, |
| 267 | { 21, 34, 37, 47, 50, 56, 59, 61 }, |
| 268 | { 35, 36, 48, 49, 57, 58, 62, 63 } |
| 269 | }; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 270 | |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 271 | static const int jpeg_zigzag_order7[7][7] = { |
| 272 | { 0, 1, 5, 6, 14, 15, 27 }, |
| 273 | { 2, 4, 7, 13, 16, 26, 28 }, |
| 274 | { 3, 8, 12, 17, 25, 29, 38 }, |
| 275 | { 9, 11, 18, 24, 30, 37, 39 }, |
| 276 | { 10, 19, 23, 31, 36, 40, 45 }, |
| 277 | { 20, 22, 32, 35, 41, 44, 46 }, |
| 278 | { 21, 33, 34, 42, 43, 47, 48 } |
| 279 | }; |
| 280 | |
| 281 | static const int jpeg_zigzag_order6[6][6] = { |
| 282 | { 0, 1, 5, 6, 14, 15 }, |
| 283 | { 2, 4, 7, 13, 16, 25 }, |
| 284 | { 3, 8, 12, 17, 24, 26 }, |
| 285 | { 9, 11, 18, 23, 27, 32 }, |
| 286 | { 10, 19, 22, 28, 31, 33 }, |
| 287 | { 20, 21, 29, 30, 34, 35 } |
| 288 | }; |
| 289 | |
| 290 | static const int jpeg_zigzag_order5[5][5] = { |
| 291 | { 0, 1, 5, 6, 14 }, |
| 292 | { 2, 4, 7, 13, 15 }, |
| 293 | { 3, 8, 12, 16, 21 }, |
| 294 | { 9, 11, 17, 20, 22 }, |
| 295 | { 10, 18, 19, 23, 24 } |
| 296 | }; |
| 297 | |
| 298 | static const int jpeg_zigzag_order4[4][4] = { |
| 299 | { 0, 1, 5, 6 }, |
| 300 | { 2, 4, 7, 12 }, |
| 301 | { 3, 8, 11, 13 }, |
| 302 | { 9, 10, 14, 15 } |
| 303 | }; |
| 304 | |
| 305 | static const int jpeg_zigzag_order3[3][3] = { |
| 306 | { 0, 1, 5 }, |
| 307 | { 2, 4, 6 }, |
| 308 | { 3, 7, 8 } |
| 309 | }; |
| 310 | |
| 311 | static const int jpeg_zigzag_order2[2][2] = { |
| 312 | { 0, 1 }, |
| 313 | { 2, 3 } |
| 314 | }; |
| 315 | |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 316 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 317 | /* |
| 318 | * Compute the derived values for a Huffman table. |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 319 | * This routine also performs some validation checks on the table. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 320 | */ |
| 321 | |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 322 | LOCAL(void) |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 323 | jpeg_make_d_derived_tbl (j_decompress_ptr cinfo, boolean isDC, int tblno, |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 324 | d_derived_tbl ** pdtbl) |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 325 | { |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 326 | JHUFF_TBL *htbl; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 327 | d_derived_tbl *dtbl; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 328 | int p, i, l, si, numsymbols; |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 329 | int lookbits, ctr; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 330 | char huffsize[257]; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 331 | unsigned int huffcode[257]; |
| 332 | unsigned int code; |
| 333 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 334 | /* Note that huffsize[] and huffcode[] are filled in code-length order, |
| 335 | * paralleling the order of the symbols themselves in htbl->huffval[]. |
| 336 | */ |
| 337 | |
| 338 | /* Find the input Huffman table */ |
| 339 | if (tblno < 0 || tblno >= NUM_HUFF_TBLS) |
| 340 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno); |
| 341 | htbl = |
| 342 | isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno]; |
| 343 | if (htbl == NULL) |
| 344 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno); |
| 345 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 346 | /* Allocate a workspace if we haven't already done so. */ |
| 347 | if (*pdtbl == NULL) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 348 | *pdtbl = (d_derived_tbl *) |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 349 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 350 | SIZEOF(d_derived_tbl)); |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 351 | dtbl = *pdtbl; |
| 352 | dtbl->pub = htbl; /* fill in back link */ |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 353 | |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 354 | /* Figure C.1: make table of Huffman code length for each symbol */ |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 355 | |
| 356 | p = 0; |
| 357 | for (l = 1; l <= 16; l++) { |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 358 | i = (int) htbl->bits[l]; |
| 359 | if (i < 0 || p + i > 256) /* protect against table overrun */ |
| 360 | ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
| 361 | while (i--) |
Thomas G. Lane | bd543f0 | 1991-12-13 00:00:00 +0000 | [diff] [blame] | 362 | huffsize[p++] = (char) l; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 363 | } |
| 364 | huffsize[p] = 0; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 365 | numsymbols = p; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 366 | |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 367 | /* Figure C.2: generate the codes themselves */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 368 | /* We also validate that the counts represent a legal Huffman code tree. */ |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 369 | |
| 370 | code = 0; |
| 371 | si = huffsize[0]; |
| 372 | p = 0; |
| 373 | while (huffsize[p]) { |
Thomas G. Lane | bd543f0 | 1991-12-13 00:00:00 +0000 | [diff] [blame] | 374 | while (((int) huffsize[p]) == si) { |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 375 | huffcode[p++] = code; |
| 376 | code++; |
| 377 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 378 | /* code is now 1 more than the last code used for codelength si; but |
| 379 | * it must still fit in si bits, since no code is allowed to be all ones. |
| 380 | */ |
| 381 | if (((INT32) code) >= (((INT32) 1) << si)) |
| 382 | ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 383 | code <<= 1; |
| 384 | si++; |
| 385 | } |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 386 | |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 387 | /* Figure F.15: generate decoding tables for bit-sequential decoding */ |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 388 | |
| 389 | p = 0; |
| 390 | for (l = 1; l <= 16; l++) { |
| 391 | if (htbl->bits[l]) { |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 392 | /* valoffset[l] = huffval[] index of 1st symbol of code length l, |
| 393 | * minus the minimum code of length l |
| 394 | */ |
| 395 | dtbl->valoffset[l] = (INT32) p - (INT32) huffcode[p]; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 396 | p += htbl->bits[l]; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 397 | dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */ |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 398 | } else { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 399 | dtbl->maxcode[l] = -1; /* -1 if no codes of this length */ |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 400 | } |
| 401 | } |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 402 | dtbl->maxcode[17] = 0xFFFFFL; /* ensures jpeg_huff_decode terminates */ |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 403 | |
| 404 | /* Compute lookahead tables to speed up decoding. |
| 405 | * First we set all the table entries to 0, indicating "too long"; |
| 406 | * then we iterate through the Huffman codes that are short enough and |
| 407 | * fill in all the entries that correspond to bit sequences starting |
| 408 | * with that code. |
| 409 | */ |
| 410 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 411 | MEMZERO(dtbl->look_nbits, SIZEOF(dtbl->look_nbits)); |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 412 | |
| 413 | p = 0; |
| 414 | for (l = 1; l <= HUFF_LOOKAHEAD; l++) { |
| 415 | for (i = 1; i <= (int) htbl->bits[l]; i++, p++) { |
| 416 | /* l = current code's length, p = its index in huffcode[] & huffval[]. */ |
| 417 | /* Generate left-justified code followed by all possible bit sequences */ |
| 418 | lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l); |
| 419 | for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 420 | dtbl->look_nbits[lookbits] = l; |
| 421 | dtbl->look_sym[lookbits] = htbl->huffval[p]; |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 422 | lookbits++; |
| 423 | } |
| 424 | } |
| 425 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 426 | |
| 427 | /* Validate symbols as being reasonable. |
| 428 | * For AC tables, we make no check, but accept all byte values 0..255. |
| 429 | * For DC tables, we require the symbols to be in range 0..15. |
| 430 | * (Tighter bounds could be applied depending on the data depth and mode, |
| 431 | * but this is sufficient to ensure safe decoding.) |
| 432 | */ |
| 433 | if (isDC) { |
| 434 | for (i = 0; i < numsymbols; i++) { |
| 435 | int sym = htbl->huffval[i]; |
| 436 | if (sym < 0 || sym > 15) |
| 437 | ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
| 438 | } |
| 439 | } |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 440 | } |
| 441 | |
| 442 | |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 443 | /* |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 444 | * Out-of-line code for bit fetching. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 445 | * Note: current values of get_buffer and bits_left are passed as parameters, |
| 446 | * but are returned in the corresponding fields of the state struct. |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 447 | * |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 448 | * On most machines MIN_GET_BITS should be 25 to allow the full 32-bit width |
| 449 | * of get_buffer to be used. (On machines with wider words, an even larger |
| 450 | * buffer could be used.) However, on some machines 32-bit shifts are |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 451 | * quite slow and take time proportional to the number of places shifted. |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 452 | * (This is true with most PC compilers, for instance.) In this case it may |
| 453 | * be a win to set MIN_GET_BITS to the minimum value of 15. This reduces the |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 454 | * average shift distance at the cost of more calls to jpeg_fill_bit_buffer. |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 455 | */ |
| 456 | |
| 457 | #ifdef SLOW_SHIFT_32 |
| 458 | #define MIN_GET_BITS 15 /* minimum allowable value */ |
| 459 | #else |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 460 | #define MIN_GET_BITS (BIT_BUF_SIZE-7) |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 461 | #endif |
| 462 | |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 463 | |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 464 | LOCAL(boolean) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 465 | jpeg_fill_bit_buffer (bitread_working_state * state, |
| 466 | register bit_buf_type get_buffer, register int bits_left, |
| 467 | int nbits) |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 468 | /* Load up the bit buffer to a depth of at least nbits */ |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 469 | { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 470 | /* Copy heavily used state fields into locals (hopefully registers) */ |
| 471 | register const JOCTET * next_input_byte = state->next_input_byte; |
| 472 | register size_t bytes_in_buffer = state->bytes_in_buffer; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 473 | j_decompress_ptr cinfo = state->cinfo; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 474 | |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 475 | /* Attempt to load at least MIN_GET_BITS bits into get_buffer. */ |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 476 | /* (It is assumed that no request will be for more than that many bits.) */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 477 | /* We fail to do so only if we hit a marker or are forced to suspend. */ |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 478 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 479 | if (cinfo->unread_marker == 0) { /* cannot advance past a marker */ |
| 480 | while (bits_left < MIN_GET_BITS) { |
| 481 | register int c; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 482 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 483 | /* Attempt to read a byte */ |
| 484 | if (bytes_in_buffer == 0) { |
| 485 | if (! (*cinfo->src->fill_input_buffer) (cinfo)) |
| 486 | return FALSE; |
| 487 | next_input_byte = cinfo->src->next_input_byte; |
| 488 | bytes_in_buffer = cinfo->src->bytes_in_buffer; |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 489 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 490 | bytes_in_buffer--; |
| 491 | c = GETJOCTET(*next_input_byte++); |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 492 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 493 | /* If it's 0xFF, check and discard stuffed zero byte */ |
| 494 | if (c == 0xFF) { |
| 495 | /* Loop here to discard any padding FF's on terminating marker, |
| 496 | * so that we can save a valid unread_marker value. NOTE: we will |
| 497 | * accept multiple FF's followed by a 0 as meaning a single FF data |
| 498 | * byte. This data pattern is not valid according to the standard. |
| 499 | */ |
| 500 | do { |
| 501 | if (bytes_in_buffer == 0) { |
| 502 | if (! (*cinfo->src->fill_input_buffer) (cinfo)) |
| 503 | return FALSE; |
| 504 | next_input_byte = cinfo->src->next_input_byte; |
| 505 | bytes_in_buffer = cinfo->src->bytes_in_buffer; |
| 506 | } |
| 507 | bytes_in_buffer--; |
| 508 | c = GETJOCTET(*next_input_byte++); |
| 509 | } while (c == 0xFF); |
| 510 | |
| 511 | if (c == 0) { |
| 512 | /* Found FF/00, which represents an FF data byte */ |
| 513 | c = 0xFF; |
| 514 | } else { |
| 515 | /* Oops, it's actually a marker indicating end of compressed data. |
| 516 | * Save the marker code for later use. |
| 517 | * Fine point: it might appear that we should save the marker into |
| 518 | * bitread working state, not straight into permanent state. But |
| 519 | * once we have hit a marker, we cannot need to suspend within the |
| 520 | * current MCU, because we will read no more bytes from the data |
| 521 | * source. So it is OK to update permanent state right away. |
| 522 | */ |
| 523 | cinfo->unread_marker = c; |
| 524 | /* See if we need to insert some fake zero bits. */ |
| 525 | goto no_more_bytes; |
| 526 | } |
| 527 | } |
| 528 | |
| 529 | /* OK, load c into get_buffer */ |
| 530 | get_buffer = (get_buffer << 8) | c; |
| 531 | bits_left += 8; |
| 532 | } /* end while */ |
| 533 | } else { |
| 534 | no_more_bytes: |
| 535 | /* We get here if we've read the marker that terminates the compressed |
| 536 | * data segment. There should be enough bits in the buffer register |
| 537 | * to satisfy the request; if so, no problem. |
| 538 | */ |
| 539 | if (nbits > bits_left) { |
| 540 | /* Uh-oh. Report corrupted data to user and stuff zeroes into |
| 541 | * the data stream, so that we can produce some kind of image. |
| 542 | * We use a nonvolatile flag to ensure that only one warning message |
| 543 | * appears per data segment. |
| 544 | */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 545 | if (! ((huff_entropy_ptr) cinfo->entropy)->insufficient_data) { |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 546 | WARNMS(cinfo, JWRN_HIT_MARKER); |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 547 | ((huff_entropy_ptr) cinfo->entropy)->insufficient_data = TRUE; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 548 | } |
| 549 | /* Fill the buffer with zero bits */ |
| 550 | get_buffer <<= MIN_GET_BITS - bits_left; |
| 551 | bits_left = MIN_GET_BITS; |
| 552 | } |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 553 | } |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 554 | |
| 555 | /* Unload the local registers */ |
| 556 | state->next_input_byte = next_input_byte; |
| 557 | state->bytes_in_buffer = bytes_in_buffer; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 558 | state->get_buffer = get_buffer; |
| 559 | state->bits_left = bits_left; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 560 | |
| 561 | return TRUE; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 562 | } |
| 563 | |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 564 | |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 565 | /* |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 566 | * Figure F.12: extend sign bit. |
| 567 | * On some machines, a shift and sub will be faster than a table lookup. |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 568 | */ |
| 569 | |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 570 | #ifdef AVOID_TABLES |
| 571 | |
| 572 | #define BIT_MASK(nbits) ((1<<(nbits))-1) |
| 573 | #define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) - ((1<<(s))-1) : (x)) |
| 574 | |
| 575 | #else |
| 576 | |
| 577 | #define BIT_MASK(nbits) bmask[nbits] |
| 578 | #define HUFF_EXTEND(x,s) ((x) <= bmask[(s) - 1] ? (x) - bmask[s] : (x)) |
| 579 | |
| 580 | static const int bmask[16] = /* bmask[n] is mask for n rightmost bits */ |
| 581 | { 0, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF, |
| 582 | 0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF }; |
| 583 | |
| 584 | #endif /* AVOID_TABLES */ |
| 585 | |
| 586 | |
| 587 | /* |
| 588 | * Out-of-line code for Huffman code decoding. |
| 589 | */ |
| 590 | |
| 591 | LOCAL(int) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 592 | jpeg_huff_decode (bitread_working_state * state, |
| 593 | register bit_buf_type get_buffer, register int bits_left, |
| 594 | d_derived_tbl * htbl, int min_bits) |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 595 | { |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 596 | register int l = min_bits; |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 597 | register INT32 code; |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 598 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 599 | /* HUFF_DECODE has determined that the code is at least min_bits */ |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 600 | /* bits long, so fetch that many bits in one swoop. */ |
| 601 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 602 | CHECK_BIT_BUFFER(*state, l, return -1); |
| 603 | code = GET_BITS(l); |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 604 | |
| 605 | /* Collect the rest of the Huffman code one bit at a time. */ |
| 606 | /* This is per Figure F.16 in the JPEG spec. */ |
| 607 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 608 | while (code > htbl->maxcode[l]) { |
Thomas G. Lane | cc7150e | 1993-02-18 00:00:00 +0000 | [diff] [blame] | 609 | code <<= 1; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 610 | CHECK_BIT_BUFFER(*state, 1, return -1); |
| 611 | code |= GET_BITS(1); |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 612 | l++; |
| 613 | } |
Thomas G. Lane | bd543f0 | 1991-12-13 00:00:00 +0000 | [diff] [blame] | 614 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 615 | /* Unload the local registers */ |
| 616 | state->get_buffer = get_buffer; |
| 617 | state->bits_left = bits_left; |
| 618 | |
Thomas G. Lane | bd543f0 | 1991-12-13 00:00:00 +0000 | [diff] [blame] | 619 | /* With garbage input we may reach the sentinel value l = 17. */ |
| 620 | |
| 621 | if (l > 16) { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 622 | WARNMS(state->cinfo, JWRN_HUFF_BAD_CODE); |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 623 | return 0; /* fake a zero as the safest result */ |
Thomas G. Lane | bd543f0 | 1991-12-13 00:00:00 +0000 | [diff] [blame] | 624 | } |
| 625 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 626 | return htbl->pub->huffval[ (int) (code + htbl->valoffset[l]) ]; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 627 | } |
| 628 | |
| 629 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 630 | /* |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 631 | * Check for a restart marker & resynchronize decoder. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 632 | * Returns FALSE if must suspend. |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 633 | */ |
| 634 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 635 | LOCAL(boolean) |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 636 | process_restart (j_decompress_ptr cinfo) |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 637 | { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 638 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
| 639 | int ci; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 640 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 641 | /* Throw away any unused bits remaining in bit buffer; */ |
| 642 | /* include any full bytes in next_marker's count of discarded bytes */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 643 | cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8; |
| 644 | entropy->bitstate.bits_left = 0; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 645 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 646 | /* Advance past the RSTn marker */ |
| 647 | if (! (*cinfo->marker->read_restart_marker) (cinfo)) |
| 648 | return FALSE; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 649 | |
| 650 | /* Re-initialize DC predictions to 0 */ |
| 651 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 652 | entropy->saved.last_dc_val[ci] = 0; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 653 | /* Re-init EOB run count, too */ |
| 654 | entropy->saved.EOBRUN = 0; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 655 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 656 | /* Reset restart counter */ |
| 657 | entropy->restarts_to_go = cinfo->restart_interval; |
| 658 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 659 | /* Reset out-of-data flag, unless read_restart_marker left us smack up |
| 660 | * against a marker. In that case we will end up treating the next data |
| 661 | * segment as empty, and we can avoid producing bogus output pixels by |
| 662 | * leaving the flag set. |
| 663 | */ |
| 664 | if (cinfo->unread_marker == 0) |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 665 | entropy->insufficient_data = FALSE; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 666 | |
| 667 | return TRUE; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 668 | } |
| 669 | |
| 670 | |
| 671 | /* |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 672 | * Huffman MCU decoding. |
| 673 | * Each of these routines decodes and returns one MCU's worth of |
| 674 | * Huffman-compressed coefficients. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 675 | * The coefficients are reordered from zigzag order into natural array order, |
| 676 | * but are not dequantized. |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 677 | * |
| 678 | * The i'th block of the MCU is stored into the block pointed to by |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 679 | * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER. |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 680 | * (Wholesale zeroing is usually a little faster than retail...) |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 681 | * |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 682 | * We return FALSE if data source requested suspension. In that case no |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 683 | * changes have been made to permanent state. (Exception: some output |
| 684 | * coefficients may already have been assigned. This is harmless for |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 685 | * spectral selection, since we'll just re-assign them on the next call. |
| 686 | * Successive approximation AC refinement has to be more careful, however.) |
| 687 | */ |
| 688 | |
| 689 | /* |
| 690 | * MCU decoding for DC initial scan (either spectral selection, |
| 691 | * or first pass of successive approximation). |
| 692 | */ |
| 693 | |
| 694 | METHODDEF(boolean) |
| 695 | decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
| 696 | { |
| 697 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
| 698 | int Al = cinfo->Al; |
| 699 | register int s, r; |
| 700 | int blkn, ci; |
| 701 | JBLOCKROW block; |
| 702 | BITREAD_STATE_VARS; |
| 703 | savable_state state; |
| 704 | d_derived_tbl * tbl; |
| 705 | jpeg_component_info * compptr; |
| 706 | |
| 707 | /* Process restart marker if needed; may have to suspend */ |
| 708 | if (cinfo->restart_interval) { |
| 709 | if (entropy->restarts_to_go == 0) |
| 710 | if (! process_restart(cinfo)) |
| 711 | return FALSE; |
| 712 | } |
| 713 | |
| 714 | /* If we've run out of data, just leave the MCU set to zeroes. |
| 715 | * This way, we return uniform gray for the remainder of the segment. |
| 716 | */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 717 | if (! entropy->insufficient_data) { |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 718 | |
| 719 | /* Load up working state */ |
| 720 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 721 | ASSIGN_STATE(state, entropy->saved); |
| 722 | |
| 723 | /* Outer loop handles each block in the MCU */ |
| 724 | |
| 725 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| 726 | block = MCU_data[blkn]; |
| 727 | ci = cinfo->MCU_membership[blkn]; |
| 728 | compptr = cinfo->cur_comp_info[ci]; |
| 729 | tbl = entropy->derived_tbls[compptr->dc_tbl_no]; |
| 730 | |
| 731 | /* Decode a single block's worth of coefficients */ |
| 732 | |
| 733 | /* Section F.2.2.1: decode the DC coefficient difference */ |
| 734 | HUFF_DECODE(s, br_state, tbl, return FALSE, label1); |
| 735 | if (s) { |
| 736 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 737 | r = GET_BITS(s); |
| 738 | s = HUFF_EXTEND(r, s); |
| 739 | } |
| 740 | |
| 741 | /* Convert DC difference to actual value, update last_dc_val */ |
| 742 | s += state.last_dc_val[ci]; |
| 743 | state.last_dc_val[ci] = s; |
| 744 | /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */ |
| 745 | (*block)[0] = (JCOEF) (s << Al); |
| 746 | } |
| 747 | |
| 748 | /* Completed MCU, so update state */ |
| 749 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
| 750 | ASSIGN_STATE(entropy->saved, state); |
| 751 | } |
| 752 | |
| 753 | /* Account for restart interval (no-op if not using restarts) */ |
| 754 | entropy->restarts_to_go--; |
| 755 | |
| 756 | return TRUE; |
| 757 | } |
| 758 | |
| 759 | |
| 760 | /* |
| 761 | * MCU decoding for AC initial scan (either spectral selection, |
| 762 | * or first pass of successive approximation). |
| 763 | */ |
| 764 | |
| 765 | METHODDEF(boolean) |
| 766 | decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
| 767 | { |
| 768 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 769 | register int s, k, r; |
| 770 | unsigned int EOBRUN; |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 771 | int Se, Al; |
| 772 | const int * natural_order; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 773 | JBLOCKROW block; |
| 774 | BITREAD_STATE_VARS; |
| 775 | d_derived_tbl * tbl; |
| 776 | |
| 777 | /* Process restart marker if needed; may have to suspend */ |
| 778 | if (cinfo->restart_interval) { |
| 779 | if (entropy->restarts_to_go == 0) |
| 780 | if (! process_restart(cinfo)) |
| 781 | return FALSE; |
| 782 | } |
| 783 | |
| 784 | /* If we've run out of data, just leave the MCU set to zeroes. |
| 785 | * This way, we return uniform gray for the remainder of the segment. |
| 786 | */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 787 | if (! entropy->insufficient_data) { |
| 788 | |
| 789 | Se = cinfo->Se; |
| 790 | Al = cinfo->Al; |
| 791 | natural_order = cinfo->natural_order; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 792 | |
| 793 | /* Load up working state. |
| 794 | * We can avoid loading/saving bitread state if in an EOB run. |
| 795 | */ |
| 796 | EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ |
| 797 | |
| 798 | /* There is always only one block per MCU */ |
| 799 | |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 800 | if (EOBRUN) /* if it's a band of zeroes... */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 801 | EOBRUN--; /* ...process it now (we do nothing) */ |
| 802 | else { |
| 803 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 804 | block = MCU_data[0]; |
| 805 | tbl = entropy->ac_derived_tbl; |
| 806 | |
| 807 | for (k = cinfo->Ss; k <= Se; k++) { |
| 808 | HUFF_DECODE(s, br_state, tbl, return FALSE, label2); |
| 809 | r = s >> 4; |
| 810 | s &= 15; |
| 811 | if (s) { |
| 812 | k += r; |
| 813 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 814 | r = GET_BITS(s); |
| 815 | s = HUFF_EXTEND(r, s); |
| 816 | /* Scale and output coefficient in natural (dezigzagged) order */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 817 | (*block)[natural_order[k]] = (JCOEF) (s << Al); |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 818 | } else { |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 819 | if (r != 15) { /* EOBr, run length is 2^r + appended bits */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 820 | if (r) { /* EOBr, r > 0 */ |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 821 | EOBRUN = 1 << r; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 822 | CHECK_BIT_BUFFER(br_state, r, return FALSE); |
| 823 | r = GET_BITS(r); |
| 824 | EOBRUN += r; |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 825 | EOBRUN--; /* this band is processed at this moment */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 826 | } |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 827 | break; /* force end-of-band */ |
| 828 | } |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 829 | k += 15; /* ZRL: skip 15 zeroes in band */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 830 | } |
| 831 | } |
| 832 | |
| 833 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
| 834 | } |
| 835 | |
| 836 | /* Completed MCU, so update state */ |
| 837 | entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ |
| 838 | } |
| 839 | |
| 840 | /* Account for restart interval (no-op if not using restarts) */ |
| 841 | entropy->restarts_to_go--; |
| 842 | |
| 843 | return TRUE; |
| 844 | } |
| 845 | |
| 846 | |
| 847 | /* |
| 848 | * MCU decoding for DC successive approximation refinement scan. |
| 849 | * Note: we assume such scans can be multi-component, although the spec |
| 850 | * is not very clear on the point. |
| 851 | */ |
| 852 | |
| 853 | METHODDEF(boolean) |
| 854 | decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
| 855 | { |
| 856 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
| 857 | int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ |
| 858 | int blkn; |
| 859 | JBLOCKROW block; |
| 860 | BITREAD_STATE_VARS; |
| 861 | |
| 862 | /* Process restart marker if needed; may have to suspend */ |
| 863 | if (cinfo->restart_interval) { |
| 864 | if (entropy->restarts_to_go == 0) |
| 865 | if (! process_restart(cinfo)) |
| 866 | return FALSE; |
| 867 | } |
| 868 | |
| 869 | /* Not worth the cycles to check insufficient_data here, |
| 870 | * since we will not change the data anyway if we read zeroes. |
| 871 | */ |
| 872 | |
| 873 | /* Load up working state */ |
| 874 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 875 | |
| 876 | /* Outer loop handles each block in the MCU */ |
| 877 | |
| 878 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| 879 | block = MCU_data[blkn]; |
| 880 | |
| 881 | /* Encoded data is simply the next bit of the two's-complement DC value */ |
| 882 | CHECK_BIT_BUFFER(br_state, 1, return FALSE); |
| 883 | if (GET_BITS(1)) |
| 884 | (*block)[0] |= p1; |
| 885 | /* Note: since we use |=, repeating the assignment later is safe */ |
| 886 | } |
| 887 | |
| 888 | /* Completed MCU, so update state */ |
| 889 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
| 890 | |
| 891 | /* Account for restart interval (no-op if not using restarts) */ |
| 892 | entropy->restarts_to_go--; |
| 893 | |
| 894 | return TRUE; |
| 895 | } |
| 896 | |
| 897 | |
| 898 | /* |
| 899 | * MCU decoding for AC successive approximation refinement scan. |
| 900 | */ |
| 901 | |
| 902 | METHODDEF(boolean) |
| 903 | decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
| 904 | { |
| 905 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 906 | register int s, k, r; |
| 907 | unsigned int EOBRUN; |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 908 | int Se, p1, m1; |
| 909 | const int * natural_order; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 910 | JBLOCKROW block; |
| 911 | JCOEFPTR thiscoef; |
| 912 | BITREAD_STATE_VARS; |
| 913 | d_derived_tbl * tbl; |
| 914 | int num_newnz; |
| 915 | int newnz_pos[DCTSIZE2]; |
| 916 | |
| 917 | /* Process restart marker if needed; may have to suspend */ |
| 918 | if (cinfo->restart_interval) { |
| 919 | if (entropy->restarts_to_go == 0) |
| 920 | if (! process_restart(cinfo)) |
| 921 | return FALSE; |
| 922 | } |
| 923 | |
| 924 | /* If we've run out of data, don't modify the MCU. |
| 925 | */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 926 | if (! entropy->insufficient_data) { |
| 927 | |
| 928 | Se = cinfo->Se; |
| 929 | p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ |
| 930 | m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */ |
| 931 | natural_order = cinfo->natural_order; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 932 | |
| 933 | /* Load up working state */ |
| 934 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 935 | EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ |
| 936 | |
| 937 | /* There is always only one block per MCU */ |
| 938 | block = MCU_data[0]; |
| 939 | tbl = entropy->ac_derived_tbl; |
| 940 | |
| 941 | /* If we are forced to suspend, we must undo the assignments to any newly |
| 942 | * nonzero coefficients in the block, because otherwise we'd get confused |
| 943 | * next time about which coefficients were already nonzero. |
| 944 | * But we need not undo addition of bits to already-nonzero coefficients; |
| 945 | * instead, we can test the current bit to see if we already did it. |
| 946 | */ |
| 947 | num_newnz = 0; |
| 948 | |
| 949 | /* initialize coefficient loop counter to start of band */ |
| 950 | k = cinfo->Ss; |
| 951 | |
| 952 | if (EOBRUN == 0) { |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 953 | do { |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 954 | HUFF_DECODE(s, br_state, tbl, goto undoit, label3); |
| 955 | r = s >> 4; |
| 956 | s &= 15; |
| 957 | if (s) { |
| 958 | if (s != 1) /* size of new coef should always be 1 */ |
| 959 | WARNMS(cinfo, JWRN_HUFF_BAD_CODE); |
| 960 | CHECK_BIT_BUFFER(br_state, 1, goto undoit); |
| 961 | if (GET_BITS(1)) |
| 962 | s = p1; /* newly nonzero coef is positive */ |
| 963 | else |
| 964 | s = m1; /* newly nonzero coef is negative */ |
| 965 | } else { |
| 966 | if (r != 15) { |
| 967 | EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */ |
| 968 | if (r) { |
| 969 | CHECK_BIT_BUFFER(br_state, r, goto undoit); |
| 970 | r = GET_BITS(r); |
| 971 | EOBRUN += r; |
| 972 | } |
| 973 | break; /* rest of block is handled by EOB logic */ |
| 974 | } |
| 975 | /* note s = 0 for processing ZRL */ |
| 976 | } |
| 977 | /* Advance over already-nonzero coefs and r still-zero coefs, |
| 978 | * appending correction bits to the nonzeroes. A correction bit is 1 |
| 979 | * if the absolute value of the coefficient must be increased. |
| 980 | */ |
| 981 | do { |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 982 | thiscoef = *block + natural_order[k]; |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 983 | if (*thiscoef) { |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 984 | CHECK_BIT_BUFFER(br_state, 1, goto undoit); |
| 985 | if (GET_BITS(1)) { |
| 986 | if ((*thiscoef & p1) == 0) { /* do nothing if already set it */ |
| 987 | if (*thiscoef >= 0) |
| 988 | *thiscoef += p1; |
| 989 | else |
| 990 | *thiscoef += m1; |
| 991 | } |
| 992 | } |
| 993 | } else { |
| 994 | if (--r < 0) |
| 995 | break; /* reached target zero coefficient */ |
| 996 | } |
| 997 | k++; |
| 998 | } while (k <= Se); |
| 999 | if (s) { |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1000 | int pos = natural_order[k]; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1001 | /* Output newly nonzero coefficient */ |
| 1002 | (*block)[pos] = (JCOEF) s; |
| 1003 | /* Remember its position in case we have to suspend */ |
| 1004 | newnz_pos[num_newnz++] = pos; |
| 1005 | } |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 1006 | k++; |
| 1007 | } while (k <= Se); |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1008 | } |
| 1009 | |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 1010 | if (EOBRUN) { |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1011 | /* Scan any remaining coefficient positions after the end-of-band |
| 1012 | * (the last newly nonzero coefficient, if any). Append a correction |
| 1013 | * bit to each already-nonzero coefficient. A correction bit is 1 |
| 1014 | * if the absolute value of the coefficient must be increased. |
| 1015 | */ |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 1016 | do { |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1017 | thiscoef = *block + natural_order[k]; |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 1018 | if (*thiscoef) { |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1019 | CHECK_BIT_BUFFER(br_state, 1, goto undoit); |
| 1020 | if (GET_BITS(1)) { |
| 1021 | if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */ |
| 1022 | if (*thiscoef >= 0) |
| 1023 | *thiscoef += p1; |
| 1024 | else |
| 1025 | *thiscoef += m1; |
| 1026 | } |
| 1027 | } |
| 1028 | } |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 1029 | k++; |
| 1030 | } while (k <= Se); |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1031 | /* Count one block completed in EOB run */ |
| 1032 | EOBRUN--; |
| 1033 | } |
| 1034 | |
| 1035 | /* Completed MCU, so update state */ |
| 1036 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
| 1037 | entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ |
| 1038 | } |
| 1039 | |
| 1040 | /* Account for restart interval (no-op if not using restarts) */ |
| 1041 | entropy->restarts_to_go--; |
| 1042 | |
| 1043 | return TRUE; |
| 1044 | |
| 1045 | undoit: |
| 1046 | /* Re-zero any output coefficients that we made newly nonzero */ |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 1047 | while (num_newnz) |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1048 | (*block)[newnz_pos[--num_newnz]] = 0; |
| 1049 | |
| 1050 | return FALSE; |
| 1051 | } |
| 1052 | |
| 1053 | |
| 1054 | /* |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1055 | * Decode one MCU's worth of Huffman-compressed coefficients, |
| 1056 | * partial blocks. |
| 1057 | */ |
| 1058 | |
| 1059 | METHODDEF(boolean) |
| 1060 | decode_mcu_sub (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
| 1061 | { |
| 1062 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
| 1063 | const int * natural_order; |
| 1064 | int Se, blkn; |
| 1065 | BITREAD_STATE_VARS; |
| 1066 | savable_state state; |
| 1067 | |
| 1068 | /* Process restart marker if needed; may have to suspend */ |
| 1069 | if (cinfo->restart_interval) { |
| 1070 | if (entropy->restarts_to_go == 0) |
| 1071 | if (! process_restart(cinfo)) |
| 1072 | return FALSE; |
| 1073 | } |
| 1074 | |
| 1075 | /* If we've run out of data, just leave the MCU set to zeroes. |
| 1076 | * This way, we return uniform gray for the remainder of the segment. |
| 1077 | */ |
| 1078 | if (! entropy->insufficient_data) { |
| 1079 | |
| 1080 | natural_order = cinfo->natural_order; |
| 1081 | Se = cinfo->lim_Se; |
| 1082 | |
| 1083 | /* Load up working state */ |
| 1084 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 1085 | ASSIGN_STATE(state, entropy->saved); |
| 1086 | |
| 1087 | /* Outer loop handles each block in the MCU */ |
| 1088 | |
| 1089 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| 1090 | JBLOCKROW block = MCU_data[blkn]; |
| 1091 | d_derived_tbl * htbl; |
| 1092 | register int s, k, r; |
| 1093 | int coef_limit, ci; |
| 1094 | |
| 1095 | /* Decode a single block's worth of coefficients */ |
| 1096 | |
| 1097 | /* Section F.2.2.1: decode the DC coefficient difference */ |
| 1098 | htbl = entropy->dc_cur_tbls[blkn]; |
| 1099 | HUFF_DECODE(s, br_state, htbl, return FALSE, label1); |
| 1100 | |
| 1101 | htbl = entropy->ac_cur_tbls[blkn]; |
| 1102 | k = 1; |
| 1103 | coef_limit = entropy->coef_limit[blkn]; |
| 1104 | if (coef_limit) { |
| 1105 | /* Convert DC difference to actual value, update last_dc_val */ |
| 1106 | if (s) { |
| 1107 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 1108 | r = GET_BITS(s); |
| 1109 | s = HUFF_EXTEND(r, s); |
| 1110 | } |
| 1111 | ci = cinfo->MCU_membership[blkn]; |
| 1112 | s += state.last_dc_val[ci]; |
| 1113 | state.last_dc_val[ci] = s; |
| 1114 | /* Output the DC coefficient */ |
| 1115 | (*block)[0] = (JCOEF) s; |
| 1116 | |
| 1117 | /* Section F.2.2.2: decode the AC coefficients */ |
| 1118 | /* Since zeroes are skipped, output area must be cleared beforehand */ |
| 1119 | for (; k < coef_limit; k++) { |
| 1120 | HUFF_DECODE(s, br_state, htbl, return FALSE, label2); |
| 1121 | |
| 1122 | r = s >> 4; |
| 1123 | s &= 15; |
| 1124 | |
| 1125 | if (s) { |
| 1126 | k += r; |
| 1127 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 1128 | r = GET_BITS(s); |
| 1129 | s = HUFF_EXTEND(r, s); |
| 1130 | /* Output coefficient in natural (dezigzagged) order. |
| 1131 | * Note: the extra entries in natural_order[] will save us |
| 1132 | * if k > Se, which could happen if the data is corrupted. |
| 1133 | */ |
| 1134 | (*block)[natural_order[k]] = (JCOEF) s; |
| 1135 | } else { |
| 1136 | if (r != 15) |
| 1137 | goto EndOfBlock; |
| 1138 | k += 15; |
| 1139 | } |
| 1140 | } |
| 1141 | } else { |
| 1142 | if (s) { |
| 1143 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 1144 | DROP_BITS(s); |
| 1145 | } |
| 1146 | } |
| 1147 | |
| 1148 | /* Section F.2.2.2: decode the AC coefficients */ |
| 1149 | /* In this path we just discard the values */ |
| 1150 | for (; k <= Se; k++) { |
| 1151 | HUFF_DECODE(s, br_state, htbl, return FALSE, label3); |
| 1152 | |
| 1153 | r = s >> 4; |
| 1154 | s &= 15; |
| 1155 | |
| 1156 | if (s) { |
| 1157 | k += r; |
| 1158 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 1159 | DROP_BITS(s); |
| 1160 | } else { |
| 1161 | if (r != 15) |
| 1162 | break; |
| 1163 | k += 15; |
| 1164 | } |
| 1165 | } |
| 1166 | |
| 1167 | EndOfBlock: ; |
| 1168 | } |
| 1169 | |
| 1170 | /* Completed MCU, so update state */ |
| 1171 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
| 1172 | ASSIGN_STATE(entropy->saved, state); |
| 1173 | } |
| 1174 | |
| 1175 | /* Account for restart interval (no-op if not using restarts) */ |
| 1176 | entropy->restarts_to_go--; |
| 1177 | |
| 1178 | return TRUE; |
| 1179 | } |
| 1180 | |
| 1181 | |
| 1182 | /* |
| 1183 | * Decode one MCU's worth of Huffman-compressed coefficients, |
| 1184 | * full-size blocks. |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1185 | */ |
| 1186 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 1187 | METHODDEF(boolean) |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1188 | decode_mcu (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1189 | { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1190 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1191 | int blkn; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 1192 | BITREAD_STATE_VARS; |
| 1193 | savable_state state; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1194 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1195 | /* Process restart marker if needed; may have to suspend */ |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1196 | if (cinfo->restart_interval) { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1197 | if (entropy->restarts_to_go == 0) |
| 1198 | if (! process_restart(cinfo)) |
| 1199 | return FALSE; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1200 | } |
| 1201 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1202 | /* If we've run out of data, just leave the MCU set to zeroes. |
| 1203 | * This way, we return uniform gray for the remainder of the segment. |
| 1204 | */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1205 | if (! entropy->insufficient_data) { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1206 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1207 | /* Load up working state */ |
| 1208 | BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
| 1209 | ASSIGN_STATE(state, entropy->saved); |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 1210 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1211 | /* Outer loop handles each block in the MCU */ |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 1212 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1213 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| 1214 | JBLOCKROW block = MCU_data[blkn]; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1215 | d_derived_tbl * htbl; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1216 | register int s, k, r; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1217 | int coef_limit, ci; |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 1218 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1219 | /* Decode a single block's worth of coefficients */ |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 1220 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1221 | /* Section F.2.2.1: decode the DC coefficient difference */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1222 | htbl = entropy->dc_cur_tbls[blkn]; |
| 1223 | HUFF_DECODE(s, br_state, htbl, return FALSE, label1); |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1224 | |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1225 | htbl = entropy->ac_cur_tbls[blkn]; |
| 1226 | k = 1; |
| 1227 | coef_limit = entropy->coef_limit[blkn]; |
| 1228 | if (coef_limit) { |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1229 | /* Convert DC difference to actual value, update last_dc_val */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1230 | if (s) { |
| 1231 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 1232 | r = GET_BITS(s); |
| 1233 | s = HUFF_EXTEND(r, s); |
| 1234 | } |
| 1235 | ci = cinfo->MCU_membership[blkn]; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1236 | s += state.last_dc_val[ci]; |
| 1237 | state.last_dc_val[ci] = s; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1238 | /* Output the DC coefficient */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1239 | (*block)[0] = (JCOEF) s; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1240 | |
| 1241 | /* Section F.2.2.2: decode the AC coefficients */ |
| 1242 | /* Since zeroes are skipped, output area must be cleared beforehand */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1243 | for (; k < coef_limit; k++) { |
| 1244 | HUFF_DECODE(s, br_state, htbl, return FALSE, label2); |
| 1245 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1246 | r = s >> 4; |
| 1247 | s &= 15; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1248 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1249 | if (s) { |
| 1250 | k += r; |
| 1251 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 1252 | r = GET_BITS(s); |
| 1253 | s = HUFF_EXTEND(r, s); |
| 1254 | /* Output coefficient in natural (dezigzagged) order. |
| 1255 | * Note: the extra entries in jpeg_natural_order[] will save us |
| 1256 | * if k >= DCTSIZE2, which could happen if the data is corrupted. |
| 1257 | */ |
| 1258 | (*block)[jpeg_natural_order[k]] = (JCOEF) s; |
| 1259 | } else { |
| 1260 | if (r != 15) |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1261 | goto EndOfBlock; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1262 | k += 15; |
| 1263 | } |
| 1264 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1265 | } else { |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1266 | if (s) { |
| 1267 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 1268 | DROP_BITS(s); |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1269 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1270 | } |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1271 | |
| 1272 | /* Section F.2.2.2: decode the AC coefficients */ |
| 1273 | /* In this path we just discard the values */ |
| 1274 | for (; k < DCTSIZE2; k++) { |
| 1275 | HUFF_DECODE(s, br_state, htbl, return FALSE, label3); |
| 1276 | |
| 1277 | r = s >> 4; |
| 1278 | s &= 15; |
| 1279 | |
| 1280 | if (s) { |
| 1281 | k += r; |
| 1282 | CHECK_BIT_BUFFER(br_state, s, return FALSE); |
| 1283 | DROP_BITS(s); |
| 1284 | } else { |
| 1285 | if (r != 15) |
| 1286 | break; |
| 1287 | k += 15; |
| 1288 | } |
| 1289 | } |
| 1290 | |
| 1291 | EndOfBlock: ; |
Thomas G. Lane | 88aeed4 | 1992-12-10 00:00:00 +0000 | [diff] [blame] | 1292 | } |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1293 | |
| 1294 | /* Completed MCU, so update state */ |
| 1295 | BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
| 1296 | ASSIGN_STATE(entropy->saved, state); |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1297 | } |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1298 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1299 | /* Account for restart interval (no-op if not using restarts) */ |
| 1300 | entropy->restarts_to_go--; |
| 1301 | |
| 1302 | return TRUE; |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1303 | } |
| 1304 | |
| 1305 | |
| 1306 | /* |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1307 | * Initialize for a Huffman-compressed scan. |
| 1308 | */ |
| 1309 | |
| 1310 | METHODDEF(void) |
| 1311 | start_pass_huff_decoder (j_decompress_ptr cinfo) |
| 1312 | { |
| 1313 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1314 | int ci, blkn, tbl, i; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1315 | jpeg_component_info * compptr; |
| 1316 | |
| 1317 | if (cinfo->progressive_mode) { |
| 1318 | /* Validate progressive scan parameters */ |
| 1319 | if (cinfo->Ss == 0) { |
| 1320 | if (cinfo->Se != 0) |
| 1321 | goto bad; |
| 1322 | } else { |
| 1323 | /* need not check Ss/Se < 0 since they came from unsigned bytes */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1324 | if (cinfo->Se < cinfo->Ss || cinfo->Se > cinfo->lim_Se) |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1325 | goto bad; |
| 1326 | /* AC scans may have only one component */ |
| 1327 | if (cinfo->comps_in_scan != 1) |
| 1328 | goto bad; |
| 1329 | } |
| 1330 | if (cinfo->Ah != 0) { |
| 1331 | /* Successive approximation refinement scan: must have Al = Ah-1. */ |
| 1332 | if (cinfo->Ah-1 != cinfo->Al) |
| 1333 | goto bad; |
| 1334 | } |
| 1335 | if (cinfo->Al > 13) { /* need not check for < 0 */ |
| 1336 | /* Arguably the maximum Al value should be less than 13 for 8-bit precision, |
| 1337 | * but the spec doesn't say so, and we try to be liberal about what we |
| 1338 | * accept. Note: large Al values could result in out-of-range DC |
| 1339 | * coefficients during early scans, leading to bizarre displays due to |
| 1340 | * overflows in the IDCT math. But we won't crash. |
| 1341 | */ |
| 1342 | bad: |
| 1343 | ERREXIT4(cinfo, JERR_BAD_PROGRESSION, |
| 1344 | cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al); |
| 1345 | } |
| 1346 | /* Update progression status, and verify that scan order is legal. |
| 1347 | * Note that inter-scan inconsistencies are treated as warnings |
| 1348 | * not fatal errors ... not clear if this is right way to behave. |
| 1349 | */ |
| 1350 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
| 1351 | int coefi, cindex = cinfo->cur_comp_info[ci]->component_index; |
| 1352 | int *coef_bit_ptr = & cinfo->coef_bits[cindex][0]; |
| 1353 | if (cinfo->Ss && coef_bit_ptr[0] < 0) /* AC without prior DC scan */ |
| 1354 | WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0); |
| 1355 | for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) { |
| 1356 | int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi]; |
| 1357 | if (cinfo->Ah != expected) |
| 1358 | WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi); |
| 1359 | coef_bit_ptr[coefi] = cinfo->Al; |
| 1360 | } |
| 1361 | } |
| 1362 | |
| 1363 | /* Select MCU decoding routine */ |
| 1364 | if (cinfo->Ah == 0) { |
| 1365 | if (cinfo->Ss == 0) |
| 1366 | entropy->pub.decode_mcu = decode_mcu_DC_first; |
| 1367 | else |
| 1368 | entropy->pub.decode_mcu = decode_mcu_AC_first; |
| 1369 | } else { |
| 1370 | if (cinfo->Ss == 0) |
| 1371 | entropy->pub.decode_mcu = decode_mcu_DC_refine; |
| 1372 | else |
| 1373 | entropy->pub.decode_mcu = decode_mcu_AC_refine; |
| 1374 | } |
| 1375 | |
| 1376 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
| 1377 | compptr = cinfo->cur_comp_info[ci]; |
| 1378 | /* Make sure requested tables are present, and compute derived tables. |
| 1379 | * We may build same derived table more than once, but it's not expensive. |
| 1380 | */ |
| 1381 | if (cinfo->Ss == 0) { |
| 1382 | if (cinfo->Ah == 0) { /* DC refinement needs no table */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1383 | tbl = compptr->dc_tbl_no; |
| 1384 | jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, |
| 1385 | & entropy->derived_tbls[tbl]); |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1386 | } |
| 1387 | } else { |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1388 | tbl = compptr->ac_tbl_no; |
| 1389 | jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, |
| 1390 | & entropy->derived_tbls[tbl]); |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1391 | /* remember the single active table */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1392 | entropy->ac_derived_tbl = entropy->derived_tbls[tbl]; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1393 | } |
| 1394 | /* Initialize DC predictions to 0 */ |
| 1395 | entropy->saved.last_dc_val[ci] = 0; |
| 1396 | } |
| 1397 | |
| 1398 | /* Initialize private state variables */ |
| 1399 | entropy->saved.EOBRUN = 0; |
| 1400 | } else { |
| 1401 | /* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG. |
| 1402 | * This ought to be an error condition, but we make it a warning because |
| 1403 | * there are some baseline files out there with all zeroes in these bytes. |
| 1404 | */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1405 | if (cinfo->Ss != 0 || cinfo->Ah != 0 || cinfo->Al != 0 || |
| 1406 | ((cinfo->is_baseline || cinfo->Se < DCTSIZE2) && |
| 1407 | cinfo->Se != cinfo->lim_Se)) |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1408 | WARNMS(cinfo, JWRN_NOT_SEQUENTIAL); |
| 1409 | |
| 1410 | /* Select MCU decoding routine */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1411 | /* We retain the hard-coded case for full-size blocks. |
| 1412 | * This is not necessary, but it appears that this version is slightly |
| 1413 | * more performant in the given implementation. |
| 1414 | * With an improved implementation we would prefer a single optimized |
| 1415 | * function. |
| 1416 | */ |
| 1417 | if (cinfo->lim_Se != DCTSIZE2-1) |
| 1418 | entropy->pub.decode_mcu = decode_mcu_sub; |
| 1419 | else |
| 1420 | entropy->pub.decode_mcu = decode_mcu; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1421 | |
| 1422 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
| 1423 | compptr = cinfo->cur_comp_info[ci]; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1424 | /* Compute derived values for Huffman tables */ |
| 1425 | /* We may do this more than once for a table, but it's not expensive */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1426 | tbl = compptr->dc_tbl_no; |
| 1427 | jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, |
| 1428 | & entropy->dc_derived_tbls[tbl]); |
| 1429 | if (cinfo->lim_Se) { /* AC needs no table when not present */ |
| 1430 | tbl = compptr->ac_tbl_no; |
| 1431 | jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, |
| 1432 | & entropy->ac_derived_tbls[tbl]); |
| 1433 | } |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1434 | /* Initialize DC predictions to 0 */ |
| 1435 | entropy->saved.last_dc_val[ci] = 0; |
| 1436 | } |
| 1437 | |
| 1438 | /* Precalculate decoding info for each block in an MCU of this scan */ |
| 1439 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| 1440 | ci = cinfo->MCU_membership[blkn]; |
| 1441 | compptr = cinfo->cur_comp_info[ci]; |
| 1442 | /* Precalculate which table to use for each block */ |
| 1443 | entropy->dc_cur_tbls[blkn] = entropy->dc_derived_tbls[compptr->dc_tbl_no]; |
| 1444 | entropy->ac_cur_tbls[blkn] = entropy->ac_derived_tbls[compptr->ac_tbl_no]; |
| 1445 | /* Decide whether we really care about the coefficient values */ |
| 1446 | if (compptr->component_needed) { |
| 1447 | ci = compptr->DCT_v_scaled_size; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1448 | i = compptr->DCT_h_scaled_size; |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1449 | switch (cinfo->lim_Se) { |
| 1450 | case (1*1-1): |
| 1451 | entropy->coef_limit[blkn] = 1; |
| 1452 | break; |
| 1453 | case (2*2-1): |
| 1454 | if (ci <= 0 || ci > 2) ci = 2; |
| 1455 | if (i <= 0 || i > 2) i = 2; |
| 1456 | entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order2[ci - 1][i - 1]; |
| 1457 | break; |
| 1458 | case (3*3-1): |
| 1459 | if (ci <= 0 || ci > 3) ci = 3; |
| 1460 | if (i <= 0 || i > 3) i = 3; |
| 1461 | entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order3[ci - 1][i - 1]; |
| 1462 | break; |
| 1463 | case (4*4-1): |
| 1464 | if (ci <= 0 || ci > 4) ci = 4; |
| 1465 | if (i <= 0 || i > 4) i = 4; |
| 1466 | entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order4[ci - 1][i - 1]; |
| 1467 | break; |
| 1468 | case (5*5-1): |
| 1469 | if (ci <= 0 || ci > 5) ci = 5; |
| 1470 | if (i <= 0 || i > 5) i = 5; |
| 1471 | entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order5[ci - 1][i - 1]; |
| 1472 | break; |
| 1473 | case (6*6-1): |
| 1474 | if (ci <= 0 || ci > 6) ci = 6; |
| 1475 | if (i <= 0 || i > 6) i = 6; |
| 1476 | entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order6[ci - 1][i - 1]; |
| 1477 | break; |
| 1478 | case (7*7-1): |
| 1479 | if (ci <= 0 || ci > 7) ci = 7; |
| 1480 | if (i <= 0 || i > 7) i = 7; |
| 1481 | entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order7[ci - 1][i - 1]; |
| 1482 | break; |
| 1483 | default: |
| 1484 | if (ci <= 0 || ci > 8) ci = 8; |
| 1485 | if (i <= 0 || i > 8) i = 8; |
| 1486 | entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order[ci - 1][i - 1]; |
| 1487 | break; |
| 1488 | } |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1489 | } else { |
| 1490 | entropy->coef_limit[blkn] = 0; |
| 1491 | } |
| 1492 | } |
| 1493 | } |
| 1494 | |
| 1495 | /* Initialize bitread state variables */ |
| 1496 | entropy->bitstate.bits_left = 0; |
| 1497 | entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 1498 | entropy->insufficient_data = FALSE; |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1499 | |
| 1500 | /* Initialize restart counter */ |
| 1501 | entropy->restarts_to_go = cinfo->restart_interval; |
| 1502 | } |
| 1503 | |
| 1504 | |
| 1505 | /* |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1506 | * Module initialization routine for Huffman entropy decoding. |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1507 | */ |
| 1508 | |
Thomas G. Lane | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame] | 1509 | GLOBAL(void) |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1510 | jinit_huff_decoder (j_decompress_ptr cinfo) |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1511 | { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1512 | huff_entropy_ptr entropy; |
| 1513 | int i; |
| 1514 | |
| 1515 | entropy = (huff_entropy_ptr) |
| 1516 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 1517 | SIZEOF(huff_entropy_decoder)); |
Guido Vollbeding | e7f88ae | 2013-01-13 00:00:00 +0000 | [diff] [blame^] | 1518 | cinfo->entropy = &entropy->pub; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1519 | entropy->pub.start_pass = start_pass_huff_decoder; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1520 | |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 1521 | if (cinfo->progressive_mode) { |
| 1522 | /* Create progression status table */ |
| 1523 | int *coef_bit_ptr, ci; |
| 1524 | cinfo->coef_bits = (int (*)[DCTSIZE2]) |
| 1525 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 1526 | cinfo->num_components*DCTSIZE2*SIZEOF(int)); |
| 1527 | coef_bit_ptr = & cinfo->coef_bits[0][0]; |
| 1528 | for (ci = 0; ci < cinfo->num_components; ci++) |
| 1529 | for (i = 0; i < DCTSIZE2; i++) |
| 1530 | *coef_bit_ptr++ = -1; |
| 1531 | |
| 1532 | /* Mark derived tables unallocated */ |
| 1533 | for (i = 0; i < NUM_HUFF_TBLS; i++) { |
| 1534 | entropy->derived_tbls[i] = NULL; |
| 1535 | } |
| 1536 | } else { |
| 1537 | /* Mark tables unallocated */ |
| 1538 | for (i = 0; i < NUM_HUFF_TBLS; i++) { |
| 1539 | entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL; |
| 1540 | } |
Thomas G. Lane | 2cbeb8a | 1991-10-07 00:00:00 +0000 | [diff] [blame] | 1541 | } |
| 1542 | } |