| 1 | import * as utils from "../utils/common.js"; |
| 2 | |
| 3 | var MAXBITS = 15; |
| 4 | var ENOUGH_LENS = 852; |
| 5 | var ENOUGH_DISTS = 592; |
| 6 | //var ENOUGH = (ENOUGH_LENS+ENOUGH_DISTS); |
| 7 | |
| 8 | var CODES = 0; |
| 9 | var LENS = 1; |
| 10 | var DISTS = 2; |
| 11 | |
| 12 | var lbase = [ /* Length codes 257..285 base */ |
| 13 | 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, |
| 14 | 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0 |
| 15 | ]; |
| 16 | |
| 17 | var lext = [ /* Length codes 257..285 extra */ |
| 18 | 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, |
| 19 | 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 72, 78 |
| 20 | ]; |
| 21 | |
| 22 | var dbase = [ /* Distance codes 0..29 base */ |
| 23 | 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, |
| 24 | 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, |
| 25 | 8193, 12289, 16385, 24577, 0, 0 |
| 26 | ]; |
| 27 | |
| 28 | var dext = [ /* Distance codes 0..29 extra */ |
| 29 | 16, 16, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, |
| 30 | 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, |
| 31 | 28, 28, 29, 29, 64, 64 |
| 32 | ]; |
| 33 | |
| 34 | export default function inflate_table(type, lens, lens_index, codes, table, table_index, work, opts) |
| 35 | { |
| 36 | var bits = opts.bits; |
| 37 | //here = opts.here; /* table entry for duplication */ |
| 38 | |
| 39 | var len = 0; /* a code's length in bits */ |
| 40 | var sym = 0; /* index of code symbols */ |
| 41 | var min = 0, max = 0; /* minimum and maximum code lengths */ |
| 42 | var root = 0; /* number of index bits for root table */ |
| 43 | var curr = 0; /* number of index bits for current table */ |
| 44 | var drop = 0; /* code bits to drop for sub-table */ |
| 45 | var left = 0; /* number of prefix codes available */ |
| 46 | var used = 0; /* code entries in table used */ |
| 47 | var huff = 0; /* Huffman code */ |
| 48 | var incr; /* for incrementing code, index */ |
| 49 | var fill; /* index for replicating entries */ |
| 50 | var low; /* low bits for current root entry */ |
| 51 | var mask; /* mask for low root bits */ |
| 52 | var next; /* next available space in table */ |
| 53 | var base = null; /* base value table to use */ |
| 54 | var base_index = 0; |
| 55 | // var shoextra; /* extra bits table to use */ |
| 56 | var end; /* use base and extra for symbol > end */ |
| 57 | var count = new utils.Buf16(MAXBITS + 1); //[MAXBITS+1]; /* number of codes of each length */ |
| 58 | var offs = new utils.Buf16(MAXBITS + 1); //[MAXBITS+1]; /* offsets in table for each length */ |
| 59 | var extra = null; |
| 60 | var extra_index = 0; |
| 61 | |
| 62 | var here_bits, here_op, here_val; |
| 63 | |
| 64 | /* |
| 65 | Process a set of code lengths to create a canonical Huffman code. The |
| 66 | code lengths are lens[0..codes-1]. Each length corresponds to the |
| 67 | symbols 0..codes-1. The Huffman code is generated by first sorting the |
| 68 | symbols by length from short to long, and retaining the symbol order |
| 69 | for codes with equal lengths. Then the code starts with all zero bits |
| 70 | for the first code of the shortest length, and the codes are integer |
| 71 | increments for the same length, and zeros are appended as the length |
| 72 | increases. For the deflate format, these bits are stored backwards |
| 73 | from their more natural integer increment ordering, and so when the |
| 74 | decoding tables are built in the large loop below, the integer codes |
| 75 | are incremented backwards. |
| 76 | |
| 77 | This routine assumes, but does not check, that all of the entries in |
| 78 | lens[] are in the range 0..MAXBITS. The caller must assure this. |
| 79 | 1..MAXBITS is interpreted as that code length. zero means that that |
| 80 | symbol does not occur in this code. |
| 81 | |
| 82 | The codes are sorted by computing a count of codes for each length, |
| 83 | creating from that a table of starting indices for each length in the |
| 84 | sorted table, and then entering the symbols in order in the sorted |
| 85 | table. The sorted table is work[], with that space being provided by |
| 86 | the caller. |
| 87 | |
| 88 | The length counts are used for other purposes as well, i.e. finding |
| 89 | the minimum and maximum length codes, determining if there are any |
| 90 | codes at all, checking for a valid set of lengths, and looking ahead |
| 91 | at length counts to determine sub-table sizes when building the |
| 92 | decoding tables. |
| 93 | */ |
| 94 | |
| 95 | /* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */ |
| 96 | for (len = 0; len <= MAXBITS; len++) { |
| 97 | count[len] = 0; |
| 98 | } |
| 99 | for (sym = 0; sym < codes; sym++) { |
| 100 | count[lens[lens_index + sym]]++; |
| 101 | } |
| 102 | |
| 103 | /* bound code lengths, force root to be within code lengths */ |
| 104 | root = bits; |
| 105 | for (max = MAXBITS; max >= 1; max--) { |
| 106 | if (count[max] !== 0) { break; } |
| 107 | } |
| 108 | if (root > max) { |
| 109 | root = max; |
| 110 | } |
| 111 | if (max === 0) { /* no symbols to code at all */ |
| 112 | //table.op[opts.table_index] = 64; //here.op = (var char)64; /* invalid code marker */ |
| 113 | //table.bits[opts.table_index] = 1; //here.bits = (var char)1; |
| 114 | //table.val[opts.table_index++] = 0; //here.val = (var short)0; |
| 115 | table[table_index++] = (1 << 24) | (64 << 16) | 0; |
| 116 | |
| 117 | |
| 118 | //table.op[opts.table_index] = 64; |
| 119 | //table.bits[opts.table_index] = 1; |
| 120 | //table.val[opts.table_index++] = 0; |
| 121 | table[table_index++] = (1 << 24) | (64 << 16) | 0; |
| 122 | |
| 123 | opts.bits = 1; |
| 124 | return 0; /* no symbols, but wait for decoding to report error */ |
| 125 | } |
| 126 | for (min = 1; min < max; min++) { |
| 127 | if (count[min] !== 0) { break; } |
| 128 | } |
| 129 | if (root < min) { |
| 130 | root = min; |
| 131 | } |
| 132 | |
| 133 | /* check for an over-subscribed or incomplete set of lengths */ |
| 134 | left = 1; |
| 135 | for (len = 1; len <= MAXBITS; len++) { |
| 136 | left <<= 1; |
| 137 | left -= count[len]; |
| 138 | if (left < 0) { |
| 139 | return -1; |
| 140 | } /* over-subscribed */ |
| 141 | } |
| 142 | if (left > 0 && (type === CODES || max !== 1)) { |
| 143 | return -1; /* incomplete set */ |
| 144 | } |
| 145 | |
| 146 | /* generate offsets into symbol table for each length for sorting */ |
| 147 | offs[1] = 0; |
| 148 | for (len = 1; len < MAXBITS; len++) { |
| 149 | offs[len + 1] = offs[len] + count[len]; |
| 150 | } |
| 151 | |
| 152 | /* sort symbols by length, by symbol order within each length */ |
| 153 | for (sym = 0; sym < codes; sym++) { |
| 154 | if (lens[lens_index + sym] !== 0) { |
| 155 | work[offs[lens[lens_index + sym]]++] = sym; |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | /* |
| 160 | Create and fill in decoding tables. In this loop, the table being |
| 161 | filled is at next and has curr index bits. The code being used is huff |
| 162 | with length len. That code is converted to an index by dropping drop |
| 163 | bits off of the bottom. For codes where len is less than drop + curr, |
| 164 | those top drop + curr - len bits are incremented through all values to |
| 165 | fill the table with replicated entries. |
| 166 | |
| 167 | root is the number of index bits for the root table. When len exceeds |
| 168 | root, sub-tables are created pointed to by the root entry with an index |
| 169 | of the low root bits of huff. This is saved in low to check for when a |
| 170 | new sub-table should be started. drop is zero when the root table is |
| 171 | being filled, and drop is root when sub-tables are being filled. |
| 172 | |
| 173 | When a new sub-table is needed, it is necessary to look ahead in the |
| 174 | code lengths to determine what size sub-table is needed. The length |
| 175 | counts are used for this, and so count[] is decremented as codes are |
| 176 | entered in the tables. |
| 177 | |
| 178 | used keeps track of how many table entries have been allocated from the |
| 179 | provided *table space. It is checked for LENS and DIST tables against |
| 180 | the constants ENOUGH_LENS and ENOUGH_DISTS to guard against changes in |
| 181 | the initial root table size constants. See the comments in inftrees.h |
| 182 | for more information. |
| 183 | |
| 184 | sym increments through all symbols, and the loop terminates when |
| 185 | all codes of length max, i.e. all codes, have been processed. This |
| 186 | routine permits incomplete codes, so another loop after this one fills |
| 187 | in the rest of the decoding tables with invalid code markers. |
| 188 | */ |
| 189 | |
| 190 | /* set up for code type */ |
| 191 | // poor man optimization - use if-else instead of switch, |
| 192 | // to avoid deopts in old v8 |
| 193 | if (type === CODES) { |
| 194 | base = extra = work; /* dummy value--not used */ |
| 195 | end = 19; |
| 196 | |
| 197 | } else if (type === LENS) { |
| 198 | base = lbase; |
| 199 | base_index -= 257; |
| 200 | extra = lext; |
| 201 | extra_index -= 257; |
| 202 | end = 256; |
| 203 | |
| 204 | } else { /* DISTS */ |
| 205 | base = dbase; |
| 206 | extra = dext; |
| 207 | end = -1; |
| 208 | } |
| 209 | |
| 210 | /* initialize opts for loop */ |
| 211 | huff = 0; /* starting code */ |
| 212 | sym = 0; /* starting code symbol */ |
| 213 | len = min; /* starting code length */ |
| 214 | next = table_index; /* current table to fill in */ |
| 215 | curr = root; /* current table index bits */ |
| 216 | drop = 0; /* current bits to drop from code for index */ |
| 217 | low = -1; /* trigger new sub-table when len > root */ |
| 218 | used = 1 << root; /* use root table entries */ |
| 219 | mask = used - 1; /* mask for comparing low */ |
| 220 | |
| 221 | /* check available table space */ |
| 222 | if ((type === LENS && used > ENOUGH_LENS) || |
| 223 | (type === DISTS && used > ENOUGH_DISTS)) { |
| 224 | return 1; |
| 225 | } |
| 226 | |
| 227 | /* process all codes and make table entries */ |
| 228 | for (;;) { |
| 229 | /* create table entry */ |
| 230 | here_bits = len - drop; |
| 231 | if (work[sym] < end) { |
| 232 | here_op = 0; |
| 233 | here_val = work[sym]; |
| 234 | } |
| 235 | else if (work[sym] > end) { |
| 236 | here_op = extra[extra_index + work[sym]]; |
| 237 | here_val = base[base_index + work[sym]]; |
| 238 | } |
| 239 | else { |
| 240 | here_op = 32 + 64; /* end of block */ |
| 241 | here_val = 0; |
| 242 | } |
| 243 | |
| 244 | /* replicate for those indices with low len bits equal to huff */ |
| 245 | incr = 1 << (len - drop); |
| 246 | fill = 1 << curr; |
| 247 | min = fill; /* save offset to next table */ |
| 248 | do { |
| 249 | fill -= incr; |
| 250 | table[next + (huff >> drop) + fill] = (here_bits << 24) | (here_op << 16) | here_val |0; |
| 251 | } while (fill !== 0); |
| 252 | |
| 253 | /* backwards increment the len-bit code huff */ |
| 254 | incr = 1 << (len - 1); |
| 255 | while (huff & incr) { |
| 256 | incr >>= 1; |
| 257 | } |
| 258 | if (incr !== 0) { |
| 259 | huff &= incr - 1; |
| 260 | huff += incr; |
| 261 | } else { |
| 262 | huff = 0; |
| 263 | } |
| 264 | |
| 265 | /* go to next symbol, update count, len */ |
| 266 | sym++; |
| 267 | if (--count[len] === 0) { |
| 268 | if (len === max) { break; } |
| 269 | len = lens[lens_index + work[sym]]; |
| 270 | } |
| 271 | |
| 272 | /* create new sub-table if needed */ |
| 273 | if (len > root && (huff & mask) !== low) { |
| 274 | /* if first time, transition to sub-tables */ |
| 275 | if (drop === 0) { |
| 276 | drop = root; |
| 277 | } |
| 278 | |
| 279 | /* increment past last table */ |
| 280 | next += min; /* here min is 1 << curr */ |
| 281 | |
| 282 | /* determine length of next table */ |
| 283 | curr = len - drop; |
| 284 | left = 1 << curr; |
| 285 | while (curr + drop < max) { |
| 286 | left -= count[curr + drop]; |
| 287 | if (left <= 0) { break; } |
| 288 | curr++; |
| 289 | left <<= 1; |
| 290 | } |
| 291 | |
| 292 | /* check for enough space */ |
| 293 | used += 1 << curr; |
| 294 | if ((type === LENS && used > ENOUGH_LENS) || |
| 295 | (type === DISTS && used > ENOUGH_DISTS)) { |
| 296 | return 1; |
| 297 | } |
| 298 | |
| 299 | /* point entry in root table to sub-table */ |
| 300 | low = huff & mask; |
| 301 | /*table.op[low] = curr; |
| 302 | table.bits[low] = root; |
| 303 | table.val[low] = next - opts.table_index;*/ |
| 304 | table[low] = (root << 24) | (curr << 16) | (next - table_index) |0; |
| 305 | } |
| 306 | } |
| 307 | |
| 308 | /* fill in remaining table entry if code is incomplete (guaranteed to have |
| 309 | at most one remaining entry, since if the code is incomplete, the |
| 310 | maximum code length that was allowed to get this far is one bit) */ |
| 311 | if (huff !== 0) { |
| 312 | //table.op[next + huff] = 64; /* invalid code marker */ |
| 313 | //table.bits[next + huff] = len - drop; |
| 314 | //table.val[next + huff] = 0; |
| 315 | table[next + huff] = ((len - drop) << 24) | (64 << 16) |0; |
| 316 | } |
| 317 | |
| 318 | /* set return parameters */ |
| 319 | //opts.table_index += used; |
| 320 | opts.bits = root; |
| 321 | return 0; |
| 322 | }; |