kesavand | c71914f | 2022-03-25 11:19:03 +0530 | [diff] [blame^] | 1 | package huff0 |
| 2 | |
| 3 | import ( |
| 4 | "errors" |
| 5 | "fmt" |
| 6 | "io" |
| 7 | "sync" |
| 8 | |
| 9 | "github.com/klauspost/compress/fse" |
| 10 | ) |
| 11 | |
| 12 | type dTable struct { |
| 13 | single []dEntrySingle |
| 14 | double []dEntryDouble |
| 15 | } |
| 16 | |
| 17 | // single-symbols decoding |
| 18 | type dEntrySingle struct { |
| 19 | entry uint16 |
| 20 | } |
| 21 | |
| 22 | // double-symbols decoding |
| 23 | type dEntryDouble struct { |
| 24 | seq [4]byte |
| 25 | nBits uint8 |
| 26 | len uint8 |
| 27 | } |
| 28 | |
| 29 | // Uses special code for all tables that are < 8 bits. |
| 30 | const use8BitTables = true |
| 31 | |
| 32 | // ReadTable will read a table from the input. |
| 33 | // The size of the input may be larger than the table definition. |
| 34 | // Any content remaining after the table definition will be returned. |
| 35 | // If no Scratch is provided a new one is allocated. |
| 36 | // The returned Scratch can be used for encoding or decoding input using this table. |
| 37 | func ReadTable(in []byte, s *Scratch) (s2 *Scratch, remain []byte, err error) { |
| 38 | s, err = s.prepare(in) |
| 39 | if err != nil { |
| 40 | return s, nil, err |
| 41 | } |
| 42 | if len(in) <= 1 { |
| 43 | return s, nil, errors.New("input too small for table") |
| 44 | } |
| 45 | iSize := in[0] |
| 46 | in = in[1:] |
| 47 | if iSize >= 128 { |
| 48 | // Uncompressed |
| 49 | oSize := iSize - 127 |
| 50 | iSize = (oSize + 1) / 2 |
| 51 | if int(iSize) > len(in) { |
| 52 | return s, nil, errors.New("input too small for table") |
| 53 | } |
| 54 | for n := uint8(0); n < oSize; n += 2 { |
| 55 | v := in[n/2] |
| 56 | s.huffWeight[n] = v >> 4 |
| 57 | s.huffWeight[n+1] = v & 15 |
| 58 | } |
| 59 | s.symbolLen = uint16(oSize) |
| 60 | in = in[iSize:] |
| 61 | } else { |
| 62 | if len(in) < int(iSize) { |
| 63 | return s, nil, fmt.Errorf("input too small for table, want %d bytes, have %d", iSize, len(in)) |
| 64 | } |
| 65 | // FSE compressed weights |
| 66 | s.fse.DecompressLimit = 255 |
| 67 | hw := s.huffWeight[:] |
| 68 | s.fse.Out = hw |
| 69 | b, err := fse.Decompress(in[:iSize], s.fse) |
| 70 | s.fse.Out = nil |
| 71 | if err != nil { |
| 72 | return s, nil, err |
| 73 | } |
| 74 | if len(b) > 255 { |
| 75 | return s, nil, errors.New("corrupt input: output table too large") |
| 76 | } |
| 77 | s.symbolLen = uint16(len(b)) |
| 78 | in = in[iSize:] |
| 79 | } |
| 80 | |
| 81 | // collect weight stats |
| 82 | var rankStats [16]uint32 |
| 83 | weightTotal := uint32(0) |
| 84 | for _, v := range s.huffWeight[:s.symbolLen] { |
| 85 | if v > tableLogMax { |
| 86 | return s, nil, errors.New("corrupt input: weight too large") |
| 87 | } |
| 88 | v2 := v & 15 |
| 89 | rankStats[v2]++ |
| 90 | // (1 << (v2-1)) is slower since the compiler cannot prove that v2 isn't 0. |
| 91 | weightTotal += (1 << v2) >> 1 |
| 92 | } |
| 93 | if weightTotal == 0 { |
| 94 | return s, nil, errors.New("corrupt input: weights zero") |
| 95 | } |
| 96 | |
| 97 | // get last non-null symbol weight (implied, total must be 2^n) |
| 98 | { |
| 99 | tableLog := highBit32(weightTotal) + 1 |
| 100 | if tableLog > tableLogMax { |
| 101 | return s, nil, errors.New("corrupt input: tableLog too big") |
| 102 | } |
| 103 | s.actualTableLog = uint8(tableLog) |
| 104 | // determine last weight |
| 105 | { |
| 106 | total := uint32(1) << tableLog |
| 107 | rest := total - weightTotal |
| 108 | verif := uint32(1) << highBit32(rest) |
| 109 | lastWeight := highBit32(rest) + 1 |
| 110 | if verif != rest { |
| 111 | // last value must be a clean power of 2 |
| 112 | return s, nil, errors.New("corrupt input: last value not power of two") |
| 113 | } |
| 114 | s.huffWeight[s.symbolLen] = uint8(lastWeight) |
| 115 | s.symbolLen++ |
| 116 | rankStats[lastWeight]++ |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | if (rankStats[1] < 2) || (rankStats[1]&1 != 0) { |
| 121 | // by construction : at least 2 elts of rank 1, must be even |
| 122 | return s, nil, errors.New("corrupt input: min elt size, even check failed ") |
| 123 | } |
| 124 | |
| 125 | // TODO: Choose between single/double symbol decoding |
| 126 | |
| 127 | // Calculate starting value for each rank |
| 128 | { |
| 129 | var nextRankStart uint32 |
| 130 | for n := uint8(1); n < s.actualTableLog+1; n++ { |
| 131 | current := nextRankStart |
| 132 | nextRankStart += rankStats[n] << (n - 1) |
| 133 | rankStats[n] = current |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | // fill DTable (always full size) |
| 138 | tSize := 1 << tableLogMax |
| 139 | if len(s.dt.single) != tSize { |
| 140 | s.dt.single = make([]dEntrySingle, tSize) |
| 141 | } |
| 142 | cTable := s.prevTable |
| 143 | if cap(cTable) < maxSymbolValue+1 { |
| 144 | cTable = make([]cTableEntry, 0, maxSymbolValue+1) |
| 145 | } |
| 146 | cTable = cTable[:maxSymbolValue+1] |
| 147 | s.prevTable = cTable[:s.symbolLen] |
| 148 | s.prevTableLog = s.actualTableLog |
| 149 | |
| 150 | for n, w := range s.huffWeight[:s.symbolLen] { |
| 151 | if w == 0 { |
| 152 | cTable[n] = cTableEntry{ |
| 153 | val: 0, |
| 154 | nBits: 0, |
| 155 | } |
| 156 | continue |
| 157 | } |
| 158 | length := (uint32(1) << w) >> 1 |
| 159 | d := dEntrySingle{ |
| 160 | entry: uint16(s.actualTableLog+1-w) | (uint16(n) << 8), |
| 161 | } |
| 162 | |
| 163 | rank := &rankStats[w] |
| 164 | cTable[n] = cTableEntry{ |
| 165 | val: uint16(*rank >> (w - 1)), |
| 166 | nBits: uint8(d.entry), |
| 167 | } |
| 168 | |
| 169 | single := s.dt.single[*rank : *rank+length] |
| 170 | for i := range single { |
| 171 | single[i] = d |
| 172 | } |
| 173 | *rank += length |
| 174 | } |
| 175 | |
| 176 | return s, in, nil |
| 177 | } |
| 178 | |
| 179 | // Decompress1X will decompress a 1X encoded stream. |
| 180 | // The length of the supplied input must match the end of a block exactly. |
| 181 | // Before this is called, the table must be initialized with ReadTable unless |
| 182 | // the encoder re-used the table. |
| 183 | // deprecated: Use the stateless Decoder() to get a concurrent version. |
| 184 | func (s *Scratch) Decompress1X(in []byte) (out []byte, err error) { |
| 185 | if cap(s.Out) < s.MaxDecodedSize { |
| 186 | s.Out = make([]byte, s.MaxDecodedSize) |
| 187 | } |
| 188 | s.Out = s.Out[:0:s.MaxDecodedSize] |
| 189 | s.Out, err = s.Decoder().Decompress1X(s.Out, in) |
| 190 | return s.Out, err |
| 191 | } |
| 192 | |
| 193 | // Decompress4X will decompress a 4X encoded stream. |
| 194 | // Before this is called, the table must be initialized with ReadTable unless |
| 195 | // the encoder re-used the table. |
| 196 | // The length of the supplied input must match the end of a block exactly. |
| 197 | // The destination size of the uncompressed data must be known and provided. |
| 198 | // deprecated: Use the stateless Decoder() to get a concurrent version. |
| 199 | func (s *Scratch) Decompress4X(in []byte, dstSize int) (out []byte, err error) { |
| 200 | if dstSize > s.MaxDecodedSize { |
| 201 | return nil, ErrMaxDecodedSizeExceeded |
| 202 | } |
| 203 | if cap(s.Out) < dstSize { |
| 204 | s.Out = make([]byte, s.MaxDecodedSize) |
| 205 | } |
| 206 | s.Out = s.Out[:0:dstSize] |
| 207 | s.Out, err = s.Decoder().Decompress4X(s.Out, in) |
| 208 | return s.Out, err |
| 209 | } |
| 210 | |
| 211 | // Decoder will return a stateless decoder that can be used by multiple |
| 212 | // decompressors concurrently. |
| 213 | // Before this is called, the table must be initialized with ReadTable. |
| 214 | // The Decoder is still linked to the scratch buffer so that cannot be reused. |
| 215 | // However, it is safe to discard the scratch. |
| 216 | func (s *Scratch) Decoder() *Decoder { |
| 217 | return &Decoder{ |
| 218 | dt: s.dt, |
| 219 | actualTableLog: s.actualTableLog, |
| 220 | bufs: &s.decPool, |
| 221 | } |
| 222 | } |
| 223 | |
| 224 | // Decoder provides stateless decoding. |
| 225 | type Decoder struct { |
| 226 | dt dTable |
| 227 | actualTableLog uint8 |
| 228 | bufs *sync.Pool |
| 229 | } |
| 230 | |
| 231 | func (d *Decoder) buffer() *[4][256]byte { |
| 232 | buf, ok := d.bufs.Get().(*[4][256]byte) |
| 233 | if ok { |
| 234 | return buf |
| 235 | } |
| 236 | return &[4][256]byte{} |
| 237 | } |
| 238 | |
| 239 | // Decompress1X will decompress a 1X encoded stream. |
| 240 | // The cap of the output buffer will be the maximum decompressed size. |
| 241 | // The length of the supplied input must match the end of a block exactly. |
| 242 | func (d *Decoder) Decompress1X(dst, src []byte) ([]byte, error) { |
| 243 | if len(d.dt.single) == 0 { |
| 244 | return nil, errors.New("no table loaded") |
| 245 | } |
| 246 | if use8BitTables && d.actualTableLog <= 8 { |
| 247 | return d.decompress1X8Bit(dst, src) |
| 248 | } |
| 249 | var br bitReaderShifted |
| 250 | err := br.init(src) |
| 251 | if err != nil { |
| 252 | return dst, err |
| 253 | } |
| 254 | maxDecodedSize := cap(dst) |
| 255 | dst = dst[:0] |
| 256 | |
| 257 | // Avoid bounds check by always having full sized table. |
| 258 | const tlSize = 1 << tableLogMax |
| 259 | const tlMask = tlSize - 1 |
| 260 | dt := d.dt.single[:tlSize] |
| 261 | |
| 262 | // Use temp table to avoid bound checks/append penalty. |
| 263 | bufs := d.buffer() |
| 264 | buf := &bufs[0] |
| 265 | var off uint8 |
| 266 | |
| 267 | for br.off >= 8 { |
| 268 | br.fillFast() |
| 269 | v := dt[br.peekBitsFast(d.actualTableLog)&tlMask] |
| 270 | br.advance(uint8(v.entry)) |
| 271 | buf[off+0] = uint8(v.entry >> 8) |
| 272 | |
| 273 | v = dt[br.peekBitsFast(d.actualTableLog)&tlMask] |
| 274 | br.advance(uint8(v.entry)) |
| 275 | buf[off+1] = uint8(v.entry >> 8) |
| 276 | |
| 277 | // Refill |
| 278 | br.fillFast() |
| 279 | |
| 280 | v = dt[br.peekBitsFast(d.actualTableLog)&tlMask] |
| 281 | br.advance(uint8(v.entry)) |
| 282 | buf[off+2] = uint8(v.entry >> 8) |
| 283 | |
| 284 | v = dt[br.peekBitsFast(d.actualTableLog)&tlMask] |
| 285 | br.advance(uint8(v.entry)) |
| 286 | buf[off+3] = uint8(v.entry >> 8) |
| 287 | |
| 288 | off += 4 |
| 289 | if off == 0 { |
| 290 | if len(dst)+256 > maxDecodedSize { |
| 291 | br.close() |
| 292 | d.bufs.Put(bufs) |
| 293 | return nil, ErrMaxDecodedSizeExceeded |
| 294 | } |
| 295 | dst = append(dst, buf[:]...) |
| 296 | } |
| 297 | } |
| 298 | |
| 299 | if len(dst)+int(off) > maxDecodedSize { |
| 300 | d.bufs.Put(bufs) |
| 301 | br.close() |
| 302 | return nil, ErrMaxDecodedSizeExceeded |
| 303 | } |
| 304 | dst = append(dst, buf[:off]...) |
| 305 | |
| 306 | // br < 8, so uint8 is fine |
| 307 | bitsLeft := uint8(br.off)*8 + 64 - br.bitsRead |
| 308 | for bitsLeft > 0 { |
| 309 | br.fill() |
| 310 | if false && br.bitsRead >= 32 { |
| 311 | if br.off >= 4 { |
| 312 | v := br.in[br.off-4:] |
| 313 | v = v[:4] |
| 314 | low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) |
| 315 | br.value = (br.value << 32) | uint64(low) |
| 316 | br.bitsRead -= 32 |
| 317 | br.off -= 4 |
| 318 | } else { |
| 319 | for br.off > 0 { |
| 320 | br.value = (br.value << 8) | uint64(br.in[br.off-1]) |
| 321 | br.bitsRead -= 8 |
| 322 | br.off-- |
| 323 | } |
| 324 | } |
| 325 | } |
| 326 | if len(dst) >= maxDecodedSize { |
| 327 | d.bufs.Put(bufs) |
| 328 | br.close() |
| 329 | return nil, ErrMaxDecodedSizeExceeded |
| 330 | } |
| 331 | v := d.dt.single[br.peekBitsFast(d.actualTableLog)&tlMask] |
| 332 | nBits := uint8(v.entry) |
| 333 | br.advance(nBits) |
| 334 | bitsLeft -= nBits |
| 335 | dst = append(dst, uint8(v.entry>>8)) |
| 336 | } |
| 337 | d.bufs.Put(bufs) |
| 338 | return dst, br.close() |
| 339 | } |
| 340 | |
| 341 | // decompress1X8Bit will decompress a 1X encoded stream with tablelog <= 8. |
| 342 | // The cap of the output buffer will be the maximum decompressed size. |
| 343 | // The length of the supplied input must match the end of a block exactly. |
| 344 | func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) { |
| 345 | if d.actualTableLog == 8 { |
| 346 | return d.decompress1X8BitExactly(dst, src) |
| 347 | } |
| 348 | var br bitReaderBytes |
| 349 | err := br.init(src) |
| 350 | if err != nil { |
| 351 | return dst, err |
| 352 | } |
| 353 | maxDecodedSize := cap(dst) |
| 354 | dst = dst[:0] |
| 355 | |
| 356 | // Avoid bounds check by always having full sized table. |
| 357 | dt := d.dt.single[:256] |
| 358 | |
| 359 | // Use temp table to avoid bound checks/append penalty. |
| 360 | bufs := d.buffer() |
| 361 | buf := &bufs[0] |
| 362 | var off uint8 |
| 363 | |
| 364 | switch d.actualTableLog { |
| 365 | case 8: |
| 366 | const shift = 8 - 8 |
| 367 | for br.off >= 4 { |
| 368 | br.fillFast() |
| 369 | v := dt[uint8(br.value>>(56+shift))] |
| 370 | br.advance(uint8(v.entry)) |
| 371 | buf[off+0] = uint8(v.entry >> 8) |
| 372 | |
| 373 | v = dt[uint8(br.value>>(56+shift))] |
| 374 | br.advance(uint8(v.entry)) |
| 375 | buf[off+1] = uint8(v.entry >> 8) |
| 376 | |
| 377 | v = dt[uint8(br.value>>(56+shift))] |
| 378 | br.advance(uint8(v.entry)) |
| 379 | buf[off+2] = uint8(v.entry >> 8) |
| 380 | |
| 381 | v = dt[uint8(br.value>>(56+shift))] |
| 382 | br.advance(uint8(v.entry)) |
| 383 | buf[off+3] = uint8(v.entry >> 8) |
| 384 | |
| 385 | off += 4 |
| 386 | if off == 0 { |
| 387 | if len(dst)+256 > maxDecodedSize { |
| 388 | br.close() |
| 389 | d.bufs.Put(bufs) |
| 390 | return nil, ErrMaxDecodedSizeExceeded |
| 391 | } |
| 392 | dst = append(dst, buf[:]...) |
| 393 | } |
| 394 | } |
| 395 | case 7: |
| 396 | const shift = 8 - 7 |
| 397 | for br.off >= 4 { |
| 398 | br.fillFast() |
| 399 | v := dt[uint8(br.value>>(56+shift))] |
| 400 | br.advance(uint8(v.entry)) |
| 401 | buf[off+0] = uint8(v.entry >> 8) |
| 402 | |
| 403 | v = dt[uint8(br.value>>(56+shift))] |
| 404 | br.advance(uint8(v.entry)) |
| 405 | buf[off+1] = uint8(v.entry >> 8) |
| 406 | |
| 407 | v = dt[uint8(br.value>>(56+shift))] |
| 408 | br.advance(uint8(v.entry)) |
| 409 | buf[off+2] = uint8(v.entry >> 8) |
| 410 | |
| 411 | v = dt[uint8(br.value>>(56+shift))] |
| 412 | br.advance(uint8(v.entry)) |
| 413 | buf[off+3] = uint8(v.entry >> 8) |
| 414 | |
| 415 | off += 4 |
| 416 | if off == 0 { |
| 417 | if len(dst)+256 > maxDecodedSize { |
| 418 | br.close() |
| 419 | d.bufs.Put(bufs) |
| 420 | return nil, ErrMaxDecodedSizeExceeded |
| 421 | } |
| 422 | dst = append(dst, buf[:]...) |
| 423 | } |
| 424 | } |
| 425 | case 6: |
| 426 | const shift = 8 - 6 |
| 427 | for br.off >= 4 { |
| 428 | br.fillFast() |
| 429 | v := dt[uint8(br.value>>(56+shift))] |
| 430 | br.advance(uint8(v.entry)) |
| 431 | buf[off+0] = uint8(v.entry >> 8) |
| 432 | |
| 433 | v = dt[uint8(br.value>>(56+shift))] |
| 434 | br.advance(uint8(v.entry)) |
| 435 | buf[off+1] = uint8(v.entry >> 8) |
| 436 | |
| 437 | v = dt[uint8(br.value>>(56+shift))] |
| 438 | br.advance(uint8(v.entry)) |
| 439 | buf[off+2] = uint8(v.entry >> 8) |
| 440 | |
| 441 | v = dt[uint8(br.value>>(56+shift))] |
| 442 | br.advance(uint8(v.entry)) |
| 443 | buf[off+3] = uint8(v.entry >> 8) |
| 444 | |
| 445 | off += 4 |
| 446 | if off == 0 { |
| 447 | if len(dst)+256 > maxDecodedSize { |
| 448 | d.bufs.Put(bufs) |
| 449 | br.close() |
| 450 | return nil, ErrMaxDecodedSizeExceeded |
| 451 | } |
| 452 | dst = append(dst, buf[:]...) |
| 453 | } |
| 454 | } |
| 455 | case 5: |
| 456 | const shift = 8 - 5 |
| 457 | for br.off >= 4 { |
| 458 | br.fillFast() |
| 459 | v := dt[uint8(br.value>>(56+shift))] |
| 460 | br.advance(uint8(v.entry)) |
| 461 | buf[off+0] = uint8(v.entry >> 8) |
| 462 | |
| 463 | v = dt[uint8(br.value>>(56+shift))] |
| 464 | br.advance(uint8(v.entry)) |
| 465 | buf[off+1] = uint8(v.entry >> 8) |
| 466 | |
| 467 | v = dt[uint8(br.value>>(56+shift))] |
| 468 | br.advance(uint8(v.entry)) |
| 469 | buf[off+2] = uint8(v.entry >> 8) |
| 470 | |
| 471 | v = dt[uint8(br.value>>(56+shift))] |
| 472 | br.advance(uint8(v.entry)) |
| 473 | buf[off+3] = uint8(v.entry >> 8) |
| 474 | |
| 475 | off += 4 |
| 476 | if off == 0 { |
| 477 | if len(dst)+256 > maxDecodedSize { |
| 478 | d.bufs.Put(bufs) |
| 479 | br.close() |
| 480 | return nil, ErrMaxDecodedSizeExceeded |
| 481 | } |
| 482 | dst = append(dst, buf[:]...) |
| 483 | } |
| 484 | } |
| 485 | case 4: |
| 486 | const shift = 8 - 4 |
| 487 | for br.off >= 4 { |
| 488 | br.fillFast() |
| 489 | v := dt[uint8(br.value>>(56+shift))] |
| 490 | br.advance(uint8(v.entry)) |
| 491 | buf[off+0] = uint8(v.entry >> 8) |
| 492 | |
| 493 | v = dt[uint8(br.value>>(56+shift))] |
| 494 | br.advance(uint8(v.entry)) |
| 495 | buf[off+1] = uint8(v.entry >> 8) |
| 496 | |
| 497 | v = dt[uint8(br.value>>(56+shift))] |
| 498 | br.advance(uint8(v.entry)) |
| 499 | buf[off+2] = uint8(v.entry >> 8) |
| 500 | |
| 501 | v = dt[uint8(br.value>>(56+shift))] |
| 502 | br.advance(uint8(v.entry)) |
| 503 | buf[off+3] = uint8(v.entry >> 8) |
| 504 | |
| 505 | off += 4 |
| 506 | if off == 0 { |
| 507 | if len(dst)+256 > maxDecodedSize { |
| 508 | d.bufs.Put(bufs) |
| 509 | br.close() |
| 510 | return nil, ErrMaxDecodedSizeExceeded |
| 511 | } |
| 512 | dst = append(dst, buf[:]...) |
| 513 | } |
| 514 | } |
| 515 | case 3: |
| 516 | const shift = 8 - 3 |
| 517 | for br.off >= 4 { |
| 518 | br.fillFast() |
| 519 | v := dt[uint8(br.value>>(56+shift))] |
| 520 | br.advance(uint8(v.entry)) |
| 521 | buf[off+0] = uint8(v.entry >> 8) |
| 522 | |
| 523 | v = dt[uint8(br.value>>(56+shift))] |
| 524 | br.advance(uint8(v.entry)) |
| 525 | buf[off+1] = uint8(v.entry >> 8) |
| 526 | |
| 527 | v = dt[uint8(br.value>>(56+shift))] |
| 528 | br.advance(uint8(v.entry)) |
| 529 | buf[off+2] = uint8(v.entry >> 8) |
| 530 | |
| 531 | v = dt[uint8(br.value>>(56+shift))] |
| 532 | br.advance(uint8(v.entry)) |
| 533 | buf[off+3] = uint8(v.entry >> 8) |
| 534 | |
| 535 | off += 4 |
| 536 | if off == 0 { |
| 537 | if len(dst)+256 > maxDecodedSize { |
| 538 | d.bufs.Put(bufs) |
| 539 | br.close() |
| 540 | return nil, ErrMaxDecodedSizeExceeded |
| 541 | } |
| 542 | dst = append(dst, buf[:]...) |
| 543 | } |
| 544 | } |
| 545 | case 2: |
| 546 | const shift = 8 - 2 |
| 547 | for br.off >= 4 { |
| 548 | br.fillFast() |
| 549 | v := dt[uint8(br.value>>(56+shift))] |
| 550 | br.advance(uint8(v.entry)) |
| 551 | buf[off+0] = uint8(v.entry >> 8) |
| 552 | |
| 553 | v = dt[uint8(br.value>>(56+shift))] |
| 554 | br.advance(uint8(v.entry)) |
| 555 | buf[off+1] = uint8(v.entry >> 8) |
| 556 | |
| 557 | v = dt[uint8(br.value>>(56+shift))] |
| 558 | br.advance(uint8(v.entry)) |
| 559 | buf[off+2] = uint8(v.entry >> 8) |
| 560 | |
| 561 | v = dt[uint8(br.value>>(56+shift))] |
| 562 | br.advance(uint8(v.entry)) |
| 563 | buf[off+3] = uint8(v.entry >> 8) |
| 564 | |
| 565 | off += 4 |
| 566 | if off == 0 { |
| 567 | if len(dst)+256 > maxDecodedSize { |
| 568 | d.bufs.Put(bufs) |
| 569 | br.close() |
| 570 | return nil, ErrMaxDecodedSizeExceeded |
| 571 | } |
| 572 | dst = append(dst, buf[:]...) |
| 573 | } |
| 574 | } |
| 575 | case 1: |
| 576 | const shift = 8 - 1 |
| 577 | for br.off >= 4 { |
| 578 | br.fillFast() |
| 579 | v := dt[uint8(br.value>>(56+shift))] |
| 580 | br.advance(uint8(v.entry)) |
| 581 | buf[off+0] = uint8(v.entry >> 8) |
| 582 | |
| 583 | v = dt[uint8(br.value>>(56+shift))] |
| 584 | br.advance(uint8(v.entry)) |
| 585 | buf[off+1] = uint8(v.entry >> 8) |
| 586 | |
| 587 | v = dt[uint8(br.value>>(56+shift))] |
| 588 | br.advance(uint8(v.entry)) |
| 589 | buf[off+2] = uint8(v.entry >> 8) |
| 590 | |
| 591 | v = dt[uint8(br.value>>(56+shift))] |
| 592 | br.advance(uint8(v.entry)) |
| 593 | buf[off+3] = uint8(v.entry >> 8) |
| 594 | |
| 595 | off += 4 |
| 596 | if off == 0 { |
| 597 | if len(dst)+256 > maxDecodedSize { |
| 598 | d.bufs.Put(bufs) |
| 599 | br.close() |
| 600 | return nil, ErrMaxDecodedSizeExceeded |
| 601 | } |
| 602 | dst = append(dst, buf[:]...) |
| 603 | } |
| 604 | } |
| 605 | default: |
| 606 | d.bufs.Put(bufs) |
| 607 | return nil, fmt.Errorf("invalid tablelog: %d", d.actualTableLog) |
| 608 | } |
| 609 | |
| 610 | if len(dst)+int(off) > maxDecodedSize { |
| 611 | d.bufs.Put(bufs) |
| 612 | br.close() |
| 613 | return nil, ErrMaxDecodedSizeExceeded |
| 614 | } |
| 615 | dst = append(dst, buf[:off]...) |
| 616 | |
| 617 | // br < 4, so uint8 is fine |
| 618 | bitsLeft := int8(uint8(br.off)*8 + (64 - br.bitsRead)) |
| 619 | shift := (8 - d.actualTableLog) & 7 |
| 620 | |
| 621 | for bitsLeft > 0 { |
| 622 | if br.bitsRead >= 64-8 { |
| 623 | for br.off > 0 { |
| 624 | br.value |= uint64(br.in[br.off-1]) << (br.bitsRead - 8) |
| 625 | br.bitsRead -= 8 |
| 626 | br.off-- |
| 627 | } |
| 628 | } |
| 629 | if len(dst) >= maxDecodedSize { |
| 630 | br.close() |
| 631 | d.bufs.Put(bufs) |
| 632 | return nil, ErrMaxDecodedSizeExceeded |
| 633 | } |
| 634 | v := dt[br.peekByteFast()>>shift] |
| 635 | nBits := uint8(v.entry) |
| 636 | br.advance(nBits) |
| 637 | bitsLeft -= int8(nBits) |
| 638 | dst = append(dst, uint8(v.entry>>8)) |
| 639 | } |
| 640 | d.bufs.Put(bufs) |
| 641 | return dst, br.close() |
| 642 | } |
| 643 | |
| 644 | // decompress1X8Bit will decompress a 1X encoded stream with tablelog <= 8. |
| 645 | // The cap of the output buffer will be the maximum decompressed size. |
| 646 | // The length of the supplied input must match the end of a block exactly. |
| 647 | func (d *Decoder) decompress1X8BitExactly(dst, src []byte) ([]byte, error) { |
| 648 | var br bitReaderBytes |
| 649 | err := br.init(src) |
| 650 | if err != nil { |
| 651 | return dst, err |
| 652 | } |
| 653 | maxDecodedSize := cap(dst) |
| 654 | dst = dst[:0] |
| 655 | |
| 656 | // Avoid bounds check by always having full sized table. |
| 657 | dt := d.dt.single[:256] |
| 658 | |
| 659 | // Use temp table to avoid bound checks/append penalty. |
| 660 | bufs := d.buffer() |
| 661 | buf := &bufs[0] |
| 662 | var off uint8 |
| 663 | |
| 664 | const shift = 56 |
| 665 | |
| 666 | //fmt.Printf("mask: %b, tl:%d\n", mask, d.actualTableLog) |
| 667 | for br.off >= 4 { |
| 668 | br.fillFast() |
| 669 | v := dt[uint8(br.value>>shift)] |
| 670 | br.advance(uint8(v.entry)) |
| 671 | buf[off+0] = uint8(v.entry >> 8) |
| 672 | |
| 673 | v = dt[uint8(br.value>>shift)] |
| 674 | br.advance(uint8(v.entry)) |
| 675 | buf[off+1] = uint8(v.entry >> 8) |
| 676 | |
| 677 | v = dt[uint8(br.value>>shift)] |
| 678 | br.advance(uint8(v.entry)) |
| 679 | buf[off+2] = uint8(v.entry >> 8) |
| 680 | |
| 681 | v = dt[uint8(br.value>>shift)] |
| 682 | br.advance(uint8(v.entry)) |
| 683 | buf[off+3] = uint8(v.entry >> 8) |
| 684 | |
| 685 | off += 4 |
| 686 | if off == 0 { |
| 687 | if len(dst)+256 > maxDecodedSize { |
| 688 | d.bufs.Put(bufs) |
| 689 | br.close() |
| 690 | return nil, ErrMaxDecodedSizeExceeded |
| 691 | } |
| 692 | dst = append(dst, buf[:]...) |
| 693 | } |
| 694 | } |
| 695 | |
| 696 | if len(dst)+int(off) > maxDecodedSize { |
| 697 | d.bufs.Put(bufs) |
| 698 | br.close() |
| 699 | return nil, ErrMaxDecodedSizeExceeded |
| 700 | } |
| 701 | dst = append(dst, buf[:off]...) |
| 702 | |
| 703 | // br < 4, so uint8 is fine |
| 704 | bitsLeft := int8(uint8(br.off)*8 + (64 - br.bitsRead)) |
| 705 | for bitsLeft > 0 { |
| 706 | if br.bitsRead >= 64-8 { |
| 707 | for br.off > 0 { |
| 708 | br.value |= uint64(br.in[br.off-1]) << (br.bitsRead - 8) |
| 709 | br.bitsRead -= 8 |
| 710 | br.off-- |
| 711 | } |
| 712 | } |
| 713 | if len(dst) >= maxDecodedSize { |
| 714 | d.bufs.Put(bufs) |
| 715 | br.close() |
| 716 | return nil, ErrMaxDecodedSizeExceeded |
| 717 | } |
| 718 | v := dt[br.peekByteFast()] |
| 719 | nBits := uint8(v.entry) |
| 720 | br.advance(nBits) |
| 721 | bitsLeft -= int8(nBits) |
| 722 | dst = append(dst, uint8(v.entry>>8)) |
| 723 | } |
| 724 | d.bufs.Put(bufs) |
| 725 | return dst, br.close() |
| 726 | } |
| 727 | |
| 728 | // Decompress4X will decompress a 4X encoded stream. |
| 729 | // The length of the supplied input must match the end of a block exactly. |
| 730 | // The *capacity* of the dst slice must match the destination size of |
| 731 | // the uncompressed data exactly. |
| 732 | func (d *Decoder) Decompress4X(dst, src []byte) ([]byte, error) { |
| 733 | if len(d.dt.single) == 0 { |
| 734 | return nil, errors.New("no table loaded") |
| 735 | } |
| 736 | if len(src) < 6+(4*1) { |
| 737 | return nil, errors.New("input too small") |
| 738 | } |
| 739 | if use8BitTables && d.actualTableLog <= 8 { |
| 740 | return d.decompress4X8bit(dst, src) |
| 741 | } |
| 742 | |
| 743 | var br [4]bitReaderShifted |
| 744 | start := 6 |
| 745 | for i := 0; i < 3; i++ { |
| 746 | length := int(src[i*2]) | (int(src[i*2+1]) << 8) |
| 747 | if start+length >= len(src) { |
| 748 | return nil, errors.New("truncated input (or invalid offset)") |
| 749 | } |
| 750 | err := br[i].init(src[start : start+length]) |
| 751 | if err != nil { |
| 752 | return nil, err |
| 753 | } |
| 754 | start += length |
| 755 | } |
| 756 | err := br[3].init(src[start:]) |
| 757 | if err != nil { |
| 758 | return nil, err |
| 759 | } |
| 760 | |
| 761 | // destination, offset to match first output |
| 762 | dstSize := cap(dst) |
| 763 | dst = dst[:dstSize] |
| 764 | out := dst |
| 765 | dstEvery := (dstSize + 3) / 4 |
| 766 | |
| 767 | const tlSize = 1 << tableLogMax |
| 768 | const tlMask = tlSize - 1 |
| 769 | single := d.dt.single[:tlSize] |
| 770 | |
| 771 | // Use temp table to avoid bound checks/append penalty. |
| 772 | buf := d.buffer() |
| 773 | var off uint8 |
| 774 | var decoded int |
| 775 | |
| 776 | // Decode 2 values from each decoder/loop. |
| 777 | const bufoff = 256 |
| 778 | for { |
| 779 | if br[0].off < 4 || br[1].off < 4 || br[2].off < 4 || br[3].off < 4 { |
| 780 | break |
| 781 | } |
| 782 | |
| 783 | { |
| 784 | const stream = 0 |
| 785 | const stream2 = 1 |
| 786 | br[stream].fillFast() |
| 787 | br[stream2].fillFast() |
| 788 | |
| 789 | val := br[stream].peekBitsFast(d.actualTableLog) |
| 790 | val2 := br[stream2].peekBitsFast(d.actualTableLog) |
| 791 | v := single[val&tlMask] |
| 792 | v2 := single[val2&tlMask] |
| 793 | br[stream].advance(uint8(v.entry)) |
| 794 | br[stream2].advance(uint8(v2.entry)) |
| 795 | buf[stream][off] = uint8(v.entry >> 8) |
| 796 | buf[stream2][off] = uint8(v2.entry >> 8) |
| 797 | |
| 798 | val = br[stream].peekBitsFast(d.actualTableLog) |
| 799 | val2 = br[stream2].peekBitsFast(d.actualTableLog) |
| 800 | v = single[val&tlMask] |
| 801 | v2 = single[val2&tlMask] |
| 802 | br[stream].advance(uint8(v.entry)) |
| 803 | br[stream2].advance(uint8(v2.entry)) |
| 804 | buf[stream][off+1] = uint8(v.entry >> 8) |
| 805 | buf[stream2][off+1] = uint8(v2.entry >> 8) |
| 806 | } |
| 807 | |
| 808 | { |
| 809 | const stream = 2 |
| 810 | const stream2 = 3 |
| 811 | br[stream].fillFast() |
| 812 | br[stream2].fillFast() |
| 813 | |
| 814 | val := br[stream].peekBitsFast(d.actualTableLog) |
| 815 | val2 := br[stream2].peekBitsFast(d.actualTableLog) |
| 816 | v := single[val&tlMask] |
| 817 | v2 := single[val2&tlMask] |
| 818 | br[stream].advance(uint8(v.entry)) |
| 819 | br[stream2].advance(uint8(v2.entry)) |
| 820 | buf[stream][off] = uint8(v.entry >> 8) |
| 821 | buf[stream2][off] = uint8(v2.entry >> 8) |
| 822 | |
| 823 | val = br[stream].peekBitsFast(d.actualTableLog) |
| 824 | val2 = br[stream2].peekBitsFast(d.actualTableLog) |
| 825 | v = single[val&tlMask] |
| 826 | v2 = single[val2&tlMask] |
| 827 | br[stream].advance(uint8(v.entry)) |
| 828 | br[stream2].advance(uint8(v2.entry)) |
| 829 | buf[stream][off+1] = uint8(v.entry >> 8) |
| 830 | buf[stream2][off+1] = uint8(v2.entry >> 8) |
| 831 | } |
| 832 | |
| 833 | off += 2 |
| 834 | |
| 835 | if off == 0 { |
| 836 | if bufoff > dstEvery { |
| 837 | d.bufs.Put(buf) |
| 838 | return nil, errors.New("corruption detected: stream overrun 1") |
| 839 | } |
| 840 | copy(out, buf[0][:]) |
| 841 | copy(out[dstEvery:], buf[1][:]) |
| 842 | copy(out[dstEvery*2:], buf[2][:]) |
| 843 | copy(out[dstEvery*3:], buf[3][:]) |
| 844 | out = out[bufoff:] |
| 845 | decoded += bufoff * 4 |
| 846 | // There must at least be 3 buffers left. |
| 847 | if len(out) < dstEvery*3 { |
| 848 | d.bufs.Put(buf) |
| 849 | return nil, errors.New("corruption detected: stream overrun 2") |
| 850 | } |
| 851 | } |
| 852 | } |
| 853 | if off > 0 { |
| 854 | ioff := int(off) |
| 855 | if len(out) < dstEvery*3+ioff { |
| 856 | d.bufs.Put(buf) |
| 857 | return nil, errors.New("corruption detected: stream overrun 3") |
| 858 | } |
| 859 | copy(out, buf[0][:off]) |
| 860 | copy(out[dstEvery:], buf[1][:off]) |
| 861 | copy(out[dstEvery*2:], buf[2][:off]) |
| 862 | copy(out[dstEvery*3:], buf[3][:off]) |
| 863 | decoded += int(off) * 4 |
| 864 | out = out[off:] |
| 865 | } |
| 866 | |
| 867 | // Decode remaining. |
| 868 | for i := range br { |
| 869 | offset := dstEvery * i |
| 870 | br := &br[i] |
| 871 | bitsLeft := br.off*8 + uint(64-br.bitsRead) |
| 872 | for bitsLeft > 0 { |
| 873 | br.fill() |
| 874 | if false && br.bitsRead >= 32 { |
| 875 | if br.off >= 4 { |
| 876 | v := br.in[br.off-4:] |
| 877 | v = v[:4] |
| 878 | low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) |
| 879 | br.value = (br.value << 32) | uint64(low) |
| 880 | br.bitsRead -= 32 |
| 881 | br.off -= 4 |
| 882 | } else { |
| 883 | for br.off > 0 { |
| 884 | br.value = (br.value << 8) | uint64(br.in[br.off-1]) |
| 885 | br.bitsRead -= 8 |
| 886 | br.off-- |
| 887 | } |
| 888 | } |
| 889 | } |
| 890 | // end inline... |
| 891 | if offset >= len(out) { |
| 892 | d.bufs.Put(buf) |
| 893 | return nil, errors.New("corruption detected: stream overrun 4") |
| 894 | } |
| 895 | |
| 896 | // Read value and increment offset. |
| 897 | val := br.peekBitsFast(d.actualTableLog) |
| 898 | v := single[val&tlMask].entry |
| 899 | nBits := uint8(v) |
| 900 | br.advance(nBits) |
| 901 | bitsLeft -= uint(nBits) |
| 902 | out[offset] = uint8(v >> 8) |
| 903 | offset++ |
| 904 | } |
| 905 | decoded += offset - dstEvery*i |
| 906 | err = br.close() |
| 907 | if err != nil { |
| 908 | return nil, err |
| 909 | } |
| 910 | } |
| 911 | d.bufs.Put(buf) |
| 912 | if dstSize != decoded { |
| 913 | return nil, errors.New("corruption detected: short output block") |
| 914 | } |
| 915 | return dst, nil |
| 916 | } |
| 917 | |
| 918 | // Decompress4X will decompress a 4X encoded stream. |
| 919 | // The length of the supplied input must match the end of a block exactly. |
| 920 | // The *capacity* of the dst slice must match the destination size of |
| 921 | // the uncompressed data exactly. |
| 922 | func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) { |
| 923 | if d.actualTableLog == 8 { |
| 924 | return d.decompress4X8bitExactly(dst, src) |
| 925 | } |
| 926 | |
| 927 | var br [4]bitReaderBytes |
| 928 | start := 6 |
| 929 | for i := 0; i < 3; i++ { |
| 930 | length := int(src[i*2]) | (int(src[i*2+1]) << 8) |
| 931 | if start+length >= len(src) { |
| 932 | return nil, errors.New("truncated input (or invalid offset)") |
| 933 | } |
| 934 | err := br[i].init(src[start : start+length]) |
| 935 | if err != nil { |
| 936 | return nil, err |
| 937 | } |
| 938 | start += length |
| 939 | } |
| 940 | err := br[3].init(src[start:]) |
| 941 | if err != nil { |
| 942 | return nil, err |
| 943 | } |
| 944 | |
| 945 | // destination, offset to match first output |
| 946 | dstSize := cap(dst) |
| 947 | dst = dst[:dstSize] |
| 948 | out := dst |
| 949 | dstEvery := (dstSize + 3) / 4 |
| 950 | |
| 951 | shift := (56 + (8 - d.actualTableLog)) & 63 |
| 952 | |
| 953 | const tlSize = 1 << 8 |
| 954 | single := d.dt.single[:tlSize] |
| 955 | |
| 956 | // Use temp table to avoid bound checks/append penalty. |
| 957 | buf := d.buffer() |
| 958 | var off uint8 |
| 959 | var decoded int |
| 960 | |
| 961 | // Decode 4 values from each decoder/loop. |
| 962 | const bufoff = 256 |
| 963 | for { |
| 964 | if br[0].off < 4 || br[1].off < 4 || br[2].off < 4 || br[3].off < 4 { |
| 965 | break |
| 966 | } |
| 967 | |
| 968 | { |
| 969 | // Interleave 2 decodes. |
| 970 | const stream = 0 |
| 971 | const stream2 = 1 |
| 972 | br1 := &br[stream] |
| 973 | br2 := &br[stream2] |
| 974 | br1.fillFast() |
| 975 | br2.fillFast() |
| 976 | |
| 977 | v := single[uint8(br1.value>>shift)].entry |
| 978 | v2 := single[uint8(br2.value>>shift)].entry |
| 979 | br1.bitsRead += uint8(v) |
| 980 | br1.value <<= v & 63 |
| 981 | br2.bitsRead += uint8(v2) |
| 982 | br2.value <<= v2 & 63 |
| 983 | buf[stream][off] = uint8(v >> 8) |
| 984 | buf[stream2][off] = uint8(v2 >> 8) |
| 985 | |
| 986 | v = single[uint8(br1.value>>shift)].entry |
| 987 | v2 = single[uint8(br2.value>>shift)].entry |
| 988 | br1.bitsRead += uint8(v) |
| 989 | br1.value <<= v & 63 |
| 990 | br2.bitsRead += uint8(v2) |
| 991 | br2.value <<= v2 & 63 |
| 992 | buf[stream][off+1] = uint8(v >> 8) |
| 993 | buf[stream2][off+1] = uint8(v2 >> 8) |
| 994 | |
| 995 | v = single[uint8(br1.value>>shift)].entry |
| 996 | v2 = single[uint8(br2.value>>shift)].entry |
| 997 | br1.bitsRead += uint8(v) |
| 998 | br1.value <<= v & 63 |
| 999 | br2.bitsRead += uint8(v2) |
| 1000 | br2.value <<= v2 & 63 |
| 1001 | buf[stream][off+2] = uint8(v >> 8) |
| 1002 | buf[stream2][off+2] = uint8(v2 >> 8) |
| 1003 | |
| 1004 | v = single[uint8(br1.value>>shift)].entry |
| 1005 | v2 = single[uint8(br2.value>>shift)].entry |
| 1006 | br1.bitsRead += uint8(v) |
| 1007 | br1.value <<= v & 63 |
| 1008 | br2.bitsRead += uint8(v2) |
| 1009 | br2.value <<= v2 & 63 |
| 1010 | buf[stream][off+3] = uint8(v >> 8) |
| 1011 | buf[stream2][off+3] = uint8(v2 >> 8) |
| 1012 | } |
| 1013 | |
| 1014 | { |
| 1015 | const stream = 2 |
| 1016 | const stream2 = 3 |
| 1017 | br1 := &br[stream] |
| 1018 | br2 := &br[stream2] |
| 1019 | br1.fillFast() |
| 1020 | br2.fillFast() |
| 1021 | |
| 1022 | v := single[uint8(br1.value>>shift)].entry |
| 1023 | v2 := single[uint8(br2.value>>shift)].entry |
| 1024 | br1.bitsRead += uint8(v) |
| 1025 | br1.value <<= v & 63 |
| 1026 | br2.bitsRead += uint8(v2) |
| 1027 | br2.value <<= v2 & 63 |
| 1028 | buf[stream][off] = uint8(v >> 8) |
| 1029 | buf[stream2][off] = uint8(v2 >> 8) |
| 1030 | |
| 1031 | v = single[uint8(br1.value>>shift)].entry |
| 1032 | v2 = single[uint8(br2.value>>shift)].entry |
| 1033 | br1.bitsRead += uint8(v) |
| 1034 | br1.value <<= v & 63 |
| 1035 | br2.bitsRead += uint8(v2) |
| 1036 | br2.value <<= v2 & 63 |
| 1037 | buf[stream][off+1] = uint8(v >> 8) |
| 1038 | buf[stream2][off+1] = uint8(v2 >> 8) |
| 1039 | |
| 1040 | v = single[uint8(br1.value>>shift)].entry |
| 1041 | v2 = single[uint8(br2.value>>shift)].entry |
| 1042 | br1.bitsRead += uint8(v) |
| 1043 | br1.value <<= v & 63 |
| 1044 | br2.bitsRead += uint8(v2) |
| 1045 | br2.value <<= v2 & 63 |
| 1046 | buf[stream][off+2] = uint8(v >> 8) |
| 1047 | buf[stream2][off+2] = uint8(v2 >> 8) |
| 1048 | |
| 1049 | v = single[uint8(br1.value>>shift)].entry |
| 1050 | v2 = single[uint8(br2.value>>shift)].entry |
| 1051 | br1.bitsRead += uint8(v) |
| 1052 | br1.value <<= v & 63 |
| 1053 | br2.bitsRead += uint8(v2) |
| 1054 | br2.value <<= v2 & 63 |
| 1055 | buf[stream][off+3] = uint8(v >> 8) |
| 1056 | buf[stream2][off+3] = uint8(v2 >> 8) |
| 1057 | } |
| 1058 | |
| 1059 | off += 4 |
| 1060 | |
| 1061 | if off == 0 { |
| 1062 | if bufoff > dstEvery { |
| 1063 | d.bufs.Put(buf) |
| 1064 | return nil, errors.New("corruption detected: stream overrun 1") |
| 1065 | } |
| 1066 | copy(out, buf[0][:]) |
| 1067 | copy(out[dstEvery:], buf[1][:]) |
| 1068 | copy(out[dstEvery*2:], buf[2][:]) |
| 1069 | copy(out[dstEvery*3:], buf[3][:]) |
| 1070 | out = out[bufoff:] |
| 1071 | decoded += bufoff * 4 |
| 1072 | // There must at least be 3 buffers left. |
| 1073 | if len(out) < dstEvery*3 { |
| 1074 | d.bufs.Put(buf) |
| 1075 | return nil, errors.New("corruption detected: stream overrun 2") |
| 1076 | } |
| 1077 | } |
| 1078 | } |
| 1079 | if off > 0 { |
| 1080 | ioff := int(off) |
| 1081 | if len(out) < dstEvery*3+ioff { |
| 1082 | d.bufs.Put(buf) |
| 1083 | return nil, errors.New("corruption detected: stream overrun 3") |
| 1084 | } |
| 1085 | copy(out, buf[0][:off]) |
| 1086 | copy(out[dstEvery:], buf[1][:off]) |
| 1087 | copy(out[dstEvery*2:], buf[2][:off]) |
| 1088 | copy(out[dstEvery*3:], buf[3][:off]) |
| 1089 | decoded += int(off) * 4 |
| 1090 | out = out[off:] |
| 1091 | } |
| 1092 | |
| 1093 | // Decode remaining. |
| 1094 | for i := range br { |
| 1095 | offset := dstEvery * i |
| 1096 | br := &br[i] |
| 1097 | bitsLeft := int(br.off*8) + int(64-br.bitsRead) |
| 1098 | for bitsLeft > 0 { |
| 1099 | if br.finished() { |
| 1100 | d.bufs.Put(buf) |
| 1101 | return nil, io.ErrUnexpectedEOF |
| 1102 | } |
| 1103 | if br.bitsRead >= 56 { |
| 1104 | if br.off >= 4 { |
| 1105 | v := br.in[br.off-4:] |
| 1106 | v = v[:4] |
| 1107 | low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) |
| 1108 | br.value |= uint64(low) << (br.bitsRead - 32) |
| 1109 | br.bitsRead -= 32 |
| 1110 | br.off -= 4 |
| 1111 | } else { |
| 1112 | for br.off > 0 { |
| 1113 | br.value |= uint64(br.in[br.off-1]) << (br.bitsRead - 8) |
| 1114 | br.bitsRead -= 8 |
| 1115 | br.off-- |
| 1116 | } |
| 1117 | } |
| 1118 | } |
| 1119 | // end inline... |
| 1120 | if offset >= len(out) { |
| 1121 | d.bufs.Put(buf) |
| 1122 | return nil, errors.New("corruption detected: stream overrun 4") |
| 1123 | } |
| 1124 | |
| 1125 | // Read value and increment offset. |
| 1126 | v := single[uint8(br.value>>shift)].entry |
| 1127 | nBits := uint8(v) |
| 1128 | br.advance(nBits) |
| 1129 | bitsLeft -= int(nBits) |
| 1130 | out[offset] = uint8(v >> 8) |
| 1131 | offset++ |
| 1132 | } |
| 1133 | decoded += offset - dstEvery*i |
| 1134 | err = br.close() |
| 1135 | if err != nil { |
| 1136 | d.bufs.Put(buf) |
| 1137 | return nil, err |
| 1138 | } |
| 1139 | } |
| 1140 | d.bufs.Put(buf) |
| 1141 | if dstSize != decoded { |
| 1142 | return nil, errors.New("corruption detected: short output block") |
| 1143 | } |
| 1144 | return dst, nil |
| 1145 | } |
| 1146 | |
| 1147 | // Decompress4X will decompress a 4X encoded stream. |
| 1148 | // The length of the supplied input must match the end of a block exactly. |
| 1149 | // The *capacity* of the dst slice must match the destination size of |
| 1150 | // the uncompressed data exactly. |
| 1151 | func (d *Decoder) decompress4X8bitExactly(dst, src []byte) ([]byte, error) { |
| 1152 | var br [4]bitReaderBytes |
| 1153 | start := 6 |
| 1154 | for i := 0; i < 3; i++ { |
| 1155 | length := int(src[i*2]) | (int(src[i*2+1]) << 8) |
| 1156 | if start+length >= len(src) { |
| 1157 | return nil, errors.New("truncated input (or invalid offset)") |
| 1158 | } |
| 1159 | err := br[i].init(src[start : start+length]) |
| 1160 | if err != nil { |
| 1161 | return nil, err |
| 1162 | } |
| 1163 | start += length |
| 1164 | } |
| 1165 | err := br[3].init(src[start:]) |
| 1166 | if err != nil { |
| 1167 | return nil, err |
| 1168 | } |
| 1169 | |
| 1170 | // destination, offset to match first output |
| 1171 | dstSize := cap(dst) |
| 1172 | dst = dst[:dstSize] |
| 1173 | out := dst |
| 1174 | dstEvery := (dstSize + 3) / 4 |
| 1175 | |
| 1176 | const shift = 56 |
| 1177 | const tlSize = 1 << 8 |
| 1178 | const tlMask = tlSize - 1 |
| 1179 | single := d.dt.single[:tlSize] |
| 1180 | |
| 1181 | // Use temp table to avoid bound checks/append penalty. |
| 1182 | buf := d.buffer() |
| 1183 | var off uint8 |
| 1184 | var decoded int |
| 1185 | |
| 1186 | // Decode 4 values from each decoder/loop. |
| 1187 | const bufoff = 256 |
| 1188 | for { |
| 1189 | if br[0].off < 4 || br[1].off < 4 || br[2].off < 4 || br[3].off < 4 { |
| 1190 | break |
| 1191 | } |
| 1192 | |
| 1193 | { |
| 1194 | // Interleave 2 decodes. |
| 1195 | const stream = 0 |
| 1196 | const stream2 = 1 |
| 1197 | br1 := &br[stream] |
| 1198 | br2 := &br[stream2] |
| 1199 | br1.fillFast() |
| 1200 | br2.fillFast() |
| 1201 | |
| 1202 | v := single[uint8(br1.value>>shift)].entry |
| 1203 | v2 := single[uint8(br2.value>>shift)].entry |
| 1204 | br1.bitsRead += uint8(v) |
| 1205 | br1.value <<= v & 63 |
| 1206 | br2.bitsRead += uint8(v2) |
| 1207 | br2.value <<= v2 & 63 |
| 1208 | buf[stream][off] = uint8(v >> 8) |
| 1209 | buf[stream2][off] = uint8(v2 >> 8) |
| 1210 | |
| 1211 | v = single[uint8(br1.value>>shift)].entry |
| 1212 | v2 = single[uint8(br2.value>>shift)].entry |
| 1213 | br1.bitsRead += uint8(v) |
| 1214 | br1.value <<= v & 63 |
| 1215 | br2.bitsRead += uint8(v2) |
| 1216 | br2.value <<= v2 & 63 |
| 1217 | buf[stream][off+1] = uint8(v >> 8) |
| 1218 | buf[stream2][off+1] = uint8(v2 >> 8) |
| 1219 | |
| 1220 | v = single[uint8(br1.value>>shift)].entry |
| 1221 | v2 = single[uint8(br2.value>>shift)].entry |
| 1222 | br1.bitsRead += uint8(v) |
| 1223 | br1.value <<= v & 63 |
| 1224 | br2.bitsRead += uint8(v2) |
| 1225 | br2.value <<= v2 & 63 |
| 1226 | buf[stream][off+2] = uint8(v >> 8) |
| 1227 | buf[stream2][off+2] = uint8(v2 >> 8) |
| 1228 | |
| 1229 | v = single[uint8(br1.value>>shift)].entry |
| 1230 | v2 = single[uint8(br2.value>>shift)].entry |
| 1231 | br1.bitsRead += uint8(v) |
| 1232 | br1.value <<= v & 63 |
| 1233 | br2.bitsRead += uint8(v2) |
| 1234 | br2.value <<= v2 & 63 |
| 1235 | buf[stream][off+3] = uint8(v >> 8) |
| 1236 | buf[stream2][off+3] = uint8(v2 >> 8) |
| 1237 | } |
| 1238 | |
| 1239 | { |
| 1240 | const stream = 2 |
| 1241 | const stream2 = 3 |
| 1242 | br1 := &br[stream] |
| 1243 | br2 := &br[stream2] |
| 1244 | br1.fillFast() |
| 1245 | br2.fillFast() |
| 1246 | |
| 1247 | v := single[uint8(br1.value>>shift)].entry |
| 1248 | v2 := single[uint8(br2.value>>shift)].entry |
| 1249 | br1.bitsRead += uint8(v) |
| 1250 | br1.value <<= v & 63 |
| 1251 | br2.bitsRead += uint8(v2) |
| 1252 | br2.value <<= v2 & 63 |
| 1253 | buf[stream][off] = uint8(v >> 8) |
| 1254 | buf[stream2][off] = uint8(v2 >> 8) |
| 1255 | |
| 1256 | v = single[uint8(br1.value>>shift)].entry |
| 1257 | v2 = single[uint8(br2.value>>shift)].entry |
| 1258 | br1.bitsRead += uint8(v) |
| 1259 | br1.value <<= v & 63 |
| 1260 | br2.bitsRead += uint8(v2) |
| 1261 | br2.value <<= v2 & 63 |
| 1262 | buf[stream][off+1] = uint8(v >> 8) |
| 1263 | buf[stream2][off+1] = uint8(v2 >> 8) |
| 1264 | |
| 1265 | v = single[uint8(br1.value>>shift)].entry |
| 1266 | v2 = single[uint8(br2.value>>shift)].entry |
| 1267 | br1.bitsRead += uint8(v) |
| 1268 | br1.value <<= v & 63 |
| 1269 | br2.bitsRead += uint8(v2) |
| 1270 | br2.value <<= v2 & 63 |
| 1271 | buf[stream][off+2] = uint8(v >> 8) |
| 1272 | buf[stream2][off+2] = uint8(v2 >> 8) |
| 1273 | |
| 1274 | v = single[uint8(br1.value>>shift)].entry |
| 1275 | v2 = single[uint8(br2.value>>shift)].entry |
| 1276 | br1.bitsRead += uint8(v) |
| 1277 | br1.value <<= v & 63 |
| 1278 | br2.bitsRead += uint8(v2) |
| 1279 | br2.value <<= v2 & 63 |
| 1280 | buf[stream][off+3] = uint8(v >> 8) |
| 1281 | buf[stream2][off+3] = uint8(v2 >> 8) |
| 1282 | } |
| 1283 | |
| 1284 | off += 4 |
| 1285 | |
| 1286 | if off == 0 { |
| 1287 | if bufoff > dstEvery { |
| 1288 | d.bufs.Put(buf) |
| 1289 | return nil, errors.New("corruption detected: stream overrun 1") |
| 1290 | } |
| 1291 | copy(out, buf[0][:]) |
| 1292 | copy(out[dstEvery:], buf[1][:]) |
| 1293 | copy(out[dstEvery*2:], buf[2][:]) |
| 1294 | copy(out[dstEvery*3:], buf[3][:]) |
| 1295 | out = out[bufoff:] |
| 1296 | decoded += bufoff * 4 |
| 1297 | // There must at least be 3 buffers left. |
| 1298 | if len(out) < dstEvery*3 { |
| 1299 | d.bufs.Put(buf) |
| 1300 | return nil, errors.New("corruption detected: stream overrun 2") |
| 1301 | } |
| 1302 | } |
| 1303 | } |
| 1304 | if off > 0 { |
| 1305 | ioff := int(off) |
| 1306 | if len(out) < dstEvery*3+ioff { |
| 1307 | return nil, errors.New("corruption detected: stream overrun 3") |
| 1308 | } |
| 1309 | copy(out, buf[0][:off]) |
| 1310 | copy(out[dstEvery:], buf[1][:off]) |
| 1311 | copy(out[dstEvery*2:], buf[2][:off]) |
| 1312 | copy(out[dstEvery*3:], buf[3][:off]) |
| 1313 | decoded += int(off) * 4 |
| 1314 | out = out[off:] |
| 1315 | } |
| 1316 | |
| 1317 | // Decode remaining. |
| 1318 | for i := range br { |
| 1319 | offset := dstEvery * i |
| 1320 | br := &br[i] |
| 1321 | bitsLeft := int(br.off*8) + int(64-br.bitsRead) |
| 1322 | for bitsLeft > 0 { |
| 1323 | if br.finished() { |
| 1324 | d.bufs.Put(buf) |
| 1325 | return nil, io.ErrUnexpectedEOF |
| 1326 | } |
| 1327 | if br.bitsRead >= 56 { |
| 1328 | if br.off >= 4 { |
| 1329 | v := br.in[br.off-4:] |
| 1330 | v = v[:4] |
| 1331 | low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) |
| 1332 | br.value |= uint64(low) << (br.bitsRead - 32) |
| 1333 | br.bitsRead -= 32 |
| 1334 | br.off -= 4 |
| 1335 | } else { |
| 1336 | for br.off > 0 { |
| 1337 | br.value |= uint64(br.in[br.off-1]) << (br.bitsRead - 8) |
| 1338 | br.bitsRead -= 8 |
| 1339 | br.off-- |
| 1340 | } |
| 1341 | } |
| 1342 | } |
| 1343 | // end inline... |
| 1344 | if offset >= len(out) { |
| 1345 | d.bufs.Put(buf) |
| 1346 | return nil, errors.New("corruption detected: stream overrun 4") |
| 1347 | } |
| 1348 | |
| 1349 | // Read value and increment offset. |
| 1350 | v := single[br.peekByteFast()].entry |
| 1351 | nBits := uint8(v) |
| 1352 | br.advance(nBits) |
| 1353 | bitsLeft -= int(nBits) |
| 1354 | out[offset] = uint8(v >> 8) |
| 1355 | offset++ |
| 1356 | } |
| 1357 | decoded += offset - dstEvery*i |
| 1358 | err = br.close() |
| 1359 | if err != nil { |
| 1360 | d.bufs.Put(buf) |
| 1361 | return nil, err |
| 1362 | } |
| 1363 | } |
| 1364 | d.bufs.Put(buf) |
| 1365 | if dstSize != decoded { |
| 1366 | return nil, errors.New("corruption detected: short output block") |
| 1367 | } |
| 1368 | return dst, nil |
| 1369 | } |
| 1370 | |
| 1371 | // matches will compare a decoding table to a coding table. |
| 1372 | // Errors are written to the writer. |
| 1373 | // Nothing will be written if table is ok. |
| 1374 | func (s *Scratch) matches(ct cTable, w io.Writer) { |
| 1375 | if s == nil || len(s.dt.single) == 0 { |
| 1376 | return |
| 1377 | } |
| 1378 | dt := s.dt.single[:1<<s.actualTableLog] |
| 1379 | tablelog := s.actualTableLog |
| 1380 | ok := 0 |
| 1381 | broken := 0 |
| 1382 | for sym, enc := range ct { |
| 1383 | errs := 0 |
| 1384 | broken++ |
| 1385 | if enc.nBits == 0 { |
| 1386 | for _, dec := range dt { |
| 1387 | if uint8(dec.entry>>8) == byte(sym) { |
| 1388 | fmt.Fprintf(w, "symbol %x has decoder, but no encoder\n", sym) |
| 1389 | errs++ |
| 1390 | break |
| 1391 | } |
| 1392 | } |
| 1393 | if errs == 0 { |
| 1394 | broken-- |
| 1395 | } |
| 1396 | continue |
| 1397 | } |
| 1398 | // Unused bits in input |
| 1399 | ub := tablelog - enc.nBits |
| 1400 | top := enc.val << ub |
| 1401 | // decoder looks at top bits. |
| 1402 | dec := dt[top] |
| 1403 | if uint8(dec.entry) != enc.nBits { |
| 1404 | fmt.Fprintf(w, "symbol 0x%x bit size mismatch (enc: %d, dec:%d).\n", sym, enc.nBits, uint8(dec.entry)) |
| 1405 | errs++ |
| 1406 | } |
| 1407 | if uint8(dec.entry>>8) != uint8(sym) { |
| 1408 | fmt.Fprintf(w, "symbol 0x%x decoder output mismatch (enc: %d, dec:%d).\n", sym, sym, uint8(dec.entry>>8)) |
| 1409 | errs++ |
| 1410 | } |
| 1411 | if errs > 0 { |
| 1412 | fmt.Fprintf(w, "%d errros in base, stopping\n", errs) |
| 1413 | continue |
| 1414 | } |
| 1415 | // Ensure that all combinations are covered. |
| 1416 | for i := uint16(0); i < (1 << ub); i++ { |
| 1417 | vval := top | i |
| 1418 | dec := dt[vval] |
| 1419 | if uint8(dec.entry) != enc.nBits { |
| 1420 | fmt.Fprintf(w, "symbol 0x%x bit size mismatch (enc: %d, dec:%d).\n", vval, enc.nBits, uint8(dec.entry)) |
| 1421 | errs++ |
| 1422 | } |
| 1423 | if uint8(dec.entry>>8) != uint8(sym) { |
| 1424 | fmt.Fprintf(w, "symbol 0x%x decoder output mismatch (enc: %d, dec:%d).\n", vval, sym, uint8(dec.entry>>8)) |
| 1425 | errs++ |
| 1426 | } |
| 1427 | if errs > 20 { |
| 1428 | fmt.Fprintf(w, "%d errros, stopping\n", errs) |
| 1429 | break |
| 1430 | } |
| 1431 | } |
| 1432 | if errs == 0 { |
| 1433 | ok++ |
| 1434 | broken-- |
| 1435 | } |
| 1436 | } |
| 1437 | if broken > 0 { |
| 1438 | fmt.Fprintf(w, "%d broken, %d ok\n", broken, ok) |
| 1439 | } |
| 1440 | } |