use crate::decompress::{EXCEPTIONAL_ENTRY, LITERAL_ENTRY}; /// Hard-coded Huffman codes used regardless of the input. /// /// These values work well for PNGs with some form of filtering enabled, but will likely make most /// other inputs worse. pub(crate) const HUFFMAN_LENGTHS: [u8; 286] = [ 2, 3, 4, 5, 5, 6, 6, 7, 7, 7, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 10, 11, 10, 10, 10, 10, 10, 10, 10, 10, 10, 9, 9, 9, 9, 9, 8, 9, 8, 8, 8, 8, 8, 7, 7, 7, 6, 6, 6, 5, 4, 3, 12, 12, 12, 9, 9, 11, 10, 11, 11, 10, 11, 11, 11, 11, 11, 11, 12, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 9, ]; pub(crate) const HUFFMAN_CODES: [u16; 286] = match crate::compute_codes(&HUFFMAN_LENGTHS) { Some(codes) => codes, None => panic!("HUFFMAN_LENGTHS is invalid"), }; /// Length code for length values (derived from deflate spec). pub(crate) const LENGTH_TO_SYMBOL: [u16; 256] = [ 257, 258, 259, 260, 261, 262, 263, 264, 265, 265, 266, 266, 267, 267, 268, 268, 269, 269, 269, 269, 270, 270, 270, 270, 271, 271, 271, 271, 272, 272, 272, 272, 273, 273, 273, 273, 273, 273, 273, 273, 274, 274, 274, 274, 274, 274, 274, 274, 275, 275, 275, 275, 275, 275, 275, 275, 276, 276, 276, 276, 276, 276, 276, 276, 277, 277, 277, 277, 277, 277, 277, 277, 277, 277, 277, 277, 277, 277, 277, 277, 278, 278, 278, 278, 278, 278, 278, 278, 278, 278, 278, 278, 278, 278, 278, 278, 279, 279, 279, 279, 279, 279, 279, 279, 279, 279, 279, 279, 279, 279, 279, 279, 280, 280, 280, 280, 280, 280, 280, 280, 280, 280, 280, 280, 280, 280, 280, 280, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 281, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 282, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 283, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 285, ]; /// Number of extra bits for length values (derived from deflate spec). pub(crate) const LENGTH_TO_LEN_EXTRA: [u8; 256] = [ 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 0, ]; pub(crate) const BITMASKS: [u32; 17] = [ 0x0000, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF, 0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, ]; /// Order of the length code length alphabet (derived from deflate spec). pub(crate) const CLCL_ORDER: [usize; 19] = [ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15, ]; /// Number of extra bits for each length code (derived from deflate spec). pub(crate) const LEN_SYM_TO_LEN_EXTRA: [u8; 29] = [ 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, ]; /// The base length for each length code (derived from deflate spec). pub(crate) const LEN_SYM_TO_LEN_BASE: [usize; 29] = [ 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, ]; /// Number of extra bits for each distance code (derived from deflate spec.) pub(crate) const DIST_SYM_TO_DIST_EXTRA: [u8; 30] = [ 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, ]; /// The base distance for each distance code (derived from deflate spec). pub(crate) const DIST_SYM_TO_DIST_BASE: [u16; 30] = [ 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577, ]; /// The main litlen_table uses a 12-bit input to lookup the meaning of the symbol. The table is /// split into 4 sections: /// /// aaaaaaaa_bbbbbbbb_1000yyyy_0000xxxx x = input_advance_bits, y = output_advance_bytes (literal) /// 0000000z_zzzzzzzz_00000yyy_0000xxxx x = input_advance_bits, y = extra_bits, z = distance_base (length) /// 00000000_00000000_01000000_0000xxxx x = input_advance_bits (EOF) /// 0000xxxx_xxxxxxxx_01100000_00000000 x = secondary_table_index /// 00000000_00000000_01000000_00000000 invalid code pub(crate) const LITLEN_TABLE_ENTRIES: [u32; 288] = { let mut entries = [EXCEPTIONAL_ENTRY; 288]; let mut i = 0; while i < 256 { entries[i] = (i as u32) << 16 | LITERAL_ENTRY | (1 << 8); i += 1; } let mut i = 257; while i < 286 { entries[i] = (LEN_SYM_TO_LEN_BASE[i - 257] as u32) << 16 | (LEN_SYM_TO_LEN_EXTRA[i - 257] as u32) << 8; i += 1; } entries }; /// The distance table is a 512-entry table that maps 9 bits of distance symbols to their meaning. /// /// 00000000_00000000_00000000_00000000 symbol is more than 9 bits /// zzzzzzzz_zzzzzzzz_0000yyyy_0000xxxx x = input_advance_bits, y = extra_bits, z = distance_base pub(crate) const DISTANCE_TABLE_ENTRIES: [u32; 32] = { let mut entries = [0; 32]; let mut i = 0; while i < 30 { entries[i] = (DIST_SYM_TO_DIST_BASE[i] as u32) << 16 | (DIST_SYM_TO_DIST_EXTRA[i] as u32) << 8 | LITERAL_ENTRY; i += 1; } entries }; pub(crate) const FIXED_LITLEN_TABLE: [u32; 512] = [ 16391, 5275912, 1081608, 7537672, 2032135, 7373064, 3178760, 12615945, 655367, 6324488, 2130184, 10518793, 33032, 8421640, 4227336, 14713097, 393223, 5800200, 1605896, 9470217, 3867399, 7897352, 3703048, 13664521, 1114375, 6848776, 2654472, 11567369, 557320, 8945928, 4751624, 15761673, 262151, 5538056, 1343752, 14877960, 2818823, 7635208, 3440904, 13140233, 852231, 6586632, 2392328, 11043081, 295176, 8683784, 4489480, 15237385, 524295, 6062344, 1868040, 9994505, 5440519, 8159496, 3965192, 14188809, 1507847, 7110920, 2916616, 12091657, 819464, 9208072, 5013768, 16285961, 196615, 5406984, 1212680, 10683656, 2294535, 7504136, 3309832, 12878089, 721159, 6455560, 2261256, 10780937, 164104, 8552712, 4358408, 14975241, 458759, 5931272, 1736968, 9732361, 4391943, 8028424, 3834120, 13926665, 1245703, 6979848, 2785544, 11829513, 688392, 9077000, 4882696, 16023817, 327687, 5669128, 1474824, 16392, 3343111, 7766280, 3571976, 13402377, 983303, 6717704, 2523400, 11305225, 426248, 8814856, 4620552, 15499529, 589831, 6193416, 1999112, 10256649, 6489095, 8290568, 4096264, 14450953, 1769991, 7241992, 3047688, 12353801, 950536, 9339144, 5144840, 16548105, 16391, 5341448, 1147144, 8586504, 2032135, 7438600, 3244296, 12747017, 655367, 6390024, 2195720, 10649865, 98568, 8487176, 4292872, 14844169, 393223, 5865736, 1671432, 9601289, 3867399, 7962888, 3768584, 13795593, 1114375, 6914312, 2720008, 11698441, 622856, 9011464, 4817160, 15892745, 262151, 5603592, 1409288, 16908296, 2818823, 7700744, 3506440, 13271305, 852231, 6652168, 2457864, 11174153, 360712, 8749320, 4555016, 15368457, 524295, 6127880, 1933576, 10125577, 5440519, 8225032, 4030728, 14319881, 1507847, 7176456, 2982152, 12222729, 885000, 9273608, 5079304, 16417033, 196615, 5472520, 1278216, 12780808, 2294535, 7569672, 3375368, 13009161, 721159, 6521096, 2326792, 10912009, 229640, 8618248, 4423944, 15106313, 458759, 5996808, 1802504, 9863433, 4391943, 8093960, 3899656, 14057737, 1245703, 7045384, 2851080, 11960585, 753928, 9142536, 4948232, 16154889, 327687, 5734664, 1540360, 16392, 3343111, 7831816, 3637512, 13533449, 983303, 6783240, 2588936, 11436297, 491784, 8880392, 4686088, 15630601, 589831, 6258952, 2064648, 10387721, 6489095, 8356104, 4161800, 14582025, 1769991, 7307528, 3113224, 12484873, 1016072, 9404680, 5210376, 16679177, 16391, 5275912, 1081608, 7537672, 2032135, 7373064, 3178760, 12681481, 655367, 6324488, 2130184, 10584329, 33032, 8421640, 4227336, 14778633, 393223, 5800200, 1605896, 9535753, 3867399, 7897352, 3703048, 13730057, 1114375, 6848776, 2654472, 11632905, 557320, 8945928, 4751624, 15827209, 262151, 5538056, 1343752, 14877960, 2818823, 7635208, 3440904, 13205769, 852231, 6586632, 2392328, 11108617, 295176, 8683784, 4489480, 15302921, 524295, 6062344, 1868040, 10060041, 5440519, 8159496, 3965192, 14254345, 1507847, 7110920, 2916616, 12157193, 819464, 9208072, 5013768, 16351497, 196615, 5406984, 1212680, 10683656, 2294535, 7504136, 3309832, 12943625, 721159, 6455560, 2261256, 10846473, 164104, 8552712, 4358408, 15040777, 458759, 5931272, 1736968, 9797897, 4391943, 8028424, 3834120, 13992201, 1245703, 6979848, 2785544, 11895049, 688392, 9077000, 4882696, 16089353, 327687, 5669128, 1474824, 16392, 3343111, 7766280, 3571976, 13467913, 983303, 6717704, 2523400, 11370761, 426248, 8814856, 4620552, 15565065, 589831, 6193416, 1999112, 10322185, 6489095, 8290568, 4096264, 14516489, 1769991, 7241992, 3047688, 12419337, 950536, 9339144, 5144840, 16613641, 16391, 5341448, 1147144, 8586504, 2032135, 7438600, 3244296, 12812553, 655367, 6390024, 2195720, 10715401, 98568, 8487176, 4292872, 14909705, 393223, 5865736, 1671432, 9666825, 3867399, 7962888, 3768584, 13861129, 1114375, 6914312, 2720008, 11763977, 622856, 9011464, 4817160, 15958281, 262151, 5603592, 1409288, 16908296, 2818823, 7700744, 3506440, 13336841, 852231, 6652168, 2457864, 11239689, 360712, 8749320, 4555016, 15433993, 524295, 6127880, 1933576, 10191113, 5440519, 8225032, 4030728, 14385417, 1507847, 7176456, 2982152, 12288265, 885000, 9273608, 5079304, 16482569, 196615, 5472520, 1278216, 12780808, 2294535, 7569672, 3375368, 13074697, 721159, 6521096, 2326792, 10977545, 229640, 8618248, 4423944, 15171849, 458759, 5996808, 1802504, 9928969, 4391943, 8093960, 3899656, 14123273, 1245703, 7045384, 2851080, 12026121, 753928, 9142536, 4948232, 16220425, 327687, 5734664, 1540360, 16392, 3343111, 7831816, 3637512, 13598985, 983303, 6783240, 2588936, 11501833, 491784, 8880392, 4686088, 15696137, 589831, 6258952, 2064648, 10453257, 6489095, 8356104, 4161800, 14647561, 1769991, 7307528, 3113224, 12550409, 1016072, 9404680, 5210376, 16744713, ]; pub(crate) const FIXED_DIST_TABLE: [u32; 32] = [ 98309, 16877317, 1147653, 268536581, 360709, 67209477, 4293893, 1073843461, 229381, 33654789, 2196485, 536972293, 623109, 134318597, 8488453, 5, 163845, 25265925, 1671941, 402754309, 491781, 100763909, 6391045, 1610714373, 294917, 50432005, 3245061, 805407749, 885253, 201427461, 12682757, 5, ]; #[cfg(test)] pub(crate) const FIXED_CODE_LENGTHS: [u8; 320] = make_fixed_code_lengths(); #[cfg(test)] const fn make_fixed_code_lengths() -> [u8; 320] { let mut i = 0; let mut lengths = [0; 320]; while i < 144 { lengths[i] = 8; i += 1; } while i < 256 { lengths[i] = 9; i += 1; } while i < 280 { lengths[i] = 7; i += 1; } while i < 288 { lengths[i] = 8; i += 1; } while i < 320 { lengths[i] = 5; i += 1; } lengths }