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Precompute fixed huffman tables #39

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Nov 30, 2024
Merged

Precompute fixed huffman tables #39

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275afc9
Use precomputed tables for fixed huffman blocks
fintelia Nov 30, 2024
eb0e59e
Use Box for decoding tables
fintelia Nov 30, 2024
6241510
Fix test
fintelia Nov 30, 2024
50d4d46
Formatting
fintelia Nov 30, 2024
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42 changes: 32 additions & 10 deletions src/decompress.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,8 @@ use simd_adler32::Adler32;
use crate::{
huffman::{self, build_table},
tables::{
self, CLCL_ORDER, DIST_SYM_TO_DIST_BASE, DIST_SYM_TO_DIST_EXTRA, FIXED_CODE_LENGTHS,
LEN_SYM_TO_LEN_BASE, LEN_SYM_TO_LEN_EXTRA, LITLEN_TABLE_ENTRIES,
self, CLCL_ORDER, DIST_SYM_TO_DIST_BASE, DIST_SYM_TO_DIST_EXTRA, FIXED_DIST_TABLE,
FIXED_LITLEN_TABLE, LEN_SYM_TO_LEN_BASE, LEN_SYM_TO_LEN_EXTRA, LITLEN_TABLE_ENTRIES,
},
};

Expand Down Expand Up @@ -62,13 +62,12 @@ pub const EXCEPTIONAL_ENTRY: u32 = 0x4000;
pub const SECONDARY_TABLE_ENTRY: u32 = 0x2000;

/// The Decompressor state for a compressed block.
#[repr(align(64))]
#[derive(Eq, PartialEq, Debug)]
struct CompressedBlock {
litlen_table: [u32; 4096],
litlen_table: Box<[u32; 4096]>,
secondary_table: Vec<u16>,

dist_table: [u32; 512],
dist_table: Box<[u32; 512]>,
dist_secondary_table: Vec<u16>,

eof_code: u16,
Expand Down Expand Up @@ -123,8 +122,8 @@ impl Decompressor {
buffer: 0,
nbits: 0,
compression: CompressedBlock {
litlen_table: [0; 4096],
dist_table: [0; 512],
litlen_table: Box::new([0; 4096]),
dist_table: Box::new([0; 512]),
secondary_table: Vec::new(),
dist_secondary_table: Vec::new(),
eof_code: 0,
Expand Down Expand Up @@ -237,7 +236,12 @@ impl Decompressor {
// Build decoding tables if the previous block wasn't also a fixed block.
if !self.fixed_table {
self.fixed_table = true;
Self::build_tables(288, &FIXED_CODE_LENGTHS, &mut self.compression)?;
for chunk in self.compression.litlen_table.chunks_exact_mut(512) {
chunk.copy_from_slice(&FIXED_LITLEN_TABLE);
}
for chunk in self.compression.dist_table.chunks_exact_mut(32) {
chunk.copy_from_slice(&FIXED_DIST_TABLE);
}
}

self.state = State::CompressedData;
Expand Down Expand Up @@ -405,7 +409,7 @@ impl Decompressor {
&code_lengths[..hlit],
&LITLEN_TABLE_ENTRIES,
&mut codes[..hlit],
&mut compression.litlen_table,
&mut *compression.litlen_table,
&mut compression.secondary_table,
false,
true,
Expand All @@ -427,7 +431,7 @@ impl Decompressor {
lengths,
&tables::DISTANCE_TABLE_ENTRIES,
&mut dist_codes,
&mut compression.dist_table,
&mut *compression.dist_table,
&mut compression.dist_secondary_table,
true,
false,
Expand Down Expand Up @@ -1154,6 +1158,23 @@ mod tests {
}
}

#[test]
fn fixed_tables() {
let mut compression = CompressedBlock {
litlen_table: Box::new([0; 4096]),
dist_table: Box::new([0; 512]),
secondary_table: Vec::new(),
dist_secondary_table: Vec::new(),
eof_code: 0,
eof_mask: 0,
eof_bits: 0,
};
Decompressor::build_tables(288, &FIXED_CODE_LENGTHS, &mut compression).unwrap();

assert_eq!(compression.litlen_table[..512], FIXED_LITLEN_TABLE);
assert_eq!(compression.dist_table[..32], FIXED_DIST_TABLE);
}

#[test]
fn it_works() {
roundtrip(b"Hello world!");
Expand Down Expand Up @@ -1259,6 +1280,7 @@ mod tests {
}

mod test_utils;
use tables::FIXED_CODE_LENGTHS;
use test_utils::{decompress_by_chunks, TestDecompressionError};

fn verify_no_sensitivity_to_input_chunking(
Expand Down
65 changes: 65 additions & 0 deletions src/tables.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -128,7 +128,72 @@ pub(crate) const DISTANCE_TABLE_ENTRIES: [u32; 32] = {
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];
Expand Down