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Diffstat (limited to 'vendor/zune-inflate/src/constants.rs')
-rw-r--r-- | vendor/zune-inflate/src/constants.rs | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/vendor/zune-inflate/src/constants.rs b/vendor/zune-inflate/src/constants.rs new file mode 100644 index 0000000..260fe5b --- /dev/null +++ b/vendor/zune-inflate/src/constants.rs @@ -0,0 +1,156 @@ +use crate::utils::const_min_usize; + +/// Number of symbols in each Huffman code. Note: for the literal/length +/// and offset codes, these are actually the maximum values; a given block +/// might use fewer symbols. +pub const DEFLATE_NUM_PRECODE_SYMS: usize = 19; +pub const DEFLATE_NUM_LITLEN_SYMS: usize = 288; +pub const DEFLATE_NUM_OFFSET_SYMS: usize = 32; + +/// Maximum possible overrun when decoding codeword lengths +pub const DELFATE_MAX_LENS_OVERRUN: usize = 137; + +/// Order which precode lengths are stored +pub static DEFLATE_PRECODE_LENS_PERMUTATION: [u8; DEFLATE_NUM_PRECODE_SYMS] = [ + 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 +]; + +pub const PRECODE_ENOUGH: usize = 128; + +/// Maximum codeword length across all codes. +pub const DEFLATE_MAX_CODEWORD_LENGTH: usize = 15; + +pub const DEFLATE_MAX_OFFSET_CODEWORD_LENGTH: usize = 15; +pub const DEFLATE_MAX_LITLEN_CODEWORD_LENGTH: usize = 15; + +pub const PRECODE_TABLE_BITS: usize = 7; + +pub const LITLEN_TABLE_BITS: usize = 11; +pub const LITLEN_ENOUGH: usize = 2342; +/// Maximum bits found in the lookup table for offsets +/// offsets larger than this require a lookup into a sub-table +pub const OFFSET_TABLEBITS: usize = 8; +/// Note, default libdeflate value is 402, but with 512, +/// we can remove a branch check by simply doing & 511, and I'll take that. +pub const OFFSET_ENOUGH: usize = 512; +/// Maximum number of symbols across all codes +pub const DEFLATE_MAX_NUM_SYMS: usize = 288; + +///Maximum codeword length in bits for each precode +pub const DEFLATE_MAX_PRE_CODEWORD_LEN: u8 = 7; + +/// Format for precode decode table entries, Bits not explicitly contain zeroes +/// +/// 20-16: presym +/// 10-8 Codeword length(not used) +/// Bit 2-0 Codeword length +/// +/// It never has sub-tables since we use PRECODE_TABLEBITS == MAX_PRECODEWORD_LENGTH +/// +/// PRECODE_DECODE_RESULTS contains static parts of the entry for each symbol, +/// make_decode_table_entry produces the final results +pub static PRECODE_DECODE_RESULTS: [u32; 19] = make_precode_static_table(); + +const fn make_precode_static_table() -> [u32; 19] +{ + let mut table: [u32; 19] = [0; 19]; + let mut i = 0; + + while i < 19 + { + table[i] = (i as u32) << 16; + i += 1; + } + + table +} + +/// Presence of a literal entry +pub const HUFFDEC_LITERAL: u32 = 0x80000000; +/// Presence of HUFFDEC_SUITABLE_POINTER or HUFFDEC_END_OF_BLOCK +pub const HUFFDEC_EXCEPTIONAL: u32 = 0x00008000; +/// Pointer entry in the litlen or offset decode table +pub const HUFFDEC_SUITABLE_POINTER: u32 = 0x00004000; +/// End of block entry in litlen decode table +pub const HUFFDEC_END_OF_BLOCK: u32 = 0x00002000; + +#[rustfmt::skip] +#[allow(clippy::zero_prefixed_literal)] +const fn construct_litlen_decode_table() -> [u32; 288] +{ + let mut results: [u32; 288] = [0; 288]; + let mut i = 0; + + while i < 256 + { + results[i] = ((i as u32) << 16) | HUFFDEC_LITERAL; + i += 1; + } + + results[i] = HUFFDEC_EXCEPTIONAL | HUFFDEC_END_OF_BLOCK; + i += 1; + + + let base_and_bits_tables = [ + (003, 0), (004, 0), (005, 0), (006, 0), + (007, 0), (008, 0), (009, 0), (010, 0), + (011, 1), (013, 1), (015, 1), (017, 1), + (019, 2), (023, 2), (027, 2), (031, 2), + (035, 3), (043, 3), (051, 3), (059, 3), + (067, 4), (083, 4), (099, 4), (115, 4), + (131, 5), (163, 5), (195, 5), (227, 5), + (258, 0), (258, 0), (258, 0), + ]; + let mut j = 0; + + while i < 288 + { + let (length_base, extra_bits) = base_and_bits_tables[j]; + results[i] = (length_base << 16) | extra_bits; + + i += 1; + j += 1; + } + + results +} + +const fn entry(base: u32, extra: u32) -> u32 +{ + base << 16 | extra +} + +#[rustfmt::skip] +#[allow(clippy::zero_prefixed_literal)] // the things we do for alignment +pub static OFFSET_DECODE_RESULTS: [u32; 32] = [ + entry(00001, 00), entry(00002, 00), entry(00003, 00), entry(00004, 00), + entry(00005, 01), entry(00007, 01), entry(00009, 02), entry(00013, 02), + entry(00017, 03), entry(00025, 03), entry(00033, 04), entry(00049, 04), + entry(00065, 05), entry(00097, 05), entry(00129, 06), entry(00193, 06), + entry(00257, 07), entry(00385, 07), entry(00513, 08), entry(00769, 08), + entry(01025, 09), entry(01537, 09), entry(02049, 10), entry(03073, 10), + entry(04097, 11), entry(06145, 11), entry(08193, 12), entry(12289, 12), + entry(16385, 13), entry(24577, 13), entry(24577, 13), entry(24577, 13), +]; + +pub static LITLEN_DECODE_RESULTS: [u32; 288] = construct_litlen_decode_table(); + +pub const DEFLATE_BLOCKTYPE_DYNAMIC_HUFFMAN: u64 = 2; + +pub const DEFLATE_BLOCKTYPE_UNCOMPRESSED: u64 = 0; +pub const DEFLATE_BLOCKTYPE_RESERVED: u64 = 3; + +pub const DEFLATE_BLOCKTYPE_STATIC: u64 = 1; + +pub const LITLEN_DECODE_BITS: usize = + const_min_usize(DEFLATE_MAX_LITLEN_CODEWORD_LENGTH, LITLEN_TABLE_BITS); + +/// Maximum length of a deflate match +pub const DEFLATE_MAX_MATCH_LEN: usize = 258; + +/// Number of bytes copied per every loop +pub const FASTCOPY_BYTES: usize = 16; + +/// Worst case maximum number of output bytes writtern during each iteration of the +/// fastloop. +pub const FASTLOOP_MAX_BYTES_WRITTEN: usize = 6 + DEFLATE_MAX_MATCH_LEN + (2 * FASTCOPY_BYTES); |