mirror of https://github.com/AxioDL/lzokay.git
77 lines
2.3 KiB
C++
77 lines
2.3 KiB
C++
#pragma once
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#include <cstddef>
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#include <cstdint>
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#include <memory>
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namespace lzokay {
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enum class EResult {
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LookbehindOverrun = -4,
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OutputOverrun = -3,
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InputOverrun = -2,
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Error = -1,
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Success = 0,
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InputNotConsumed = 1,
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};
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class DictBase {
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protected:
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static constexpr uint32_t HashSize = 0x4000;
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static constexpr uint32_t MaxDist = 0xbfff;
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static constexpr uint32_t MaxMatchLen = 0x800;
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static constexpr uint32_t BufSize = MaxDist + MaxMatchLen;
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/* List encoding of previous 3-byte data matches */
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struct Match3 {
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uint16_t head[HashSize]; /* key -> chain-head-pos */
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uint16_t chain_sz[HashSize]; /* key -> chain-size */
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uint16_t chain[BufSize]; /* chain-pos -> next-chain-pos */
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uint16_t best_len[BufSize]; /* chain-pos -> best-match-length */
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};
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/* Encoding of 2-byte data matches */
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struct Match2 {
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uint16_t head[1 << 16]; /* 2-byte-data -> head-pos */
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};
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struct Data {
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Match3 match3;
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Match2 match2;
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/* Circular buffer caching enough data to access the maximum lookback
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* distance of 48K + maximum match length of 2K. An additional 2K is
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* allocated so the start of the buffer may be replicated at the end,
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* therefore providing efficient circular access.
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*/
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uint8_t buffer[BufSize + MaxMatchLen];
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};
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using storage_type = Data;
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storage_type* _storage;
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DictBase() = default;
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friend struct State;
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friend EResult compress(const uint8_t* src, std::size_t src_size,
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uint8_t* dst, std::size_t& dst_size, DictBase& dict);
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};
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template <template<typename> class _Alloc = std::allocator>
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class Dict : public DictBase {
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_Alloc<DictBase::storage_type> _allocator;
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public:
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Dict() { _storage = _allocator.allocate(1); }
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~Dict() { _allocator.deallocate(_storage, 1); }
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};
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EResult decompress(const uint8_t* src, std::size_t src_size,
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uint8_t* dst, std::size_t& dst_size);
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EResult compress(const uint8_t* src, std::size_t src_size,
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uint8_t* dst, std::size_t& dst_size, DictBase& dict);
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inline EResult compress(const uint8_t* src, std::size_t src_size,
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uint8_t* dst, std::size_t& dst_size) {
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Dict<> dict;
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return compress(src, src_size, dst, dst_size, dict);
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}
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constexpr std::size_t compress_worst_size(std::size_t s) {
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return s + s / 16 + 64 + 3;
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}
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}
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