123 lines
4.4 KiB
C
123 lines
4.4 KiB
C
/* VaptVupt codec — originally Apache-2.0 by Cristian Cezar Moisés
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* Integrated into Zupt — MIT License
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* Copyright (c) 2026 Cristian Cezar Moisés
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* SPDX-License-Identifier: MIT AND Apache-2.0
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*/
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/*
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* VaptVupt — tANS Entropy Codec (v2: sparse header + 4-way interleaved)
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*
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* Standalone: define VV_ANS_STANDALONE to use without VaptVupt.
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* ZUPT-COMPAT: this header has zero VaptVupt dependencies when standalone.
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*
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* v0.6 changes:
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* - Adaptive sparse/dense header (Item 1): 3× smaller on typical data
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* - 4-way interleaved encode/decode (Item 2): ~2.5× faster decode
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*/
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#ifndef VV_ANS_H
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#define VV_ANS_H
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#include <stdint.h>
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#include <stddef.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define VVA_TABLE_LOG 12
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#define VVA_TABLE_SIZE (1 << VVA_TABLE_LOG) /* 4096 */
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#define VVA_MAX_SYMBOL 256
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/* Header format discriminators */
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#define VVA_HDR_SINGLE 0x01 /* Single symbol: 0-bit encoding */
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#define VVA_HDR_SPARSE 0x02 /* ≤32 active symbols: (sym,freq) pairs */
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#define VVA_HDR_DENSE 0x03 /* >32 active symbols: max_sym + freq array */
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/* ZUPT-COMPAT: v0.5 legacy format detected by first byte being 0x00-0xFF
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* without matching any HDR_* code — fall back to old read path. */
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#define VVA_HDR_LEGACY 0x00 /* v0.5 format: [max_sym] [2B×(max_sym+1)] */
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#ifdef VV_ANS_STANDALONE
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typedef enum {
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VVA_OK = 0,
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VVA_ERR_IO = -1,
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VVA_ERR_CORRUPT = -2,
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VVA_ERR_NOMEM = -3,
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VVA_ERR_OVERFLOW = -4,
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VVA_ERR_PARAM = -6,
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} vva_error_t;
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#else
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#include "vaptvupt.h"
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typedef vv_error_t vva_error_t;
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#define VVA_OK VV_OK
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#define VVA_ERR_CORRUPT VV_ERR_CORRUPT
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#define VVA_ERR_NOMEM VV_ERR_NOMEM
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#define VVA_ERR_OVERFLOW VV_ERR_OVERFLOW
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#define VVA_ERR_PARAM VV_ERR_PARAM
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#endif
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typedef struct {
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uint8_t symbol;
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uint8_t nbits;
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uint16_t baseline;
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} vva_dec_entry_t;
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/* ═══ Public API ═══ */
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/* Single-stream encode/decode (tag 'A', backward compat with v0.5) */
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vva_error_t vva_encode(const uint8_t *src, size_t src_len,
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uint8_t *dst, size_t dst_cap, size_t *dst_len);
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vva_error_t vva_decode(const uint8_t *src, size_t src_len,
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uint8_t *dst, size_t dst_cap,
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size_t num_literals, size_t *src_consumed);
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/* 4-way interleaved encode/decode (tag 'I', v0.6+) */
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vva_error_t vva_encode4(const uint8_t *src, size_t src_len,
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uint8_t *dst, size_t dst_cap, size_t *dst_len);
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vva_error_t vva_decode4(const uint8_t *src, size_t src_len,
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uint8_t *dst, size_t dst_cap,
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size_t num_literals, size_t *src_consumed);
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/* Order-1 context model encode/decode (tag 'C', v0.7+)
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* Uses 256 ANS tables — one per previous byte. Contexts with too few
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* observations inherit from the global table. 4 MB decode memory. */
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vva_error_t vva_encode_ctx(const uint8_t *src, size_t src_len,
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uint8_t *dst, size_t dst_cap, size_t *dst_len);
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vva_error_t vva_decode_ctx(const uint8_t *src, size_t src_len,
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uint8_t *dst, size_t dst_cap,
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size_t num_literals, size_t *src_consumed);
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/* ═══ Sequence coding (tag 'S', v0.8+) ═══
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* ZUPT-COMPAT: available when VV_ANS_STANDALONE is defined.
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*
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* Encodes an LZ token stream using 3 ANS tables: literals, match-length
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* codes (36 symbols), and offset codes (24 symbols). Replaces raw varint
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* storage of match metadata, saving 8-15% on typical data.
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*
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* Input token format (from LZ engine):
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* [token: litlen:4|matchlen:4] [litlen_ext] [literal_bytes] [2B offset LE] [matchlen_ext]
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* Output: [3 table headers] [4B seq_count] [4B lit_count] [ANS bitstream]
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*/
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#define VVA_ML_CODES 36 /* Match length code count */
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#define VVA_OF_CODES 27 /* Offset code count: 3 rep + 24 explicit */
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vva_error_t vva_encode_sequences(const uint8_t *tokens, size_t tok_len,
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uint8_t *dst, size_t dst_cap, size_t *dst_len,
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int off_bytes);
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vva_error_t vva_decode_sequences(const uint8_t *src, size_t src_len,
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uint8_t *dst, size_t dst_cap, size_t *dst_len,
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const uint8_t *dst_base);
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static inline size_t vva_bound(size_t src_len) {
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/* Context model header can be up to ~10KB, seq coding adds 3 table headers */
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return 12288 + (src_len * 15 + 7) / 8 + 16;
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* VV_ANS_H */
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