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/* @file
* nghttp2 - HTTP/2 C Library
*
* Copyright (c) 2013 Tatsuhiro Tsujikawa
*
* SPDX-License-Identifier: MIT
*/
#ifndef NGHTTP2_HD_HUFFMAN_H
#define NGHTTP2_HD_HUFFMAN_H
#include <config.h>
#include <stdlib.h>
#include <stdint.h>
typedef enum {
/* FSA accepts this state as the end of huffman encoding
sequence. */
NGHTTP2_HUFF_ACCEPTED = 1 << 14,
/* This state emits symbol */
NGHTTP2_HUFF_SYM = 1 << 15,
} nghttp2_huff_decode_flag;
typedef struct {
/* fstate is the current huffman decoding state, which is actually
the node ID of internal huffman tree with
nghttp2_huff_decode_flag OR-ed. We have 257 leaf nodes, but they
are identical to root node other than emitting a symbol, so we
have 256 internal nodes [1..255], inclusive. The node ID 256 is
a special node and it is a terminal state that means decoding
failed. */
uint16_t fstate;
/* symbol if NGHTTP2_HUFF_SYM flag set */
uint8_t sym;
} nghttp2_huff_decode;
typedef nghttp2_huff_decode huff_decode_table_type[16];
typedef struct {
/* fstate is the current huffman decoding state. */
uint16_t fstate;
} nghttp2_hd_huff_decode_context;
typedef struct {
/* The number of bits in this code */
uint32_t nbits;
/* Huffman code aligned to LSB */
uint32_t code;
} nghttp2_huff_sym;
extern const nghttp2_huff_sym huff_sym_table[];
extern const nghttp2_huff_decode huff_decode_table[][16];
#endif /* NGHTTP2_HD_HUFFMAN_H */
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