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