nghttp2/lib/nghttp2_hd_huffman.h

75 lines
2.5 KiB
C

/*
* nghttp2 - HTTP/2 C Library
*
* Copyright (c) 2013 Tatsuhiro Tsujikawa
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef NGHTTP2_HD_HUFFMAN_H
#define NGHTTP2_HD_HUFFMAN_H
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif /* HAVE_CONFIG_H */
#include <nghttp2/nghttp2.h>
typedef enum {
/* FSA accepts this state as the end of huffman encoding
sequence. */
NGHTTP2_HUFF_ACCEPTED = 1,
/* This state emits symbol */
NGHTTP2_HUFF_SYM = (1 << 1),
/* If state machine reaches this state, decoding fails. */
NGHTTP2_HUFF_FAIL = (1 << 2)
} nghttp2_huff_decode_flag;
typedef struct {
/* huffman decoding state, which is actually the node ID of internal
huffman tree. 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. */
uint8_t state;
/* bitwise OR of zero or more of the nghttp2_huff_decode_flag */
uint8_t flags;
/* symbol if NGHTTP2_HUFF_SYM flag set */
uint8_t sym;
} nghttp2_huff_decode;
typedef nghttp2_huff_decode huff_decode_table_type[16];
typedef struct {
/* Current huffman decoding state. We stripped leaf nodes, so the
value range is [0..255], inclusive. */
uint8_t state;
/* nonzero if we can say that the decoding process succeeds at this
state */
uint8_t accept;
} 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;
#endif /* NGHTTP2_HD_HUFFMAN_H */