1/*
2 * nghttp2 - HTTP/2 C Library
3 *
4 * Copyright (c) 2013 Tatsuhiro Tsujikawa
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining
7 * a copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sublicense, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be
15 * included in all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
21 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
22 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
23 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
24 */
25#ifndef NGHTTP2_HD_HUFFMAN_H
26#define NGHTTP2_HD_HUFFMAN_H
27
28#ifdef HAVE_CONFIG_H
29#  include <config.h>
30#endif /* HAVE_CONFIG_H */
31
32#include <nghttp2/nghttp2.h>
33
34typedef enum {
35  /* FSA accepts this state as the end of huffman encoding
36     sequence. */
37  NGHTTP2_HUFF_ACCEPTED = 1 << 14,
38  /* This state emits symbol */
39  NGHTTP2_HUFF_SYM = 1 << 15,
40} nghttp2_huff_decode_flag;
41
42typedef struct {
43  /* fstate is the current huffman decoding state, which is actually
44     the node ID of internal huffman tree with
45     nghttp2_huff_decode_flag OR-ed.  We have 257 leaf nodes, but they
46     are identical to root node other than emitting a symbol, so we
47     have 256 internal nodes [1..255], inclusive.  The node ID 256 is
48     a special node and it is a terminal state that means decoding
49     failed. */
50  uint16_t fstate;
51  /* symbol if NGHTTP2_HUFF_SYM flag set */
52  uint8_t sym;
53} nghttp2_huff_decode;
54
55typedef nghttp2_huff_decode huff_decode_table_type[16];
56
57typedef struct {
58  /* fstate is the current huffman decoding state. */
59  uint16_t fstate;
60} nghttp2_hd_huff_decode_context;
61
62typedef struct {
63  /* The number of bits in this code */
64  uint32_t nbits;
65  /* Huffman code aligned to LSB */
66  uint32_t code;
67} nghttp2_huff_sym;
68
69extern const nghttp2_huff_sym huff_sym_table[];
70extern const nghttp2_huff_decode huff_decode_table[][16];
71
72#endif /* NGHTTP2_HD_HUFFMAN_H */
73