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 34 typedef 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 42 typedef 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 55 typedef nghttp2_huff_decode huff_decode_table_type[16]; 56 57 typedef struct { 58 /* fstate is the current huffman decoding state. */ 59 uint16_t fstate; 60 } nghttp2_hd_huff_decode_context; 61 62 typedef 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 69 extern const nghttp2_huff_sym huff_sym_table[]; 70 extern const nghttp2_huff_decode huff_decode_table[][16]; 71 72 #endif /* NGHTTP2_HD_HUFFMAN_H */ 73