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nghttp2/lib/nghttp2_hd_huffman.h

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+/*
+ * 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 << 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 */