Import libcds.

[SXSI/libcds.git] / src / coders / huff.h

diff --git a/src/coders/huff.h b/src/coders/huff.h
new file mode 100644 (file)
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+/* huff.h
+   Copyright (C) 2008, Gonzalo Navarro, all rights reserved.
+
+   Canonical Huffman
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   This library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this library; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+#ifndef HUFFINCLUDED
+#define HUFFINCLUDED
+
+#include <basics.h>
+
+typedef struct
+   { uint max,lim;   // maximum symbol (0..max), same excluding zero freqs
+     uint depth; // max symbol length
+     union
+       { uint *spos; // symbol positions after sorting by decr freq (enc)
+        uint *symb; // symbols sorted by freq (dec)
+       } s;
+     uint *num;  // first pos of each length (dec), number of each length (enc)
+     uint *fst;  // first code (numeric) of each length (dec)
+     ulong total; // total length to achieve, in bits
+   } THuff;
+
+
+/** Creates Huffman encoder given symbols 0..lim with frequencies 
+ *  freq[i], ready for compression 
+ * 
+ *  @author Gonzalo Navarro
+ */
+THuff createHuff (uint *freq, uint lim);
+
+/** Encodes symb using H, over stream[ptr...lim] (ptr and lim are
+ *  bit positions of stream). Returns the new ptr. 
+ * 
+ *  @author Gonzalo Navarro
+ */
+ulong encodeHuff (THuff H, uint symb, uint *stream, ulong ptr);
+
+/** Decodes *symb using H, over stream[ptr...lim] (ptr and lim are
+ *  bit positions of stream). Returns the new ptr. 
+ * 
+ *  @author Gonzalo Navarro
+ */
+ulong decodeHuff (THuff H, uint *symb, uint *stream, ulong ptr);
+
+/** Writes H in file f 
+ * 
+ *  @author Gonzalo Navarro
+ */
+void saveHuff (THuff H, FILE *f);
+
+/** Size of H written on file 
+ * 
+ *  @author Gonzalo Navarro
+ */
+uint sizeHuff (THuff H);
+
+/** Frees H 
+ * 
+ *  @author Gonzalo Navarro
+ */    
+void freeHuff (THuff H);
+
+/** Loads H from file f, prepared for encoding or decoding depending
+ *  on enc 
+ * 
+ *  @author Gonzalo Navarro
+ */
+THuff loadHuff (FILE *f, int enc);
+
+#endif