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comparison: sources/huffman/huffman.cpp

sources/huffman/huffman.cpp

changeset 76
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parent 75
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child 77
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75:5f8a03274d75 76:6de6d9a64ebd
1 /*
2 * Replacement for older Skulltag Launcher Protocol's huffman.cpp
3 *
4 * Copyright 2009 Timothy Landers
5 * email: code.vortexcortex@gmail.com
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
24 */
25
26 // required for atexit()
27 #include <stdlib.h>
28 #include <stdio.h>
29
30 #include "huffman.h"
31 #include "huffcodec.h"
32 // #include "i_system.h"
33
34 using namespace skulltag;
35 // Global Variables
36
37 /** Reference to the HuffmanCodec Object that will perform the encoding and decoding. */
38 static HuffmanCodec * __codec = NULL;
39
40 // Function Implementation
41
42 /** Creates and intitializes a HuffmanCodec Object. <br>
43 * Also arranges for HUFFMAN_Destruct() to be called upon termination. */
44 void HUFFMAN_Construct(){
45
46 // The exact structure description of a Huffman tree
47 static unsigned char const compatible_huffman_tree[] = {
48 0, 0, 0, 1,128, 0, 0, 0, 3, 38, 34, 2, 1, 80, 3,110,
49 144, 67, 0, 2, 1, 74, 3,243,142, 37, 2, 3,124, 58,182, 0,
50 0, 1, 36, 0, 3,221,131, 3,245,163, 1, 35, 3,113, 85, 0,
51 1, 41, 1, 77, 3,199,130, 0, 1,206, 3,185,153, 3, 70,118,
52 0, 3, 3, 5, 0, 0, 1, 24, 0, 2, 3,198,190, 63, 2, 3,
53 139,186, 75, 0, 1, 44, 2, 3,240,218, 56, 3, 40, 39, 0, 0,
54 2, 2, 3,244,247, 81, 65, 0, 3, 9,125, 3, 68, 60, 0, 0,
55 1, 25, 3,191,138, 3, 86, 17, 0, 1, 23, 3,220,178, 2, 3,
56 165,194, 14, 1, 0, 2, 2, 0, 0, 2, 1,208, 3,150,157,181,
57 1,222, 2, 3,216,230,211, 0, 2, 2, 3,252,141, 10, 42, 0,
58 2, 3,134,135,104, 1,103, 3,187,225, 95, 32, 0, 0, 0, 0,
59 0, 0, 1, 57, 1, 61, 3,183,237, 0, 0, 3,233,234, 3,246,
60 203, 2, 3,250,147, 79, 1,129, 0, 1, 7, 3,143,136, 1, 20,
61 3,179,148, 0, 0, 0, 3, 28,106, 3,101, 87, 1, 66, 0, 3,
62 180,219, 3,227,241, 0, 1, 26, 1,251, 3,229,214, 3, 54, 69,
63 0, 0, 0, 0, 0, 3,231,212, 3,156,176, 3, 93, 83, 0, 3,
64 96,253, 3, 30, 13, 0, 0, 2, 3,175,254, 94, 3,159, 27, 2,
65 1, 8, 3,204,226, 78, 0, 0, 0, 3,107, 88, 1, 31, 3,137,
66 169, 2, 2, 3,215,145, 6, 4, 1,127, 0, 1, 99, 3,209,217,
67 0, 3,213,238, 3,177,170, 1,132, 0, 0, 0, 2, 3, 22, 12,
68 114, 2, 2, 3,158,197, 97, 45, 0, 1, 46, 1,112, 3,174,249,
69 0, 3,224,102, 2, 3,171,151,193, 0, 0, 0, 3, 15, 16, 3,
70 2,168, 1, 49, 3, 91,146, 0, 1, 48, 3,173, 29, 0, 3, 19,
71 126, 3, 92,242, 0, 0, 0, 0, 0, 0, 3,205,192, 2, 3,235,
72 149,255, 2, 3,223,184,248, 0, 0, 3,108,236, 3,111, 90, 2,
73 3,117,115, 71, 0, 0, 3, 11, 50, 0, 3,188,119, 1,122, 3,
74 167,162, 1,160, 1,133, 3,123, 21, 0, 0, 2, 1, 59, 2, 3,
75 155,154, 98, 43, 0, 3, 76, 51, 2, 3,201,116, 72, 2, 0, 2,
76 3,109,100,121, 2, 3,195,232, 18, 1, 0, 2, 0, 1,164, 2,
77 3,120,189, 73, 0, 1,196, 3,239,210, 3, 64, 62, 89, 0, 0,
78 1, 33, 2, 3,228,161, 55, 2, 3, 84,152, 47, 0, 0, 2, 3,
79 207,172,140, 3, 82,166, 0, 3, 53,105, 1, 52, 3,202,200
80 };
81
82 // create a HuffmanCodec that is compatible with the previous implementation.
83 __codec = new HuffmanCodec( compatible_huffman_tree, sizeof compatible_huffman_tree );
84
85 // set up the HuffmanCodec to perform in a backwards compatible fashion.
86 __codec->reversedBytes( true );
87 __codec->allowExpansion( false );
88
89 // request that the destruct function be called upon exit.
90 // atterm( HUFFMAN_Destruct );
91 atexit( HUFFMAN_Destruct );
92 }
93
94 /** Releases resources allocated by the HuffmanCodec. */
95 void HUFFMAN_Destruct(){
96 delete __codec;
97 __codec = NULL;
98 }
99
100 /** Applies Huffman encoding to a block of data. */
101 void HUFFMAN_Encode(
102 /** in: Pointer to start of data that is to be encoded. */
103 unsigned char const * const inputBuffer,
104 /** out: Pointer to destination buffer where encoded data will be stored. */
105 unsigned char * const outputBuffer,
106 /** in: Number of chars to read from inputBuffer. */
107 int const &inputBufferSize,
108 /**< in+out: Max chars to write into outputBuffer. <br>
109 * Upon return holds the number of chars stored or 0 if an error occurs. */
110 int * outputBufferSize
111 ){
112 int bytesWritten = __codec->encode( inputBuffer, outputBuffer, inputBufferSize, *outputBufferSize );
113
114 // expansion occured -- provide backwards compatibility
115 if ( bytesWritten < 0 ){
116 // check buffer sizes
117 if ( *outputBufferSize < (inputBufferSize + 1) ){
118 // outputBuffer too small, return "no bytes written"
119 *outputBufferSize = 0;
120 return;
121 }
122
123 // perform the unencoded copy
124 for ( int i = 0; i < inputBufferSize; i++ ) outputBuffer[i+1] = inputBuffer[i];
125 // supply the "unencoded" signal and bytesWritten
126 outputBuffer[0] = 0xff;
127 *outputBufferSize = inputBufferSize + 1;
128 } else {
129 // assign the bytesWritten return value
130 *outputBufferSize = bytesWritten;
131 }
132 } // end function HUFFMAN_Encode
133
134 /** Decodes a block of data that is Huffman encoded. */
135 void HUFFMAN_Decode(
136 unsigned char const * const inputBuffer, /**< in: Pointer to start of data that is to be decoded. */
137 unsigned char * const outputBuffer, /**< out: Pointer to destination buffer where decoded data will be stored. */
138 int const &inputBufferSize, /**< in: Number of chars to read from inputBuffer. */
139 int *outputBufferSize /**< in+out: Max chars to write into outputBuffer. Upon return holds the number of chars stored or 0 if an error occurs. */
140 ){
141 // check for "unencoded" signal & provide backwards compatibility
142 if ((inputBufferSize > 0) && ((inputBuffer[0]&0xff) == 0xff)){
143 // check buffer sizes
144 if ( *outputBufferSize < (inputBufferSize - 1) ){
145 // outputBuffer too small, return "no bytes written"
146 *outputBufferSize = 0;
147 return;
148 }
149
150 // perform the unencoded copy
151 for ( int i = 1; i < inputBufferSize; i++ ) outputBuffer[i-1] = inputBuffer[i];
152
153 // supply the bytesWritten
154 *outputBufferSize = inputBufferSize - 1;
155 } else {
156 // decode the data
157 *outputBufferSize = __codec->decode( inputBuffer, outputBuffer, inputBufferSize, *outputBufferSize );
158 }
159 } // end function HUFFMAN_Decode

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