1
2 /*-------------------------------------------------------------*/
3 /*--- Huffman coding low-level stuff ---*/
4 /*--- huffman.c ---*/
5 /*-------------------------------------------------------------*/
6
7 /*--
8 This file is a part of bzip2 and/or libbzip2, a program and
9 library for lossless, block-sorting data compression.
10
11 Copyright (C) 1996-1999 Julian R Seward. All rights reserved.
12
13 Redistribution and use in source and binary forms, with or without
14 modification, are permitted provided that the following conditions
15 are met:
16
17 1. Redistributions of source code must retain the above copyright
18 notice, this list of conditions and the following disclaimer.
19
20 2. The origin of this software must not be misrepresented; you must
21 not claim that you wrote the original software. If you use this
22 software in a product, an acknowledgment in the product
23 documentation would be appreciated but is not required.
24
25 3. Altered source versions must be plainly marked as such, and must
26 not be misrepresented as being the original software.
27
28 4. The name of the author may not be used to endorse or promote
29 products derived from this software without specific prior written
30 permission.
31
32 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
33 OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
34 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35 ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
36 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
38 GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
39 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
40 WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
41 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
42 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
43
44 Julian Seward, Cambridge, UK.
45 jseward@acm.org
46 bzip2/libbzip2 version 0.9.5 of 24 May 1999
47
48 This program is based on (at least) the work of:
49 Mike Burrows
50 David Wheeler
51 Peter Fenwick
52 Alistair Moffat
53 Radford Neal
54 Ian H. Witten
55 Robert Sedgewick
56 Jon L. Bentley
57
58 For more information on these sources, see the manual.
59 --*/
60
61
62 #include "stdafx.h"
63
64 /*---------------------------------------------------*/
65 #define WEIGHTOF(zz0) ((zz0) & 0xffffff00)
66 #define DEPTHOF(zz1) ((zz1) & 0x000000ff)
67 #define MYMAX(zz2,zz3) ((zz2) > (zz3) ? (zz2) : (zz3))
68
69 #define ADDWEIGHTS(zw1,zw2) \
70 (WEIGHTOF(zw1)+WEIGHTOF(zw2)) | \
71 (1 + MYMAX(DEPTHOF(zw1),DEPTHOF(zw2)))
72
73 #define UPHEAP(z) \
74 { \
75 Int32 zz, tmp; \
76 zz = z; tmp = heap[zz]; \
77 while (weight[tmp] < weight[heap[zz >> 1]]) { \
78 heap[zz] = heap[zz >> 1]; \
79 zz >>= 1; \
80 } \
81 heap[zz] = tmp; \
82 }
83
84 #define DOWNHEAP(z) \
85 { \
86 Int32 zz, yy, tmp; \
87 zz = z; tmp = heap[zz]; \
88 while (True) { \
89 yy = zz << 1; \
90 if (yy > nHeap) break; \
91 if (yy < nHeap && \
92 weight[heap[yy+1]] < weight[heap[yy]]) \
93 yy++; \
94 if (weight[tmp] < weight[heap[yy]]) break; \
95 heap[zz] = heap[yy]; \
96 zz = yy; \
97 } \
98 heap[zz] = tmp; \
99 }
100
101
102 /*---------------------------------------------------*/
hbMakeCodeLengths(UChar * len,Int32 * freq,Int32 alphaSize,Int32 maxLen)103 void hbMakeCodeLengths ( UChar *len,
104 Int32 *freq,
105 Int32 alphaSize,
106 Int32 maxLen )
107 {
108 /*--
109 Nodes and heap entries run from 1. Entry 0
110 for both the heap and nodes is a sentinel.
111 --*/
112 Int32 nNodes, nHeap, n1, n2, i, j, k;
113 Bool tooLong;
114
115 Int32 heap [ BZ_MAX_ALPHA_SIZE + 2 ];
116 Int32 weight [ BZ_MAX_ALPHA_SIZE * 2 ];
117 Int32 parent [ BZ_MAX_ALPHA_SIZE * 2 ];
118
119 for (i = 0; i < alphaSize; i++)
120 weight[i+1] = (freq[i] == 0 ? 1 : freq[i]) << 8;
121
122 while (True) {
123
124 nNodes = alphaSize;
125 nHeap = 0;
126
127 heap[0] = 0;
128 weight[0] = 0;
129 parent[0] = -2;
130
131 for (i = 1; i <= alphaSize; i++) {
132 parent[i] = -1;
133 nHeap++;
134 heap[nHeap] = i;
135 UPHEAP(nHeap);
136 }
137
138 AssertH( nHeap < (BZ_MAX_ALPHA_SIZE+2), 2001 );
139
140 while (nHeap > 1) {
141 n1 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
142 n2 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
143 nNodes++;
144 parent[n1] = parent[n2] = nNodes;
145 weight[nNodes] = ADDWEIGHTS(weight[n1], weight[n2]);
146 parent[nNodes] = -1;
147 nHeap++;
148 heap[nHeap] = nNodes;
149 UPHEAP(nHeap);
150 }
151
152 AssertH( nNodes < (BZ_MAX_ALPHA_SIZE * 2), 2002 );
153
154 tooLong = False;
155 for (i = 1; i <= alphaSize; i++) {
156 j = 0;
157 k = i;
158 while (parent[k] >= 0) { k = parent[k]; j++; }
159 len[i-1] = j;
160 if (j > maxLen) tooLong = True;
161 }
162
163 if (! tooLong) break;
164
165 for (i = 1; i < alphaSize; i++) {
166 j = weight[i] >> 8;
167 j = 1 + (j / 2);
168 weight[i] = j << 8;
169 }
170 }
171 }
172
173
174 /*---------------------------------------------------*/
hbAssignCodes(Int32 * code,UChar * length,Int32 minLen,Int32 maxLen,Int32 alphaSize)175 void hbAssignCodes ( Int32 *code,
176 UChar *length,
177 Int32 minLen,
178 Int32 maxLen,
179 Int32 alphaSize )
180 {
181 Int32 n, vec, i;
182
183 vec = 0;
184 for (n = minLen; n <= maxLen; n++) {
185 for (i = 0; i < alphaSize; i++)
186 if (length[i] == n) { code[i] = vec; vec++; };
187 vec <<= 1;
188 }
189 }
190
191
192 /*---------------------------------------------------*/
hbCreateDecodeTables(Int32 * limit,Int32 * base,Int32 * perm,UChar * length,Int32 minLen,Int32 maxLen,Int32 alphaSize)193 void hbCreateDecodeTables ( Int32 *limit,
194 Int32 *base,
195 Int32 *perm,
196 UChar *length,
197 Int32 minLen,
198 Int32 maxLen,
199 Int32 alphaSize )
200 {
201 Int32 pp, i, j, vec;
202
203 pp = 0;
204 for (i = minLen; i <= maxLen; i++)
205 for (j = 0; j < alphaSize; j++)
206 if (length[j] == i) { perm[pp] = j; pp++; };
207
208 for (i = 0; i < BZ_MAX_CODE_LEN; i++) base[i] = 0;
209 for (i = 0; i < alphaSize; i++) base[length[i]+1]++;
210
211 for (i = 1; i < BZ_MAX_CODE_LEN; i++) base[i] += base[i-1];
212
213 for (i = 0; i < BZ_MAX_CODE_LEN; i++) limit[i] = 0;
214 vec = 0;
215
216 for (i = minLen; i <= maxLen; i++) {
217 vec += (base[i+1] - base[i]);
218 limit[i] = vec-1;
219 vec <<= 1;
220 }
221 for (i = minLen + 1; i <= maxLen; i++)
222 base[i] = ((limit[i-1] + 1) << 1) - base[i];
223 }
224
225
226 /*-------------------------------------------------------------*/
227 /*--- end huffman.c ---*/
228 /*-------------------------------------------------------------*/
229