1 #include <config.h> 2 3 /*-------------------------------------------------------------*/ 4 /*--- Huffman coding low-level stuff ---*/ 5 /*--- huffman.c ---*/ 6 /*-------------------------------------------------------------*/ 7 8 /*-- 9 This file is a part of bzip2 and/or libbzip2, a program and 10 library for lossless, block-sorting data compression. 11 12 Copyright (C) 1996-2002 Julian R Seward. All rights reserved. 13 14 Redistribution and use in source and binary forms, with or without 15 modification, are permitted provided that the following conditions 16 are met: 17 18 1. Redistributions of source code must retain the above copyright 19 notice, this list of conditions and the following disclaimer. 20 21 2. The origin of this software must not be misrepresented; you must 22 not claim that you wrote the original software. If you use this 23 software in a product, an acknowledgment in the product 24 documentation would be appreciated but is not required. 25 26 3. Altered source versions must be plainly marked as such, and must 27 not be misrepresented as being the original software. 28 29 4. The name of the author may not be used to endorse or promote 30 products derived from this software without specific prior written 31 permission. 32 33 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 34 OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 35 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 36 ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 37 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 38 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE 39 GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 40 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 41 WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 42 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 43 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 44 45 Julian Seward, Cambridge, UK. 46 jseward@acm.org 47 bzip2/libbzip2 version 1.0 of 21 March 2000 48 49 This program is based on (at least) the work of: 50 Mike Burrows 51 David Wheeler 52 Peter Fenwick 53 Alistair Moffat 54 Radford Neal 55 Ian H. Witten 56 Robert Sedgewick 57 Jon L. Bentley 58 59 For more information on these sources, see the manual. 60 --*/ 61 62 63 #include "bzlib_private.h" 64 65 /*---------------------------------------------------*/ 66 #define WEIGHTOF(zz0) ((zz0) & 0xffffff00) 67 #define DEPTHOF(zz1) ((zz1) & 0x000000ff) 68 #define MYMAX(zz2,zz3) ((zz2) > (zz3) ? (zz2) : (zz3)) 69 70 #define ADDWEIGHTS(zw1,zw2) \ 71 (WEIGHTOF(zw1)+WEIGHTOF(zw2)) | \ 72 (1 + MYMAX(DEPTHOF(zw1),DEPTHOF(zw2))) 73 74 #define UPHEAP(z) \ 75 { \ 76 Int32 zz, tmp; \ 77 zz = z; tmp = heap[zz]; \ 78 while (weight[tmp] < weight[heap[zz >> 1]]) { \ 79 heap[zz] = heap[zz >> 1]; \ 80 zz >>= 1; \ 81 } \ 82 heap[zz] = tmp; \ 83 } 84 85 #define DOWNHEAP(z) \ 86 { \ 87 Int32 zz, yy, tmp; \ 88 zz = z; tmp = heap[zz]; \ 89 while (True) { \ 90 yy = zz << 1; \ 91 if (yy > nHeap) break; \ 92 if (yy < nHeap && \ 93 weight[heap[yy+1]] < weight[heap[yy]]) \ 94 yy++; \ 95 if (weight[tmp] < weight[heap[yy]]) break; \ 96 heap[zz] = heap[yy]; \ 97 zz = yy; \ 98 } \ 99 heap[zz] = tmp; \ 100 } 101 102 103 /*---------------------------------------------------*/ BZ2_hbMakeCodeLengths(UChar * len,Int32 * freq,Int32 alphaSize,Int32 maxLen)104 void BZ2_hbMakeCodeLengths ( UChar *len, 105 Int32 *freq, 106 Int32 alphaSize, 107 Int32 maxLen ) 108 { 109 /*-- 110 Nodes and heap entries run from 1. Entry 0 111 for both the heap and nodes is a sentinel. 112 --*/ 113 Int32 nNodes, nHeap, n1, n2, i, j, k; 114 Bool tooLong; 115 116 Int32 heap [ BZ_MAX_ALPHA_SIZE + 2 ]; 117 Int32 weight [ BZ_MAX_ALPHA_SIZE * 2 ]; 118 Int32 parent [ BZ_MAX_ALPHA_SIZE * 2 ]; 119 120 for (i = 0; i < alphaSize; i++) 121 weight[i+1] = (freq[i] == 0 ? 1 : freq[i]) << 8; 122 123 while (True) { 124 125 nNodes = alphaSize; 126 nHeap = 0; 127 128 heap[0] = 0; 129 weight[0] = 0; 130 parent[0] = -2; 131 132 for (i = 1; i <= alphaSize; i++) { 133 parent[i] = -1; 134 nHeap++; 135 heap[nHeap] = i; 136 UPHEAP(nHeap); 137 } 138 139 AssertH( nHeap < (BZ_MAX_ALPHA_SIZE+2), 2001 ); 140 141 while (nHeap > 1) { 142 n1 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1); 143 n2 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1); 144 nNodes++; 145 parent[n1] = parent[n2] = nNodes; 146 weight[nNodes] = ADDWEIGHTS(weight[n1], weight[n2]); 147 parent[nNodes] = -1; 148 nHeap++; 149 heap[nHeap] = nNodes; 150 UPHEAP(nHeap); 151 } 152 153 AssertH( nNodes < (BZ_MAX_ALPHA_SIZE * 2), 2002 ); 154 155 tooLong = False; 156 for (i = 1; i <= alphaSize; i++) { 157 j = 0; 158 k = i; 159 while (parent[k] >= 0) { k = parent[k]; j++; } 160 len[i-1] = j; 161 if (j > maxLen) tooLong = True; 162 } 163 164 if (! tooLong) break; 165 166 for (i = 1; i < alphaSize; i++) { 167 j = weight[i] >> 8; 168 j = 1 + (j / 2); 169 weight[i] = j << 8; 170 } 171 } 172 } 173 174 175 /*---------------------------------------------------*/ BZ2_hbAssignCodes(Int32 * code,UChar * length,Int32 minLen,Int32 maxLen,Int32 alphaSize)176 void BZ2_hbAssignCodes ( Int32 *code, 177 UChar *length, 178 Int32 minLen, 179 Int32 maxLen, 180 Int32 alphaSize ) 181 { 182 Int32 n, vec, i; 183 184 vec = 0; 185 for (n = minLen; n <= maxLen; n++) { 186 for (i = 0; i < alphaSize; i++) 187 if (length[i] == n) { code[i] = vec; vec++; }; 188 vec <<= 1; 189 } 190 } 191 192 193 /*---------------------------------------------------*/ BZ2_hbCreateDecodeTables(Int32 * limit,Int32 * base,Int32 * perm,UChar * length,Int32 minLen,Int32 maxLen,Int32 alphaSize)194 void BZ2_hbCreateDecodeTables ( Int32 *limit, 195 Int32 *base, 196 Int32 *perm, 197 UChar *length, 198 Int32 minLen, 199 Int32 maxLen, 200 Int32 alphaSize ) 201 { 202 Int32 pp, i, j, vec; 203 204 pp = 0; 205 for (i = minLen; i <= maxLen; i++) 206 for (j = 0; j < alphaSize; j++) 207 if (length[j] == i) { perm[pp] = j; pp++; }; 208 209 for (i = 0; i < BZ_MAX_CODE_LEN; i++) base[i] = 0; 210 for (i = 0; i < alphaSize; i++) base[length[i]+1]++; 211 212 for (i = 1; i < BZ_MAX_CODE_LEN; i++) base[i] += base[i-1]; 213 214 for (i = 0; i < BZ_MAX_CODE_LEN; i++) limit[i] = 0; 215 vec = 0; 216 217 for (i = minLen; i <= maxLen; i++) { 218 vec += (base[i+1] - base[i]); 219 limit[i] = vec-1; 220 vec <<= 1; 221 } 222 for (i = minLen + 1; i <= maxLen; i++) 223 base[i] = ((limit[i-1] + 1) << 1) - base[i]; 224 } 225 226 227 /*-------------------------------------------------------------*/ 228 /*--- end huffman.c ---*/ 229 /*-------------------------------------------------------------*/ 230