| |
| /*-------------------------------------------------------------*/ |
| /*--- Huffman coding low-level stuff ---*/ |
| /*--- huffman.c ---*/ |
| /*-------------------------------------------------------------*/ |
| |
| /*-- |
| This file is a part of bzip2 and/or libbzip2, a program and |
| library for lossless, block-sorting data compression. |
| |
| Copyright (C) 1996-2000 Julian R Seward. All rights reserved. |
| |
| Redistribution and use in source and binary forms, with or without |
| modification, are permitted provided that the following conditions |
| are met: |
| |
| 1. Redistributions of source code must retain the above copyright |
| notice, this list of conditions and the following disclaimer. |
| |
| 2. The origin of this software must not be misrepresented; you must |
| not claim that you wrote the original software. If you use this |
| software in a product, an acknowledgment in the product |
| documentation would be appreciated but is not required. |
| |
| 3. Altered source versions must be plainly marked as such, and must |
| not be misrepresented as being the original software. |
| |
| 4. The name of the author may not be used to endorse or promote |
| products derived from this software without specific prior written |
| permission. |
| |
| THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS |
| OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
| WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
| DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE |
| GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| Julian Seward, Cambridge, UK. |
| jseward@acm.org |
| bzip2/libbzip2 version 1.0 of 21 March 2000 |
| |
| This program is based on (at least) the work of: |
| Mike Burrows |
| David Wheeler |
| Peter Fenwick |
| Alistair Moffat |
| Radford Neal |
| Ian H. Witten |
| Robert Sedgewick |
| Jon L. Bentley |
| |
| For more information on these sources, see the manual. |
| --*/ |
| |
| |
| #include "os.h" |
| #include "bzlib.h" |
| #include "bzlib_private.h" |
| |
| /*---------------------------------------------------*/ |
| #define WEIGHTOF(zz0) ((zz0) & 0xffffff00) |
| #define DEPTHOF(zz1) ((zz1) & 0x000000ff) |
| #define MYMAX(zz2,zz3) ((zz2) > (zz3) ? (zz2) : (zz3)) |
| |
| #define ADDWEIGHTS(zw1,zw2) \ |
| (WEIGHTOF(zw1)+WEIGHTOF(zw2)) | \ |
| (1 + MYMAX(DEPTHOF(zw1),DEPTHOF(zw2))) |
| |
| #define UPHEAP(z) \ |
| { \ |
| Int32 zz, tmp; \ |
| zz = z; tmp = heap[zz]; \ |
| while (weight[tmp] < weight[heap[zz >> 1]]) { \ |
| heap[zz] = heap[zz >> 1]; \ |
| zz >>= 1; \ |
| } \ |
| heap[zz] = tmp; \ |
| } |
| |
| #define DOWNHEAP(z) \ |
| { \ |
| Int32 zz, yy, tmp; \ |
| zz = z; tmp = heap[zz]; \ |
| while (True) { \ |
| yy = zz << 1; \ |
| if (yy > nHeap) break; \ |
| if (yy < nHeap && \ |
| weight[heap[yy+1]] < weight[heap[yy]]) \ |
| yy++; \ |
| if (weight[tmp] < weight[heap[yy]]) break; \ |
| heap[zz] = heap[yy]; \ |
| zz = yy; \ |
| } \ |
| heap[zz] = tmp; \ |
| } |
| |
| |
| /*---------------------------------------------------*/ |
| void BZ2_hbMakeCodeLengths ( UChar *len, |
| Int32 *freq, |
| Int32 alphaSize, |
| Int32 maxLen ) |
| { |
| /*-- |
| Nodes and heap entries run from 1. Entry 0 |
| for both the heap and nodes is a sentinel. |
| --*/ |
| Int32 nNodes, nHeap, n1, n2, i, j, k; |
| Bool tooLong; |
| |
| Int32 heap [ BZ_MAX_ALPHA_SIZE + 2 ]; |
| Int32 weight [ BZ_MAX_ALPHA_SIZE * 2 ]; |
| Int32 parent [ BZ_MAX_ALPHA_SIZE * 2 ]; |
| |
| for (i = 0; i < alphaSize; i++) |
| weight[i+1] = (freq[i] == 0 ? 1 : freq[i]) << 8; |
| |
| while (True) { |
| |
| nNodes = alphaSize; |
| nHeap = 0; |
| |
| heap[0] = 0; |
| weight[0] = 0; |
| parent[0] = -2; |
| |
| for (i = 1; i <= alphaSize; i++) { |
| parent[i] = -1; |
| nHeap++; |
| heap[nHeap] = i; |
| UPHEAP(nHeap); |
| } |
| |
| AssertH( nHeap < (BZ_MAX_ALPHA_SIZE+2), 2001 ); |
| |
| while (nHeap > 1) { |
| n1 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1); |
| n2 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1); |
| nNodes++; |
| parent[n1] = parent[n2] = nNodes; |
| weight[nNodes] = ADDWEIGHTS(weight[n1], weight[n2]); |
| parent[nNodes] = -1; |
| nHeap++; |
| heap[nHeap] = nNodes; |
| UPHEAP(nHeap); |
| } |
| |
| AssertH( nNodes < (BZ_MAX_ALPHA_SIZE * 2), 2002 ); |
| |
| tooLong = False; |
| for (i = 1; i <= alphaSize; i++) { |
| j = 0; |
| k = i; |
| while (parent[k] >= 0) { k = parent[k]; j++; } |
| len[i-1] = j; |
| if (j > maxLen) tooLong = True; |
| } |
| |
| if (! tooLong) break; |
| |
| for (i = 1; i < alphaSize; i++) { |
| j = weight[i] >> 8; |
| j = 1 + (j / 2); |
| weight[i] = j << 8; |
| } |
| } |
| } |
| |
| |
| /*---------------------------------------------------*/ |
| void BZ2_hbAssignCodes ( Int32 *code, |
| UChar *length, |
| Int32 minLen, |
| Int32 maxLen, |
| Int32 alphaSize ) |
| { |
| Int32 n, vec, i; |
| |
| vec = 0; |
| for (n = minLen; n <= maxLen; n++) { |
| for (i = 0; i < alphaSize; i++) |
| if (length[i] == n) { code[i] = vec; vec++; }; |
| vec <<= 1; |
| } |
| } |
| |
| |
| /*---------------------------------------------------*/ |
| void BZ2_hbCreateDecodeTables ( Int32 *limit, |
| Int32 *base, |
| Int32 *perm, |
| UChar *length, |
| Int32 minLen, |
| Int32 maxLen, |
| Int32 alphaSize ) |
| { |
| Int32 pp, i, j, vec; |
| |
| pp = 0; |
| for (i = minLen; i <= maxLen; i++) |
| for (j = 0; j < alphaSize; j++) |
| if (length[j] == i) { perm[pp] = j; pp++; }; |
| |
| for (i = 0; i < BZ_MAX_CODE_LEN; i++) base[i] = 0; |
| for (i = 0; i < alphaSize; i++) base[length[i]+1]++; |
| |
| for (i = 1; i < BZ_MAX_CODE_LEN; i++) base[i] += base[i-1]; |
| |
| for (i = 0; i < BZ_MAX_CODE_LEN; i++) limit[i] = 0; |
| vec = 0; |
| |
| for (i = minLen; i <= maxLen; i++) { |
| vec += (base[i+1] - base[i]); |
| limit[i] = vec-1; |
| vec <<= 1; |
| } |
| for (i = minLen + 1; i <= maxLen; i++) |
| base[i] = ((limit[i-1] + 1) << 1) - base[i]; |
| } |
| |
| |
| /*-------------------------------------------------------------*/ |
| /*--- end huffman.c ---*/ |
| /*-------------------------------------------------------------*/ |
