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huffman.c File Reference

#include "bzlib_private.h"

Go to the source code of this file.

Defines

#define WEIGHTOF(zz0)   ((zz0) & 0xffffff00)
#define DEPTHOF(zz1)   ((zz1) & 0x000000ff)
#define MYMAX(zz2, zz3)   ((zz2) > (zz3) ? (zz2) : (zz3))
#define ADDWEIGHTS(zw1, zw2)
#define UPHEAP(z)
#define DOWNHEAP(z)

Functions

void hbMakeCodeLengths (UChar *len, Int32 *freq, Int32 alphaSize, Int32 maxLen)
void hbAssignCodes (Int32 *code, UChar *length, Int32 minLen, Int32 maxLen, Int32 alphaSize)
void hbCreateDecodeTables (Int32 *limit, Int32 *base, Int32 *perm, UChar *length, Int32 minLen, Int32 maxLen, Int32 alphaSize)


Define Documentation

#define ADDWEIGHTS (  zw1,
zw2    ) 
 

Value:

(WEIGHTOF(zw1)+WEIGHTOF(zw2)) |                    \
   (1 + MYMAX(DEPTHOF(zw1),DEPTHOF(zw2)))

Definition at line 69 of file huffman.c.

Referenced by hbMakeCodeLengths().

#define DEPTHOF (  zz1    )     ((zz1) & 0x000000ff)
 

Definition at line 66 of file huffman.c.

#define DOWNHEAP (  z    ) 
 

Value:

{                                                     \
   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;                                    \
}

Definition at line 84 of file huffman.c.

Referenced by hbMakeCodeLengths().

#define MYMAX (  zz2,
zz3    )     ((zz2) > (zz3) ? (zz2) : (zz3))
 

Definition at line 67 of file huffman.c.

#define UPHEAP (  z    ) 
 

Value:

{                                                     \
   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;                                    \
}

Definition at line 73 of file huffman.c.

Referenced by hbMakeCodeLengths().

#define WEIGHTOF (  zz0    )     ((zz0) & 0xffffff00)
 

Definition at line 65 of file huffman.c.


Function Documentation

void hbAssignCodes (  Int32 *    code,
UChar *    length,
Int32    minLen,
Int32    maxLen,
Int32    alphaSize
) 
 

Definition at line 175 of file huffman.c.

Referenced by sendMTFValues().

00180 {
00181    Int32 n, vec, i;
00182 
00183    vec = 0;
00184    for (n = minLen; n <= maxLen; n++) {
00185       for (i = 0; i < alphaSize; i++)
00186          if (length[i] == n) { code[i] = vec; vec++; };
00187       vec <<= 1;
00188    }
00189 }

void hbCreateDecodeTables (  Int32 *    limit,
Int32 *    base,
Int32 *    perm,
UChar *    length,
Int32    minLen,
Int32    maxLen,
Int32    alphaSize
) 
 

Definition at line 193 of file huffman.c.

Referenced by decompress().

00200 {
00201    Int32 pp, i, j, vec;
00202 
00203    pp = 0;
00204    for (i = minLen; i <= maxLen; i++)
00205       for (j = 0; j < alphaSize; j++)
00206          if (length[j] == i) { perm[pp] = j; pp++; };
00207 
00208    for (i = 0; i < BZ_MAX_CODE_LEN; i++) base[i] = 0;
00209    for (i = 0; i < alphaSize; i++) base[length[i]+1]++;
00210 
00211    for (i = 1; i < BZ_MAX_CODE_LEN; i++) base[i] += base[i-1];
00212 
00213    for (i = 0; i < BZ_MAX_CODE_LEN; i++) limit[i] = 0;
00214    vec = 0;
00215 
00216    for (i = minLen; i <= maxLen; i++) {
00217       vec += (base[i+1] - base[i]);
00218       limit[i] = vec-1;
00219       vec <<= 1;
00220    }
00221    for (i = minLen + 1; i <= maxLen; i++)
00222       base[i] = ((limit[i-1] + 1) << 1) - base[i];
00223 }

void hbMakeCodeLengths (  UChar *    len,
Int32 *    freq,
Int32    alphaSize,
Int32    maxLen
) 
 

Definition at line 103 of file huffman.c.

Referenced by sendMTFValues().

00107 {
00108    /*--
00109       Nodes and heap entries run from 1.  Entry 0
00110       for both the heap and nodes is a sentinel.
00111    --*/
00112    Int32 nNodes, nHeap, n1, n2, i, j, k;
00113    Bool  tooLong;
00114 
00115    Int32 heap   [ BZ_MAX_ALPHA_SIZE + 2 ];
00116    Int32 weight [ BZ_MAX_ALPHA_SIZE * 2 ];
00117    Int32 parent [ BZ_MAX_ALPHA_SIZE * 2 ]; 
00118 
00119    for (i = 0; i < alphaSize; i++)
00120       weight[i+1] = (freq[i] == 0 ? 1 : freq[i]) << 8;
00121 
00122    while (True) {
00123 
00124       nNodes = alphaSize;
00125       nHeap = 0;
00126 
00127       heap[0] = 0;
00128       weight[0] = 0;
00129       parent[0] = -2;
00130 
00131       for (i = 1; i <= alphaSize; i++) {
00132          parent[i] = -1;
00133          nHeap++;
00134          heap[nHeap] = i;
00135          UPHEAP(nHeap);
00136       }
00137 
00138       AssertH( nHeap < (BZ_MAX_ALPHA_SIZE+2), 2001 );
00139    
00140       while (nHeap > 1) {
00141          n1 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
00142          n2 = heap[1]; heap[1] = heap[nHeap]; nHeap--; DOWNHEAP(1);
00143          nNodes++;
00144          parent[n1] = parent[n2] = nNodes;
00145          weight[nNodes] = ADDWEIGHTS(weight[n1], weight[n2]);
00146          parent[nNodes] = -1;
00147          nHeap++;
00148          heap[nHeap] = nNodes;
00149          UPHEAP(nHeap);
00150       }
00151 
00152       AssertH( nNodes < (BZ_MAX_ALPHA_SIZE * 2), 2002 );
00153 
00154       tooLong = False;
00155       for (i = 1; i <= alphaSize; i++) {
00156          j = 0;
00157          k = i;
00158          while (parent[k] >= 0) { k = parent[k]; j++; }
00159          len[i-1] = j;
00160          if (j > maxLen) tooLong = True;
00161       }
00162       
00163       if (! tooLong) break;
00164 
00165       for (i = 1; i < alphaSize; i++) {
00166          j = weight[i] >> 8;
00167          j = 1 + (j / 2);
00168          weight[i] = j << 8;
00169       }
00170    }
00171 }


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