1 /* Compress/HuffmanEncode.c */
3 #include "HuffmanEncode.h"
4 #include "../../Sort.h"
8 #define MASK ((1 << NUM_BITS) - 1)
10 #define NUM_COUNTERS 64
12 /* use BLOCK_SORT_EXTERNAL_FLAGS if blockSize > 1M */
13 #define HUFFMAN_SPEED_OPT
15 void Huffman_Generate(const UInt32 *freqs, UInt32 *p, Byte *lens, UInt32 numSymbols, UInt32 maxLen)
18 /* if (maxLen > 10) maxLen = 10; */
22 #ifdef HUFFMAN_SPEED_OPT
24 UInt32 counters[NUM_COUNTERS];
25 for (i = 0; i < NUM_COUNTERS; i++)
27 for (i = 0; i < numSymbols; i++)
29 UInt32 freq = freqs[i];
30 counters[(freq < NUM_COUNTERS - 1) ? freq : NUM_COUNTERS - 1]++;
33 for (i = 1; i < NUM_COUNTERS; i++)
35 UInt32 temp = counters[i];
40 for (i = 0; i < numSymbols; i++)
42 UInt32 freq = freqs[i];
46 p[counters[((freq < NUM_COUNTERS - 1) ? freq : NUM_COUNTERS - 1)]++] = i | (freq << NUM_BITS);
49 HeapSort(p + counters[NUM_COUNTERS - 2], counters[NUM_COUNTERS - 1] - counters[NUM_COUNTERS - 2]);
53 for (i = 0; i < numSymbols; i++)
55 UInt32 freq = freqs[i];
59 p[num++] = i | (freq << NUM_BITS);
72 maxCode = p[0] & MASK;
78 lens[minCode] = lens[maxCode] = 1;
89 n = (i != num && (b == e || (p[i] >> NUM_BITS) <= (p[b] >> NUM_BITS))) ? i++ : b++;
90 freq = (p[n] & ~MASK);
91 p[n] = (p[n] & MASK) | (e << NUM_BITS);
92 m = (i != num && (b == e || (p[i] >> NUM_BITS) <= (p[b] >> NUM_BITS))) ? i++ : b++;
93 freq += (p[m] & ~MASK);
94 p[m] = (p[m] & MASK) | (e << NUM_BITS);
95 p[e] = (p[e] & MASK) | freq;
101 UInt32 lenCounters[kMaxLen + 1];
102 for (i = 0; i <= kMaxLen; i++)
109 UInt32 len = (p[p[--e] >> NUM_BITS] >> NUM_BITS) + 1;
110 p[e] = (p[e] & MASK) | (len << NUM_BITS);
112 for (len = maxLen - 1; lenCounters[len] == 0; len--);
114 lenCounters[len + 1] += 2;
120 for (len = maxLen; len != 0; len--)
123 for (num = lenCounters[len]; num != 0; num--)
124 lens[p[i++] & MASK] = (Byte)len;
129 UInt32 nextCodes[kMaxLen + 1];
133 for (len = 1; len <= kMaxLen; len++)
134 nextCodes[len] = code = (code + lenCounters[len - 1]) << 1;
136 /* if (code + lenCounters[kMaxLen] - 1 != (1 << kMaxLen) - 1) throw 1; */
140 for (i = 0; i < numSymbols; i++)
141 p[i] = nextCodes[lens[i]]++;