home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Day Cry
/
Day Cry CD.bin
/
oh_towns
/
taropyon
/
splib
/
splib.lzh
/
PRG
/
LHX
/
MAKETREE.C
< prev
next >
Wrap
C/C++ Source or Header
|
1992-12-30
|
3KB
|
189 lines
/***********************************************************
maketree.c -- make Huffman tree
***********************************************************/
#include "lh386.h"
#include "slidehuf.h"
#ifdef __HIGHC__
# pragma On(Print_reg_vars);
# pragma On(Align_all_labels);
#endif
static short n = 0, heapsize = 0, heap[NC + 1];
static ushort *freq, *sort = NULL;
static uchar *len;
static ushort len_cnt[17];
void make_code(short n, uchar len[], ushort code[])
{
ushort weight[17]; /* 0x10000ul >> bitlen */
ushort start[17]; /* start code */
REG ushort j;
REG int i;
{
REG ushort k;
j = 0;
k = 1 << (16 - 1);
for (i = 1; i <= 16; i++)
{
start[i] = j;
j += (weight[i] = k) * len_cnt[i];
k >>= 1;
}
}
start[0] = weight[0] = 0;
for (i = 0; i < n; i++)
{
j = len[i];
code[i] = start[j];
start[j] += weight[j];
}
}
static void count_len(short i)
/* call with i = root */
{
static uchar depth = 0;
if (i < n)
len_cnt[depth < 16 ? depth : 16]++;
else
{
depth++;
count_len(left[i]);
count_len(right[i]);
depth--;
}
}
static void make_len(short root)
{
REG int i;
REG uint cum;
for (i = 0; i <= 16; i++)
len_cnt[i] = 0;
count_len(root);
cum = 0;
for (i = 16; i > 0; i--)
{
cum += len_cnt[i] << (16 - i);
}
#if (UINT_MAX != 0xffff)
cum &= 0xffff;
#endif
/* adjust len */
if (cum)
{
LHX_fprintf(stderr, "17");
len_cnt[16] -= cum; /* always len_cnt[16] > cum */
do
{
for (i = 15; i > 0; i--)
{
if (len_cnt[i])
{
len_cnt[i]--;
len_cnt[i + 1] += 2;
break;
}
}
} while (--cum);
}
/* make len */
for (i = 16; i > 0; i--)
{
REG int k;
k = len_cnt[i];
while (k > 0)
{
len[*sort++] = i;
k--;
}
}
}
static void downheap(short i)
/* priority queue; send i-th entry down heap */
{
REG short j, k;
k = heap[i];
while ((j = 2 * i) <= heapsize)
{
if (j < heapsize && freq[heap[j]] > freq[heap[j + 1]])
j++;
if (freq[k] <= freq[heap[j]])
break;
heap[i] = heap[j];
i = j;
}
heap[i] = k;
}
short make_tree(short nparm, ushort freqparm[], uchar lenparm[], ushort codeparm[])
/* make tree, calculate len[], return root */
{
short avail;
n = nparm;
freq = freqparm;
len = lenparm;
avail = n;
heapsize = 0;
heap[1] = 0;
{
REG short i;
for (i = 0; i < n; i++)
{
len[i] = 0;
if (freq[i])
heap[++heapsize] = i;
}
}
if (heapsize < 2)
{
codeparm[heap[1]] = 0;
return heap[1];
}
{
REG short i;
for (i = heapsize / 2; i >= 1; i--)
downheap(i); /* make priority queue */
}
sort = codeparm;
short k;
do
{
short i, j;
/* while queue has at least two entries */
i = heap[1]; /* take out least-freq entry */
if (i < n)
*sort++ = i;
heap[1] = heap[heapsize--];
downheap(1);
j = heap[1]; /* next least-freq entry */
if (j < n)
*sort++ = j;
k = avail++; /* generate new node */
freq[k] = freq[i] + freq[j];
heap[1] = k;
downheap(1); /* put into queue */
left[k] = i;
right[k] = j;
} while (heapsize > 1);
sort = codeparm;
make_len(k);
make_code(nparm, lenparm, codeparm);
return k; /* return root */
}