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Language/OS - Multiplatform Resource Library
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LANGUAGE OS.iso
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unix
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lha101u
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huf.c
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C/C++ Source or Header
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1992-04-24
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7KB
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337 lines
/***********************************************************
huf.c -- new static Huffman
***********************************************************/
#ifdef sony_news
#include <sys/param.h>
#endif
#if defined(__STDC__) || defined(NEWSOS)
#include <stdlib.h>
#endif
#include "slidehuf.h"
#define NP (MAX_DICBIT + 1)
#define NT (USHRT_BIT + 3)
#define PBIT 4 /* smallest integer such that (1 << PBIT) > NP */
#define TBIT 5 /* smallest integer such that (1 << TBIT) > NT */
/*#if NT > NP
#define NPT NT
#else
#define NPT NP
#endif*/
#define NPT 0x80
unsigned short left[2 * NC - 1], right[2 * NC - 1];
unsigned char c_len[NC], pt_len[NPT];
unsigned short c_freq[2 * NC - 1], c_table[4096], c_code[NC],
p_freq[2 * NP - 1], pt_table[256], pt_code[NPT],
t_freq[2 * NT - 1];
static unsigned char *buf;
static unsigned short bufsiz;
static unsigned short blocksize;
/***** encoding *****/
static void count_t_freq(void)
{
short i, k, n, count;
for (i = 0; i < NT; i++) t_freq[i] = 0;
n = NC;
while (n > 0 && c_len[n - 1] == 0) n--;
i = 0;
while (i < n) {
k = c_len[i++];
if (k == 0) {
count = 1;
while (i < n && c_len[i] == 0) { i++; count++; }
if (count <= 2) t_freq[0] += count;
else if (count <= 18) t_freq[1]++;
else if (count == 19) { t_freq[0]++; t_freq[1]++; }
else t_freq[2]++;
} else t_freq[k + 2]++;
}
}
static void write_pt_len(n, nbit, i_special)
short n;
short nbit;
short i_special;
{
short i, k;
while (n > 0 && pt_len[n - 1] == 0) n--;
putbits(nbit, n);
i = 0;
while (i < n) {
k = pt_len[i++];
if (k <= 6) putbits(3, k);
else putbits(k - 3, USHRT_MAX << 1);
if (i == i_special) {
while (i < 6 && pt_len[i] == 0) i++;
putbits(2, i - 3);
}
}
}
static void write_c_len(void)
{
short i, k, n, count;
n = NC;
while (n > 0 && c_len[n - 1] == 0) n--;
putbits(CBIT, n);
i = 0;
while (i < n) {
k = c_len[i++];
if (k == 0) {
count = 1;
while (i < n && c_len[i] == 0) { i++; count++; }
if (count <= 2) {
for (k = 0; k < count; k++)
putcode(pt_len[0], pt_code[0]);
} else if (count <= 18) {
putcode(pt_len[1], pt_code[1]);
putbits(4, count - 3);
} else if (count == 19) {
putcode(pt_len[0], pt_code[0]);
putcode(pt_len[1], pt_code[1]);
putbits(4, 15);
} else {
putcode(pt_len[2], pt_code[2]);
putbits(CBIT, count - 20);
}
} else putcode(pt_len[k + 2], pt_code[k + 2]);
}
}
static void encode_c(c)
short c;
{
putcode(c_len[c], c_code[c]);
}
static void encode_p(p)
unsigned short p;
{
unsigned short c, q;
c = 0; q = p; while (q) { q >>= 1; c++; }
putcode(pt_len[c], pt_code[c]);
if (c > 1) putbits(c - 1, p);
}
static void send_block(void)
{
unsigned char flags;
unsigned short i, k, root, pos, size;
root = make_tree(NC, c_freq, c_len, c_code);
size = c_freq[root]; putbits(16, size);
if (root >= NC) {
count_t_freq();
root = make_tree(NT, t_freq, pt_len, pt_code);
if (root >= NT) {
write_pt_len(NT, TBIT, 3);
} else {
putbits(TBIT, 0); putbits(TBIT, root);
}
write_c_len();
} else {
putbits(TBIT, 0); putbits(TBIT, 0);
putbits(CBIT, 0); putbits(CBIT, root);
}
root = make_tree(NP, p_freq, pt_len, pt_code);
if (root >= NP) {
write_pt_len(NP, PBIT, -1);
} else {
putbits(PBIT, 0); putbits(PBIT, root);
}
pos = 0;
for (i = 0; i < size; i++) {
if (i % CHAR_BIT == 0) flags = buf[pos++]; else flags <<= 1;
if (flags & (1 << (CHAR_BIT - 1))) {
encode_c(buf[pos++] + (1 << CHAR_BIT));
k = buf[pos++] << CHAR_BIT; k += buf[pos++];
encode_p(k);
} else encode_c(buf[pos++]);
if (unpackable) return;
}
for (i = 0; i < NC; i++) c_freq[i] = 0;
for (i = 0; i < NP; i++) p_freq[i] = 0;
}
static unsigned short output_pos, output_mask;
void output_st1(c, p)
unsigned short c;
unsigned short p;
{
static unsigned short cpos;
output_mask >>= 1;
if (output_mask == 0) {
output_mask = 1 << (CHAR_BIT - 1);
if (output_pos >= bufsiz - 3 * CHAR_BIT) {
send_block();
if (unpackable) return;
output_pos = 0;
}
cpos = output_pos++; buf[cpos] = 0;
}
buf[output_pos++] = (unsigned char) c; c_freq[c]++;
if (c >= (1 << CHAR_BIT)) {
buf[cpos] |= output_mask;
buf[output_pos++] = (unsigned char)(p >> CHAR_BIT);
buf[output_pos++] = (unsigned char) p;
c = 0; while (p) { p >>= 1; c++; }
p_freq[c]++;
}
}
unsigned char *alloc_buf(void)
{
bufsiz = 16 * 1024; /* 65408U; */
while ((buf = (unsigned char *)malloc(bufsiz)) == NULL) {
bufsiz = (bufsiz / 10) * 9;
if (bufsiz < 4 * 1024) break;
}
return buf;
}
void encode_start_st1(void)
{
int i;
for (i = 0; i < NC; i++) c_freq[i] = 0;
for (i = 0; i < NP; i++) p_freq[i] = 0;
output_pos = output_mask = 0;
init_putbits();
buf[0] = 0;
}
void encode_end_st1(void)
{
if (! unpackable) {
send_block();
putbits(CHAR_BIT - 1, 0); /* flush remaining bits */
}
}
/***** decoding *****/
static void read_pt_len(nn, nbit, i_special)
short nn;
short nbit;
short i_special;
{
short i, c, n;
n = getbits(nbit);
if (n == 0) {
c = getbits(nbit);
for (i = 0; i < nn; i++) pt_len[i] = 0;
for (i = 0; i < 256; i++) pt_table[i] = c;
} else {
i = 0;
while (i < n) {
c = bitbuf >> (16 - 3);
if (c == 7) {
unsigned short mask = 1 << (16 - 4);
while (mask & bitbuf) { mask >>= 1; c++; }
}
fillbuf((c < 7) ? 3 : c - 3);
pt_len[i++] = c;
if (i == i_special) {
c = getbits(2);
while (--c >= 0) pt_len[i++] = 0;
}
}
while (i < nn) pt_len[i++] = 0;
make_table(nn, pt_len, 8, pt_table);
}
}
static void read_c_len(void)
{
short i, c, n;
n = getbits(CBIT);
if (n == 0) {
c = getbits(CBIT);
for (i = 0; i < NC; i++) c_len[i] = 0;
for (i = 0; i < 4096; i++) c_table[i] = c;
} else {
i = 0;
while (i < n) {
c = pt_table[bitbuf >> (16 - 8)];
if (c >= NT) {
unsigned short mask = 1 << (16 - 9);
do {
if (bitbuf & mask) c = right[c];
else c = left [c];
mask >>= 1;
} while (c >= NT);
}
fillbuf(pt_len[c]);
if (c <= 2) {
if (c == 0) c = 1;
else if (c == 1) c = getbits(4) + 3;
else c = getbits(CBIT) + 20;
while (--c >= 0) c_len[i++] = 0;
} else c_len[i++] = c - 2;
}
while (i < NC) c_len[i++] = 0;
make_table(NC, c_len, 12, c_table);
}
}
unsigned short decode_c_st1(void)
{
unsigned short j, mask;
if (blocksize == 0) {
blocksize = getbits(16);
read_pt_len(NT, TBIT, 3);
read_c_len();
read_pt_len(NP, PBIT, -1);
}
blocksize--;
j = c_table[bitbuf >> 4];
if (j < NC) fillbuf(c_len[j]);
else {
fillbuf(12); mask = 1 << (16 - 1);
do {
if (bitbuf & mask) j = right[j];
else j = left [j];
mask >>= 1;
} while (j >= NC);
fillbuf(c_len[j] - 12);
}
return j;
}
unsigned short decode_p_st1(void)
{
unsigned short j, mask;
j = pt_table[bitbuf >> (16 - 8)];
if (j < NP) fillbuf(pt_len[j]);
else {
fillbuf(8); mask = 1 << (16 - 1);
do {
if (bitbuf & mask) j = right[j];
else j = left [j];
mask >>= 1;
} while (j >= NP);
fillbuf(pt_len[j] - 8);
}
if (j != 0) j = (1 << (j - 1)) + getbits(j - 1);
return j;
}
void decode_start_st1(void)
{
init_getbits();
blocksize = 0;
}