Category : OS/2 Files
Archive : ZOO21E.ZIP
Filename : HUF.C
Output of file : HUF.C contained in archive : ZOO21E.ZIP
/*$Id: huf.c,v 1.9 91/07/09 01:39:55 dhesi Exp $*/
/***********************************************************
huf.c -- static Huffman
Adapted from "ar" archiver written by Haruhiko Okumura.
***********************************************************/
#include "options.h"
#include "zoo.h"
#include "ar.h"
#include "lzh.h"
#include "errors.i"
extern void prterror();
#ifdef ANSI_HDRS
# include
#endif
#define NP (DICBIT + 1)
#define NT (CODE_BIT + 3)
#define PBIT 4 /* smallest integer such that (1U << PBIT) > NP */
#define TBIT 5 /* smallest integer such that (1U << TBIT) > NT */
#if NT > NP
# define NPT NT
#else
# define NPT NP
#endif
int decoded; /* for use in decode.c */
ushort left[2 * NC - 1], right[2 * NC - 1];
static uchar *buf, c_len[NC], pt_len[NPT];
static uint bufsiz = 0, blocksize;
static ushort 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];
/***** encoding *****/
static void count_t_freq()
{
int 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)
int n;
int nbit;
int i_special;
{
int i, k;
while (n > 0 && pt_len[n - 1] == 0) n--;
putbits(nbit, (uint) n);
i = 0;
while (i < n) {
k = pt_len[i++];
if (k <= 6) putbits(3, (uint) k);
else putbits(k - 3, (uint) (((unsigned) 1 << (k - 3)) - 2));
if (i == i_special) {
while (i < 6 && pt_len[i] == 0) i++;
putbits(2, (uint) ((i - 3) & 3));
}
}
}
static void write_c_len()
{
int i, k, n, count;
n = NC;
while (n > 0 && c_len[n - 1] == 0) n--;
putbits(CBIT, (uint) 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++)
putbits((int) pt_len[0], (uint) pt_code[0]);
} else if (count <= 18) {
putbits((int) pt_len[1], (uint) pt_code[1]);
putbits(4, (uint) (count - 3));
} else if (count == 19) {
putbits((int) pt_len[0], (uint) pt_code[0]);
putbits((int) pt_len[1], (uint) pt_code[1]);
putbits(4, 15);
} else {
putbits((int) pt_len[2], (uint) pt_code[2]);
putbits(CBIT, (uint) (count - 20));
}
} else putbits((int) pt_len[k + 2], (uint) pt_code[k + 2]);
}
}
static void encode_c(c)
int c;
{
putbits((int) c_len[c], (uint) c_code[c]);
}
static void encode_p(p)
uint p;
{
uint c, q;
c = 0; q = p; while (q) { q >>= 1; c++; }
putbits((int) pt_len[c], (uint) pt_code[c]);
if (c > 1) putbits((int) (c - 1), (uint) (p & ((unsigned) 0xFFFF >> (17 - c))));
}
static void send_block()
{
uint i, k, flags, root, pos, size;
root = make_tree(NC, c_freq, c_len, c_code);
size = c_freq[root];
#if 0
/*debug*/ (void) fprintf(stderr, "\nsize = %u\n", size);
#endif
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 & ((unsigned) 1 << (CHAR_BIT - 1))) {
encode_c((int) (buf[pos++] + ((unsigned) 1 << CHAR_BIT)));
k = buf[pos++] << CHAR_BIT; k += buf[pos++];
encode_p(k);
} else encode_c((int) 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 uint output_pos, output_mask;
void output(c, p)
uint c;
uint p;
{
static uint cpos;
if ((output_mask >>= 1) == 0) {
output_mask = (unsigned) 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++] = (uchar) c; c_freq[c]++;
if (c >= ((unsigned) 1 << CHAR_BIT)) {
buf[cpos] |= output_mask;
buf[output_pos++] = (uchar)(p >> CHAR_BIT);
buf[output_pos++] = (uchar) p;
c = 0; while (p) { p >>= 1; c++; }
p_freq[c]++;
}
}
void huf_encode_start()
{
int i;
if (bufsiz == 0) {
bufsiz = 16 * (unsigned) 1024;
while ((buf = (uchar *) malloc(bufsiz)) == NULL) {
bufsiz = (bufsiz / (unsigned) 10) * (unsigned) 9;
if (bufsiz < 4 * (unsigned) 1024)
prterror('f', no_memory);
}
}
buf[0] = 0;
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();
}
void huf_encode_end()
{
if (! unpackable) {
send_block();
putbits(CHAR_BIT - 1, 0); /* flush remaining bits */
putbits(16, 0); /* EOF marker */
}
}
/***** decoding *****/
static void read_pt_len(nn, nbit, i_special)
int nn;
int nbit;
int i_special;
{
int i, c, n;
uint mask;
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 >> (BITBUFSIZ - 3);
if (c == 7) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 3);
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()
{
int i, c, n;
uint mask;
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 >> (BITBUFSIZ - 8)];
if (c >= NT) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
do {
if (bitbuf & mask) c = right[c];
else c = left [c];
mask >>= 1;
} while (c >= NT);
}
fillbuf((int) 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);
}
}
uint decode_c()
{
uint j, mask;
if (blocksize == 0) {
blocksize = getbits(16);
if (blocksize == 0) {
#if 0
(void) fprintf(stderr, "block size = 0, decoded\n"); /* debug */
#endif
decoded = 1;
return 0;
}
read_pt_len(NT, TBIT, 3);
read_c_len();
read_pt_len(NP, PBIT, -1);
}
blocksize--;
j = c_table[bitbuf >> (BITBUFSIZ - 12)];
if (j >= NC) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 12);
do {
if (bitbuf & mask) j = right[j];
else j = left [j];
mask >>= 1;
} while (j >= NC);
}
fillbuf((int) c_len[j]);
return j;
}
uint decode_p()
{
uint j, mask;
j = pt_table[bitbuf >> (BITBUFSIZ - 8)];
if (j >= NP) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
do {
if (bitbuf & mask) j = right[j];
else j = left [j];
mask >>= 1;
} while (j >= NP);
}
fillbuf((int) pt_len[j]);
if (j != 0) j = ((unsigned) 1 << (j - 1)) + getbits((int) (j - 1));
return j;
}
void huf_decode_start()
{
init_getbits(); blocksize = 0;
}
Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!
This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/