home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
EnigmA Amiga Run 1998 July
/
EnigmA AMIGA RUN 29 (1998)(G.R. Edizioni)(IT)[!][issue 1998-07 & 08].iso
/
earcd
/
phase5
/
lha-ppc
/
orig_src
/
shuf.c
< prev
next >
Wrap
C/C++ Source or Header
|
1992-05-08
|
3KB
|
172 lines
/***********************************************************
shuf.c -- extract static Huffman coding
***********************************************************/
#include <stdio.h>
#include "slidehuf.h"
#ifdef __STDC__
#include <stdlib.h>
#endif
#define N1 286 /* alphabet size */
#define N2 (2 * N1 - 1) /* # of nodes in Huffman tree */
#define EXTRABITS 8
/* >= log2(F-THRESHOLD+258-N1) */
#define BUFBITS 16 /* >= log2(MAXBUF) */
#define LENFIELD 4 /* bit size of length field for tree output */
#define NP (8 * 1024 / 64)
#define NP2 (NP * 2 - 1)
static unsigned int np;
void decode_start_st0(void)
{
n_max = 286;
maxmatch = MAXMATCH;
init_getbits();
np = 1 << (MAX_DICBIT - 6);
}
void encode_p_st0(j)
unsigned short j;
{
unsigned short i;
i = j >> 6;
putcode(pt_len[i], pt_code[i]);
putbits(6, j & 0x3f);
}
int fixed[2][16] = {
{3, 0x01, 0x04, 0x0c, 0x18, 0x30, 0}, /* old compatible */
{2, 0x01, 0x01, 0x03, 0x06, 0x0D, 0x1F, 0x4E, 0} /* 8K buf */
};
static void ready_made(method)
int method;
{
int i, j;
unsigned int code, weight;
int *tbl;
tbl = fixed[method];
j = *tbl++;
weight = 1 << (16 - j);
code = 0;
for (i = 0; i < np; i++) {
while (*tbl == i) {
j++;
tbl++;
weight >>= 1;
}
pt_len[i] = j;
pt_code[i] = code;
code += weight;
}
}
void encode_start_fix(void)
{
n_max = 314;
maxmatch = 60;
np = 1 << (12 - 6);
init_putbits();
start_c_dyn();
ready_made(0);
}
static void read_tree_c(void) /* read tree from file */
{
int i, c;
i = 0;
while (i < N1) {
if (getbits(1)) c_len[i] = getbits(LENFIELD) + 1;
else c_len[i] = 0;
if (++i == 3 && c_len[0] == 1 && c_len[1] == 1 && c_len[2] == 1) {
c = getbits(CBIT);
for (i = 0; i < N1; i++) c_len[i] = 0;
for (i = 0; i < 4096; i++) c_table[i] = c;
return;
}
}
make_table(N1, c_len, 12, c_table);
}
static void read_tree_p(void) /* read tree from file */
{
int i, c;
i = 0;
while (i < NP) {
pt_len[i] = getbits(LENFIELD);
if (++i == 3 && pt_len[0] == 1 && pt_len[1] == 1 && pt_len[2] == 1) {
c = getbits(MAX_DICBIT - 6);
for (i = 0; i < NP; i++) c_len[i] = 0;
for (i = 0; i < 256; i++) c_table[i] = c;
return;
}
}
}
void decode_start_fix(void)
{
n_max = 314;
maxmatch = 60;
init_getbits();
np = 1 << (12 - 6);
start_c_dyn();
ready_made(0);
make_table(np, pt_len, 8, pt_table);
}
unsigned short decode_c_st0(void)
{
int i, j;
static unsigned short blocksize = 0;
if (blocksize == 0) { /* read block head */
blocksize = getbits(BUFBITS); /* read block blocksize */
read_tree_c();
if (getbits(1)) {
read_tree_p();
} else {
ready_made(1);
}
make_table(NP, pt_len, 8, pt_table);
}
blocksize--;
j = c_table[bitbuf >> 4];
if (j < N1) fillbuf(c_len[j]);
else {
fillbuf(12); i = bitbuf;
do {
if ((short)i < 0) j = right[j];
else j = left [j];
i <<= 1;
} while (j >= N1);
fillbuf(c_len[j] - 12);
}
if (j == N1 - 1)
j += getbits(EXTRABITS);
return j;
}
unsigned short decode_p_st0(void)
{
int i, j;
j = pt_table[bitbuf >> 8];
if (j < np) {
fillbuf(pt_len[j]);
} else {
fillbuf(8); i = bitbuf;
do {
if ((short)i < 0) j = right[j];
else j = left [j];
i <<= 1;
} while (j >= np);
fillbuf(pt_len[j] - 8);
}
return (j << 6) + getbits(6);
}