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maketbl.c
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C/C++ Source or Header
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1998-02-17
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2KB
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94 lines
/*
* xDMS v1.0 - Portable DMS archive unpacker - Public Domain
* Written by Andre R. de la Rocha <adlroc@usa.net>
*
* Makes decoding table for Heavy LZH decompression
* From UNIX LHA made by Masaru Oki
*
*/
#include "cdata.h"
#include "maketbl.h"
static SHORT c;
static USHORT n, tblsiz, len, depth, maxdepth, avail;
static USHORT codeword, bit, *tbl, TabErr;
static UCHAR *blen;
static USHORT mktbl(void);
USHORT make_table(USHORT nchar, UCHAR bitlen[],USHORT tablebits, USHORT table[]){
n = avail = nchar;
blen = bitlen;
tbl = table;
tblsiz = (USHORT) (1U << tablebits);
bit = (USHORT) (tblsiz / 2);
maxdepth = (USHORT)(tablebits + 1);
depth = len = 1;
c = -1;
codeword = 0;
TabErr = 0;
(void) mktbl(); /* left subtree */
if (TabErr) return TabErr;
(void) mktbl(); /* right subtree */
if (TabErr) return TabErr;
if (codeword != tblsiz) return 5;
return 0;
}
static USHORT mktbl(void)
{
USHORT i=0;
if (TabErr) return 0;
if (len == depth) {
while (++c < n)
if (blen[c] == len) {
i = codeword;
codeword += bit;
if (codeword > tblsiz) {
TabErr=1;
return 0;
}
while (i < codeword) tbl[i++] = (USHORT)c;
return (USHORT)c;
}
c = -1;
len++;
bit >>= 1;
}
depth++;
if (depth < maxdepth) {
(void) mktbl();
(void) mktbl();
} else if (depth > 32) {
TabErr = 2;
return 0;
} else {
if ((i = avail++) >= 2 * n - 1) {
TabErr = 3;
return 0;
}
left[i] = mktbl();
right[i] = mktbl();
if (codeword >= tblsiz) {
TabErr = 4;
return 0;
}
if (depth == maxdepth) tbl[codeword++] = i;
}
depth--;
return i;
}