/*
 *     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;
}