/*$Source: /usr/home/dhesi/zoo/RCS/maketbl.c,v $*/
/*$Id: maketbl.c,v 1.8 91/07/09 01:39:52 dhesi Exp $*/
/***********************************************************
    maketbl.c -- make table for decoding

Adapted from "ar" archiver written by Haruhiko Okumura.
***********************************************************/
// Modified for in-memory decompression by Natalia Portillo, 2025

#include "ar.h"
#include "lzh.h"

void make_table(int nchar, uint8_t *bitlen, int tablebits, uint16_t *table)
{
    uint16_t count[17], weight[17], start[18], *p;
    uint32_t i, k, len, ch, jutbits, avail, nextcode, mask;

    for(i = 1; i <= 16; i++) count[i] = 0;
    for(i = 0; i < nchar; i++) count[bitlen[i]]++;

    start[1] = 0;
    for(i = 1; i <= 16; i++) start[i + 1] = start[i] + (count[i] << (16 - i));
    if(start[17] != (uint16_t)((unsigned)1 << 16)) fprintf(stderr, "Bad decode table\n");

    jutbits = 16 - tablebits;
    for(i = 1; i <= tablebits; i++)
    {
        start[i] >>= jutbits;
        weight[i] = (unsigned)1 << (tablebits - i);
    }
    while(i <= 16)
    {
        weight[i] = (unsigned)1 << (16 - i);
        i++;
    }

    i = start[tablebits + 1] >> jutbits;
    if(i != (uint16_t)((unsigned)1 << 16))
    {
        k = 1 << tablebits;
        while(i != k) table[i++] = 0;
    }

    avail = nchar;
    mask  = (unsigned)1 << (15 - tablebits);
    for(ch = 0; ch < nchar; ch++)
    {
        if((len = bitlen[ch]) == 0) continue;
        nextcode = start[len] + weight[len];
        if(len <= tablebits)
        {
            for(i = start[len]; i < nextcode; i++) table[i] = ch;
        }
        else
        {
            k = start[len];
            p = &table[k >> jutbits];
            i = len - tablebits;
            while(i != 0)
            {
                if(*p == 0)
                {
                    right[avail] = left[avail] = 0;
                    *p                         = avail++;
                }
                if(k & mask)
                    p = &right[*p];
                else
                    p = &left[*p];
                k <<= 1;
                i--;
            }
            *p = ch;
        }
        start[len] = nextcode;
    }
}