mirror of
https://github.com/aaru-dps/Aaru.Compression.Native.git
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78 lines
2.2 KiB
C
78 lines
2.2 KiB
C
/*$Source: /usr/home/dhesi/zoo/RCS/maketbl.c,v $*/
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/*$Id: maketbl.c,v 1.8 91/07/09 01:39:52 dhesi Exp $*/
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/***********************************************************
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maketbl.c -- make table for decoding
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Adapted from "ar" archiver written by Haruhiko Okumura.
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***********************************************************/
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// Modified for in-memory decompression by Natalia Portillo, 2025
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#include "ar.h"
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#include "lzh.h"
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void make_table(int nchar, uint8_t *bitlen, int tablebits, uint16_t *table)
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{
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uint16_t count[17], weight[17], start[18], *p;
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uint32_t i, k, len, ch, jutbits, avail, nextcode, mask;
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for(i = 1; i <= 16; i++) count[i] = 0;
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for(i = 0; i < nchar; i++) count[bitlen[i]]++;
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start[1] = 0;
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for(i = 1; i <= 16; i++) start[i + 1] = start[i] + (count[i] << (16 - i));
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if(start[17] != (uint16_t)((unsigned)1 << 16)) fprintf(stderr, "Bad decode table\n");
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jutbits = 16 - tablebits;
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for(i = 1; i <= tablebits; i++)
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{
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start[i] >>= jutbits;
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weight[i] = (unsigned)1 << (tablebits - i);
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}
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while(i <= 16)
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{
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weight[i] = (unsigned)1 << (16 - i);
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i++;
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}
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i = start[tablebits + 1] >> jutbits;
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if(i != (uint16_t)((unsigned)1 << 16))
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{
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k = 1 << tablebits;
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while(i != k) table[i++] = 0;
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}
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avail = nchar;
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mask = (unsigned)1 << (15 - tablebits);
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for(ch = 0; ch < nchar; ch++)
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{
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if((len = bitlen[ch]) == 0) continue;
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nextcode = start[len] + weight[len];
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if(len <= tablebits)
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{
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for(i = start[len]; i < nextcode; i++) table[i] = ch;
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}
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else
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{
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k = start[len];
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p = &table[k >> jutbits];
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i = len - tablebits;
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while(i != 0)
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{
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if(*p == 0)
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{
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right[avail] = left[avail] = 0;
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*p = avail++;
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}
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if(k & mask)
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p = &right[*p];
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else
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p = &left[*p];
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k <<= 1;
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i--;
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}
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*p = ch;
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}
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start[len] = nextcode;
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}
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}
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