/*
* This file is part of the Aaru Data Preservation Suite.
* Copyright (c) 2019-2026 Natalia Portillo.
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of the
* License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see .
*/
/* StuffIt method 13: Dynamic/Static Huffman LZSS with 64KB window */
#include
#include
#include "../pak/bitstream.h"
#include "../pak/prefixcode.h"
#include "stuffit.h"
#define M13_WINDOW_SIZE 65536
#define M13_CODE_SIZE 321
/* Meta-code table for dynamic mode (37 symbols, LSB-first) */
static const int meta_code_values[37] = {0x5d8, 0x058, 0x040, 0x0c0, 0x000, 0x078, 0x02b, 0x014, 0x00c, 0x01c,
0x01b, 0x00b, 0x010, 0x020, 0x038, 0x018, 0x0d8, 0xbd8, 0x180, 0x680,
0x380, 0xf80, 0x780, 0x480, 0x080, 0x280, 0x3d8, 0xfd8, 0x7d8, 0x9d8,
0x1d8, 0x004, 0x001, 0x002, 0x007, 0x003, 0x008};
static const int meta_code_lengths[37] = {11, 8, 8, 8, 8, 7, 6, 5, 5, 5, 5, 6, 5, 6, 7, 7, 9, 12, 10,
11, 11, 12, 12, 11, 11, 11, 12, 12, 12, 12, 12, 5, 2, 2, 3, 4, 5};
static PrefixCode *m13_build_meta_code(void)
{
PrefixCode *pc = prefix_code_alloc();
if(!pc) return NULL;
for(int i = 0; i < 37; i++) prefix_code_add_value_low_bit_first(pc, i, meta_code_values[i], meta_code_lengths[i]);
return pc;
}
static PrefixCode *m13_parse_dynamic_code(int num_codes, PrefixCode *meta, BitStream *bs)
{
int length = 0;
int *lengths = calloc(num_codes, sizeof(int));
if(!lengths) return NULL;
for(int i = 0; i < num_codes; i++)
{
int val = prefix_code_read_symbol_le(bs, meta);
if(val < 0)
{
free(lengths);
return NULL;
}
switch(val)
{
case 31:
length = -1;
break;
case 32:
length++;
break;
case 33:
length--;
break;
case 34:
if(bitstream_read_bits_le(bs, 1)) lengths[i++] = length;
break;
case 35:
{
int rep = bitstream_read_bits_le(bs, 3) + 2;
while(rep-- > 0) lengths[i++] = length;
break;
}
case 36:
{
int rep = bitstream_read_bits_le(bs, 6) + 10;
while(rep-- > 0) lengths[i++] = length;
break;
}
default:
length = val + 1;
break;
}
lengths[i] = length;
}
int maxlen = 0;
for(int i = 0; i < num_codes; i++)
if(lengths[i] > maxlen) maxlen = lengths[i];
PrefixCode *pc = prefix_code_alloc_with_lengths(lengths, num_codes, maxlen > 0 ? maxlen : 1, true);
free(lengths);
return pc;
}
/* Include static code length tables (5 sets) */
#include "method13_tables.h"
int stuffit_method13_decode_buffer(uint8_t *dst, size_t *dst_size, const uint8_t *src, size_t src_size)
{
size_t limit = *dst_size;
size_t di = 0;
BitStream bs;
bitstream_init(&bs, src, src_size);
/* Read control byte */
int control = bitstream_read_bits_le(&bs, 8);
int mode = control >> 4;
PrefixCode *first_code = NULL, *second_code = NULL, *offset_code = NULL;
if(mode == 0)
{
PrefixCode *meta = m13_build_meta_code();
if(!meta) return -1;
first_code = m13_parse_dynamic_code(321, meta, &bs);
if(!first_code)
{
prefix_code_free(meta);
return -1;
}
if(control & 0x08)
second_code = first_code; /* shared */
else
{
second_code = m13_parse_dynamic_code(321, meta, &bs);
if(!second_code)
{
prefix_code_free(meta);
prefix_code_free(first_code);
return -1;
}
}
offset_code = m13_parse_dynamic_code((control & 0x07) + 10, meta, &bs);
prefix_code_free(meta);
if(!offset_code)
{
prefix_code_free(first_code);
if(second_code != first_code) prefix_code_free(second_code);
return -1;
}
}
else if(mode >= 1 && mode <= 5)
{
int idx = mode - 1;
int maxlen = 0;
for(int i = 0; i < 321; i++)
{
if(m13_first_code_lengths[idx][i] > maxlen) maxlen = m13_first_code_lengths[idx][i];
}
first_code = prefix_code_alloc_with_lengths(m13_first_code_lengths[idx], 321, maxlen, true);
maxlen = 0;
for(int i = 0; i < 321; i++)
{
if(m13_second_code_lengths[idx][i] > maxlen) maxlen = m13_second_code_lengths[idx][i];
}
second_code = prefix_code_alloc_with_lengths(m13_second_code_lengths[idx], 321, maxlen, true);
maxlen = 0;
int osize = m13_offset_code_sizes[idx];
for(int i = 0; i < osize; i++)
{
if(m13_offset_code_lengths[idx][i] > maxlen) maxlen = m13_offset_code_lengths[idx][i];
}
offset_code = prefix_code_alloc_with_lengths(m13_offset_code_lengths[idx], osize, maxlen, true);
}
else
{
*dst_size = 0;
return -1;
}
if(!first_code || !second_code || !offset_code)
{
prefix_code_free(first_code);
if(second_code != first_code) prefix_code_free(second_code);
prefix_code_free(offset_code);
return -1;
}
uint8_t *window = calloc(1, M13_WINDOW_SIZE);
if(!window)
{
prefix_code_free(first_code);
if(second_code != first_code) prefix_code_free(second_code);
prefix_code_free(offset_code);
return -1;
}
int win_pos = 0;
PrefixCode *curr = first_code;
while(di < limit)
{
int sym = prefix_code_read_symbol_le(&bs, curr);
if(sym < 0) break;
if(sym < 0x100)
{
curr = first_code;
dst[di++] = (uint8_t)sym;
window[win_pos] = (uint8_t)sym;
win_pos = (win_pos + 1) & (M13_WINDOW_SIZE - 1);
}
else
{
curr = second_code;
int length, offset;
if(sym == 0x140) break; /* end */
if(sym < 0x13e)
length = sym - 0x100 + 3;
else if(sym == 0x13e)
length = bitstream_read_bits_le(&bs, 10) + 65;
else /* 0x13f */
length = bitstream_read_bits_le(&bs, 15) + 65;
int bitlength = prefix_code_read_symbol_le(&bs, offset_code);
if(bitlength < 0) break;
if(bitlength == 0)
offset = 1;
else if(bitlength == 1)
offset = 2;
else
offset = (1 << (bitlength - 1)) + bitstream_read_bits_le(&bs, bitlength - 1) + 1;
int src_pos = (win_pos - offset + M13_WINDOW_SIZE) & (M13_WINDOW_SIZE - 1);
for(int j = 0; j < length && di < limit; j++)
{
uint8_t b = window[src_pos];
dst[di++] = b;
window[win_pos] = b;
win_pos = (win_pos + 1) & (M13_WINDOW_SIZE - 1);
src_pos = (src_pos + 1) & (M13_WINDOW_SIZE - 1);
}
}
}
free(window);
prefix_code_free(first_code);
if(second_code != first_code) prefix_code_free(second_code);
prefix_code_free(offset_code);
*dst_size = di;
return 0;
}