104 lines
2.5 KiB
C++
104 lines
2.5 KiB
C++
/* REminiscence - Flashback interpreter
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* Copyright (C) 2005-2007 Gregory Montoir
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "unpack.h"
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static int rcr(UnpackCtx *uc, int CF) {
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int rCF = (uc->chk & 1);
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uc->chk >>= 1;
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if (CF) {
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uc->chk |= 0x80000000;
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}
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return rCF;
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}
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static int next_chunk(UnpackCtx *uc) {
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int CF = rcr(uc, 0);
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if (uc->chk == 0) {
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uc->chk = READ_BE_UINT32(uc->src); uc->src -= 4;
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uc->crc ^= uc->chk;
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CF = rcr(uc, 1);
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}
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return CF;
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}
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static uint16 get_code(UnpackCtx *uc, uint8 num_chunks) {
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uint16 c = 0;
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while (num_chunks--) {
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c <<= 1;
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if (next_chunk(uc)) {
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c |= 1;
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}
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}
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return c;
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}
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static void dec_unk1(UnpackCtx *uc, uint8 num_chunks, uint8 add_count) {
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uint16 count = get_code(uc, num_chunks) + add_count + 1;
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uc->datasize -= count;
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while (count--) {
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*uc->dst = (uint8)get_code(uc, 8);
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--uc->dst;
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}
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}
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static void dec_unk2(UnpackCtx *uc, uint8 num_chunks) {
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uint16 i = get_code(uc, num_chunks);
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uint16 count = uc->size + 1;
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uc->datasize -= count;
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while (count--) {
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*uc->dst = *(uc->dst + i);
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--uc->dst;
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}
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}
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bool delphine_unpack(uint8 *dst, const uint8 *src, int len) {
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UnpackCtx uc;
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uc.src = src + len - 4;
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uc.datasize = READ_BE_UINT32(uc.src); uc.src -= 4;
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uc.dst = dst + uc.datasize - 1;
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uc.size = 0;
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uc.crc = READ_BE_UINT32(uc.src); uc.src -= 4;
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uc.chk = READ_BE_UINT32(uc.src); uc.src -= 4;
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debug(DBG_UNPACK, "delphine_unpack() crc=0x%X datasize=0x%X", uc.crc, uc.datasize);
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uc.crc ^= uc.chk;
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do {
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if (!next_chunk(&uc)) {
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uc.size = 1;
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if (!next_chunk(&uc)) {
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dec_unk1(&uc, 3, 0);
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} else {
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dec_unk2(&uc, 8);
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}
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} else {
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uint16 c = get_code(&uc, 2);
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if (c == 3) {
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dec_unk1(&uc, 8, 8);
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} else if (c < 2) {
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uc.size = c + 2;
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dec_unk2(&uc, c + 9);
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} else {
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uc.size = get_code(&uc, 8);
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dec_unk2(&uc, 12);
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}
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}
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} while (uc.datasize > 0);
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return uc.crc == 0;
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}
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