124 lines
3.0 KiB
C++
124 lines
3.0 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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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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*
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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, see <http://www.gnu.org/licenses/>.
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*
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*/
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/*
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* Based on ScottFree interpreter version 1.14 developed by Swansea
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* University Computer Society without disassembly of any other game
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* drivers, only of game databases as permitted by EEC law (for purposes
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* of compatibility).
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*
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* Licensed under GPLv2
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*
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* https://github.com/angstsmurf/spatterlight/tree/master/terps/scott
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*/
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#include "common/str.h"
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#include "glk/scott/decompress_text.h"
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namespace Glk {
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namespace Scott {
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int rotateLeftWithCarry(uint8_t *byte, int lastCarry) {
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int carry = ((*byte & 0x80) > 0);
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*byte = *byte << 1;
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if (lastCarry)
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*byte = *byte | 0x01;
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return carry;
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}
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int decompressOne(uint8_t *bytes) {
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uint8_t result = 0;
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int carry;
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for (int i = 0; i < 5; i++) {
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carry = 0;
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for (int j = 0; j < 5; j++) {
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carry = rotateLeftWithCarry(bytes + 4 - j, carry);
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}
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rotateLeftWithCarry(&result, carry);
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}
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return result;
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}
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char *decompressText(uint8_t *source, int stringIndex) {
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// Lookup table
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const char *alphabet = " abcdefghijklmnopqrstuvwxyz'\x01,.\x00";
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//Common::String alphabet = " abcdefghijklmnopqrstuvwxyz'\x01,.\x00";
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int pos, c, uppercase, i, j;
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uint8_t decompressed[256];
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uint8_t buffer[5];
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int idx = 0;
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// Find the start of the compressed message
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for (i = 0; i < stringIndex; i++) {
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pos = *source;
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pos = pos & 0x7F;
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source += pos;
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};
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uppercase = ((*source & 0x40) == 0); // Test bit 6
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source++;
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do {
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// Get five compressed bytes
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for (i = 0; i < 5; i++) {
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buffer[i] = *source++;
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}
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for (j = 0; j < 8; j++) {
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// Decompress one character:
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int next = decompressOne(buffer);
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c = alphabet[next];
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if (c == 0x01) {
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uppercase = 1;
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c = ' ';
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}
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if (c >= 'a' && uppercase) {
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c = toupper(c);
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uppercase = 0;
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}
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decompressed[idx++] = c;
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if (idx > 255)
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return nullptr;
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if (idx == 255)
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c = 0; // We've gone too far, return
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if (c == 0) {
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char *result = new char[idx];
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memcpy(result, decompressed, idx);
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return result;
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} else if (c == '.' || c == ',') {
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if (c == '.')
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uppercase = 1;
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decompressed[idx++] = ' ';
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}
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}
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} while (idx < 0xff); // Chosen arbitrarily, might be too small
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return nullptr;
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}
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} // End of namespace Scott
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} // End of namespace Glk
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