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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
/*
* Based on ScottFree interpreter version 1.14 developed by Swansea
* University Computer Society without disassembly of any other game
* drivers, only of game databases as permitted by EEC law (for purposes
* of compatibility).
*
* Licensed under GPLv2
*
* https://github.com/angstsmurf/spatterlight/tree/master/terps/scott
*/
#include "common/str.h"
#include "glk/scott/decompress_text.h"
namespace Glk {
namespace Scott {
int rotateLeftWithCarry(uint8_t *byte, int lastCarry) {
int carry = ((*byte & 0x80) > 0);
*byte = *byte << 1;
if (lastCarry)
*byte = *byte | 0x01;
return carry;
}
int decompressOne(uint8_t *bytes) {
uint8_t result = 0;
int carry;
for (int i = 0; i < 5; i++) {
carry = 0;
for (int j = 0; j < 5; j++) {
carry = rotateLeftWithCarry(bytes + 4 - j, carry);
}
rotateLeftWithCarry(&result, carry);
}
return result;
}
char *decompressText(uint8_t *source, int stringIndex) {
// Lookup table
const char *alphabet = " abcdefghijklmnopqrstuvwxyz'\x01,.\x00";
//Common::String alphabet = " abcdefghijklmnopqrstuvwxyz'\x01,.\x00";
int pos, c, uppercase, i, j;
uint8_t decompressed[256];
uint8_t buffer[5];
int idx = 0;
// Find the start of the compressed message
for (i = 0; i < stringIndex; i++) {
pos = *source;
pos = pos & 0x7F;
source += pos;
};
uppercase = ((*source & 0x40) == 0); // Test bit 6
source++;
do {
// Get five compressed bytes
for (i = 0; i < 5; i++) {
buffer[i] = *source++;
}
for (j = 0; j < 8; j++) {
// Decompress one character:
int next = decompressOne(buffer);
c = alphabet[next];
if (c == 0x01) {
uppercase = 1;
c = ' ';
}
if (c >= 'a' && uppercase) {
c = toupper(c);
uppercase = 0;
}
decompressed[idx++] = c;
if (idx > 255)
return nullptr;
if (idx == 255)
c = 0; // We've gone too far, return
if (c == 0) {
char *result = new char[idx];
memcpy(result, decompressed, idx);
return result;
} else if (c == '.' || c == ',') {
if (c == '.')
uppercase = 1;
decompressed[idx++] = ' ';
}
}
} while (idx < 0xff); // Chosen arbitrarily, might be too small
return nullptr;
}
} // End of namespace Scott
} // End of namespace Glk
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