Initial commit

engines/bladerunner/decompress_lzo.cpp

@@ -0,0 +1,133 @@
+/* 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/>.
+ *
+ */
+
+#include "bladerunner/decompress_lzo.h"
+
+namespace BladeRunner {
+
+static inline uint32 decode_count(const uint8 **pp) {
+	uint32 v = 0;
+	for (; !**pp; ++(*pp))
+		v += 255;
+
+	v += **pp;
+	++(*pp);
+
+	return v;
+}
+
+static inline void copy(uint8 **dst, const uint8 **src, int count) {
+	assert(count > 0);
+
+	uint8 *d = *dst;
+	const uint8 *s = *src;
+
+	*dst += count;
+	*src += count;
+
+	do { *d++ = *s++; } while (--count);
+}
+
+int decompress_lzo1x(const uint8 *in, size_t inLen, uint8 *out, size_t *outLen) {
+	uint32 t;
+	uint8 *op;
+	const uint8 *ip, *m_pos;
+	const uint8 * const ip_end = in + inLen;
+
+	*outLen = 0;
+
+	op = out;
+	ip = in;
+
+	if (*ip > 17) {
+		t = *ip++ - 17;
+		if (t < 4)
+			goto match_next;
+		copy(&op, &ip, t);
+		goto first_literal_run;
+	}
+
+	for (;;) {
+		t = *ip++;
+		if (t >= 16)
+			goto match;
+
+		if (t == 0)
+			t = 15 + decode_count(&ip);
+		copy(&op, &ip, t + 3);
+
+first_literal_run:
+		t = *ip++;
+		if (t >= 16)
+			goto match;
+		m_pos = op - 0x0801 - (t >> 2) - (*ip++ << 2);
+		copy(&op, &m_pos, 3);
+		goto match_done;
+
+		for (;;) {
+match:
+			if (t >= 64) {
+				m_pos = op - 1 - ((t >> 2) & 7) - (*ip++ << 3);
+				t = (t >> 5) - 1;
+				goto copy_match;
+			} else if (t >= 32) {
+				t &= 31;
+				if (t == 0)
+					t = 31 + decode_count(&ip);
+				m_pos = op - 1 - (ip[0] >> 2) - (ip[1] << 6);
+				ip += 2;
+			} else if (t >= 16) {
+				m_pos = op - ((t & 8) << 11);
+				t &= 7;
+				if (t == 0)
+					t = 7 + decode_count(&ip);
+				m_pos -= (ip[0] >> 2) + (ip[1] << 6);
+				ip += 2;
+				if (m_pos == op)
+					goto eof_found;
+				m_pos -= 0x4000;
+			} else {
+				m_pos = op - 1 - (t >> 2) - (*ip++ << 2);
+				copy(&op, &m_pos, 2);
+				goto match_done;
+			}
+
+copy_match:
+			copy(&op, &m_pos, t + 2);
+
+match_done:
+			t = ip[-2] & 3;
+			if (t == 0)
+				break;
+
+match_next:
+ 			assert(t > 0 && t <= 3);
+			copy(&op, &ip, t);
+			t = *ip++;
+		}
+	}
+
+eof_found:
+	*outLen = op - out;
+	return ip != ip_end;
+}
+
+} // End of namespace BladeRunner