1 files changed, 171 insertions, 0 deletions
diff --git a/engines/prince/decompress.cpp b/engines/prince/decompress.cpp
new file mode 100644
index 0000000000..7fba179541
--- /dev/null
+++ b/engines/prince/decompress.cpp
@@ -0,0 +1,171 @@
+/* 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 2
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+// John_Doe's implementation
+
+#include "prince/decompress.h"
+
+namespace Prince {
+
+static const uint16 table1[] = {
+    0x8000, 0x0002,
+    0x4000, 0x0004,
+    0x2000, 0x0008,
+    0x1000, 0x0010,
+    0x0800, 0x0020,
+    0x0400, 0x0040,
+    0x0200, 0x0080,
+    0x0100, 0x0100,
+    0x0080, 0x0200,
+    0x0040, 0x0400
+};
+
+static const uint32 table2[] = {
+    0x0000F000,
+    0x0020FC00,
+    0x00A0FF00,
+    0x02A0FF80,
+    0x06A0FFC0,
+    0x0EA0FFE0,
+    0x1EA0FFF0,
+    0x3EA0FFF8
+};
+
+static const uint16 table3[] = {
+    0x8000, 0x0000,
+    0x4000, 0x0002,
+    0x2000, 0x0006,
+    0x1000, 0x000E,
+    0x0800, 0x001E,
+    0x0400, 0x003E,
+    0x0200, 0x007E,
+    0x0100, 0x00FE,
+    0x0080, 0x01FE,
+    0x0040, 0x03FE,
+    0x0020, 0x07FE,
+    0x0010, 0x0FFE,
+    0x0008, 0x1FFE,
+    0x0004, 0x3FFE,
+    0x0002, 0x7FFE,
+    0x0001, 0xFFFE
+};
+
+void Decompressor::decompress(byte *source, byte *dest, uint32 destSize) {
+    byte *destEnd = dest + destSize;
+    int more;
+    _src = source;
+    _dst = dest;
+    _bitBuffer = 0x80;
+    while (_dst < destEnd) {
+        uint32 ebp;
+        uint16 offset, length;
+        if (getBit()) {
+            if (getBit()) {
+                if (getBit()) {
+                    if (getBit()) {
+                        if (getBit()) {
+                            if (getBit()) {
+                                uint32 tableIndex = 0;
+                                while (getBit())
+                                    tableIndex++;
+                                length = table3[tableIndex * 2 + 0];
+                                do {
+                                    more = !(length & 0x8000);
+                                    length = (length << 1) | getBit();
+                                } while (more);
+                                length += table3[tableIndex * 2 + 1];
+                                length++;
+                                memcpy(_dst, _src, length);
+                                _src += length;
+                                _dst += length;
+                            }
+                            *_dst++ = *_src++;
+                        }
+                        *_dst++ = *_src++;
+                    }
+                    *_dst++ = *_src++;
+                }
+                *_dst++ = *_src++;
+            }
+            *_dst++ = *_src++;
+        }
+        if (!getBit()) {
+            if (getBit()) {
+                uint32 tableIndex = getBit();
+                tableIndex = (tableIndex << 1) | getBit();
+                tableIndex = (tableIndex << 1) | getBit();
+                ebp = table2[tableIndex];
+                length = 1;
+            } else {
+                ebp = 0x0000FF00;
+                length = 0;
+            }
+        } else {
+            uint32 tableIndex = 0;
+            while (getBit())
+                tableIndex++;
+            length = table1[tableIndex * 2 + 0];
+            do {
+                more = !(length & 0x8000);
+                length = (length << 1) | getBit();
+            } while (more);
+            length += table1[tableIndex * 2 + 1];
+            tableIndex = getBit();
+            tableIndex = (tableIndex << 1) | getBit();
+            tableIndex = (tableIndex << 1) | getBit();
+            ebp = table2[tableIndex];
+        }
+        offset = ebp & 0xFFFF;
+        do {
+            if (_bitBuffer == 0x80) {
+                if (offset >= 0xFF00) {
+                    offset = (offset << 8) | *_src++;
+                }
+            }
+            more = offset & 0x8000;
+            offset = (offset << 1) | getBit();
+        } while (more);
+        offset += (ebp >> 16);
+        length += 2;
+        while (length--) {
+            if (_dst >= destEnd) {
+                return;
+            }
+            *_dst = *(_dst - offset);
+            _dst++;
+        }
+    }
+}
+
+int Decompressor::getBit() {
+    int bit = (_bitBuffer & 0x80) >> 7;
+    _bitBuffer <<= 1;
+    if (_bitBuffer == 0) {
+        _bitBuffer = *_src++;
+        bit = (_bitBuffer & 0x80) >> 7;
+        _bitBuffer <<= 1;
+        _bitBuffer |= 1;
+    }
+    return bit;
+}
+
+} // End of namespace Prince