DM: Add support for Dungeon.dat uncompression

Add DungeonMan class with support for loading and uncompressing
Dungeon.dat file into memory

1 files changed, 62 insertions, 0 deletions

diff --git a/engines/dm/dungeonman.cpp b/engines/dm/dungeonman.cpp
new file mode 100644
index 0000000000..6ddf966eb9
--- /dev/null
+++ b/engines/dm/dungeonman.cpp
@@ -0,0 +1,62 @@
+#include "dungeonman.h"
+#include "common/file.h"
+
+
+namespace DM {
+DungeonMan::DungeonMan(DMEngine *dmEngine) : _vm(dmEngine), _dungeonDataSize(0), _dungeonData(NULL) {}
+DungeonMan::~DungeonMan() { delete[] _dungeonData; }
+void DungeonMan::loadDungeonFile() {
+	Common::File f;
+	f.open("Dungeon.dat");
+	if (f.readUint16BE() == 0x8104) {
+		_dungeonDataSize = f.readUint32BE();
+		_dungeonData = new byte[_dungeonDataSize];
+		f.readUint16BE();
+		byte common[4];
+		for (uint16 i = 0; i < 4; ++i)
+			common[i] = f.readByte();
+		byte lessCommon[16];
+		for (uint16 i = 0; i < 16; ++i)
+			lessCommon[i] = f.readByte();
+
+		// start unpacking
+		uint32 uncompIndex = 0;
+		uint8 bitsUsedInWord = 0;
+		uint16 wordBuff = f.readUint16BE();
+		uint8 bitsLeftInByte = 8;
+		byte byteBuff = f.readByte();
+		while (uncompIndex < _dungeonDataSize) {
+			while (bitsUsedInWord != 0) {
+				uint8 shiftVal;
+				if (f.eos()) {
+					shiftVal = bitsUsedInWord;
+					wordBuff <<= shiftVal;
+				} else {
+					shiftVal = MIN(bitsLeftInByte, bitsUsedInWord);
+					wordBuff <<= shiftVal;
+					wordBuff |= (byteBuff >> (8 - shiftVal));
+					byteBuff <<= shiftVal;
+					bitsLeftInByte -= shiftVal;
+					if (!bitsLeftInByte) {
+						byteBuff = f.readByte();
+						bitsLeftInByte = 8;
+					}
+				}
+				bitsUsedInWord -= shiftVal;
+			}
+			if (((wordBuff >> 15) & 1) == 0) {
+				_dungeonData[uncompIndex++] = common[(wordBuff >> 13) & 3];
+				bitsUsedInWord += 3;
+			} else if (((wordBuff >> 14) & 3) == 2) {
+				_dungeonData[uncompIndex++] = lessCommon[(wordBuff >> 10) & 15];
+				bitsUsedInWord += 6;
+			} else if (((wordBuff >> 14) & 3) == 3) {
+				_dungeonData[uncompIndex++] = (wordBuff >> 6) & 255;
+				bitsUsedInWord += 10;
+			}
+		}
+	}
+	f.close();
+}
+
+}
\ No newline at end of file