1 files changed, 48 insertions, 1 deletions
diff --git a/common/iff_container.cpp b/common/iff_container.cpp
index 7bcbf86e0f..9c6e5f124a 100644
--- a/common/iff_container.cpp
+++ b/common/iff_container.cpp
@@ -22,6 +22,7 @@
 
 #include "common/iff_container.h"
 #include "common/substream.h"
+#include "common/util.h"
 
 namespace Common {
 
@@ -75,4 +76,50 @@ void IFFParser::parse(IFFCallback &callback) {
 	} while (!stop);
 }
 
-}	// End of namespace Common
+
+PackBitsReadStream::PackBitsReadStream(Common::ReadStream &input) : _input(&input) {
+}
+
+PackBitsReadStream::~PackBitsReadStream() {
+}
+
+bool PackBitsReadStream::eos() const {
+	return _input->eos();
+}
+
+uint32 PackBitsReadStream::read(void *dataPtr, uint32 dataSize) {
+	byte *out = (byte *)dataPtr;
+	uint32 left = dataSize;
+
+	uint32 lenR = 0, lenW = 0;
+	while (left > 0 && !_input->eos()) {
+		lenR = _input->readByte();
+
+		if (lenR == 128) {
+			// no-op
+			lenW = 0;
+		} else if (lenR <= 127) {
+			// literal run
+			lenR++;
+			lenW = MIN(lenR, left);
+			for (uint32 j = 0; j < lenW; j++) {
+				*out++ = _input->readByte();
+			}
+			for (; lenR > lenW; lenR--) {
+				_input->readByte();
+			}
+		} else {  // len > 128
+			// expand run
+			lenW = MIN((256 - lenR) + 1, left);
+			byte val = _input->readByte();
+			memset(out, val, lenW);
+			out += lenW;
+		}
+
+		left -= lenW;
+	}
+
+	return dataSize - left;
+}
+
+} // End of namespace Common