COMMON: Add PackBitsReadStream to iff_container

2 files changed, 80 insertions, 8 deletions

diff --git a/common/iff_container.cpp b/common/iff_container.cpp
index 7bcbf86e0f..ffaa5c6d06 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);
 }
 
+
+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
diff --git a/common/iff_container.h b/common/iff_container.h
index 104ecf0f36..a730930b2c 100644
--- a/common/iff_container.h
+++ b/common/iff_container.h
@@ -77,22 +77,22 @@ page 376) */
 #define ID_copy     MKTAG('(','c',')',' ')
 /* EA IFF 85 Generic Copyright text chunk */
 
-/* ILBM chunks */
+/* IFF chunks */
 
 #define ID_BMHD     MKTAG('B','M','H','D')
-/* ILBM BitmapHeader */
+/* IFF BitmapHeader */
 #define ID_CMAP     MKTAG('C','M','A','P')
-/* ILBM 8bit RGB colormap */
+/* IFF 8bit RGB colormap */
 #define ID_GRAB     MKTAG('G','R','A','B')
-/* ILBM "hotspot" coordiantes */
+/* IFF "hotspot" coordiantes */
 #define ID_DEST     MKTAG('D','E','S','T')
-/* ILBM destination image info */
+/* IFF destination image info */
 #define ID_SPRT     MKTAG('S','P','R','T')
-/* ILBM sprite identifier */
+/* IFF sprite identifier */
 #define ID_CAMG     MKTAG('C','A','M','G')
 /* Amiga viewportmodes */
 #define ID_BODY     MKTAG('B','O','D','Y')
-/* ILBM image data */
+/* IFF image data */
 #define ID_CRNG     MKTAG('C','R','N','G')
 /* color cycling */
 #define ID_CCRT     MKTAG('C','C','R','T')
@@ -114,7 +114,7 @@ page 376) */
 #define ID_PCHG     MKTAG('P','C','H','G')
 /* Line by line palette control information (Sebastiano Vigna) */
 #define ID_PRVW     MKTAG('P','R','V','W')
-/* A mini duplicate ILBM used for preview (Gary Bonham) */
+/* A mini duplicate IFF used for preview (Gary Bonham) */
 #define ID_XBMI     MKTAG('X','B','M','I')
 /* eXtended BitMap Information (Soft-Logik) */
 #define ID_CTBL     MKTAG('C','T','B','L')
@@ -239,6 +239,31 @@ public:
 };
 
 
+/**
+ * Decode a given PackBits encoded stream.
+ *
+ * PackBits is an RLE compression algorithm introduced by Apple. It is also
+ * used to encode ILBM and PBM subtypes of IFF files, and some flavors of
+ * TIFF.
+ *
+ * As there is no compression across row boundaries in the above formats,
+ * read() will extract a *new* line on each call, discarding any alignment
+ * or padding.
+ */
+class PackBitsReadStream : public Common::ReadStream {
+
+protected:
+	Common::ReadStream *_input;
+
+public:
+	PackBitsReadStream(Common::ReadStream &input);
+	~PackBitsReadStream();
+
+	virtual bool eos() const;
+
+	uint32 read(void *dataPtr, uint32 dataSize);
+};
+
 } // namespace Common
 
 #endif