GLK: ADRIFT: Implement zlib decompression

2 files changed, 85 insertions, 0 deletions

diff --git a/common/zlib.cpp b/common/zlib.cpp
index 6afffb14d2..e4a3d47e35 100644
--- a/common/zlib.cpp
+++ b/common/zlib.cpp
@@ -141,6 +141,79 @@ bool inflateZlibInstallShield(byte *dst, uint dstLen, const byte *src, uint srcL
 	return true;
 }
 
+bool inflateZlibHeaderless(Common::WriteStream *dst, Common::SeekableReadStream *src) {
+	byte *inBuffer, *outBuffer;
+	z_stream stream;
+	int status;
+
+	// Allocate buffers
+	inBuffer = new byte[kTempBufSize];
+	outBuffer = new byte[kTempBufSize];
+
+	/* Initialize Zlib inflation functions. */
+	stream.next_out = outBuffer;
+	stream.avail_out = kTempBufSize;
+	stream.next_in = inBuffer;
+	stream.avail_in = 0;
+
+	stream.zalloc = Z_NULL;
+	stream.zfree = Z_NULL;
+	stream.opaque = Z_NULL;
+
+	status = inflateInit(&stream);
+	if (status != Z_OK) {
+		delete[] inBuffer;
+		delete[] outBuffer;
+		return false;
+	}
+
+	// Inflate the input buffers. */
+	for (;;) {
+		int inBytes, outBytes;
+
+		/* If the input buffer is empty, try to obtain more data. */
+		if (stream.avail_in == 0) {
+			inBytes = src->read(inBuffer, kTempBufSize);
+			stream.next_in = inBuffer;
+			stream.avail_in = inBytes;
+		}
+
+		// Decompress as much stream data as we can. */
+		status = inflate(&stream, Z_SYNC_FLUSH);
+		if (status != Z_STREAM_END && status != Z_OK) {
+			delete[] inBuffer;
+			delete[] outBuffer;
+			return false;
+		}
+		outBytes = kTempBufSize - stream.avail_out;
+
+		// See if decompressed data is available. */
+		if (outBytes > 0) {
+			// Add data from the buffer to the output
+			int consumed = dst->write(outBuffer, outBytes);
+
+			// Move unused buffer data to buffer start
+			memmove(outBuffer, outBuffer + consumed, kTempBufSize - consumed);
+
+			// Reset inflation stream for available space
+			stream.next_out = outBuffer + outBytes - consumed;
+			stream.avail_out += consumed;
+		}
+
+		// If at inflation stream end and output is empty, leave loop
+		if (status == Z_STREAM_END && stream.avail_out == kTempBufSize)
+			break;
+	}
+
+	// End inflation buffers
+	status = inflateEnd(&stream);
+	delete[] inBuffer;
+	delete[] outBuffer;
+
+	// Return result
+	return (status == Z_OK);
+}
+
 #ifndef RELEASE_BUILD
 static bool _shownBackwardSeekingWarning = false;
 #endif
diff --git a/common/zlib.h b/common/zlib.h
index eb0548344d..a172399511 100644
--- a/common/zlib.h
+++ b/common/zlib.h
@@ -96,6 +96,18 @@ bool inflateZlibHeaderless(byte *dst, uint dstLen, const byte *src, uint srcLen,
  */
 bool inflateZlibInstallShield(byte *dst, uint dstLen, const byte *src, uint srcLen);
 
+/**
+ * Wrapper around zlib's inflate functions. This function is used by Glk to
+ * decompress TAF 4.0 files, which are headerless Zlib compressed streams with a
+ * custom header
+ *
+ * @param dst       the destination stream to write decompressed data out to
+ * @param src       the Source stream
+ *
+ * @return true on success (Z_OK or Z_STREAM_END), false otherwise.
+ */
+bool inflateZlibHeaderless(Common::WriteStream *dst, Common::SeekableReadStream *src);
+
 #endif
 
 /**