GEEKING

App/util/Base64BinaryInputStream.cpp

@@ -0,0 +1,54 @@
+#include "stdafx.h"
+#include "Util/Base64BinaryInputStream.h"
+
+#include "Rbx/Debug.h"
+
+namespace RBX {
+
+unsigned char Base64BinaryInputStream::decode(unsigned char charFromString) {
+	if (charFromString >= 'A' && charFromString <= 'Z') {
+		return charFromString - 'A';
+	}
+	if (charFromString >= 'a' && charFromString <= 'z') {
+		return 26 + (charFromString - 'a');
+	}
+	if (charFromString >= '0' && charFromString <= '9') {
+		return 52 + (charFromString - '0');
+	}
+	if (charFromString == '+') {
+		return 62;
+	}
+	if (charFromString == '/') {
+		return 63;
+	}
+	RBXASSERT(false);
+	return 0;
+}
+
+Base64BinaryInputStream::Base64BinaryInputStream(const char* source) : 
+	source(source), buffer(0), readableBitsInBuffer(0) {}
+
+void Base64BinaryInputStream::ReadBits(unsigned char* output, size_t numBitsToRead) {
+	RBXASSERT(numBitsToRead <= 8);
+    RBXASSERT(numBitsToRead >= 1);
+
+	while (numBitsToRead > readableBitsInBuffer) {
+		boost::uint16_t nextValue = decode(*source);
+		source++;
+
+		// decode produced a 6 bit number. Shift that to the head (16 - 6 = 10),
+		// leaving room for the readableBits
+		nextValue <<= (10 - readableBitsInBuffer);
+		buffer |= nextValue;
+		readableBitsInBuffer += 6;
+	}
+
+	RBXASSERT(numBitsToRead <= readableBitsInBuffer);
+
+	unsigned char tmp = buffer >> (16 - numBitsToRead);
+	(*output) = tmp;
+	buffer <<= numBitsToRead;
+	readableBitsInBuffer -= numBitsToRead;
+}
+
+}