DataBuffer.swift

class DataBuffer {
	var internalData: NSData;
	
	init(fromData: NSData) {
		self.internalData = NSData.dataWithData(fromData) as NSData;
	}
	
	init(fromFilePath: String) {
		self.internalData = NSData.dataWithContentsOfFile(fromFilePath, options: .DataReadingMappedIfSafe, error: nil) as NSData;
	}
	
	// subscripting syntax to access raw pointer to bytes from offset ORIGIN
	// e.g.: var pointer = myData[<offset from origin>]
	subscript(origin: Int) -> UnsafePointer<UInt8> {
		get {
			var result: UnsafePointer<UInt8> = nil;
			var dataLength = self.internalData.length();
			if (origin < dataLength) {
				var newLength = dataLength - origin;
				var tempData = self.internalData.subdataWithRange(NSMakeRange(origin, newLength));
				result = UnsafePointer<UInt8>(tempData.bytes());
			}
			return result;
		}
	}
	
	// subscripting syntax to access SIZE number of bytes from offset ORIGIN
	// e.g.: var value = myData[<offset from origin>, <number of bytes>]
	subscript(origin: Int, size: Int) -> CChar[] {
		get {
			var result: CChar[] = [];
			var dataLength = self.internalData.length();
			if (origin < dataLength) {
				var tempData = self.internalData.subdataWithRange(NSMakeRange(origin, size));
				for index in 0...(tempData.length()-1) {
					var byte = UnsafePointer<CChar>(tempData.bytes())[index];
					result.append(byte);
				}
			}
			return result;
		}
	}
}