VarInt reading/writing from Glowstone

varint.java

    /**
     * The bit flag indicating a varint continues.
     */
    public static final byte VARINT_MORE_FLAG = (byte) (1 << 7);
    
    /**
     * Read a protobuf varint from the buffer.
     * @param buf The buffer.
     * @return The value read.
     */
    public static int readVarInt(ChannelBuffer buf) {
        int ret = 0;
        short read;
        byte offset = 0;
        do {
            read = buf.readUnsignedByte();
            ret = ret | ((read & ~VARINT_MORE_FLAG) << offset);
            offset += 7;
        } while (((read >> 7) & 1) != 0);
        return ret;
    }

    /**
     * Write a protobuf varint to the buffer.
     * @param buf The buffer.
     * @param num The value to write.
     */
    public static void writeVarInt(ChannelBuffer buf, int num) {
        do {
            short write = (short) (num & ~VARINT_MORE_FLAG);
            num >>= 7;
            if (num != 0) {
                write |= VARINT_MORE_FLAG;
            }
            buf.writeByte(write);
        } while (num != 0);
    }