Int64ToBytes

gistfile1.cs

public static byte[] Int64ToBytes(long value) {
            if (value <= 255) return new byte[] { (byte)value };
            const int msb = 0xff;
            byte[] buffer = new byte[8];
            var index = 0;
            var sValue = 0L;
            unchecked {
                buffer[index++] = (byte)(value & msb);
                if ((sValue = (value >> 8) & msb) > 0) {
                    buffer[index++] = (byte)sValue;
                    if ((sValue = (value >> 16) & msb) > 0) {
                        buffer[index++] = (byte)sValue;
                        if ((sValue = (value >> 24) & msb) > 0) {
                            buffer[index++] = (byte)sValue;
                            if ((sValue = (value >> 32) & msb) > 0) {
                                buffer[index++] = (byte)sValue;
                                if ((sValue = (value >> 40) & msb) > 0) {
                                    buffer[index++] = (byte)sValue;
                                    if ((sValue = (value >> 48) & msb) > 0) {
                                        buffer[index++] = (byte)sValue;
                                        if ((sValue = (value >> 56) & msb) > 0) 
                                            buffer[index++] = (byte)sValue;
                                    }
                                }
                            }
                        }
                    }
                }
            }
            var buffer2 = new byte[index];
            Buffer.BlockCopy(buffer, 0, buffer2, 0, index);
            return buffer2;
        }