import "crypto/md5"
import "fmt"
sign := md5.Sum([]byte("date string"))
signStr := fmt.Sprintf("%x", sign) //將[]byte轉成16進制

var b2m_map map[byte]uint64 = map[byte]uint64{
	0x00: 0,
	0x01: 1,
	0x02: 2,
	0x03: 3,
	0x04: 4,
	0x05: 5,
	0x06: 6,
	0x07: 7,
	0x08: 8,
	0x09: 9,
	0x0A: 10,
	0x0B: 11,
	0x0C: 12,
	0x0D: 13,
	0x0E: 14,
	0x0F: 15,
	0x10: 16,
	0x11: 17,
	0x12: 18,
	0x13: 19,
	0x14: 20,
	0x15: 21,
	0x16: 22,
	0x17: 23,
	0x18: 24,
	0x19: 25,
	0x1A: 26,
	0x1B: 27,
	0x1C: 28,
	0x1D: 29,
	0x1E: 30,
	0x1F: 31,
	0x20: 32,
	0x21: 33,
	0x22: 34,
	0x23: 35,
	0x24: 36,
	0x25: 37,
	0x26: 38,
	0x27: 39,
	0x28: 40,
	0x29: 41,
	0x2A: 42,
	0x2B: 43,
	0x2C: 44,
	0x2D: 45,
	0x2E: 46,
	0x2F: 47,
	0x30: 48,
	0x31: 49,
	0x32: 50,
	0x33: 51,
	0x34: 52,
	0x35: 53,
	0x36: 54,
	0x37: 55,
	0x38: 56,
	0x39: 57,
	0x3A: 58,
	0x3B: 59,
	0x3C: 60,
	0x3D: 61,
	0x3E: 62,
	0x3F: 63,
	0x40: 64,
	0x41: 65,
	0x42: 66,
	0x43: 67,
	0x44: 68,
	0x45: 69,
	0x46: 70,
	0x47: 71,
	0x48: 72,
	0x49: 73,
	0x4A: 74,
	0x4B: 75,
	0x4C: 76,
	0x4D: 77,
	0x4E: 78,
	0x4F: 79,
	0x50: 80,
	0x51: 81,
	0x52: 82,
	0x53: 83,
	0x54: 84,
	0x55: 85,
	0x56: 86,
	0x57: 87,
	0x58: 88,
	0x59: 89,
	0x5A: 90,
	0x5B: 91,
	0x5C: 92,
	0x5D: 93,
	0x5E: 94,
	0x5F: 95,
	0x60: 96,
	0x61: 97,
	0x62: 98,
	0x63: 99,
	0x64: 100,
	0x65: 101,
	0x66: 102,
	0x67: 103,
	0x68: 104,
	0x69: 105,
	0x6A: 106,
	0x6B: 107,
	0x6C: 108,
	0x6D: 109,
	0x6E: 110,
	0x6F: 111,
	0x70: 112,
	0x71: 113,
	0x72: 114,
	0x73: 115,
	0x74: 116,
	0x75: 117,
	0x76: 118,
	0x77: 119,
	0x78: 120,
	0x79: 121,
	0x7A: 122,
	0x7B: 123,
	0x7C: 124,
	0x7D: 125,
	0x7E: 126,
	0x7F: 127,
	0x80: 128,
	0x81: 129,
	0x82: 130,
	0x83: 131,
	0x84: 132,
	0x85: 133,
	0x86: 134,
	0x87: 135,
	0x88: 136,
	0x89: 137,
	0x8A: 138,
	0x8B: 139,
	0x8C: 140,
	0x8D: 141,
	0x8E: 142,
	0x8F: 143,
	0x90: 144,
	0x91: 145,
	0x92: 146,
	0x93: 147,
	0x94: 148,
	0x95: 149,
	0x96: 150,
	0x97: 151,
	0x98: 152,
	0x99: 153,
	0x9A: 154,
	0x9B: 155,
	0x9C: 156,
	0x9D: 157,
	0x9E: 158,
	0x9F: 159,
	0xA0: 160,
	0xA1: 161,
	0xA2: 162,
	0xA3: 163,
	0xA4: 164,
	0xA5: 165,
	0xA6: 166,
	0xA7: 167,
	0xA8: 168,
	0xA9: 169,
	0xAA: 170,
	0xAB: 171,
	0xAC: 172,
	0xAD: 173,
	0xAE: 174,
	0xAF: 175,
	0xB0: 176,
	0xB1: 177,
	0xB2: 178,
	0xB3: 179,
	0xB4: 180,
	0xB5: 181,
	0xB6: 182,
	0xB7: 183,
	0xB8: 184,
	0xB9: 185,
	0xBA: 186,
	0xBB: 187,
	0xBC: 188,
	0xBD: 189,
	0xBE: 190,
	0xBF: 191,
	0xC0: 192,
	0xC1: 193,
	0xC2: 194,
	0xC3: 195,
	0xC4: 196,
	0xC5: 197,
	0xC6: 198,
	0xC7: 199,
	0xC8: 200,
	0xC9: 201,
	0xCA: 202,
	0xCB: 203,
	0xCC: 204,
	0xCD: 205,
	0xCE: 206,
	0xCF: 207,
	0xD0: 208,
	0xD1: 209,
	0xD2: 210,
	0xD3: 211,
	0xD4: 212,
	0xD5: 213,
	0xD6: 214,
	0xD7: 215,
	0xD8: 216,
	0xD9: 217,
	0xDA: 218,
	0xDB: 219,
	0xDC: 220,
	0xDD: 221,
	0xDE: 222,
	0xDF: 223,
	0xE0: 224,
	0xE1: 225,
	0xE2: 226,
	0xE3: 227,
	0xE4: 228,
	0xE5: 229,
	0xE6: 230,
	0xE7: 231,
	0xE8: 232,
	0xE9: 233,
	0xEA: 234,
	0xEB: 235,
	0xEC: 236,
	0xED: 237,
	0xEE: 238,
	0xEF: 239,
	0xF0: 240,
	0xF1: 241,
	0xF2: 242,
	0xF3: 243,
	0xF4: 244,
	0xF5: 245,
	0xF6: 246,
	0xF7: 247,
	0xF8: 248,
	0xF9: 249,
	0xFA: 250,
	0xFB: 251,
	0xFC: 252,
	0xFD: 253,
	0xFE: 254,
	0xFF: 255,
}
func hex2int(hexB *[]byte) uint64 {
	var retInt uint64
	hexLen := len(*hexB)
	for k, v := range *hexB {
		retInt += b2m_map[v] * exponent(16, uint64(2*(hexLen-k-1)))
	}
	return retInt
}
func exponent(a, n uint64) uint64 {
	result := uint64(1)
	for i := n; i > 0; i >>= 1 {
		if i1 != 0 {
			result *= a
		}
		a *= a
	}
	return result
}

goos: windows
goarch: amd64
pkg: benchmark
Benchmark_General-4  	10000000	    144 ns/op
Benchmark_Better-4  	10000000	    128 ns/op
PASS
ok 	benchmark	3.086s