strconv.ParseInt Faster Implementation to convert strings to int64

parseInt64.go

// Ascii numbers 0-9
const (
	ascii_0 = 48
	ascii_9 = 57
)

// parseInt64 expects decimal positive numbers. We
// return -1 to signal error
func parseInt64(d []byte) (n int64) {
	if len(d) == 0 {
		return -1
	}
	for _, dec := range d {
		if dec < ascii_0 || dec > ascii_9 {
			return -1
		}
		n = n*10 + (int64(dec) - ascii_0)
	}
	return n
}