in glog.go [615:628]
func (buf *buffer) someDigits(i, d int) int {
// Print into the top, then copy down. We know there's space for at least
// a 10-digit number.
j := len(buf.tmp)
for {
j--
buf.tmp[j] = digits[d%10]
d /= 10
if d == 0 {
break
}
}
return copy(buf.tmp[i:], buf.tmp[j:])
}