Function leftEncode

crypto/sha3/cshake.go:109–127

leftEncode encodes integer in a variable-length encoding unambiguously parseable from the beginning of a string. Used to encode strings for all cSHAKE functions.

(d *state, value uint64)

// unambiguously parseable from the beginning of a string.
// Used to encode strings for all cSHAKE functions.
func leftEncode(d *state, value uint64) int {
	input := d.varintbuf[:]
	copy(input, zero[:])
	var offset uint
	if value == 0 {
		offset = 8
	} else {
		binary.BigEndian.PutUint64(input[1:], value)
		for offset = 0; offset < 9; offset++ {
			if input[offset] != 0 {
				break
			}
		}
	}
	input[offset-1] = byte(9 - offset)
	b := input[offset-1:]
	d.Write(b)
	return len(b)
}