// Copyright (c) 2015 The btcsuite developers
//
// Permission to use, copy, modify, and distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

// This file implements range-based zeroing, which as of Go 1.5 is
// optimized using a Duff's device.  See slice14.go for an implementation
// optimized for previous Go versions.
//
// +build !go1.3,!go1.4

package zero

import "math/big"

// Bytes sets all bytes in the passed slice to zero.  This is used to
// explicitly clear private key material from memory.
//
// In general, prefer to use the fixed-sized zeroing functions (Bytea*)
// when zeroing bytes as they are much more efficient than the variable
// sized zeroing func Bytes.
func Bytes(b []byte) {
	for i := range b {
		b[i] = 0
	}
}

// BigInt sets all bytes in the passed big int to zero and then sets the
// value to 0.  This differs from simply setting the value in that it
// specifically clears the underlying bytes whereas simply setting the value
// does not.  This is mostly useful to forcefully clear private keys.
func BigInt(x *big.Int) {
	b := x.Bits()
	for i := range b {
		b[i] = 0
	}
	x.SetInt64(0)
}