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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build s390x,go1.11,!gccgo,!appengine
package poly1305
import (
"golang.org/x/sys/cpu"
)
// poly1305vx is an assembly implementation of Poly1305 that uses vector
// instructions. It must only be called if the vector facility (vx) is
// available.
//go:noescape
func poly1305vx(out *[16]byte, m *byte, mlen uint64, key *[32]byte)
// poly1305vmsl is an assembly implementation of Poly1305 that uses vector
// instructions, including VMSL. It must only be called if the vector facility (vx) is
// available and if VMSL is supported.
//go:noescape
func poly1305vmsl(out *[16]byte, m *byte, mlen uint64, key *[32]byte)
// Sum generates an authenticator for m using a one-time key and puts the
// 16-byte result into out. Authenticating two different messages with the same
// key allows an attacker to forge messages at will.
func Sum(out *[16]byte, m []byte, key *[32]byte) {
if cpu.S390X.HasVX {
var mPtr *byte
if len(m) > 0 {
mPtr = &m[0]
}
if cpu.S390X.HasVXE && len(m) > 256 {
poly1305vmsl(out, mPtr, uint64(len(m)), key)
} else {
poly1305vx(out, mPtr, uint64(len(m)), key)
}
} else {
sumGeneric(out, m, key)
}
}