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// +build amd64,!noasm
package csidh
import "math/bits"
//go:noescape
func mul512(a, b *fp, c uint64)
//go:noescape
func mul576(a *[9]uint64, b *fp, c uint64)
//go:noescape
func cswap512(x, y *fp, choice uint8)
//go:noescape
func mulBmiAsm(res, x, y *fp)
// mulRdc performs montgomery multiplication r = x * y mod P.
// Returned result r is already reduced and in Montgomery domain.
func mulRdc(r, x, y *fp) {
var t fp
var c uint64
if hasADXandBMI2 {
mulBmiAsm(r, x, y)
} else {
mulGeneric(r, x, y)
}
// if p <= r < 2p then r = r-p
t[0], c = bits.Sub64(r[0], p[0], 0)
t[1], c = bits.Sub64(r[1], p[1], c)
t[2], c = bits.Sub64(r[2], p[2], c)
t[3], c = bits.Sub64(r[3], p[3], c)
t[4], c = bits.Sub64(r[4], p[4], c)
t[5], c = bits.Sub64(r[5], p[5], c)
t[6], c = bits.Sub64(r[6], p[6], c)
t[7], c = bits.Sub64(r[7], p[7], c)
var w = 0 - c
r[0] = ctPick64(w, r[0], t[0])
r[1] = ctPick64(w, r[1], t[1])
r[2] = ctPick64(w, r[2], t[2])
r[3] = ctPick64(w, r[3], t[3])
r[4] = ctPick64(w, r[4], t[4])
r[5] = ctPick64(w, r[5], t[5])
r[6] = ctPick64(w, r[6], t[6])
r[7] = ctPick64(w, r[7], t[7])
}
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