golang p224_invert 代码
文件路径：/src/crypto/internal/nistec/fiat/p224_invert.go
/ Copyright 2021 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.
/ Code generated by addchain. DO NOT EDIT.
package fiat
/ Invert sets e = 1/x, and returns e.
/
/ If x == 0, Invert returns e = 0.
func (e *P224Element) Invert(x *P224Element) *P224Element {
/ Inversion is implemented as exponentiation with exponent p − 2.
/ The sequence of 11 multiplications and 223 squarings is derived from the
/ following addition chain generated with github.com/mmcloughlin/addchain v0.3.0.
/
/ _10 = 2*1
/ _11 = 1 + _10
/ _110 = 2*_11
/ _111 = 1 + _110
/ _111000 = _111 << 3
/ _111111 = _111 + _111000
/ x12 = _111111 << 6 + _111111
/ x14 = x12 << 2 + _11
/ x17 = x14 << 3 + _111
/ x31 = x17 << 14 + x14
/ x48 = x31 << 17 + x17
/ x96 = x48 << 48 + x48
/ x127 = x96 << 31 + x31
/ return x127 << 97 + x96
/
var z = new(P224Element).Set(e)
var t0 = new(P224Element)
var t1 = new(P224Element)
var t2 = new(P224Element)
z.Square(x)
t0.Mul(x, z)
z.Square(t0)
z.Mul(x, z)
t1.Square(z)
for s := 1; s < 3; s++ {
t1.Square(t1)
}
t1.Mul(z, t1)
t2.Square(t1)
for s := 1; s < 6; s++ {
t2.Square(t2)
}
t1.Mul(t1, t2)
for s := 0; s < 2; s++ {
t1.Square(t1)
}
t0.Mul(t0, t1)
t1.Square(t0)
for s := 1; s < 3; s++ {
t1.Square(t1)
}
z.Mul(z, t1)
t1.Square(z)
for s := 1; s < 14; s++ {
t1.Square(t1)
}
t0.Mul(t0, t1)
t1.Square(t0)
for s := 1; s < 17; s++ {
t1.Square(t1)
}
z.Mul(z, t1)
t1.Square(z)
for s := 1; s < 48; s++ {
t1.Square(t1)
}
z.Mul(z, t1)
t1.Square(z)
for s := 1; s < 31; s++ {
t1.Square(t1)
}
t0.Mul(t0, t1)
for s := 0; s < 97; s++ {
t0.Square(t0)
}
z.Mul(z, t0)
return e.Set(z)
}