1// Copyright 2021 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// Code generated by addchain. DO NOT EDIT. 6 7package fiat 8 9// Invert sets e = 1/x, and returns e. 10// 11// If x == 0, Invert returns e = 0. 12func (e *P224Element) Invert(x *P224Element) *P224Element { 13 // Inversion is implemented as exponentiation with exponent p − 2. 14 // The sequence of 11 multiplications and 223 squarings is derived from the 15 // following addition chain generated with github.com/mmcloughlin/addchain v0.4.0. 16 // 17 // _10 = 2*1 18 // _11 = 1 + _10 19 // _110 = 2*_11 20 // _111 = 1 + _110 21 // _111000 = _111 << 3 22 // _111111 = _111 + _111000 23 // x12 = _111111 << 6 + _111111 24 // x14 = x12 << 2 + _11 25 // x17 = x14 << 3 + _111 26 // x31 = x17 << 14 + x14 27 // x48 = x31 << 17 + x17 28 // x96 = x48 << 48 + x48 29 // x127 = x96 << 31 + x31 30 // return x127 << 97 + x96 31 // 32 33 var z = new(P224Element).Set(e) 34 var t0 = new(P224Element) 35 var t1 = new(P224Element) 36 var t2 = new(P224Element) 37 38 z.Square(x) 39 t0.Mul(x, z) 40 z.Square(t0) 41 z.Mul(x, z) 42 t1.Square(z) 43 for s := 1; s < 3; s++ { 44 t1.Square(t1) 45 } 46 t1.Mul(z, t1) 47 t2.Square(t1) 48 for s := 1; s < 6; s++ { 49 t2.Square(t2) 50 } 51 t1.Mul(t1, t2) 52 for s := 0; s < 2; s++ { 53 t1.Square(t1) 54 } 55 t0.Mul(t0, t1) 56 t1.Square(t0) 57 for s := 1; s < 3; s++ { 58 t1.Square(t1) 59 } 60 z.Mul(z, t1) 61 t1.Square(z) 62 for s := 1; s < 14; s++ { 63 t1.Square(t1) 64 } 65 t0.Mul(t0, t1) 66 t1.Square(t0) 67 for s := 1; s < 17; s++ { 68 t1.Square(t1) 69 } 70 z.Mul(z, t1) 71 t1.Square(z) 72 for s := 1; s < 48; s++ { 73 t1.Square(t1) 74 } 75 z.Mul(z, t1) 76 t1.Square(z) 77 for s := 1; s < 31; s++ { 78 t1.Square(t1) 79 } 80 t0.Mul(t0, t1) 81 for s := 0; s < 97; s++ { 82 t0.Square(t0) 83 } 84 z.Mul(z, t0) 85 86 return e.Set(z) 87} 88