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 *P384Element) Invert(x *P384Element) *P384Element { 13 // Inversion is implemented as exponentiation with exponent p − 2. 14 // The sequence of 15 multiplications and 383 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 // x24 = x12 << 12 + x12 25 // x30 = x24 << 6 + _111111 26 // x31 = 2*x30 + 1 27 // x32 = 2*x31 + 1 28 // x63 = x32 << 31 + x31 29 // x126 = x63 << 63 + x63 30 // x252 = x126 << 126 + x126 31 // x255 = x252 << 3 + _111 32 // i397 = ((x255 << 33 + x32) << 94 + x30) << 2 33 // return 1 + i397 34 // 35 36 var z = new(P384Element).Set(e) 37 var t0 = new(P384Element) 38 var t1 = new(P384Element) 39 var t2 = new(P384Element) 40 var t3 = new(P384Element) 41 42 z.Square(x) 43 z.Mul(x, z) 44 z.Square(z) 45 t1.Mul(x, z) 46 z.Square(t1) 47 for s := 1; s < 3; s++ { 48 z.Square(z) 49 } 50 z.Mul(t1, z) 51 t0.Square(z) 52 for s := 1; s < 6; s++ { 53 t0.Square(t0) 54 } 55 t0.Mul(z, t0) 56 t2.Square(t0) 57 for s := 1; s < 12; s++ { 58 t2.Square(t2) 59 } 60 t0.Mul(t0, t2) 61 for s := 0; s < 6; s++ { 62 t0.Square(t0) 63 } 64 z.Mul(z, t0) 65 t0.Square(z) 66 t2.Mul(x, t0) 67 t0.Square(t2) 68 t0.Mul(x, t0) 69 t3.Square(t0) 70 for s := 1; s < 31; s++ { 71 t3.Square(t3) 72 } 73 t2.Mul(t2, t3) 74 t3.Square(t2) 75 for s := 1; s < 63; s++ { 76 t3.Square(t3) 77 } 78 t2.Mul(t2, t3) 79 t3.Square(t2) 80 for s := 1; s < 126; s++ { 81 t3.Square(t3) 82 } 83 t2.Mul(t2, t3) 84 for s := 0; s < 3; s++ { 85 t2.Square(t2) 86 } 87 t1.Mul(t1, t2) 88 for s := 0; s < 33; s++ { 89 t1.Square(t1) 90 } 91 t0.Mul(t0, t1) 92 for s := 0; s < 94; s++ { 93 t0.Square(t0) 94 } 95 z.Mul(z, t0) 96 for s := 0; s < 2; s++ { 97 z.Square(z) 98 } 99 z.Mul(x, z) 100 101 return e.Set(z) 102} 103