// 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.

//go:build (amd64 && !generic) || (arm64 && !generic)
// +build amd64,!generic arm64,!generic

package sm2

import (
	"encoding/binary"
	"reflect"
	"testing"
)

func TestP256PrecomputedTable(t *testing.T) {

	basePoint := []uint64{
		0x61328990f418029e, 0x3e7981eddca6c050, 0xd6a1ed99ac24c3c3, 0x91167a5ee1c13b05,
		0xc1354e593c2d0ddd, 0xc1f5e5788d3295fa, 0x8d4cfb066e2a48f8, 0x63cd65d481d735bd,
		0x0000000000000001, 0x00000000ffffffff, 0x0000000000000000, 0x0000000100000000,
	}
	t1 := make([]uint64, 12)
	t2 := make([]uint64, 12)
	copy(t2, basePoint)

	zInv := make([]uint64, 4)
	zInvSq := make([]uint64, 4)
	for j := 0; j < 32; j++ {
		copy(t1, t2)
		for i := 0; i < 43; i++ {
			// The window size is 6 so we need to double 6 times.
			if i != 0 {
				for k := 0; k < 6; k++ {
					p256PointDoubleAsm(t1, t1)
				}
			}
			// Convert the point to affine form. (Its values are
			// still in Montgomery form however.)
			p256Inverse(zInv, t1[8:12])
			p256Sqr(zInvSq, zInv, 1)
			p256Mul(zInv, zInv, zInvSq)

			p256Mul(t1[:4], t1[:4], zInvSq)
			p256Mul(t1[4:8], t1[4:8], zInv)

			copy(t1[8:12], basePoint[8:12])

			buf := make([]byte, 8*8)
			for i, u := range t1[:8] {
				binary.LittleEndian.PutUint64(buf[i*8:i*8+8], u)
			}
			start := i*32*8*8 + j*8*8
			if got, want := p256Precomputed[start:start+64], string(buf); !reflect.DeepEqual(got, want) {
				t.Fatalf("Unexpected table entry at [%d][%d:%d]: got %v, want %v", i, j*8, (j*8)+8, got, want)
			}
		}
		if j == 0 {
			p256PointDoubleAsm(t2, basePoint)
		} else {
			p256PointAddAsm(t2, t2, basePoint)
		}
	}

}