From 31b941908a4b59aa4dc4cd6d06983a41e9eb3d7e Mon Sep 17 00:00:00 2001
From: Sun Yimin <emmansun@users.noreply.github.com>
Date: Tue, 14 Oct 2025 15:14:10 +0800
Subject: [PATCH] internal/sm2ec: loong64 p256Add

---
 internal/sm2ec/p256_asm_loong64.s          | 92 ++++++++++++++++++++++
 internal/sm2ec/sm2p256_asm_loong64.go      |  3 +
 internal/sm2ec/sm2p256_asm_loong64_test.go | 55 +++++++++++++
 3 files changed, 150 insertions(+)

diff --git a/internal/sm2ec/p256_asm_loong64.s b/internal/sm2ec/p256_asm_loong64.s
index dd08fb9..0d1e7b5 100644
--- a/internal/sm2ec/p256_asm_loong64.s
+++ b/internal/sm2ec/p256_asm_loong64.s
@@ -1419,3 +1419,95 @@ TEXT ·p256MulBy2(SB),NOSPLIT,$0
 	MOVV x2, (8*2)(res_ptr)
 	MOVV x3, (8*3)(res_ptr)
 	RET
+
+/* ---------------------------------------*/
+// func p256PointAddAffineAsm(res, in1 *SM2P256Point, in2 *p256AffinePoint, sign, sel, zero int)
+TEXT ·p256PointAddAffineAsm(SB),0,$264-48
+	RET
+
+// (x3, x2, x1, x0) = (x3, x2, x1, x0) + (y3, y2, y1, y0)
+#define p256AddInline          \
+	ADDV x0, y0, x0;  \
+	SGTU y0, x0, t0;  \
+	ADDV x1, y1, x1;  \
+	SGTU y1, x1, t1;  \
+	ADDV t0, x1, x1;  \
+	SGTU t0, x1, t2;  \
+	OR t1, t2, t0;  \
+	ADDV x2, y2, x2;  \
+	SGTU y2, x2, t1;  \
+	ADDV t0, x2, x2;  \
+	SGTU t0, x2, t2;  \
+	OR t1, t2, t0;  \
+	ADDV x3, y3, x3;  \
+	SGTU y3, x3, t1;  \
+	ADDV t0, x3, x3;  \
+	SGTU t0, x3, t2;  \
+	OR t1, t2, t2;  \
+	;\
+	ADDV $1, x0, acc4;  \
+	SGTU x0, acc4, t0;  \
+	ADDV const0, t0, t0;  \
+	ADDV x1, t0, acc5;  \
+	SGTU x1, acc5, t0;  \
+	ADDV t0, x2, acc6;  \
+	SGTU x2, acc6, t0;  \
+	ADDV const1, t0, t0;  \
+	ADDV x3, t0, acc7;  \
+	SGTU x3, acc7, t0;  \
+	OR t0, t2, t0;  \
+	MASKNEZ t0, x0, x0;  \
+	MASKEQZ t0, acc4, acc4;  \
+	OR acc4, x0;  \
+	MASKNEZ t0, x1, x1;  \
+	MASKEQZ t0, acc5, acc5;  \
+	OR acc5, x1;  \
+	MASKNEZ t0, x2, x2;  \
+	MASKEQZ t0, acc6, acc6;  \
+	OR acc6, x2;  \
+	MASKNEZ t0, x3, x3;  \
+	MASKEQZ t0, acc7, acc7;  \
+	OR acc7, x3
+
+
+/* ---------------------------------------*/
+// func p256Add(res, in1, in2 *p256Element)
+TEXT ·p256Add(SB),NOSPLIT,$0
+	MOVV res+0(FP), res_ptr
+	MOVV in1+8(FP), x_ptr
+	MOVV in2+16(FP), y_ptr
+	MOVV (8*0)(x_ptr), y0
+	MOVV (8*1)(x_ptr), y1
+	MOVV (8*2)(x_ptr), y2
+	MOVV (8*3)(x_ptr), y3
+
+	MOVV (8*0)(y_ptr), x0
+	MOVV (8*1)(y_ptr), x1
+	MOVV (8*2)(y_ptr), x2
+	MOVV (8*3)(y_ptr), x3
+
+	MOVV p256one<>+0x08(SB), const0
+	ADDV $1, const0, const1
+
+	p256AddInline
+
+	MOVV x0, (8*0)(res_ptr)
+	MOVV x1, (8*1)(res_ptr)
+	MOVV x2, (8*2)(res_ptr)
+	MOVV x3, (8*3)(res_ptr)
+	RET
+
+/* ---------------------------------------*/
+//func p256PointDoubleAsm(res, in *SM2P256Point)
+TEXT ·p256PointDoubleAsm(SB),NOSPLIT,$136-16
+	RET
+
+/* ---------------------------------------*/
+//func p256PointDouble6TimesAsm(res, in *SM2P256Point)
+TEXT ·p256PointDouble6TimesAsm(SB),NOSPLIT,$136-16
+	RET
+
+/* ---------------------------------------*/
+// func p256PointAddAsm(res, in1, in2 *SM2P256Point) int
+TEXT ·p256PointAddAsm(SB),0,$392-32
+	RET
diff --git a/internal/sm2ec/sm2p256_asm_loong64.go b/internal/sm2ec/sm2p256_asm_loong64.go
index d804620..16a0c19 100644
--- a/internal/sm2ec/sm2p256_asm_loong64.go
+++ b/internal/sm2ec/sm2p256_asm_loong64.go
@@ -54,6 +54,9 @@ func p256FromMont(res, in *p256Element)
 //go:noescape
 func p256OrdReduce(s *p256OrdElement)
 
+//go:noescape
+func p256Add(res, in1, in2 *p256Element)
+
 //go:noescape
 func p256Sub(res, in1, in2 *p256Element)
 
diff --git a/internal/sm2ec/sm2p256_asm_loong64_test.go b/internal/sm2ec/sm2p256_asm_loong64_test.go
index fb86cd6..eeefba9 100644
--- a/internal/sm2ec/sm2p256_asm_loong64_test.go
+++ b/internal/sm2ec/sm2p256_asm_loong64_test.go
@@ -319,3 +319,58 @@ func TestP256MulBy2(t *testing.T) {
 	p256MulBy2Test(t, big.NewInt(0), p, r)
 	p256MulBy2Test(t, big.NewInt(1), p, r)
 }
+
+func p256AddTest(t *testing.T, x, y, p, r *big.Int) {
+	x1 := new(big.Int).Mul(x, r)
+	x1 = x1.Mod(x1, p)
+	y1 := new(big.Int).Mul(y, r)
+	y1 = y1.Mod(y1, p)
+	ax := new(p256Element)
+	ay := new(p256Element)
+	res := new(p256Element)
+	res2 := new(p256Element)
+	fromBig(ax, x1)
+	fromBig(ay, y1)
+	p256Add(res2, ax, ay)
+	p256FromMont(res, res2)
+	resInt := toBigInt(res)
+
+	expected := new(big.Int).Add(x, y)
+	expected = expected.Mod(expected, p)
+	if resInt.Cmp(expected) != 0 {
+		t.Fatalf("p256Add(%x, %x) = %x, want %x", x, y, resInt, expected)
+	}
+}
+
+func TestP256AddPMinus1(t *testing.T) {
+	p, _ := new(big.Int).SetString("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF", 16)
+	r, _ := new(big.Int).SetString("10000000000000000000000000000000000000000000000000000000000000000", 16)
+	pMinus1 := new(big.Int).Sub(p, big.NewInt(1))
+	p256AddTest(t, pMinus1, pMinus1, p, r)
+}
+
+func TestFuzzyP256Add(t *testing.T) {
+	p, _ := new(big.Int).SetString("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF", 16)
+	r, _ := new(big.Int).SetString("10000000000000000000000000000000000000000000000000000000000000000", 16)
+	var scalar1 [32]byte
+	var scalar2 [32]byte
+	var timeout *time.Timer
+
+	if testing.Short() {
+		timeout = time.NewTimer(10 * time.Millisecond)
+	} else {
+		timeout = time.NewTimer(2 * time.Second)
+	}
+	for {
+		select {
+		case <-timeout.C:
+			return
+		default:
+		}
+		io.ReadFull(rand.Reader, scalar1[:])
+		io.ReadFull(rand.Reader, scalar2[:])
+		x := new(big.Int).SetBytes(scalar1[:])
+		y := new(big.Int).SetBytes(scalar2[:])
+		p256AddTest(t, x, y, p, r)
+	}
+}