From ebe5413d1eec08544f540b2f95bee2f96d0e3367 Mon Sep 17 00:00:00 2001
From: Sun Yimin <emmansun@users.noreply.github.com>
Date: Mon, 26 Aug 2024 11:45:46 +0800
Subject: [PATCH] internal/sm2ec: change order for s390x

---
 internal/sm2ec/sm2p256_asm.go | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/internal/sm2ec/sm2p256_asm.go b/internal/sm2ec/sm2p256_asm.go
index 102533d..a4ea7e6 100644
--- a/internal/sm2ec/sm2p256_asm.go
+++ b/internal/sm2ec/sm2p256_asm.go
@@ -15,6 +15,7 @@ import (
 	_ "embed"
 	"errors"
 	"math/bits"
+	"runtime"
 	"unsafe"
 
 	"golang.org/x/sys/cpu"
@@ -384,8 +385,22 @@ var p256Precomputed *[43]p256AffineTable
 //go:embed p256_asm_table.bin
 var p256PrecomputedEmbed string
 
+func leUint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
 func init() {
 	p256PrecomputedPtr := (*unsafe.Pointer)(unsafe.Pointer(&p256PrecomputedEmbed))
+	if runtime.GOARCH == "s390x" {
+		var newTable [43 * 32 * 2 * 4]uint64
+		for i, x := range (*[43 * 32 * 2 * 4][8]byte)(*p256PrecomputedPtr) {
+			newTable[i] = leUint64(x[:])
+		}
+		newTablePtr := unsafe.Pointer(&newTable)
+		p256PrecomputedPtr = &newTablePtr
+	}
 	p256Precomputed = (*[43]p256AffineTable)(*p256PrecomputedPtr)
 }