From c1e37c09b531b14ae12a501eb6fd529b31cecdaa Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <brad@danga.com>
Date: Mon, 12 Dec 2022 19:16:15 -0800
Subject: [PATCH] native: add IsBigEndian bool const

Per https://github.com/golang/go/issues/57237#issuecomment-1347539315

Updates golang/go#57237
---
 endian_big.go     | 6 ++++++
 endian_generic.go | 4 ++++
 endian_little.go  | 6 ++++++
 endian_test.go    | 9 +++++++++
 4 files changed, 25 insertions(+)

diff --git a/endian_big.go b/endian_big.go
index 9912716..77744fd 100644
--- a/endian_big.go
+++ b/endian_big.go
@@ -5,4 +5,10 @@ package native
 
 import "encoding/binary"
 
+// Endian is the encoding/binary.ByteOrder implementation for the
+// current CPU's native byte order.
 var Endian = binary.BigEndian
+
+// IsBigEndian is whether the current CPU's native byte order is big
+// endian.
+const IsBigEndian = true
diff --git a/endian_generic.go b/endian_generic.go
index 7961edd..c15228f 100644
--- a/endian_generic.go
+++ b/endian_generic.go
@@ -16,12 +16,16 @@ import (
 
 var Endian binary.ByteOrder
 
+var IsBigEndian bool
+
 func init() {
 	b := uint16(0xff) // one byte
 	if *(*byte)(unsafe.Pointer(&b)) == 0 {
 		Endian = binary.BigEndian
+		IsBigEndian = true
 	} else {
 		Endian = binary.LittleEndian
+		IsBigEndian = false
 	}
 	log.Printf("github.com/josharian/native: unrecognized arch %v (%v), please file an issue", runtime.GOARCH, Endian)
 }
diff --git a/endian_little.go b/endian_little.go
index bfbf127..5098fec 100644
--- a/endian_little.go
+++ b/endian_little.go
@@ -5,4 +5,10 @@ package native
 
 import "encoding/binary"
 
+// Endian is the encoding/binary.ByteOrder implementation for the
+// current CPU's native byte order.
 var Endian = binary.LittleEndian
+
+// IsBigEndian is whether the current CPU's native byte order is big
+// endian.
+const IsBigEndian = false
diff --git a/endian_test.go b/endian_test.go
index 39a854d..7540bef 100644
--- a/endian_test.go
+++ b/endian_test.go
@@ -1,6 +1,7 @@
 package native_test
 
 import (
+	"encoding/binary"
 	"testing"
 
 	"github.com/josharian/native"
@@ -8,4 +9,12 @@ import (
 
 func TestPrintEndianness(t *testing.T) {
 	t.Logf("native endianness is %v", native.Endian)
+
+	var want binary.ByteOrder = binary.BigEndian
+	if !native.IsBigEndian {
+		want = binary.LittleEndian
+	}
+	if native.Endian != want {
+		t.Errorf("IsBigEndian = %v not consistent with native.Endian = %T", native.IsBigEndian, want)
+	}
 }