pkg/cpuutil: add cpuutil

A package for unsafe cpu-ish things.

pkg/cpuutil/doc.go

@@ -0,0 +1,16 @@
+// Copyright 2017 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package cpuutil provides facilities for detecting cpu-specific features.
+package cpuutil

pkg/cpuutil/endian.go

@@ -0,0 +1,36 @@
+// Copyright 2017 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cpuutil
+
+import (
+	"encoding/binary"
+	"unsafe"
+)
+
+const intWidth int = int(unsafe.Sizeof(0))
+
+var byteOrder binary.ByteOrder
+
+// ByteOrder returns the byte order for the CPU's native endianness.
+func ByteOrder() binary.ByteOrder { return byteOrder }
+
+func init() {
+	var i int = 0x1
+	if v := (*[intWidth]byte)(unsafe.Pointer(&i)); v[0] == 0 {
+		byteOrder = binary.BigEndian
+	} else {
+		byteOrder = binary.LittleEndian
+	}
+}