1// Copyright 2019 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package cpu 6 7import ( 8 "runtime" 9) 10 11// byteOrder is a subset of encoding/binary.ByteOrder. 12type byteOrder interface { 13 Uint32([]byte) uint32 14 Uint64([]byte) uint64 15} 16 17type littleEndian struct{} 18type bigEndian struct{} 19 20func (littleEndian) Uint32(b []byte) uint32 { 21 _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808 22 return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24 23} 24 25func (littleEndian) Uint64(b []byte) uint64 { 26 _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808 27 return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | 28 uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56 29} 30 31func (bigEndian) Uint32(b []byte) uint32 { 32 _ = b[3] // bounds check hint to compiler; see golang.org/issue/14808 33 return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24 34} 35 36func (bigEndian) Uint64(b []byte) uint64 { 37 _ = b[7] // bounds check hint to compiler; see golang.org/issue/14808 38 return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 | 39 uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56 40} 41 42// hostByteOrder returns littleEndian on little-endian machines and 43// bigEndian on big-endian machines. 44func hostByteOrder() byteOrder { 45 switch runtime.GOARCH { 46 case "386", "amd64", "amd64p32", 47 "alpha", 48 "arm", "arm64", 49 "mipsle", "mips64le", "mips64p32le", 50 "nios2", 51 "ppc64le", 52 "riscv", "riscv64", 53 "sh": 54 return littleEndian{} 55 case "armbe", "arm64be", 56 "m68k", 57 "mips", "mips64", "mips64p32", 58 "ppc", "ppc64", 59 "s390", "s390x", 60 "shbe", 61 "sparc", "sparc64": 62 return bigEndian{} 63 } 64 panic("unknown architecture") 65} 66