github.com/sandwichdev/go-internals@v0.0.0-20210605002614-12311ac6b2c5/cpu/cpu_arm64_freebsd.go (about)

     1  // Copyright 2020 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  
     5  // +build arm64
     6  
     7  package cpu
     8  
     9  func osInit() {
    10  	// Retrieve info from system register ID_AA64ISAR0_EL1.
    11  	isar0 := getisar0()
    12  
    13  	// ID_AA64ISAR0_EL1
    14  	switch extractBits(isar0, 4, 7) {
    15  	case 1:
    16  		ARM64.HasAES = true
    17  	case 2:
    18  		ARM64.HasAES = true
    19  		ARM64.HasPMULL = true
    20  	}
    21  
    22  	switch extractBits(isar0, 8, 11) {
    23  	case 1:
    24  		ARM64.HasSHA1 = true
    25  	}
    26  
    27  	switch extractBits(isar0, 12, 15) {
    28  	case 1, 2:
    29  		ARM64.HasSHA2 = true
    30  	}
    31  
    32  	switch extractBits(isar0, 16, 19) {
    33  	case 1:
    34  		ARM64.HasCRC32 = true
    35  	}
    36  
    37  	switch extractBits(isar0, 20, 23) {
    38  	case 2:
    39  		ARM64.HasATOMICS = true
    40  	}
    41  }
    42  
    43  func extractBits(data uint64, start, end uint) uint {
    44  	return (uint)(data>>start) & ((1 << (end - start + 1)) - 1)
    45  }