unix/dev_freebsd.go

// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Functions to access/create device major and minor numbers matching the
// encoding used in FreeBSD's sys/types.h header.
//
// The information below is extracted and adapted from sys/types.h:
//
// Minor gives a cookie instead of an index since in order to avoid changing the
// meanings of bits 0-15 or wasting time and space shifting bits 16-31 for
// devices that don't use them.

package unix

// Major returns the major component of a FreeBSD device number.
func Major(dev uint64) uint32 {
	return uint32((dev >> 8) & 0xff)
}

// Minor returns the minor component of a FreeBSD device number.
func Minor(dev uint64) uint32 {
	return uint32(dev & 0xffff00ff)
}

// Mkdev returns a FreeBSD device number generated from the given major and
// minor components.
func Mkdev(major, minor uint32) uint64 {
	return (uint64(major) << 8) | uint64(minor)
}