1
// Copyright 2017 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
// Functions to access/create device major and minor numbers matching the
6
// encoding used in FreeBSD's sys/types.h header.
7
//
8
// The information below is extracted and adapted from sys/types.h:
9
//
10
// Minor gives a cookie instead of an index since in order to avoid changing the
11
// meanings of bits 0-15 or wasting time and space shifting bits 16-31 for
12
// devices that don't use them.
13

14
package unix
15

16
// Major returns the major component of a FreeBSD device number.
17
func Major(dev uint64) uint32 {
18
	return uint32((dev >> 8) & 0xff)
19
}
20

21
// Minor returns the minor component of a FreeBSD device number.
22
func Minor(dev uint64) uint32 {
23
	return uint32(dev & 0xffff00ff)
24
}
25

26
// Mkdev returns a FreeBSD device number generated from the given major and
27
// minor components.
28
func Mkdev(major, minor uint32) uint64 {
29
	return (uint64(major) << 8) | uint64(minor)
30
}
31

32