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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 | } |