Mercurial > yakumo_izuru > aya

comparison vendor/golang.org/x/sys/unix/dev_linux.go @ 66:787b5ee0289d draft

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Use vendored modules Signed-off-by: Izuru Yakumo <yakumo.izuru@chaotic.ninja>
author yakumo.izuru
date Sun, 23 Jul 2023 13:18:53 +0000
parents
children
comparison
equal deleted inserted replaced
65:6d985efa0f7a 66:787b5ee0289d
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 by the Linux kernel and glibc.
7 //
8 // The information below is extracted and adapted from bits/sysmacros.h in the
9 // glibc sources:
10 //
11 // dev_t in glibc is 64-bit, with 32-bit major and minor numbers. glibc's
12 // default encoding is MMMM Mmmm mmmM MMmm, where M is a hex digit of the major
13 // number and m is a hex digit of the minor number. This is backward compatible
14 // with legacy systems where dev_t is 16 bits wide, encoded as MMmm. It is also
15 // backward compatible with the Linux kernel, which for some architectures uses
16 // 32-bit dev_t, encoded as mmmM MMmm.
17
18 package unix
19
20 // Major returns the major component of a Linux device number.
21 func Major(dev uint64) uint32 {
22 major := uint32((dev & 0x00000000000fff00) >> 8)
23 major |= uint32((dev & 0xfffff00000000000) >> 32)
24 return major
25 }
26
27 // Minor returns the minor component of a Linux device number.
28 func Minor(dev uint64) uint32 {
29 minor := uint32((dev & 0x00000000000000ff) >> 0)
30 minor |= uint32((dev & 0x00000ffffff00000) >> 12)
31 return minor
32 }
33
34 // Mkdev returns a Linux device number generated from the given major and minor
35 // components.
36 func Mkdev(major, minor uint32) uint64 {
37 dev := (uint64(major) & 0x00000fff) << 8
38 dev |= (uint64(major) & 0xfffff000) << 32
39 dev |= (uint64(minor) & 0x000000ff) << 0
40 dev |= (uint64(minor) & 0xffffff00) << 12
41 return dev
42 }