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033028a6b4
Add Major, Minor and Mkdev functions for converting devices numbers to their major/minor components and vice versa. The functions follow the behavior of the macros defined in OpenBSD's sys/types.h header. However, the parameter and return types are changed to match the existing implementations of these functions. Test the conversion macros with some well-known device numbers. Updates golang/go#8106 Change-Id: Ia50b7ccab18ff7c7e9dd77ddc7e4aa6cf5c79963 Reviewed-on: https://go-review.googlesource.com/63070 Reviewed-by: Ian Lance Taylor <iant@golang.org> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
30 lines
918 B
Go
30 lines
918 B
Go
// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Functions to access/create device major and minor numbers matching the
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// encoding used in OpenBSD's sys/types.h header.
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package unix
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// Major returns the major component of an OpenBSD device number.
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func Major(dev uint64) uint32 {
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return uint32((dev & 0x0000ff00) >> 8)
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}
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// Minor returns the minor component of an OpenBSD device number.
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func Minor(dev uint64) uint32 {
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minor := uint32((dev & 0x000000ff) >> 0)
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minor |= uint32((dev & 0xffff0000) >> 8)
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return minor
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}
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// Mkdev returns an OpenBSD device number generated from the given major and minor
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// components.
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func Mkdev(major, minor uint32) uint64 {
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dev := (uint64(major) << 8) & 0x0000ff00
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dev |= (uint64(minor) << 8) & 0xffff0000
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dev |= (uint64(minor) << 0) & 0x000000ff
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return dev
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}
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