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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 DragonFlyBSD'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: I84c128dff3108821caaa75dcec620cf5bdb1f32d Reviewed-on: https://go-review.googlesource.com/61630 Reviewed-by: Ian Lance Taylor <iant@golang.org> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
31 lines
1022 B
Go
31 lines
1022 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 Dragonfly's sys/types.h header.
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//
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// The information below is extracted and adapted from sys/types.h:
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//
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// Minor gives a cookie instead of an index since in order to avoid changing the
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// meanings of bits 0-15 or wasting time and space shifting bits 16-31 for
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// devices that don't use them.
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package unix
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// Major returns the major component of a DragonFlyBSD device number.
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func Major(dev uint64) uint32 {
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return uint32((dev >> 8) & 0xff)
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}
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// Minor returns the minor component of a DragonFlyBSD device number.
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func Minor(dev uint64) uint32 {
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return uint32(dev & 0xffff00ff)
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}
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// Mkdev returns a DragonFlyBSD device number generated from the given major and
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// minor components.
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func Mkdev(major, minor uint32) uint64 {
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return uint64((major << 8) | minor)
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}
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