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1 // Copyright 2017 The Go Authors. All rights reserved.
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2 // Use of this source code is governed by a BSD-style
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3 // license that can be found in the LICENSE file.
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4
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5 // Functions to access/create device major and minor numbers matching the
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6 // encoding used in FreeBSD's sys/types.h header.
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7 //
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8 // The information below is extracted and adapted from sys/types.h:
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9 //
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10 // Minor gives a cookie instead of an index since in order to avoid changing the
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11 // meanings of bits 0-15 or wasting time and space shifting bits 16-31 for
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12 // devices that don't use them.
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13
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14 package unix
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15
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16 // Major returns the major component of a FreeBSD device number.
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17 func Major(dev uint64) uint32 {
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18 return uint32((dev >> 8) & 0xff)
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19 }
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20
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21 // Minor returns the minor component of a FreeBSD device number.
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22 func Minor(dev uint64) uint32 {
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23 return uint32(dev & 0xffff00ff)
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24 }
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25
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26 // Mkdev returns a FreeBSD device number generated from the given major and
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27 // minor components.
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28 func Mkdev(major, minor uint32) uint64 {
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29 return (uint64(major) << 8) | uint64(minor)
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30 }
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