dev_freebsd.go raw

   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  }
  31