56 lines
1.7 KiB
Go
56 lines
1.7 KiB
Go
// Copyright 2018 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package linux
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// MakeDeviceID encodes a major and minor device number into a single device ID.
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//
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// Format (see linux/kdev_t.h:new_encode_dev):
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//
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// Bits 7:0 - minor bits 7:0
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// Bits 19:8 - major bits 11:0
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// Bits 31:20 - minor bits 19:8
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func MakeDeviceID(major uint16, minor uint32) uint32 {
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return (minor & 0xff) | ((uint32(major) & 0xfff) << 8) | ((minor >> 8) << 20)
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}
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// DecodeDeviceID decodes a device ID into major and minor device numbers.
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func DecodeDeviceID(rdev uint32) (uint16, uint32) {
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major := uint16((rdev >> 8) & 0xfff)
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minor := (rdev & 0xff) | ((rdev >> 20) << 8)
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return major, minor
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}
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// Character device IDs.
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//
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// See Documentations/devices.txt and uapi/linux/major.h.
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const (
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// TTYAUX_MAJOR is the major device number for alternate TTY devices.
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TTYAUX_MAJOR = 5
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// UNIX98_PTY_MASTER_MAJOR is the initial major device number for
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// Unix98 PTY masters.
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UNIX98_PTY_MASTER_MAJOR = 128
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// UNIX98_PTY_SLAVE_MAJOR is the initial major device number for
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// Unix98 PTY slaves.
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UNIX98_PTY_SLAVE_MAJOR = 136
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)
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// Minor device numbers for TTYAUX_MAJOR.
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const (
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// PTMX_MINOR is the minor device number for /dev/ptmx.
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PTMX_MINOR = 2
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)
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