mirror of
https://github.com/Luzifer/culmqtt.git
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322 lines
8.2 KiB
Go
322 lines
8.2 KiB
Go
// Copyright 2011 Aaron Jacobs. All Rights Reserved.
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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 serial
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import (
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"fmt"
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"io"
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"os"
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"sync"
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"syscall"
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"unsafe"
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)
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type serialPort struct {
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f *os.File
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fd syscall.Handle
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rl sync.Mutex
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wl sync.Mutex
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ro *syscall.Overlapped
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wo *syscall.Overlapped
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}
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type structDCB struct {
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DCBlength, BaudRate uint32
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flags [4]byte
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wReserved, XonLim, XoffLim uint16
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ByteSize, Parity, StopBits byte
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XonChar, XoffChar, ErrorChar, EofChar, EvtChar byte
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wReserved1 uint16
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}
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type structTimeouts struct {
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ReadIntervalTimeout uint32
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ReadTotalTimeoutMultiplier uint32
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ReadTotalTimeoutConstant uint32
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WriteTotalTimeoutMultiplier uint32
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WriteTotalTimeoutConstant uint32
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}
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func openInternal(options OpenOptions) (io.ReadWriteCloser, error) {
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if len(options.PortName) > 0 && options.PortName[0] != '\\' {
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options.PortName = "\\\\.\\" + options.PortName
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}
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h, err := syscall.CreateFile(syscall.StringToUTF16Ptr(options.PortName),
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syscall.GENERIC_READ|syscall.GENERIC_WRITE,
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0,
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nil,
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syscall.OPEN_EXISTING,
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syscall.FILE_ATTRIBUTE_NORMAL|syscall.FILE_FLAG_OVERLAPPED,
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0)
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if err != nil {
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return nil, err
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}
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f := os.NewFile(uintptr(h), options.PortName)
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defer func() {
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if err != nil {
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f.Close()
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}
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}()
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if err = setCommState(h, options); err != nil {
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return nil, err
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}
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if err = setupComm(h, 64, 64); err != nil {
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return nil, err
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}
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if err = setCommTimeouts(h, options); err != nil {
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return nil, err
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}
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if err = setCommMask(h); err != nil {
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return nil, err
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}
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ro, err := newOverlapped()
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if err != nil {
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return nil, err
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}
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wo, err := newOverlapped()
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if err != nil {
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return nil, err
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}
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port := new(serialPort)
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port.f = f
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port.fd = h
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port.ro = ro
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port.wo = wo
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return port, nil
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}
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func (p *serialPort) Close() error {
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return p.f.Close()
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}
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func (p *serialPort) Write(buf []byte) (int, error) {
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p.wl.Lock()
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defer p.wl.Unlock()
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if err := resetEvent(p.wo.HEvent); err != nil {
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return 0, err
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}
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var n uint32
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err := syscall.WriteFile(p.fd, buf, &n, p.wo)
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if err != nil && err != syscall.ERROR_IO_PENDING {
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return int(n), err
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}
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return getOverlappedResult(p.fd, p.wo)
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}
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func (p *serialPort) Read(buf []byte) (int, error) {
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if p == nil || p.f == nil {
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return 0, fmt.Errorf("Invalid port on read %v %v", p, p.f)
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}
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p.rl.Lock()
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defer p.rl.Unlock()
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if err := resetEvent(p.ro.HEvent); err != nil {
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return 0, err
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}
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var done uint32
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err := syscall.ReadFile(p.fd, buf, &done, p.ro)
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if err != nil && err != syscall.ERROR_IO_PENDING {
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return int(done), err
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}
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return getOverlappedResult(p.fd, p.ro)
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}
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var (
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nSetCommState,
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nSetCommTimeouts,
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nSetCommMask,
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nSetupComm,
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nGetOverlappedResult,
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nCreateEvent,
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nResetEvent uintptr
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)
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func init() {
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k32, err := syscall.LoadLibrary("kernel32.dll")
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if err != nil {
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panic("LoadLibrary " + err.Error())
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}
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defer syscall.FreeLibrary(k32)
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nSetCommState = getProcAddr(k32, "SetCommState")
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nSetCommTimeouts = getProcAddr(k32, "SetCommTimeouts")
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nSetCommMask = getProcAddr(k32, "SetCommMask")
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nSetupComm = getProcAddr(k32, "SetupComm")
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nGetOverlappedResult = getProcAddr(k32, "GetOverlappedResult")
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nCreateEvent = getProcAddr(k32, "CreateEventW")
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nResetEvent = getProcAddr(k32, "ResetEvent")
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}
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func getProcAddr(lib syscall.Handle, name string) uintptr {
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addr, err := syscall.GetProcAddress(lib, name)
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if err != nil {
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panic(name + " " + err.Error())
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}
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return addr
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}
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func setCommState(h syscall.Handle, options OpenOptions) error {
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var params structDCB
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params.DCBlength = uint32(unsafe.Sizeof(params))
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params.flags[0] = 0x01 // fBinary
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params.flags[0] |= 0x10 // Assert DSR
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if options.ParityMode != PARITY_NONE {
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params.flags[0] |= 0x03 // fParity
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params.Parity = byte(options.ParityMode)
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}
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if options.StopBits == 1 {
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params.StopBits = 0
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} else if options.StopBits == 2 {
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params.StopBits = 2
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}
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params.BaudRate = uint32(options.BaudRate)
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params.ByteSize = byte(options.DataBits)
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if options.RTSCTSFlowControl {
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params.flags[0] |= 0x04 // fOutxCtsFlow = 0x1
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params.flags[1] |= 0x20 // fRtsControl = RTS_CONTROL_HANDSHAKE (0x2)
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}
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r, _, err := syscall.Syscall(nSetCommState, 2, uintptr(h), uintptr(unsafe.Pointer(¶ms)), 0)
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if r == 0 {
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return err
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}
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return nil
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}
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func setCommTimeouts(h syscall.Handle, options OpenOptions) error {
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var timeouts structTimeouts
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const MAXDWORD = 1<<32 - 1
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timeoutConstant := uint32(round(float64(options.InterCharacterTimeout) / 100.0))
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readIntervalTimeout := uint32(options.MinimumReadSize)
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if timeoutConstant > 0 && readIntervalTimeout == 0 {
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//Assume we're setting for non blocking IO.
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timeouts.ReadIntervalTimeout = MAXDWORD
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timeouts.ReadTotalTimeoutMultiplier = MAXDWORD
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timeouts.ReadTotalTimeoutConstant = timeoutConstant
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} else if readIntervalTimeout > 0 {
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// Assume we want to block and wait for input.
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timeouts.ReadIntervalTimeout = readIntervalTimeout
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timeouts.ReadTotalTimeoutMultiplier = 1
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timeouts.ReadTotalTimeoutConstant = 1
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} else {
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// No idea what we intended, use defaults
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// default config does what it did before.
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timeouts.ReadIntervalTimeout = MAXDWORD
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timeouts.ReadTotalTimeoutMultiplier = MAXDWORD
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timeouts.ReadTotalTimeoutConstant = MAXDWORD - 1
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}
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/*
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Empirical testing has shown that to have non-blocking IO we need to set:
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ReadTotalTimeoutConstant > 0 and
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ReadTotalTimeoutMultiplier = MAXDWORD and
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ReadIntervalTimeout = MAXDWORD
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The documentation states that ReadIntervalTimeout is set in MS but
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empirical investigation determines that it seems to interpret in units
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of 100ms.
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If InterCharacterTimeout is set at all it seems that the port will block
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indefinitly until a character is received. Not all circumstances have been
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tested. The input of an expert would be appreciated.
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From http://msdn.microsoft.com/en-us/library/aa363190(v=VS.85).aspx
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For blocking I/O see below:
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Remarks:
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If an application sets ReadIntervalTimeout and
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ReadTotalTimeoutMultiplier to MAXDWORD and sets
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ReadTotalTimeoutConstant to a value greater than zero and
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less than MAXDWORD, one of the following occurs when the
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ReadFile function is called:
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If there are any bytes in the input buffer, ReadFile returns
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immediately with the bytes in the buffer.
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If there are no bytes in the input buffer, ReadFile waits
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until a byte arrives and then returns immediately.
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If no bytes arrive within the time specified by
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ReadTotalTimeoutConstant, ReadFile times out.
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*/
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r, _, err := syscall.Syscall(nSetCommTimeouts, 2, uintptr(h), uintptr(unsafe.Pointer(&timeouts)), 0)
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if r == 0 {
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return err
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}
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return nil
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}
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func setupComm(h syscall.Handle, in, out int) error {
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r, _, err := syscall.Syscall(nSetupComm, 3, uintptr(h), uintptr(in), uintptr(out))
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if r == 0 {
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return err
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}
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return nil
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}
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func setCommMask(h syscall.Handle) error {
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const EV_RXCHAR = 0x0001
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r, _, err := syscall.Syscall(nSetCommMask, 2, uintptr(h), EV_RXCHAR, 0)
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if r == 0 {
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return err
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}
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return nil
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}
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func resetEvent(h syscall.Handle) error {
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r, _, err := syscall.Syscall(nResetEvent, 1, uintptr(h), 0, 0)
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if r == 0 {
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return err
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}
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return nil
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}
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func newOverlapped() (*syscall.Overlapped, error) {
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var overlapped syscall.Overlapped
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r, _, err := syscall.Syscall6(nCreateEvent, 4, 0, 1, 0, 0, 0, 0)
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if r == 0 {
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return nil, err
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}
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overlapped.HEvent = syscall.Handle(r)
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return &overlapped, nil
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}
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func getOverlappedResult(h syscall.Handle, overlapped *syscall.Overlapped) (int, error) {
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var n int
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r, _, err := syscall.Syscall6(nGetOverlappedResult, 4,
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uintptr(h),
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uintptr(unsafe.Pointer(overlapped)),
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uintptr(unsafe.Pointer(&n)), 1, 0, 0)
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if r == 0 {
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return n, err
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}
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return n, nil
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}
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