comm.cpp

Win 32系统下的串行通信类。采用文件I/O函数提供的打开和关闭通信资源句柄及读写操作的基本接口。

#define STRICT
#include <windows.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

void PrintError( LPCSTR str )
{
   LPVOID lpMessageBuffer;
   int error = GetLastError();
   FormatMessage(
      FORMAT_MESSAGE_ALLOCATE_BUFFER |
      FORMAT_MESSAGE_FROM_SYSTEM,
      NULL,
      error,
      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), //The user default language
      (LPTSTR) &lpMessageBuffer,
      0,
      NULL
   );
   printf("%s: (%d) %s\n",str,error,lpMessageBuffer);
   LocalFree( lpMessageBuffer );
}


DWORD CALLBACK ConInThread( HANDLE h )
{
   // starts a user input thread using the console
   //
   // takes console characters and sends them to the com port


   OVERLAPPED ov;
   HANDLE hconn = GetStdHandle(STD_INPUT_HANDLE);
   BOOL quit = FALSE;

   ZeroMemory(&ov,sizeof(ov));
   ov.hEvent = CreateEvent(NULL,FALSE,FALSE,NULL);
   if(ov.hEvent == INVALID_HANDLE_VALUE) {
      PrintError("CreateEvent failed");
      SetCommMask(h,0);
      return 0;
   }

   SetConsoleMode(hconn,0);
   printf("press Esc to terminate\n");
   do {
      char buf[10];
      DWORD read = 0;

      // wait for user to type something
      WaitForSingleObject(hconn,INFINITE);

      // read the console buffer

      if(!ReadConsole(hconn,buf,sizeof(buf),&read,NULL)) {
         PrintError("ReadConsole failed");
         quit  = TRUE;
      }
      if(read) {
         DWORD write;
         // check for Esc
         for(write=0;write<read;write++) {
            // terminate when Esc pressed
            if( buf[write] == 0x1b ) {
               quit = TRUE;
               break;
            }
         }
         // send it to the com port
         if(write) {
            if( !WriteFile(h,buf,write,&write,&ov) ) {
               if(GetLastError() == ERROR_IO_PENDING) {
                  if( !GetOverlappedResult(h,&ov,&write,TRUE) ) {
                     PrintError("GetOverlappedResult failed");
                     quit = TRUE;
                  }
               }
            } else {
               PrintError("WriteFile failed");
               quit = TRUE;
            }
         }
      }

   } while(!quit);

   // tell terminal thread to quit
   SetCommMask(h,0);

   return 0;
}


void Terminal( HANDLE h )
{
   HANDLE hconn = GetStdHandle(STD_OUTPUT_HANDLE);
   DWORD mask;
   DWORD id;
   OVERLAPPED ov;


   HANDLE hconin = CreateThread(NULL,0,ConInThread,h,0,&id);
   if( hconin == INVALID_HANDLE_VALUE ) {
      PrintError("CreateThread failed");
      return;
   }
   CloseHandle(hconin);  // don't need this handle

   ZeroMemory(&ov,sizeof(ov));

   // create event for overlapped I/O
   ov.hEvent = CreateEvent(NULL,FALSE,FALSE,NULL);
   if(ov.hEvent == INVALID_HANDLE_VALUE)
      PrintError("CreateEvent failed");

   // wait for received characters
   if(!SetCommMask(h,EV_RXCHAR))
      PrintError("SetCommMask failed");

   while( 1 ) {
      // get the event mask
      if( !WaitCommEvent(h,&mask,&ov) ) {
         DWORD e = GetLastError();
         if( e == ERROR_IO_PENDING ) {
            DWORD r;
            if( !GetOverlappedResult(h,&ov,&r,TRUE) ) {
               PrintError("GetOverlappedResult failed");
               break;
            }
         } else {
            PrintError("WaitCommEvent failed");
            break;
         }
      }

      // if no event, then UI thread terminated with SetCommMask(h,0)
      if( mask == 0 ) {
         break;
      }

      if( mask & EV_RXCHAR) {
         char buf[10];
         DWORD read;
         do {
            read = 0;
            if( !ReadFile(h,buf,sizeof(buf),&read,&ov) ) {
               if( GetLastError() == ERROR_IO_PENDING ) {
                  if( !GetOverlappedResult(h,&ov,&read,TRUE) ) {
                     PrintError("GetOverlappedResult failed");
                     break;
                  }
               } else {
                  PrintError("ReadFile failed");
                  break;
               }
            }
            if(read)
               WriteFile(hconn,buf,read,&read,NULL);
         } while(read);
      }
      mask = 0;
   }
   CloseHandle(ov.hEvent);  // close the event
}


int main( int argc, char **argv )
{
   if(argc>1) {
      // open port for overlapped I/O
      HANDLE h = CreateFile(argv[1],
                    GENERIC_READ|GENERIC_WRITE,
                    0,NULL,
                    OPEN_EXISTING,FILE_FLAG_OVERLAPPED,NULL);

      if(h == INVALID_HANDLE_VALUE) {
         PrintError("Failed to open port");
      } else {
         // set timeouts
         COMMTIMEOUTS cto = { 2, 1, 1, 0, 0 };
         DCB dcb;
         if(!SetCommTimeouts(h,&cto))
            PrintError("SetCommTimeouts failed");

         // set DCB
         memset(&dcb,0,sizeof(dcb));
         dcb.DCBlength = sizeof(dcb);
         dcb.BaudRate = 9600;
         if(argc>2 && atoi(argv[2]) )
            dcb.BaudRate = atoi(argv[2]);
         dcb.fBinary = 1;
         dcb.fDtrControl = DTR_CONTROL_ENABLE;

         dcb.fOutxCtsFlow = 1;
         dcb.fRtsControl = DTR_CONTROL_HANDSHAKE;

         dcb.Parity = NOPARITY;
         dcb.StopBits = ONESTOPBIT;
         dcb.ByteSize = 8;

         if(!SetCommState(h,&dcb))
            PrintError("SetCommState failed");

         // start terminal
         Terminal(h);

         CloseHandle(h);
      }
   } else {
      printf("commtty port [speed]\n");
   }
   return 0;
}