summaryrefslogtreecommitdiff
path: root/rs232.c
blob: 4f943f70d219ee4b83a9f57b8f4ee20fa0db0631 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
/*
***************************************************************************
*
* Author: Teunis van Beelen
*
* Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 Teunis van Beelen
*
* Email: teuniz@gmail.com
*
***************************************************************************
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>.
*
***************************************************************************
*/


/* Last revision: November 22, 2017 */

/* For more info and how to use this library, visit: http://www.teuniz.net/RS-232/ */


#include "rs232.h"


#if defined(__linux__) || defined(__FreeBSD__)   /* Linux & FreeBSD */

#define RS232_PORTNR  38


int Cport[RS232_PORTNR],
    error;

struct termios new_port_settings,
       old_port_settings[RS232_PORTNR];

char * comports[RS232_PORTNR]={"/dev/ttyS0","/dev/ttyS1","/dev/ttyS2","/dev/ttyS3","/dev/ttyS4","/dev/ttyS5",
                       "/dev/ttyS6","/dev/ttyS7","/dev/ttyS8","/dev/ttyS9","/dev/ttyS10","/dev/ttyS11",
                       "/dev/ttyS12","/dev/ttyS13","/dev/ttyS14","/dev/ttyS15","/dev/ttyUSB0",
                       "/dev/ttyUSB1","/dev/ttyUSB2","/dev/ttyUSB3","/dev/ttyUSB4","/dev/ttyUSB5",
                       "/dev/ttyAMA0","/dev/ttyAMA1","/dev/ttyACM0","/dev/ttyACM1",
                       "/dev/rfcomm0","/dev/rfcomm1","/dev/ircomm0","/dev/ircomm1",
                       "/dev/cuau0","/dev/cuau1","/dev/cuau2","/dev/cuau3",
                       "/dev/cuaU0","/dev/cuaU1","/dev/cuaU2","/dev/cuaU3"};

int RS232_OpenComport(int comport_number, int baudrate, const char *mode)
{
  int baudr,
      status;

  if((comport_number>=RS232_PORTNR)||(comport_number<0))
  {
    printf("illegal comport number\n");
    return(1);
  }

  switch(baudrate)
  {
    case      50 : baudr = B50;
                   break;
    case      75 : baudr = B75;
                   break;
    case     110 : baudr = B110;
                   break;
    case     134 : baudr = B134;
                   break;
    case     150 : baudr = B150;
                   break;
    case     200 : baudr = B200;
                   break;
    case     300 : baudr = B300;
                   break;
    case     600 : baudr = B600;
                   break;
    case    1200 : baudr = B1200;
                   break;
    case    1800 : baudr = B1800;
                   break;
    case    2400 : baudr = B2400;
                   break;
    case    4800 : baudr = B4800;
                   break;
    case    9600 : baudr = B9600;
                   break;
    case   19200 : baudr = B19200;
                   break;
    case   38400 : baudr = B38400;
                   break;
    case   57600 : baudr = B57600;
                   break;
    case  115200 : baudr = B115200;
                   break;
    case  230400 : baudr = B230400;
                   break;
    case  460800 : baudr = B460800;
                   break;
    case  500000 : baudr = B500000;
                   break;
    case  576000 : baudr = B576000;
                   break;
    case  921600 : baudr = B921600;
                   break;
    case 1000000 : baudr = B1000000;
                   break;
    case 1152000 : baudr = B1152000;
                   break;
    case 1500000 : baudr = B1500000;
                   break;
    case 2000000 : baudr = B2000000;
                   break;
    case 2500000 : baudr = B2500000;
                   break;
    case 3000000 : baudr = B3000000;
                   break;
    case 3500000 : baudr = B3500000;
                   break;
    case 4000000 : baudr = B4000000;
                   break;
    default      : printf("invalid baudrate\n");
                   return(1);
                   break;
  }

  int cbits=CS8,
      cpar=0,
      ipar=IGNPAR,
      bstop=0;

  if(strlen(mode) != 3)
  {
    printf("invalid mode \"%s\"\n", mode);
    return(1);
  }

  switch(mode[0])
  {
    case '8': cbits = CS8;
              break;
    case '7': cbits = CS7;
              break;
    case '6': cbits = CS6;
              break;
    case '5': cbits = CS5;
              break;
    default : printf("invalid number of data-bits '%c'\n", mode[0]);
              return(1);
              break;
  }

  switch(mode[1])
  {
    case 'N':
    case 'n': cpar = 0;
              ipar = IGNPAR;
              break;
    case 'E':
    case 'e': cpar = PARENB;
              ipar = INPCK;
              break;
    case 'O':
    case 'o': cpar = (PARENB | PARODD);
              ipar = INPCK;
              break;
    default : printf("invalid parity '%c'\n", mode[1]);
              return(1);
              break;
  }

  switch(mode[2])
  {
    case '1': bstop = 0;
              break;
    case '2': bstop = CSTOPB;
              break;
    default : printf("invalid number of stop bits '%c'\n", mode[2]);
              return(1);
              break;
  }

/*
http://pubs.opengroup.org/onlinepubs/7908799/xsh/termios.h.html

http://man7.org/linux/man-pages/man3/termios.3.html
*/

  Cport[comport_number] = open(comports[comport_number], O_RDWR | O_NOCTTY | O_NDELAY);
  if(Cport[comport_number]==-1)
  {
    perror("unable to open comport ");
    return(1);
  }

  /* lock access so that another process can't also use the port */
  if(flock(Cport[comport_number], LOCK_EX | LOCK_NB) != 0)
  {
    close(Cport[comport_number]);
    perror("Another process has locked the comport.");
    return(1);
  }

  error = tcgetattr(Cport[comport_number], old_port_settings + comport_number);
  if(error==-1)
  {
    close(Cport[comport_number]);
    flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
    perror("unable to read portsettings ");
    return(1);
  }
  memset(&new_port_settings, 0, sizeof(new_port_settings));  /* clear the new struct */

  new_port_settings.c_cflag = cbits | cpar | bstop | CLOCAL | CREAD;
  new_port_settings.c_iflag = ipar;
  new_port_settings.c_oflag = 0;
  new_port_settings.c_lflag = 0;
  new_port_settings.c_cc[VMIN] = 0;      /* block untill n bytes are received */
  new_port_settings.c_cc[VTIME] = 0;     /* block untill a timer expires (n * 100 mSec.) */

  cfsetispeed(&new_port_settings, baudr);
  cfsetospeed(&new_port_settings, baudr);

  error = tcsetattr(Cport[comport_number], TCSANOW, &new_port_settings);
  if(error==-1)
  {
    tcsetattr(Cport[comport_number], TCSANOW, old_port_settings + comport_number);
    close(Cport[comport_number]);
    flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
    perror("unable to adjust portsettings ");
    return(1);
  }

/* http://man7.org/linux/man-pages/man4/tty_ioctl.4.html */

  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
  {
    tcsetattr(Cport[comport_number], TCSANOW, old_port_settings + comport_number);
    flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
    perror("unable to get portstatus");
    return(1);
  }

  status |= TIOCM_DTR;    /* turn on DTR */
  status |= TIOCM_RTS;    /* turn on RTS */

  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
  {
    tcsetattr(Cport[comport_number], TCSANOW, old_port_settings + comport_number);
    flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
    perror("unable to set portstatus");
    return(1);
  }

  return(0);
}


int RS232_PollComport(int comport_number, unsigned char *buf, int size)
{
  int n;

  n = read(Cport[comport_number], buf, size);

  if(n < 0)
  {
    if(errno == EAGAIN)  return 0;
  }

  return(n);
}


int RS232_SendByte(int comport_number, unsigned char byte)
{
  int n = write(Cport[comport_number], &byte, 1);
  if(n < 0)
  {
    if(errno == EAGAIN)
    {
      return 0;
    }
    else
    {
      return 1;
    }
  }

  return(0);
}


int RS232_SendBuf(int comport_number, unsigned char *buf, int size)
{
  int n = write(Cport[comport_number], buf, size);
  if(n < 0)
  {
    if(errno == EAGAIN)
    {
      return 0;
    }
    else
    {
      return -1;
    }
  }

  return(n);
}


void RS232_CloseComport(int comport_number)
{
  int status;

  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
  {
    perror("unable to get portstatus");
  }

  status &= ~TIOCM_DTR;    /* turn off DTR */
  status &= ~TIOCM_RTS;    /* turn off RTS */

  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
  {
    perror("unable to set portstatus");
  }

  tcsetattr(Cport[comport_number], TCSANOW, old_port_settings + comport_number);
  close(Cport[comport_number]);

  flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
}

/*
Constant  Description
TIOCM_LE        DSR (data set ready/line enable)
TIOCM_DTR       DTR (data terminal ready)
TIOCM_RTS       RTS (request to send)
TIOCM_ST        Secondary TXD (transmit)
TIOCM_SR        Secondary RXD (receive)
TIOCM_CTS       CTS (clear to send)
TIOCM_CAR       DCD (data carrier detect)
TIOCM_CD        see TIOCM_CAR
TIOCM_RNG       RNG (ring)
TIOCM_RI        see TIOCM_RNG
TIOCM_DSR       DSR (data set ready)

http://man7.org/linux/man-pages/man4/tty_ioctl.4.html
*/

int RS232_IsDCDEnabled(int comport_number)
{
  int status;

  ioctl(Cport[comport_number], TIOCMGET, &status);

  if(status&TIOCM_CAR) return(1);
  else return(0);
}


int RS232_IsCTSEnabled(int comport_number)
{
  int status;

  ioctl(Cport[comport_number], TIOCMGET, &status);

  if(status&TIOCM_CTS) return(1);
  else return(0);
}


int RS232_IsDSREnabled(int comport_number)
{
  int status;

  ioctl(Cport[comport_number], TIOCMGET, &status);

  if(status&TIOCM_DSR) return(1);
  else return(0);
}


void RS232_enableDTR(int comport_number)
{
  int status;

  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
  {
    perror("unable to get portstatus");
  }

  status |= TIOCM_DTR;    /* turn on DTR */

  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
  {
    perror("unable to set portstatus");
  }
}


void RS232_disableDTR(int comport_number)
{
  int status;

  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
  {
    perror("unable to get portstatus");
  }

  status &= ~TIOCM_DTR;    /* turn off DTR */

  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
  {
    perror("unable to set portstatus");
  }
}


void RS232_enableRTS(int comport_number)
{
  int status;

  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
  {
    perror("unable to get portstatus");
  }

  status |= TIOCM_RTS;    /* turn on RTS */

  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
  {
    perror("unable to set portstatus");
  }
}


void RS232_disableRTS(int comport_number)
{
  int status;

  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
  {
    perror("unable to get portstatus");
  }

  status &= ~TIOCM_RTS;    /* turn off RTS */

  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
  {
    perror("unable to set portstatus");
  }
}


void RS232_flushRX(int comport_number)
{
  tcflush(Cport[comport_number], TCIFLUSH);
}


void RS232_flushTX(int comport_number)
{
  tcflush(Cport[comport_number], TCOFLUSH);
}


void RS232_flushRXTX(int comport_number)
{
  tcflush(Cport[comport_number], TCIOFLUSH);
}


#else  /* windows */

#define RS232_PORTNR  16

HANDLE Cport[RS232_PORTNR];


char *comports[RS232_PORTNR]={"\\\\.\\COM1",  "\\\\.\\COM2",  "\\\\.\\COM3",  "\\\\.\\COM4",
                              "\\\\.\\COM5",  "\\\\.\\COM6",  "\\\\.\\COM7",  "\\\\.\\COM8",
                              "\\\\.\\COM9",  "\\\\.\\COM10", "\\\\.\\COM11", "\\\\.\\COM12",
                              "\\\\.\\COM13", "\\\\.\\COM14", "\\\\.\\COM15", "\\\\.\\COM16"};

char mode_str[128];


int RS232_OpenComport(int comport_number, int baudrate, const char *mode)
{
  if((comport_number>=RS232_PORTNR)||(comport_number<0))
  {
    printf("illegal comport number\n");
    return(1);
  }

  switch(baudrate)
  {
    case     110 : strcpy(mode_str, "baud=110");
                   break;
    case     300 : strcpy(mode_str, "baud=300");
                   break;
    case     600 : strcpy(mode_str, "baud=600");
                   break;
    case    1200 : strcpy(mode_str, "baud=1200");
                   break;
    case    2400 : strcpy(mode_str, "baud=2400");
                   break;
    case    4800 : strcpy(mode_str, "baud=4800");
                   break;
    case    9600 : strcpy(mode_str, "baud=9600");
                   break;
    case   19200 : strcpy(mode_str, "baud=19200");
                   break;
    case   38400 : strcpy(mode_str, "baud=38400");
                   break;
    case   57600 : strcpy(mode_str, "baud=57600");
                   break;
    case  115200 : strcpy(mode_str, "baud=115200");
                   break;
    case  128000 : strcpy(mode_str, "baud=128000");
                   break;
    case  256000 : strcpy(mode_str, "baud=256000");
                   break;
    case  500000 : strcpy(mode_str, "baud=500000");
                   break;
    case 1000000 : strcpy(mode_str, "baud=1000000");
                   break;
    default      : printf("invalid baudrate\n");
                   return(1);
                   break;
  }

  if(strlen(mode) != 3)
  {
    printf("invalid mode \"%s\"\n", mode);
    return(1);
  }

  switch(mode[0])
  {
    case '8': strcat(mode_str, " data=8");
              break;
    case '7': strcat(mode_str, " data=7");
              break;
    case '6': strcat(mode_str, " data=6");
              break;
    case '5': strcat(mode_str, " data=5");
              break;
    default : printf("invalid number of data-bits '%c'\n", mode[0]);
              return(1);
              break;
  }

  switch(mode[1])
  {
    case 'N':
    case 'n': strcat(mode_str, " parity=n");
              break;
    case 'E':
    case 'e': strcat(mode_str, " parity=e");
              break;
    case 'O':
    case 'o': strcat(mode_str, " parity=o");
              break;
    default : printf("invalid parity '%c'\n", mode[1]);
              return(1);
              break;
  }

  switch(mode[2])
  {
    case '1': strcat(mode_str, " stop=1");
              break;
    case '2': strcat(mode_str, " stop=2");
              break;
    default : printf("invalid number of stop bits '%c'\n", mode[2]);
              return(1);
              break;
  }

  strcat(mode_str, " dtr=on rts=on");

/*
http://msdn.microsoft.com/en-us/library/windows/desktop/aa363145%28v=vs.85%29.aspx

http://technet.microsoft.com/en-us/library/cc732236.aspx
*/

  Cport[comport_number] = CreateFileA(comports[comport_number],
                      GENERIC_READ|GENERIC_WRITE,
                      0,                          /* no share  */
                      NULL,                       /* no security */
                      OPEN_EXISTING,
                      0,                          /* no threads */
                      NULL);                      /* no templates */

  if(Cport[comport_number]==INVALID_HANDLE_VALUE)
  {
    printf("unable to open comport\n");
    return(1);
  }

  DCB port_settings;
  memset(&port_settings, 0, sizeof(port_settings));  /* clear the new struct  */
  port_settings.DCBlength = sizeof(port_settings);

  if(!BuildCommDCBA(mode_str, &port_settings))
  {
    printf("unable to set comport dcb settings\n");
    CloseHandle(Cport[comport_number]);
    return(1);
  }

  if(!SetCommState(Cport[comport_number], &port_settings))
  {
    printf("unable to set comport cfg settings\n");
    CloseHandle(Cport[comport_number]);
    return(1);
  }

  COMMTIMEOUTS Cptimeouts;

  Cptimeouts.ReadIntervalTimeout         = MAXDWORD;
  Cptimeouts.ReadTotalTimeoutMultiplier  = 0;
  Cptimeouts.ReadTotalTimeoutConstant    = 0;
  Cptimeouts.WriteTotalTimeoutMultiplier = 0;
  Cptimeouts.WriteTotalTimeoutConstant   = 0;

  if(!SetCommTimeouts(Cport[comport_number], &Cptimeouts))
  {
    printf("unable to set comport time-out settings\n");
    CloseHandle(Cport[comport_number]);
    return(1);
  }

  return(0);
}


int RS232_PollComport(int comport_number, unsigned char *buf, int size)
{
  int n;

/* added the void pointer cast, otherwise gcc will complain about */
/* "warning: dereferencing type-punned pointer will break strict aliasing rules" */

  ReadFile(Cport[comport_number], buf, size, (LPDWORD)((void *)&n), NULL);

  return(n);
}


int RS232_SendByte(int comport_number, unsigned char byte)
{
  int n;

  WriteFile(Cport[comport_number], &byte, 1, (LPDWORD)((void *)&n), NULL);

  if(n<0)  return(1);

  return(0);
}


int RS232_SendBuf(int comport_number, unsigned char *buf, int size)
{
  int n;

  if(WriteFile(Cport[comport_number], buf, size, (LPDWORD)((void *)&n), NULL))
  {
    return(n);
  }

  return(-1);
}


void RS232_CloseComport(int comport_number)
{
  CloseHandle(Cport[comport_number]);
}

/*
http://msdn.microsoft.com/en-us/library/windows/desktop/aa363258%28v=vs.85%29.aspx
*/

int RS232_IsDCDEnabled(int comport_number)
{
  int status;

  GetCommModemStatus(Cport[comport_number], (LPDWORD)((void *)&status));

  if(status&MS_RLSD_ON) return(1);
  else return(0);
}


int RS232_IsCTSEnabled(int comport_number)
{
  int status;

  GetCommModemStatus(Cport[comport_number], (LPDWORD)((void *)&status));

  if(status&MS_CTS_ON) return(1);
  else return(0);
}


int RS232_IsDSREnabled(int comport_number)
{
  int status;

  GetCommModemStatus(Cport[comport_number], (LPDWORD)((void *)&status));

  if(status&MS_DSR_ON) return(1);
  else return(0);
}


void RS232_enableDTR(int comport_number)
{
  EscapeCommFunction(Cport[comport_number], SETDTR);
}


void RS232_disableDTR(int comport_number)
{
  EscapeCommFunction(Cport[comport_number], CLRDTR);
}


void RS232_enableRTS(int comport_number)
{
  EscapeCommFunction(Cport[comport_number], SETRTS);
}


void RS232_disableRTS(int comport_number)
{
  EscapeCommFunction(Cport[comport_number], CLRRTS);
}

/*
https://msdn.microsoft.com/en-us/library/windows/desktop/aa363428%28v=vs.85%29.aspx
*/

void RS232_flushRX(int comport_number)
{
  PurgeComm(Cport[comport_number], PURGE_RXCLEAR | PURGE_RXABORT);
}


void RS232_flushTX(int comport_number)
{
  PurgeComm(Cport[comport_number], PURGE_TXCLEAR | PURGE_TXABORT);
}


void RS232_flushRXTX(int comport_number)
{
  PurgeComm(Cport[comport_number], PURGE_RXCLEAR | PURGE_RXABORT);
  PurgeComm(Cport[comport_number], PURGE_TXCLEAR | PURGE_TXABORT);
}


#endif


void RS232_cputs(int comport_number, const char *text)  /* sends a string to serial port */
{
  while(*text != 0)   RS232_SendByte(comport_number, *(text++));
}


/* return index in comports matching to device name or -1 if not found */
int RS232_GetPortnr(const char *devname)
{
  int i;

  char str[32];

#if defined(__linux__) || defined(__FreeBSD__)   /* Linux & FreeBSD */
  strcpy(str, "/dev/");
#else  /* windows */
  strcpy(str, "\\\\.\\");
#endif
  strncat(str, devname, 16);
  str[31] = 0;

  for(i=0; i<RS232_PORTNR; i++)
  {
    if(!strcmp(comports[i], str))
    {
      return i;
    }
  }

  return -1;  /* device not found */
}