1 /*
2  * SpanDSP - a series of DSP components for telephony
3  *
4  * modem_monitor.cpp - Display QAM constellations, using the FLTK toolkit.
5  *
6  * Written by Steve Underwood <steveu@coppice.org>
7  *
8  * Copyright (C) 2004 Steve Underwood
9  *
10  * All rights reserved.
11  *
12  * This program is free software; you can redistribute it and/or modify
13  * it under the terms of the GNU General Public License version 2, as
14  * published by the Free Software Foundation.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24  */
25 
26 #if defined(HAVE_CONFIG_H)
27 #include "config.h"
28 #endif
29 
30 #if defined(HAVE_FL_FL_H)  &&  defined(HAVE_FL_FL_CARTESIAN_H)
31 
32 #define __STDC_LIMIT_MACROS
33 
34 #include <inttypes.h>
35 #include <stdio.h>
36 #include <math.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <unistd.h>
40 #include <sys/select.h>
41 
42 #include <FL/Fl.H>
43 #include <FL/Fl_Overlay_Window.H>
44 #include <FL/Fl_Light_Button.H>
45 #include <FL/Fl_Cartesian.H>
46 #include <FL/Fl_Audio_Meter.H>
47 #include <FL/Fl_Output.H>
48 #include <FL/fl_draw.H>
49 
50 #include "spandsp.h"
51 
52 #define SYMBOL_TRACKER_POINTS   12000
53 #define CARRIER_TRACKER_POINTS  12000
54 
55 struct qam_monitor_s
56 {
57     float constel_scaling;
58 
59     Fl_Double_Window *w;
60     Fl_Group *c_const;
61     Fl_Group *c_right;
62     Fl_Group *c_eq;
63     Fl_Group *c_symbol_track;
64 
65     /* Constellation stuff */
66     Ca_Canvas *canvas_const;
67     Ca_X_Axis *sig_i;
68     Ca_Y_Axis *sig_q;
69 
70     Ca_Point *constel_point[100000];
71     int constel_window;
72     int next_constel_point;
73     int skip;
74 
75     /* Equalizer stuff */
76     Ca_Canvas *canvas_eq;
77 
78     Ca_X_Axis *eq_x;
79     Ca_Y_Axis *eq_y;
80 
81     Ca_Line *eq_re;
82     Ca_Line *eq_im;
83 
84     double eq_re_plot[200];
85     double eq_im_plot[200];
86 
87     /* Carrier and symbol tracking stuff */
88     Ca_Canvas *canvas_track;
89 
90     Ca_X_Axis *track_x;
91     Ca_Y_Axis *symbol_track_y;
92     Ca_Y_Axis *carrier_y;
93 
94     Ca_Line *symbol_track;
95     Ca_Line *carrier;
96 
97     float symbol_tracker[SYMBOL_TRACKER_POINTS];
98     double symbol_track_plot[SYMBOL_TRACKER_POINTS*2];
99     int symbol_track_points;
100     int symbol_track_ptr;
101     int symbol_track_window;
102 
103     float carrier_tracker[CARRIER_TRACKER_POINTS];
104     double carrier_plot[CARRIER_TRACKER_POINTS*2];
105     int carrier_points;
106     int carrier_ptr;
107     int carrier_window;
108 
109     /* Audio meter stuff */
110     Fl_Audio_Meter *audio_meter;
111     Fl_Output *audio_level;
112     int32_t power_reading;
113 };
114 
115 #include "modem_monitor.h"
116 
qam_monitor_clear_constel(qam_monitor_t * s)117 int qam_monitor_clear_constel(qam_monitor_t *s)
118 {
119     int i;
120 
121     s->canvas_const->current(s->canvas_const);
122     for (i = 0;  i < s->constel_window;  i++)
123     {
124         if (s->constel_point[i])
125         {
126             delete s->constel_point[i];
127             s->constel_point[i] = NULL;
128         }
129     }
130     s->next_constel_point = 0;
131     Fl::check();
132     return 0;
133 }
134 /*- End of function --------------------------------------------------------*/
135 
qam_monitor_update_constel(qam_monitor_t * s,const complexf_t * pt)136 int qam_monitor_update_constel(qam_monitor_t *s, const complexf_t *pt)
137 {
138     int i;
139 
140     s->canvas_const->current(s->canvas_const);
141     if (s->constel_point[s->next_constel_point])
142         delete s->constel_point[s->next_constel_point];
143     s->constel_point[s->next_constel_point++] = new Ca_Point(pt->re, pt->im, FL_BLACK);
144     if (s->next_constel_point >= s->constel_window)
145         s->next_constel_point = 0;
146     if (++s->skip >= 100)
147     {
148         s->skip = 0;
149         Fl::check();
150     }
151     return 0;
152 }
153 /*- End of function --------------------------------------------------------*/
154 
qam_monitor_update_equalizer(qam_monitor_t * s,const complexf_t * coeffs,int len)155 int qam_monitor_update_equalizer(qam_monitor_t *s, const complexf_t *coeffs, int len)
156 {
157     int i;
158     float min;
159     float max;
160 
161     /* Protect against screwy values */
162     for (i = 0;  i < len;  i++)
163     {
164         if (isnan(coeffs[i].re)  ||  isinf(coeffs[i].re))
165             break;
166         if (isnan(coeffs[i].im)  ||  isinf(coeffs[i].im))
167             break;
168         if (coeffs[i].re < -20.0f  ||  coeffs[i].re > 20.0f)
169             break;
170         if (coeffs[i].im < -20.0f  ||  coeffs[i].im > 20.0f)
171             break;
172     }
173     if (i != len)
174         return -1;
175 
176     if (s->eq_re)
177         delete s->eq_re;
178     if (s->eq_im)
179         delete s->eq_im;
180 
181     s->canvas_eq->current(s->canvas_eq);
182     i = 0;
183     min = coeffs[i].re;
184     if (min > coeffs[i].im)
185         min = coeffs[i].im;
186     max = coeffs[i].re;
187     if (max < coeffs[i].im)
188         max = coeffs[i].im;
189     for (i = 0;  i < len;  i++)
190     {
191         s->eq_re_plot[2*i] = (i - len/2)/2.0;
192         s->eq_re_plot[2*i + 1] = coeffs[i].re*s->constel_scaling;
193         if (min > coeffs[i].re)
194             min = coeffs[i].re;
195         if (max < coeffs[i].re)
196             max = coeffs[i].re;
197 
198         s->eq_im_plot[2*i] = (i - len/2)/2.0;
199         s->eq_im_plot[2*i + 1] = coeffs[i].im*s->constel_scaling;
200         if (min > coeffs[i].im)
201             min = coeffs[i].im;
202         if (max < coeffs[i].im)
203             max = coeffs[i].im;
204     }
205 
206     s->eq_x->minimum(-len/4.0);
207     s->eq_x->maximum(len/4.0);
208     s->eq_y->maximum((max == min)  ?  max + 0.2  :  max);
209     s->eq_y->minimum(min);
210     s->eq_re = new Ca_Line(len, s->eq_re_plot, 0, 0, FL_BLUE, CA_NO_POINT);
211     s->eq_im = new Ca_Line(len, s->eq_im_plot, 0, 0, FL_RED, CA_NO_POINT);
212     Fl::check();
213     return 0;
214 }
215 /*- End of function --------------------------------------------------------*/
216 
qam_monitor_update_int_equalizer(qam_monitor_t * s,const complexi16_t * coeffs,int len)217 int qam_monitor_update_int_equalizer(qam_monitor_t *s, const complexi16_t *coeffs, int len)
218 {
219     int i;
220     float min;
221     float max;
222 
223     if (s->eq_re)
224         delete s->eq_re;
225     if (s->eq_im)
226         delete s->eq_im;
227 
228     s->canvas_eq->current(s->canvas_eq);
229     i = 0;
230     min = coeffs[i].re;
231     if (min > coeffs[i].im)
232         min = coeffs[i].im;
233     max = coeffs[i].re;
234     if (max < coeffs[i].im)
235         max = coeffs[i].im;
236     for (i = 0;  i < len;  i++)
237     {
238         if (min > coeffs[i].re)
239             min = coeffs[i].re;
240         if (max < coeffs[i].re)
241             max = coeffs[i].re;
242         s->eq_re_plot[2*i] = (i - len/2)/2.0f;
243         s->eq_re_plot[2*i + 1] = coeffs[i].re*s->constel_scaling;
244 
245         if (min > coeffs[i].im)
246             min = coeffs[i].im;
247         if (max < coeffs[i].im)
248             max = coeffs[i].im;
249         s->eq_im_plot[2*i] = (i - len/2)/2.0f;
250         s->eq_im_plot[2*i + 1] = coeffs[i].im*s->constel_scaling;
251     }
252     min *= s->constel_scaling;
253     max *= s->constel_scaling;
254 
255     s->eq_x->minimum(-len/4.0);
256     s->eq_x->maximum(len/4.0);
257     s->eq_y->maximum((max == min)  ?  max + 0.2  :  max);
258     s->eq_y->minimum(min);
259     s->eq_re = new Ca_Line(len, s->eq_re_plot, 0, 0, FL_BLUE, CA_NO_POINT);
260     s->eq_im = new Ca_Line(len, s->eq_im_plot, 0, 0, FL_RED, CA_NO_POINT);
261     Fl::check();
262     return 0;
263 }
264 /*- End of function --------------------------------------------------------*/
265 
qam_monitor_update_symbol_tracking(qam_monitor_t * s,float total_correction)266 int qam_monitor_update_symbol_tracking(qam_monitor_t *s, float total_correction)
267 {
268     int i;
269     int j;
270     float min;
271     float max;
272 
273     s->symbol_tracker[s->symbol_track_ptr++] = total_correction;
274     if (s->symbol_track_points < SYMBOL_TRACKER_POINTS)
275         s->symbol_track_points++;
276     if (s->symbol_track_ptr >= SYMBOL_TRACKER_POINTS)
277         s->symbol_track_ptr = 0;
278 
279     s->canvas_track->current(s->canvas_track);
280     if (s->symbol_track)
281         delete s->symbol_track;
282     s->track_x->current();
283     s->symbol_track_y->current();
284 
285     min =
286     max = s->symbol_tracker[0];
287     for (i = s->symbol_track_ptr, j = 0;  i < s->symbol_track_points;  i++, j++)
288     {
289         if (min > s->symbol_tracker[i])
290             min = s->symbol_tracker[i];
291         if (max < s->symbol_tracker[i])
292             max = s->symbol_tracker[i];
293         s->symbol_track_plot[2*j] = j;
294         s->symbol_track_plot[2*j + 1] = s->symbol_tracker[i];
295     }
296     for (i = 0;  i < s->symbol_track_ptr;  i++, j++)
297     {
298         if (min > s->symbol_tracker[i])
299             min = s->symbol_tracker[i];
300         if (max < s->symbol_tracker[i])
301             max = s->symbol_tracker[i];
302         s->symbol_track_plot[2*j] = j;
303         s->symbol_track_plot[2*j + 1] = s->symbol_tracker[i];
304     }
305     s->symbol_track_y->maximum((fabs(max - min) < 0.05)  ?  max + 0.05  :  max);
306     s->symbol_track_y->minimum(min);
307 
308     s->symbol_track = new Ca_Line(s->symbol_track_points, s->symbol_track_plot, 0, 0, FL_RED, CA_NO_POINT);
309     //Fl::check();
310     return 0;
311 }
312 /*- End of function --------------------------------------------------------*/
313 
qam_monitor_update_audio_level(qam_monitor_t * s,const int16_t amp[],int len)314 int qam_monitor_update_audio_level(qam_monitor_t *s, const int16_t amp[], int len)
315 {
316     int i;
317     char buf[11];
318     double val;
319 
320     for (i = 0;  i < len;  i++)
321     {
322         s->audio_meter->sample(amp[i]/32768.0);
323         s->power_reading += ((amp[i]*amp[i] - s->power_reading) >> 10);
324     }
325     val = 10.0*log10((double) s->power_reading/(32767.0*32767.0) + 1.0e-10) + 3.14 + 3.02;
326 
327     snprintf(buf, sizeof(buf), "%5.1fdBm0", val);
328     s->audio_level->value(buf);
329     return 0;
330 }
331 /*- End of function --------------------------------------------------------*/
332 
qam_monitor_update_carrier_tracking(qam_monitor_t * s,float carrier_freq)333 int qam_monitor_update_carrier_tracking(qam_monitor_t *s, float carrier_freq)
334 {
335     int i;
336     int j;
337     float min;
338     float max;
339 
340     s->carrier_tracker[s->carrier_ptr++] = carrier_freq;
341     if (s->carrier_points < CARRIER_TRACKER_POINTS)
342         s->carrier_points++;
343     if (s->carrier_ptr >= CARRIER_TRACKER_POINTS)
344         s->carrier_ptr = 0;
345 
346     s->canvas_track->current(s->canvas_track);
347     if (s->carrier)
348         delete s->carrier;
349     s->track_x->current();
350     s->carrier_y->current();
351 
352     min =
353     max = s->carrier_tracker[0];
354     for (i = s->carrier_ptr, j = 0;  i < s->carrier_points;  i++, j++)
355     {
356         s->carrier_plot[2*j] = j;
357         s->carrier_plot[2*j + 1] = s->carrier_tracker[i];
358         if (min > s->carrier_tracker[i])
359             min = s->carrier_tracker[i];
360         if (max < s->carrier_tracker[i])
361             max = s->carrier_tracker[i];
362     }
363     for (i = 0;  i < s->carrier_ptr;  i++, j++)
364     {
365         s->carrier_plot[2*j] = j;
366         s->carrier_plot[2*j + 1] = s->carrier_tracker[i];
367         if (min > s->carrier_tracker[i])
368             min = s->carrier_tracker[i];
369         if (max < s->carrier_tracker[i])
370             max = s->carrier_tracker[i];
371     }
372 
373     s->carrier_y->maximum((fabs(max - min) < 0.05)  ?  max + 0.05  :  max);
374     s->carrier_y->minimum(min);
375 
376     s->carrier = new Ca_Line(s->carrier_points, s->carrier_plot, 0, 0, FL_BLUE, CA_NO_POINT);
377     //Fl::check();
378     return 0;
379 }
380 /*- End of function --------------------------------------------------------*/
381 
qam_monitor_init(float constel_width,float constel_scaling,const char * tag)382 qam_monitor_t *qam_monitor_init(float constel_width, float constel_scaling, const char *tag)
383 {
384     char buf[132 + 1];
385     float x;
386     float y;
387     qam_monitor_t *s;
388 
389     if ((s = (qam_monitor_t *) malloc(sizeof(*s))) == NULL)
390         return NULL;
391 
392     s->w = new Fl_Double_Window(905, 400, (tag)  ?  tag  :  "QAM monitor");
393 
394     s->constel_scaling = 1.0/constel_scaling;
395 
396     s->c_const = new Fl_Group(0, 0, 380, 400);
397     s->c_const->box(FL_DOWN_BOX);
398     s->c_const->align(FL_ALIGN_TOP | FL_ALIGN_INSIDE);
399 
400     s->canvas_const = new Ca_Canvas(60, 30, 300, 300, "Constellation");
401     s->canvas_const->box(FL_PLASTIC_DOWN_BOX);
402     s->canvas_const->color(7);
403     s->canvas_const->align(FL_ALIGN_TOP);
404     s->canvas_const->border(15);
405 
406     s->sig_i = new Ca_X_Axis(65, 330, 290, 30, "I");
407     s->sig_i->align(FL_ALIGN_BOTTOM);
408     s->sig_i->minimum(-constel_width);
409     s->sig_i->maximum(constel_width);
410     s->sig_i->label_format("%g");
411     s->sig_i->minor_grid_color(fl_gray_ramp(20));
412     s->sig_i->major_grid_color(fl_gray_ramp(15));
413     s->sig_i->label_grid_color(fl_gray_ramp(10));
414     s->sig_i->grid_visible(CA_LABEL_GRID | CA_ALWAYS_VISIBLE);
415     s->sig_i->minor_grid_style(FL_DOT);
416     s->sig_i->major_step(5);
417     s->sig_i->label_step(1);
418     s->sig_i->axis_color(FL_BLACK);
419     s->sig_i->axis_align(CA_BOTTOM | CA_LINE);
420 
421     s->sig_q = new Ca_Y_Axis(20, 35, 40, 290, "Q");
422     s->sig_q->align(FL_ALIGN_LEFT);
423     s->sig_q->minimum(-constel_width);
424     s->sig_q->maximum(constel_width);
425     s->sig_q->minor_grid_color(fl_gray_ramp(20));
426     s->sig_q->major_grid_color(fl_gray_ramp(15));
427     s->sig_q->label_grid_color(fl_gray_ramp(10));
428     //s->sig_q->grid_visible(CA_MINOR_TICK | CA_MAJOR_TICK | CA_LABEL_GRID | CA_ALWAYS_VISIBLE);
429     s->sig_q->grid_visible(CA_LABEL_GRID | CA_ALWAYS_VISIBLE);
430     s->sig_q->minor_grid_style(FL_DOT);
431     s->sig_q->major_step(5);
432     s->sig_q->label_step(1);
433     s->sig_q->axis_color(FL_BLACK);
434 
435     s->sig_q->current();
436 
437     s->c_const->end();
438 
439     s->c_right = new Fl_Group(440, 0, 465, 405);
440 
441     s->c_eq = new Fl_Group(380, 0, 265, 200);
442     s->c_eq->box(FL_DOWN_BOX);
443     s->c_eq->align(FL_ALIGN_TOP | FL_ALIGN_INSIDE);
444     s->c_eq->current();
445     s->canvas_eq = new Ca_Canvas(460, 35, 150, 100, "Equalizer");
446     s->canvas_eq->box(FL_PLASTIC_DOWN_BOX);
447     s->canvas_eq->color(7);
448     s->canvas_eq->align(FL_ALIGN_TOP);
449     Fl_Group::current()->resizable(s->canvas_eq);
450     s->canvas_eq->border(15);
451 
452     s->eq_x = new Ca_X_Axis(465, 135, 140, 30, "Symbol");
453     s->eq_x->align(FL_ALIGN_BOTTOM);
454     s->eq_x->minimum(-8.0);
455     s->eq_x->maximum(8.0);
456     s->eq_x->label_format("%g");
457     s->eq_x->minor_grid_color(fl_gray_ramp(20));
458     s->eq_x->major_grid_color(fl_gray_ramp(15));
459     s->eq_x->label_grid_color(fl_gray_ramp(10));
460     s->eq_x->grid_visible(CA_LABEL_GRID | CA_ALWAYS_VISIBLE);
461     s->eq_x->minor_grid_style(FL_DOT);
462     s->eq_x->major_step(5);
463     s->eq_x->label_step(1);
464     s->eq_x->axis_align(CA_BOTTOM | CA_LINE);
465     s->eq_x->axis_color(FL_BLACK);
466     s->eq_x->current();
467 
468     s->eq_y = new Ca_Y_Axis(420, 40, 40, 90, "Amp");
469     s->eq_y->align(FL_ALIGN_LEFT);
470     s->eq_y->minimum(-0.1);
471     s->eq_y->maximum(0.1);
472     s->eq_y->minor_grid_color(fl_gray_ramp(20));
473     s->eq_y->major_grid_color(fl_gray_ramp(15));
474     s->eq_y->label_grid_color(fl_gray_ramp(10));
475     s->eq_y->grid_visible(CA_LABEL_GRID | CA_ALWAYS_VISIBLE);
476     s->eq_y->minor_grid_style(FL_DOT);
477     s->eq_y->major_step(5);
478     s->eq_y->label_step(1);
479     s->eq_y->axis_color(FL_BLACK);
480     s->eq_y->current();
481 
482     s->c_eq->end();
483 
484     s->c_symbol_track = new Fl_Group(380, 200, 525, 200);
485     s->c_symbol_track->box(FL_DOWN_BOX);
486     s->c_symbol_track->align(FL_ALIGN_TOP | FL_ALIGN_INSIDE);
487     s->c_symbol_track->current();
488 
489     s->canvas_track = new Ca_Canvas(490, 235, 300, 100, "Symbol and carrier tracking");
490     s->canvas_track->box(FL_PLASTIC_DOWN_BOX);
491     s->canvas_track->color(7);
492     s->canvas_track->align(FL_ALIGN_TOP);
493     Fl_Group::current()->resizable(s->canvas_track);
494     s->canvas_track->border(15);
495 
496     s->track_x = new Ca_X_Axis(495, 335, 290, 30, "Time (symbols)");
497     s->track_x->align(FL_ALIGN_BOTTOM);
498     s->track_x->minimum(0.0);
499     s->track_x->maximum(2400.0*5.0);
500     s->track_x->label_format("%g");
501     s->track_x->minor_grid_color(fl_gray_ramp(20));
502     s->track_x->major_grid_color(fl_gray_ramp(15));
503     s->track_x->label_grid_color(fl_gray_ramp(10));
504     s->track_x->grid_visible(CA_LABEL_GRID | CA_ALWAYS_VISIBLE);
505     s->track_x->minor_grid_style(FL_DOT);
506     s->track_x->major_step(5);
507     s->track_x->label_step(1);
508     s->track_x->axis_align(CA_BOTTOM | CA_LINE);
509     s->track_x->axis_color(FL_BLACK);
510     s->track_x->current();
511 
512     s->symbol_track_y = new Ca_Y_Axis(420, 240, 70, 90, "Cor");
513     s->symbol_track_y->align(FL_ALIGN_LEFT);
514     s->symbol_track_y->minimum(-0.1);
515     s->symbol_track_y->maximum(0.1);
516     s->symbol_track_y->minor_grid_color(fl_gray_ramp(20));
517     s->symbol_track_y->major_grid_color(fl_gray_ramp(15));
518     s->symbol_track_y->label_grid_color(fl_gray_ramp(10));
519     s->symbol_track_y->grid_visible(CA_LABEL_GRID | CA_ALWAYS_VISIBLE);
520     s->symbol_track_y->minor_grid_style(FL_DOT);
521     s->symbol_track_y->major_step(5);
522     s->symbol_track_y->label_step(1);
523     s->symbol_track_y->axis_color(FL_RED);
524     s->symbol_track_y->current();
525 
526     s->carrier_y = new Ca_Y_Axis(790, 240, 70, 90, "Freq");
527     s->carrier_y->align(FL_ALIGN_RIGHT);
528     s->carrier_y->minimum(-0.1);
529     s->carrier_y->maximum(0.1);
530     s->carrier_y->minor_grid_color(fl_gray_ramp(20));
531     s->carrier_y->major_grid_color(fl_gray_ramp(15));
532     s->carrier_y->label_grid_color(fl_gray_ramp(10));
533     s->carrier_y->grid_visible(CA_LABEL_GRID | CA_ALWAYS_VISIBLE);
534     s->carrier_y->minor_grid_style(FL_DOT);
535     s->carrier_y->major_step(5);
536     s->carrier_y->label_step(1);
537     s->carrier_y->axis_align(CA_RIGHT);
538     s->carrier_y->axis_color(FL_BLUE);
539     s->carrier_y->current();
540 
541     s->c_symbol_track->end();
542 
543     s->audio_meter = new Fl_Audio_Meter(672, 10, 16, 150, "");
544     s->audio_meter->box(FL_PLASTIC_UP_BOX);
545     s->audio_meter->type(FL_VERT_AUDIO_METER);
546 
547     s->audio_level = new Fl_Output(650, 170, 60, 20, "");
548     s->audio_level->textsize(10);
549 
550     s->c_right->end();
551 
552     Fl_Group::current()->resizable(s->c_right);
553     s->w->end();
554     s->w->show();
555 
556     s->next_constel_point = 0;
557     s->constel_window = 10000;
558 
559     s->carrier_points = 0;
560     s->carrier_ptr = 0;
561     s->carrier_window = 100;
562 
563     s->symbol_track_points = 0;
564     s->symbol_track_window = 10000;
565     Fl::check();
566     return s;
567 }
568 /*- End of function --------------------------------------------------------*/
569 
qam_wait_to_end(qam_monitor_t * s)570 void qam_wait_to_end(qam_monitor_t *s)
571 {
572     fd_set rfds;
573     int res;
574     struct timeval tv;
575 
576     fprintf(stderr, "Processing complete.  Press the <enter> key to end\n");
577     do
578     {
579         usleep(100000);
580         Fl::check();
581         FD_ZERO(&rfds);
582         FD_SET(0, &rfds);
583         tv.tv_usec = 100000;
584         tv.tv_sec = 0;
585         res = select(1, &rfds, NULL, NULL, &tv);
586     }
587     while (res <= 0);
588 }
589 /*- End of function --------------------------------------------------------*/
590 #endif
591 /*- End of file ------------------------------------------------------------*/
592