tg.c

网络时间协议NTP 源码 版本v4.2.0b 该源码用于linux平台下

		exit(1);
	}
	rval = ioctl(fd, AUDIO_GETINFO, &info);
	if (rval < 0) {
		printf("audio control %s\n", strerror(errno));
		exit(0);
	}
	info.play.port = port;
	info.play.gain = level;
	info.play.sample_rate = SECOND;
	info.play.channels = 1;
	info.play.precision = 8;
	info.play.encoding = AUDIO_ENCODING_ULAW;
	printf("port %d gain %d rate %d chan %d prec %d encode %d\n",
	    info.play.port, info.play.gain, info.play.sample_rate,
	    info.play.channels, info.play.precision,
	    info.play.encoding);
	ioctl(fd, AUDIO_SETINFO, &info);

 	/*
	 * Unless specified otherwise, read the system clock and
	 * initialize the time.
	 */
	if (!utc) {
		gettimeofday(&tv, NULL);
		tm = gmtime(&tv.tv_sec);
		minute = tm->tm_min;
		hour = tm->tm_hour;
		day = tm->tm_yday + 1;
		year = tm->tm_year % 100;
		second = tm->tm_sec;

		/*
		 * Delay the first second so the generator is accurately
		 * aligned with the system clock within one sample (125
		 * microseconds ).
		 */
		delay(SECOND - tv.tv_usec * 8 / 1000);
	}
	memset(code, 0, sizeof(code));
	switch (encode) {

	/*
	 * For WWV/H and default time, carefully set the signal
	 * generator seconds number to agree with the current time.
	 */ 
	case WWV:
		printf("year %d day %d time %02d:%02d:%02d tone %d\n",
		    year, day, hour, minute, second, tone);
		sprintf(code, "%01d%03d%02d%02d%01d", year / 10, day,
		    hour, minute, year % 10);
		printf("%s\n", code);
		ptr = 8;
		for (i = 0; i <= second; i++) {
			if (progx[i].sw == DEC)
				ptr--;
		}
		break;

	/*
	 * For IRIG the signal generator runs every second, so requires
	 * no additional alignment.
	 */
	case IRIG:
		printf("sbs %x year %d day %d time %02d:%02d:%02d\n",
		    0, year, day, hour, minute, second);
		break;
	}

	/*
	 * Run the signal generator to generate new timecode strings
	 * once per minute for WWV/H and once per second for IRIG.
	 */
	while(1) {

		/*
		 * Crank the state machine to propagate carries to the
		 * year of century. Note that we delayed up to one
		 * second for alignment after reading the time, so this
		 * is the next second.
		 */
		second = (second + 1) % 60;
		if (second == 0) {
			minute++;
			if (minute >= 60) {
				minute = 0;
				hour++;
			}
			if (hour >= 24) {
				hour = 0;
				day++;
			}

			/*
			 * At year rollover check for leap second.
			 */
			if (day >= (year & 0x3 ? 366 : 367)) {
				if (leap) {
					sec(DATA0);
					printf("\nleap!");
					leap = 0;
				}
				day = 1;
				year++;
			}
			if (encode == WWV) {
				sprintf(code, "%01d%03d%02d%02d%01d",
				    year / 10, day, hour, minute, year %
				    10);
				printf("\n%s\n", code);
				ptr = 8;
			}
		}
		if (encode == IRIG) {
			sprintf(code, "%04x%04d%06d%02d%02d%02d", 0,
			    year, day, hour, minute, second);
			printf("%s\n", code);
			ptr = 19;
		}

		/*
		 * Generate data for the second
		 */
		switch(encode) {

		/*
		 * The IRIG second consists of 20 BCD digits of width-
		 * modulateod pulses at 2, 5 and 8 ms and modulated 50
		 * percent on the 1000-Hz carrier.
		 */
		case IRIG:
			for (i = 0; i < 100; i++) {
				if (i < 10) {
					sw = progz[i].sw;
					arg = progz[i].arg;
				} else {
					sw = progy[i % 10].sw;
					arg = progy[i % 10].arg;
				}
				switch(sw) {

				case COEF:	/* send BCD bit */
					if (code[ptr] & arg) {
						peep(M5, 1000, HIGH);
						peep(M5, 1000, LOW);
						printf("1");
					} else {
						peep(M2, 1000, HIGH);
						peep(M8, 1000, LOW);
						printf("0");
					}
					break;

				case DEC:	/* send IM/PI bit */
					ptr--;
					printf(" ");
					peep(arg, 1000, HIGH);
					peep(10 - arg, 1000, LOW);
					break;

				case MIN:	/* send data bit */
					peep(arg, 1000, HIGH);
					peep(10 - arg, 1000, LOW);
					printf("M ");
					break;
				}
				if (ptr < 0)
					break;
			}
			printf("\n");
			break;

		/*
		 * The WWV/H second consists of 9 BCD digits of width-
		 * modulateod pulses 200, 500 and 800 ms at 100-Hz.
		 */
		case WWV:
			sw = progx[second].sw;
			arg = progx[second].arg;
			switch(sw) {

			case DATA:		/* send data bit */
				sec(arg);
				break;

			case COEF:		/* send BCD bit */
				if (code[ptr] & arg) {
					sec(DATA1);
					printf("1");
				} else {
					sec(DATA0);
					printf("0");
				}
				break;

			case LEAP:		/* send leap bit */
				if (leap) {
					sec(DATA1);
					printf("L ");
				} else {
					sec(DATA0);
					printf("  ");
				}
				break;

			case DEC:		/* send data bit */
				ptr--;
				sec(arg);
				printf(" ");
				break;

			case MIN:		/* send minute sync */
				peep(arg, tone, HIGH);
				peep(1000 - arg, tone, OFF);
				break;

			case DUT1:		/* send DUT1 bits */
				if (dut1 & arg)
					sec(DATA1);
				else
					sec(DATA0);
				break;
				
			case DST1:		/* send DST1 bit */
				ptr--;
				if (dst)
					sec(DATA1);
				else
					sec(DATA0);
				printf(" ");
				break;

			case DST2:		/* send DST2 bit */
				if (dst)
					sec(DATA1);
				else
					sec(DATA0);
				break;
			}
		}
	}
}


/*
 * Generate WWV/H 0 or 1 data pulse.
 */
void sec(
	int	code		/* DATA0, DATA1, PI */
	)
{
	/*
	 * The WWV data pulse begins with 5 ms of 1000 Hz follwed by a
	 * guard time of 25 ms. The data pulse is 170, 570 or 770 ms at
	 * 100 Hz corresponding to 0, 1 or position indicator (PI),
	 * respectively. Note the 100-Hz data pulses are transmitted 6
	 * dB below the 1000-Hz sync pulses. Originally the data pulses
	 * were transmited 10 dB below the sync pulses, but the station
	 * engineers increased that to 6 dB because the Heath GC-1000
	 * WWV/H radio clock worked much better.
	 */
	peep(5, tone, HIGH);		/* send seconds tick */
	peep(25, tone, OFF);
	peep(code - 30, 100, LOW);	/* send data */
	peep(1000 - code, 100, OFF);
}


/*
 * Generate cycles of 100 Hz or any multiple of 100 Hz.
 */
void peep(
	int	pulse,		/* pulse length (ms) */
	int	freq,		/* frequency (Hz) */
	int	amp		/* amplitude */
	)
{
	int	increm;		/* phase increment */
	int	i, j;

	if (amp == OFF || freq == 0)
		increm = 10;
	else
		increm = freq / 100;
	j = 0;
	for (i = 0 ; i < pulse * 8; i++) {
		switch (amp) {

		case HIGH:
			buffer[bufcnt++] = ~c6000[j];
			break;

		case LOW:
			buffer[bufcnt++] = ~c3000[j];
			break;

		default:
			buffer[bufcnt++] = ~0;
		}
		if (bufcnt >= BUFLNG) {
			write(fd, buffer, BUFLNG);
			bufcnt = 0;
		}
		j = (j + increm) % 80;
	}
}


/*
 * Delay for initial phasing
 */
void delay (
	int	delay		/* delay in samples */
	)
{
	int	samples;	/* samples remaining */

	samples = delay;
	memset(buffer, 0, BUFLNG);
	while (samples >= BUFLNG) {
		write(fd, buffer, BUFLNG);
		samples -= BUFLNG;
	}
		write(fd, buffer, samples);
}