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modified post 8c4e by Anonymous on Wed 11th Dec 2019 15:56
original post 6675d by Anonymous on Wed 11th Dec 2019 15:37
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/*

1	1		/*
2	2		* qaweep1.c - Quantron beeper-weeper demo V0.0.1
3	3		*
4	4		* Written by Roland Mainz <r.mainz@eckelmann.de>
5	5		*/
	6	+
6	11		#include <errno.h>
7	12		#include <fcntl.h>
8	13		#include <stdio.h>
9	14		#include <stdlib.h>
10	15		#include <sys/stat.h>
11	16		#include <sys/types.h>
12	17		#include <unistd.h>
13	18
14	19		#define NUM_ELEMENTS_IN_ARRAY(ar) (sizeof(ar) / sizeof (ar[0]))
15	20		const double freqs[] = {
16	21		440.0000,
17	22		466.1638,
18	23		493.8833,
19	24		523.2511,
20	25		554.3653,
21	26		587.3295,
22	27		622.2540,
23	28		659.2551,
24	29		698.4565,
25	30		739.9888,
26	31		783.9909,
27	32		830.6094,
28	33		880.0000,
29	34		932.3275,
30	35		987.7666,
31	36		1046.502,
32	37		1108.731,
33	38		1174.659,
34	39		1244.508
35	40		};
36	41
	42	+	#define MICROSECONDS_PER_SEC (1000000L)
37	43
38	44		int main(int ac, char *av[])
39	45		{
40	46		int retval = EXIT_FAILURE;
41	47		int fd,
42	48		gpiodirfd = -1;
43	49
44	50		fd = open("/sys/class/gpio/export", O_WRONLY);
45	51		if (fd == -1) {
46	52		perror("Unable to open /sys/class/gpio/export");
47	53		goto exit_ioerr;
48	54		}
49	55
50	56		if (write(fd, "11", 2) != 2) {
51	57		perror("Error writing to /sys/class/gpio/export");
52	58		goto exit_ioerr;
53	59		}
54	60
55	61		(void)close(fd);
56	62
57	63		gpiodirfd = open("/sys/class/gpio/gpio11/", O_DIRECTORY);
58	64		if (gpiodirfd == -1) {
59	65		perror("Unable to open /sys/class/gpio/gpio11/");
60	66		goto exit_ioerr;
61	67		}
62	68
63	69		fd = openat(gpiodirfd, "direction", O_WRONLY);
64	70		if (fd == -1) {
65	71		perror("Unable to open direction");
66	72		goto exit_ioerr;
67	73		}
68	74
69	75		if (write(fd, "out", 3) != 3) {
70	76		perror("Error writing to /sys/class/gpio/gpio11/direction");
71	77		goto exit_ioerr;
72	78		}
73	79
74	80		(void)close(fd);
75	81
76	82		fd = openat(gpiodirfd, "value", O_WRONLY);
77	83		if (fd == -1) {
78	84		perror("Unable to open value");
79	85		goto exit_ioerr;
80	86		}
81	87
82	88		int i, j;
83	89		for (j=0 ; j < NUM_ELEMENTS_IN_ARRAY(freqs) ; j++)
84	90		{
85	91		double f = freqs[j];
86		-	long delay = 999999./f;
	92	+	long delay = ((double)(MICROSECONDS_PER_SEC))/f;
87	93		long cycles = (100. * f) / 440.;
88	94
	95	+	(void)printf("freq=%4.4f\tdelay=%ld\tcycles=%ld\n",
89	100		for (i = 0; i < cycles; i++) {
90	101		if (write(fd, "1", 1) != 1) {
91	102		perror("Error writing 0 to value");
92	103		goto exit_ioerr;
93	104		}
94	105
95	106		(void)usleep(delay/2);
96	107
97	108		if (write(fd, "0", 1) != 1) {
98	109		perror("Error writing 1 to value");
99	110		goto exit_ioerr;
100	111		}
101	112
102	113		(void)usleep(delay/2);
103	114		}
104	115
105		-	(void)usleep(100);
	116	+	/* Wait 1/10 second */
	117	+	(void)usleep(MICROSECONDS_PER_SEC/10);
106	118		}
107	119
108	120		(void)close(fd);
109	121
110	122		fd = open("/sys/class/gpio/unexport", O_WRONLY);
111	123		if (fd == -1) {
112	124		perror("Unable to open /sys/class/gpio/unexport");
113	125		goto exit_ioerr;
114	126		}
115	127
116	128		if (write(fd, "11", 2) != 2) {
117	129		perror("Error writing to /sys/class/gpio/unexport");
118	130		goto exit_ioerr;
119	131		}
120	132
121	133		retval = EXIT_SUCCESS;
122	134		exit_ioerr:
123	135		if (fd >=0)
124	136		(void)close(fd);
125	137		if (gpiodirfd >=0)
126	138		(void)close(gpiodirfd);
127	139
128	140		return retval;
129	141		}
130	142