83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
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//
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// Written for Computer Networks and Systems lab classes
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// AUTHOR : Sergiusz Warga
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#include <fcntl.h>
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <time.h>
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#include "CircBuffer.h"
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#include "funs.h"
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int crosses_zero(double prev, double curr) {
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// let's just ignore 0 for now
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return (prev > 0 && curr < 0) || (prev < 0 && curr > 0);
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}
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_Noreturn void k_f0(int fd, int sampling_frequency, int refreshing_frequency) {
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printf("A k_f0 has been called\n");
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//----- Initialize the buffer -----
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struct CircBuffer *buffer;
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buffer = mmap(NULL, sizeof(struct CircBuffer), PROT_READ, MAP_SHARED, fd, 0);
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if (buffer == MAP_FAILED) {
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fprintf(stderr, "mmap: ");
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exit(EXIT_FAILURE);
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}
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struct timespec tic, toc;
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// delay.tv_sec = 0;
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// delay.tv_nsec = (1./refreshing_frequency * 1000000000L); // 1/f in nanoseconds
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unsigned long long delay = NSEC_PER_SEC*1./refreshing_frequency;
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clock_gettime(CLOCK_REALTIME, &tic);
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int transitions = 0;
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int samples = 0;
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int read_idx;
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read_idx = buffer->info.free_idx - 1;
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while (1) {
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clock_gettime(CLOCK_REALTIME, &toc);
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if (timespec_diff_nano(&toc, &tic) > delay) {
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double t_samp = 1./sampling_frequency;
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// printf("t_samp = %fs\n", t_samp);
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// printf("n_samp = %d\n", samples);
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double t_anal = t_samp*samples;
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// printf("t_anal = %fs\n", t_anal);
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// printf("n_tran = %d\n", transitions);
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printf("f = %fHz\n", transitions/(2*t_anal));
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transitions = 0;
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samples = 0;
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clock_gettime(CLOCK_REALTIME, &tic);
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}
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if (crosses_zero(buffer->data[read_idx-1], buffer->data[read_idx])) {
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++transitions;
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}
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while (read_idx == ((buffer->info.free_idx - 1) % buffer->info.size)) {};
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read_idx = ++read_idx % buffer->info.size;
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++samples;
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}
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}
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int main(int argc, char *argv[]) {
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//----- Open a shared memory -----
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const char *memory_name = "/dsp";
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int fd = shm_open(memory_name, O_RDONLY, 0777);
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if (fd < 0) {
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fprintf(stderr, "shm_open: ");
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exit(EXIT_FAILURE);
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}
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printf("Shared memory file descriptor: %d\n", fd);
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k_f0(fd, 2000, 1);
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return 0;
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}
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