108 lines
3.4 KiB
C
108 lines
3.4 KiB
C
//
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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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#define PI 3.14
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#define SIG_FREQ 100
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void handle_arguments(int argc, char *argv[]) {
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if (argc != 2) {
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fprintf(stderr, "Usage: %s SAMPLING_FREQUENCY\n", argv[0]);
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exit(EXIT_FAILURE);
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}
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if (strtol(argv[1], NULL, 10) < 400) {
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fprintf(stderr, "Sampling frequency should be at least 400Hz!\n");
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exit(EXIT_FAILURE);
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}
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}
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double get_sample(int signal_frequeuncy, int sampling_frequency, unsigned int sample_no) {
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// TODO: Just a sketch, gotta rewrite
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double step = 2.*PI/((double)sampling_frequency/signal_frequeuncy); // Step in radians
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return sin(sample_no*step);
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}
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_Noreturn void producer(int fd, int sampling_frequency) { // That's something new I've learned and I think that
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// function specifiers are cute.
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printf("The producer 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_WRITE, 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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unsigned int i = 0;
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int free_idx;
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struct timespec delay, tic, toc;
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delay.tv_sec = 0;
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delay.tv_nsec = (int) (1./sampling_frequency * NSEC_PER_SEC); // 1/f in nanoseconds
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clock_gettime(CLOCK_REALTIME, &tic);
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clock_gettime(CLOCK_REALTIME, &toc);
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printf("Starting to sampling the signal at %dHz with t_s = %ldns\n", sampling_frequency, delay.tv_nsec);
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//----- Fill the buffer -----
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while (1) {
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clock_gettime(CLOCK_REALTIME, &toc);
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free_idx = buffer->info.free_idx;
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buffer->data[free_idx] = get_sample(SIG_FREQ, sampling_frequency, i);
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// printf("CircBuffer[%d] = \t %lf\n", free_idx, buffer->data[free_idx]);
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buffer->info.free_idx = (free_idx + 1 ) % buffer->info.size;
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++i;
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while (timespec_diff_nano(&toc, &tic) < delay.tv_nsec) {
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// printf("%lld\n", timespec_diff_nano(&toc, &tic));
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clock_gettime(CLOCK_REALTIME, &toc);
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}
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clock_gettime(CLOCK_REALTIME, &tic);
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}
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}
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int main(int argc, char *argv[]) {
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//----- Arguments handling -----
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handle_arguments(argc, argv);
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int sampling_frequency = strtol(argv[1], NULL, 10) ;
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//----- Create a shared memory -----
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const char *memory_name = "/dsp";
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int fd = shm_open(memory_name, O_CREAT | O_RDWR, 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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//----- Truncate memory to the buffer's size
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if (ftruncate(fd, sizeof(struct CircBuffer)) < 0) {
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fprintf(stderr, "ftruncate: \n");
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exit(EXIT_FAILURE);
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}
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//----- Initialize the buffer -----
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struct CircBuffer *buffer;
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buffer = (struct CircBuffer *)mmap(NULL, sizeof(struct CircBuffer), PROT_WRITE, 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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buffer->info.size = sizeof(buffer->data)/sizeof(double);
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buffer->info.free_idx = 0;
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//----- Sample the producer -----
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producer(fd, sampling_frequency);
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return 0;
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} |