80 lines
2.0 KiB
C
80 lines
2.0 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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#define PI 3.14
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#define SIG_FREQ 100
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#define SAM_FREQ 2000
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_Noreturn void k_avg(int fd) {
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// Exponential Moving Average should be updated with f = 10Hz (i.e. every 200 samples).
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int samples = 200;
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printf("A k_avg has been called\n");
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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 delay;
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delay.tv_sec = 0;
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delay.tv_nsec = 100000000ULL*1; // 100ms == 100 000 000ns -> 10Hz
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double alpha = 0.1;
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double ema;
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int start_idx = 0;
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while (1) {
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start_idx = buffer->info.free_idx;
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ema = buffer->data[start_idx];
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printf("start_idx = %d\n", start_idx);
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printf("EMA = %lf\n", ema);
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nanosleep(&delay, NULL);
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}
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// while (1) {
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// start_idx = (buffer->info.free_idx - samples) % buffer->info.size;
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// printf("start_idx = %d\n", start_idx);
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// ema = buffer->data[start_idx];
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// for (int read_idx = start_idx + 1; read_idx < samples; read_idx = ++read_idx % buffer->info.size) {
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// ema = alpha*buffer->data[read_idx] + (1 - alpha) * ema;
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// printf("EMA[%d] = %lf\n", read_idx, ema);
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// }
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// printf("EMA = %lf\n", ema);
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// nanosleep(&delay, NULL);
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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_avg(fd);
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return 0;
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} |