87 lines
2.4 KiB
C
87 lines
2.4 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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#define PI 3.14
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#define SIG_FREQ 100
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#define SAM_FREQ 2000
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double get_sample(int signal_frequeuncy, int sampling_frequency, int sample_no) {
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// TODO: Just a sketch, gotta rewrite
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double step = 2.*PI/200;
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return sin(sample_no*step);
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}
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_Noreturn void producer(int fd) { // 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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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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int i = 0;
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int free_idx = 0;
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struct timespec delay;
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delay.tv_sec = 0;
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delay.tv_nsec = 500000ULL*1; // 0.5ms == 500 000ns -> 2kHz
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while (1) {
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free_idx = buffer->info.free_idx; // For more readable code
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buffer->data[free_idx] = get_sample(SIG_FREQ, SAM_FREQ, i+1); // Put a sample into the buffer
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buffer->info.free_idx = (free_idx + 1 ) % buffer->info.size; // Increase the free-cell index
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printf("CircBuffer[%d] = \t %lf\n", free_idx, buffer->data[free_idx]);
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i = ++i % 200;
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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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//----- 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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producer(fd);
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return 0;
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}
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