cava/input/shmem.c

#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>

#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

typedef unsigned int u32_t;
typedef short s16_t;


// #define BUFSIZE 1024
#define BUFSIZE 2048

int rc;

#define VIS_BUF_SIZE 16384
#define VB_OFFSET 8192+4096

typedef struct {
	pthread_rwlock_t rwlock;
	u32_t buf_size;
	u32_t buf_index;
	bool running;
	u32_t rate;
	time_t updated;
	s16_t buffer[VIS_BUF_SIZE];
}  vis_t;


//input: SHMEM
void* input_shmem(void* data)
{
	struct audio_data *audio = (struct audio_data *)data;
	vis_t *mmap_area;
	int fd; /* file descriptor to mmaped area */
	int mmap_count = sizeof( vis_t);
	int n = 0;
	int i;

	printf("input_shmem: source: %s", audio->source);

	fd = shm_open(audio->source, O_RDWR, 0666);

	if (fd < 0 ) {
		printf("Could not open source '%s': %s\n", audio->source, strerror( errno ) );
		exit(EXIT_FAILURE);
	} else {
		mmap_area = mmap(NULL, sizeof( vis_t), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
		if ((intptr_t)mmap_area == -1) {
			printf("mmap failed - check if squeezelite is running with visualization enabled\n");
			exit(EXIT_FAILURE);
		}
	}
	// printf("bufs: %u / run: %u / rate: %u\n",mmap_area->buf_size, mmap_area->running, mmap_area->rate);
	audio->rate = mmap_area->rate;

	while (1) {
		for (i = VB_OFFSET; i < BUFSIZE+VB_OFFSET; i += 2) {
			if (audio->channels == 1) {
				audio->audio_out_l[n] = (mmap_area->buffer[i] + mmap_area->buffer[i + 1]) / 2;
			} else if (audio->channels == 2) {
				audio->audio_out_l[n] = mmap_area->buffer[i];
				audio->audio_out_r[n] = mmap_area->buffer[i + 1];
			}
			n++;
			if (n == 2048 - 1) n = 0;
		}
		if (audio->terminate == 1) {
			break;
		}
	}

	// cleanup
	if ( fd > 0 ) {
		if ( close( fd ) != 0 ) {
			printf("Could not close file descriptor %d: %s", fd, strerror( errno ) );
		}
	} else {
		printf("Wrong file descriptor %d", fd );
	}

	if ( munmap( mmap_area, mmap_count ) != 0 ) {
		printf("Could not munmap() area %p+%d. %s", mmap_area, mmap_count, strerror( errno ) );
	}
	return 0;
}