ALSA project - the C library reference: /test/timer.c

# /test/timer.c

    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <sys/time.h>
    #include "../include/asoundlib.h"

    void show_status(void *handle)
    {
            int err;
            snd_timer_status_t *status;

            snd_timer_status_alloca(&status);
            if ((err = snd_timer_status(handle, status)) < 0) {
                    fprintf(stderr, "timer status %i (%s)\n", err, snd_strerror(err));
                    return;
            }
            printf("STATUS:\n");
            printf("  resolution = %li\n", snd_timer_status_get_resolution(status));
            printf("  lost = %li\n", snd_timer_status_get_lost(status));
            printf("  overrun = %li\n", snd_timer_status_get_overrun(status));
            printf("  queue = %li\n", snd_timer_status_get_queue(status));
    }

    void read_loop(void *handle, int master_ticks, int timeout)
    {
            int count, err;
            struct pollfd *fds;
            snd_timer_read_t tr;

            count = snd_timer_poll_descriptors_count(handle);
            fds = calloc(count, sizeof(struct pollfd));
            if (fds == NULL) {
                    fprintf(stderr, "malloc error\n");
                    exit(EXIT_FAILURE);
            }
            while (master_ticks-- > 0) {
                    if ((err = snd_timer_poll_descriptors(handle, fds, count)) < 0) {
                            fprintf(stderr, "snd_timer_poll_descriptors error: %s\n", snd_strerror(err));
                            exit(EXIT_FAILURE);
                    }
                    if ((err = poll(fds, count, timeout)) < 0) {
                            fprintf(stderr, "poll error %i (%s)\n", err, strerror(err));
                            exit(EXIT_FAILURE);
                    }
                    if (err == 0) {
                            fprintf(stderr, "timer time out!!\n");
                            exit(EXIT_FAILURE);
                    }
                    while (snd_timer_read(handle, &tr, sizeof(tr)) == sizeof(tr)) {
                            printf("TIMER: resolution = %uns, ticks = %u\n",
                                    tr.resolution, tr.ticks);
                    }
            }
            free(fds);
    }

    static void async_callback(snd_async_handler_t *ahandler)
    {
            snd_timer_t *handle = snd_async_handler_get_timer(ahandler);
            int *acount = snd_async_handler_get_callback_private(ahandler);
            snd_timer_read_t tr;

            while (snd_timer_read(handle, &tr, sizeof(tr)) == sizeof(tr)) {
                    printf("TIMER: resolution = %uns, ticks = %u\n",
                            tr.resolution, tr.ticks);
            }
            (*acount)++;
    }

    int main(int argc, char *argv[])
    {
            int idx, err;
            int class = SND_TIMER_CLASS_GLOBAL;
            int sclass = SND_TIMER_CLASS_NONE;
            int card = 0;
            int device = SND_TIMER_GLOBAL_SYSTEM;
            int subdevice = 0;
            int list = 0;
            int async = 0;
            int acount = 0;
            snd_timer_t *handle;
            snd_timer_id_t *id;
            snd_timer_info_t *info;
            snd_timer_params_t *params;
            char timername[64];
            snd_async_handler_t *ahandler;

            snd_timer_id_alloca(&id);
            snd_timer_info_alloca(&info);
            snd_timer_params_alloca(&params);

            idx = 1;
            while (idx < argc) {
                    if (!strncmp(argv[idx], "class=", 5)) {
                            class = atoi(argv[idx]+6);
                    } else if (!strncmp(argv[idx], "sclass=", 6)) {
                            sclass = atoi(argv[idx]+7);
                    } else if (!strncmp(argv[idx], "card=", 5)) {
                            card = atoi(argv[idx]+5);
                    } else if (!strncmp(argv[idx], "device=", 7)) {
                            device = atoi(argv[idx]+7);
                    } else if (!strncmp(argv[idx], "subdevice=", 10)) {
                            subdevice = atoi(argv[idx]+10);
                    } else if (!strcmp(argv[idx], "list")) {
                            list = 1;
                    } else if (!strcmp(argv[idx], "async")) {
                            async = 1;
                    }
                    idx++;
            }
            if (class == SND_TIMER_CLASS_SLAVE && sclass == SND_TIMER_SCLASS_NONE) {
                    fprintf(stderr, "slave class is not set\n");
                    exit(EXIT_FAILURE);
            }
            if (list) {
                    snd_timer_query_t *qhandle;
                    if ((err = snd_timer_query_open(&qhandle, "hw", 0)) < 0) {
                            fprintf(stderr, "snd_timer_query_open error: %s\n", snd_strerror(err));
                            exit(EXIT_FAILURE);
                    }
                    snd_timer_id_set_class(id, SND_TIMER_CLASS_NONE);
                    while (1) {
                            if ((err = snd_timer_query_next_device(qhandle, id)) < 0) {
                                    fprintf(stderr, "timer next device error: %s\n", snd_strerror(err));
                                    break;
                            }
                            if (snd_timer_id_get_class(id) < 0)
                                    break;
                            printf("Timer device: class %i, sclass %i, card %i, device %i, subdevice %i\n",
                                            snd_timer_id_get_class(id),
                                            snd_timer_id_get_sclass(id),
                                            snd_timer_id_get_card(id),
                                            snd_timer_id_get_device(id),
                                            snd_timer_id_get_subdevice(id));
                    }
                    snd_timer_query_close(qhandle);
                    exit(EXIT_SUCCESS);
            }
            sprintf(timername, "hw:CLASS=%i,SCLASS=%i,CARD=%i,DEV=%i,SUBDEV=%i", class, sclass, card, device, subdevice);
            if ((err = snd_timer_open(&handle, timername, SND_TIMER_OPEN_NONBLOCK))<0) {
                    fprintf(stderr, "timer open %i (%s)\n", err, snd_strerror(err));
                    exit(EXIT_FAILURE);
            }
            printf("Using timer class %i, slave class %i, card %i, device %i, subdevice %i\n", class, sclass, card, device, subdevice);
            if ((err = snd_timer_info(handle, info)) < 0) {
                    fprintf(stderr, "timer info %i (%s)\n", err, snd_strerror(err));
                    exit(0);
            }
            printf("Timer info:\n");
            printf("  slave = %s\n", snd_timer_info_is_slave(info) ? "yes" : "no");
            printf("  card = %i\n", snd_timer_info_get_card(info));
            printf("  id = '%s'\n", snd_timer_info_get_id(info));
            printf("  name = '%s'\n", snd_timer_info_get_name(info));
            printf("  average resolution = %li\n", snd_timer_info_get_resolution(info));
            snd_timer_params_set_auto_start(params, 1);
            if (!snd_timer_info_is_slave(info)) {
                    snd_timer_params_set_ticks(params, (1000000000 / snd_timer_info_get_resolution(info)) / 50); /* 50Hz */
                    if (snd_timer_params_get_ticks(params) < 1)
                            snd_timer_params_set_ticks(params, 1);
                    printf("Using %li tick(s)\n", snd_timer_params_get_ticks(params));
            } else {
                    snd_timer_params_set_ticks(params, 1);
            }
            if ((err = snd_timer_params(handle, params)) < 0) {
                    fprintf(stderr, "timer params %i (%s)\n", err, snd_strerror(err));
                    exit(0);
            }
            show_status(handle);
            if (async) {
                    err = snd_async_add_timer_handler(&ahandler, handle, async_callback, &acount);
                    if (err < 0) {
                            fprintf(stderr, "unable to add async handler %i (%s)\n", err, snd_strerror(err));
                            exit(EXIT_FAILURE);
                    }
            }
            if ((err = snd_timer_start(handle)) < 0) {
                    fprintf(stderr, "timer start %i (%s)\n", err, snd_strerror(err));
                    exit(EXIT_FAILURE);
            }
            if (async) {
                    /* because all other work is done in the signal handler,
                       suspend the process */
                    while (acount < 25)
                            sleep(1);
                    snd_timer_stop(handle);
            } else {
                    read_loop(handle, 25, snd_timer_info_is_slave(info) ? 10000 : 25);
            }
            show_status(handle);
            snd_timer_close(handle);
            printf("Done\n");
            return EXIT_SUCCESS;
    }

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