#include <sys/ioctl.h>
#include <sys/kd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <signal.h>
#include <stdio.h>

#define CLOCK_TICK_RATE   1193180

#define NUMNOTES 12
unsigned long notes[NUMNOTES] = { 26163, 27718, 29366, 31113, 32963, 34923, 
                                  37000, 39200, 41530, 44000, 46616, 49388 };

int default_note = 10;  // 1-based

#define DEFAULT_PARAMS_LEN 3
static const char *default_params[DEFAULT_PARAMS_LEN] = { 
                  "beep", "-10", "10" };

static int fd = -1;

void exiting(int signum) {
    int tone = 0;
    if (fd >= 0)
        ioctl(fd, KIOCSOUND, tone);
}

int check_sound_capabilities(const char *filename, int *fd) {
    int tone;
    int lfd;

    if (strcmp(filename, "-")) {
        lfd = open(filename, O_RDONLY);
        if (lfd < 0) {
            perror(filename);
            return 0;
        }
    } else {
        lfd = 0;
    }

    tone = 0;
    if (ioctl(lfd, KIOCSOUND, tone)) {
        close(lfd);
        perror(filename);
        return 0;
    }

    if (fd != NULL) {
        *fd = lfd;
    }

    return 1;
}

int main(int argc, char *argv[]) {
    int i;
    unsigned int tone;
    int hertz, length;
    int param_len;
    const char **params;

    if (!check_sound_capabilities("/dev/pcspeaker", &fd) &&
        !check_sound_capabilities("-", &fd) &&
	!check_sound_capabilities("/dev/tty0", &fd)) {
        exit(EXIT_FAILURE);
    }

    if (argc <= 1) {
        params = default_params;
        param_len = DEFAULT_PARAMS_LEN;
    } else {
        params = (const char **)argv;
        param_len = argc;
    }

    signal(SIGHUP, exiting);
    signal(SIGINT, exiting);
    signal(SIGQUIT, exiting);
    signal(SIGPIPE, exiting);
    signal(SIGTERM, exiting);
    signal(SIGTSTP, exiting);

    for (i = 1; i < param_len; i += 2) {
        hertz = strtol(params[i], NULL, 0);
        if (hertz < 0) {
            if (hertz < -NUMNOTES)
                hertz = -default_note;
            hertz = notes[-hertz - 1];
        }
        if (i + 1 < param_len)
            length = strtol(params[i + 1], NULL, 0);
        else
            length = 10;

        // printf("hertz %d\n", hertz); fflush(stdout);

        tone = (CLOCK_TICK_RATE * 100) / hertz;
        ioctl(fd, KIOCSOUND, tone);
        usleep(((unsigned long)length) * 10000);
        tone = 0;
        ioctl(fd, KIOCSOUND, tone);
    }

    close(fd);
    fd = -1;
    exit(EXIT_SUCCESS);
    return 0;
}