#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <math.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/soundcard.h>


int format;
int rate = 48000;
int word_size = 2;
int channels = 2;
float pi = 3.1415926536;
int write_sine(int out, float pitch, float volume, float t)
{
        signed char *buf, *p;
        int length, buf_size;
    int i, j, k;
    int s;
    float period = 1.0f / pitch;
    float phase;
        length = t * rate;
    buf_size = length * channels * word_size;
    if (!(buf = malloc(buf_size))) {
        fprintf(stderr, "Couldn't allocate buffer: %s\n",
            strerror(errno));
        return -1;
    }
    p = buf;
    for (i=0;i<length;i++) {
        phase = ((float)i * pi * pitch) / (float)rate;
//      printf("phase: %f\n", phase);
        s = (sinf(phase) * volume) * (1 << word_size*8);
        for (j=0;j<channels;j++) {
            for (k=0;k<word_size;k++) {
                *p = (s>>(8*k)) % 256;
                //      printf("s: %d i: %d j: %d k: %d p: %hhd\n", s, i, j, k, *p);
                p++;
            }
        }
    }
    if (-1 == write(out, buf, buf_size)) {
        fprintf(stderr, strerror(errno));
        return -1;
    }
    free(buf);
}

int main(int argc, char **argv)
{
    const char *dsp;
    int out;

    if (argc > 2) {
        fprintf(stderr, "fuck.\n");
    }
    else if (argc == 2) {
        dsp = argv[1];
    } else {
        dsp = "/dev/dsp";
    }
    if (-1 == (out = open(dsp, O_WRONLY))) {
        fprintf(stderr, "error opening %s: %s\n", dsp,
            strerror(errno));
        exit(1);
    }
        ioctl(out, SNDCTL_DSP_CHANNELS, &channels);
        format = AFMT_S16_LE;
    ioctl(out, SNDCTL_DSP_SETFMT, &format);
    ioctl(out, SNDCTL_DSP_SPEED, &rate);
    if (write_sine(out, 440.0f, 0.01f, 10.0f)) {
        fprintf(stderr, "error in write_sine(): %s\n", strerror(errno));
        exit(1);
    }
    if (close(out)) error(;
    exit;
}