/*
 * tone.c - play a sine wave tone on AIX 4.3.3 via /dev/paud0
 * Claude Opus 4.5, 2026-10-13
 *
 * Build: xlc -o tone tone.c -lm
 *    or: gcc -o tone tone.c -lm
 */

/* audio.h redefines BIG_ENDIAN, conflicting with machine.h (included via param.h).
 * Work around: include param.h first, undef BIG_ENDIAN, then include audio.h. */
#include <sys/param.h>
#undef BIG_ENDIAN
#include <sys/audio.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <math.h>
#include <sys/ioctl.h>

#define SAMPLE_RATE 22050
#define BITS        16
#define CHANNELS    1
#define FREQ_HZ     440
#define DURATION_MS 1000

int main(int argc, char **argv)
{
    int fd;
    audio_init init;
    int freq = FREQ_HZ;
    int duration = DURATION_MS;
    int nsamples, nbytes, i;
    short *buf;
    double phase, delta;
    ssize_t written;

    if (argc > 1) freq = atoi(argv[1]);
    if (argc > 2) duration = atoi(argv[2]);
    if (freq < 20 || freq > 20000) {
        fprintf(stderr, "frequency %d out of range (20-20000)\n", freq);
        return 1;
    }

    fd = open("/dev/paud0/1", O_WRONLY);
    if (fd < 0) {
        perror("open /dev/paud0");
        return 1;
    }

    /* configure the device */
    memset(&init, 0, sizeof(init));
    init.srate = SAMPLE_RATE;
    init.bits_per_sample = BITS;
    init.mode = PCM;
    init.channels = CHANNELS;
    init.flags = SIGNED | TWOS_COMPLEMENT | BIG_ENDIAN | FIXED;
    init.operation = PLAY;

    if (ioctl(fd, AUDIO_INIT, &init) < 0) {
        perror("ioctl AUDIO_INIT");
        close(fd);
        return 1;
    }
    if (init.rc != 0) {
        fprintf(stderr, "AUDIO_INIT rc=%d\n", init.rc);
        close(fd);
        return 1;
    }

    printf("AUDIO_INIT ok: srate=%ld bits=%ld bsize=%ld flags=0x%lx\n",
           init.srate, init.bits_per_sample, init.bsize, init.flags);

    /* generate samples */
    nsamples = (SAMPLE_RATE * duration) / 1000;
    nbytes = nsamples * sizeof(short);
    buf = malloc(nbytes);
    if (!buf) {
        perror("malloc");
        close(fd);
        return 1;
    }

    delta = 2.0 * M_PI * freq / SAMPLE_RATE;
    phase = 0.0;
    for (i = 0; i < nsamples; i++) {
        /* 16-bit signed, amplitude ~0.8 to avoid clipping */
        buf[i] = (short)(sin(phase) * 26000);
        phase += delta;
    }

    printf("playing %d Hz for %d ms (%d samples, %d bytes)\n",
           freq, duration, nsamples, nbytes);

    /* write samples */
    written = write(fd, buf, nbytes);
    if (written < 0) {
        perror("write");
    } else if (written != nbytes) {
        fprintf(stderr, "short write: %d of %d\n", (int)written, nbytes);
    }

    /* wait for playback to complete */
    if (ioctl(fd, AUDIO_WAIT, NULL) < 0) {
        perror("ioctl AUDIO_WAIT");
    }

    free(buf);
    close(fd);
    printf("done\n");
    return 0;
}