main.c

#include "SDL.h"
#include <stdio.h>

#define SAMPLE_COUNT 4096
#define CHANNEL_COUNT 2
#define AUDIO_BUFFER_SIZE CHANNEL_COUNT*SAMPLE_COUNT
#define AUDIO_BUFFER_BYTES sizeof(short)*AUDIO_BUFFER_SIZE

int main(int argc, char** argv)
{
    if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "SDL ERROR", "Init Error", nullptr);
        SDL_Log("Something went wrong with SDL Init %s", SDL_GetError());
        return 1;
    }

    short* buffer = (short*)malloc(AUDIO_BUFFER_BYTES);

    if (!buffer) {
        return 2;
    }

    double freq = 1000; // your freq
    double level = 16384; // something not full clipping party
    double K = 2.0 * M_PI / 48000.0 * freq; // constant

    for (int i = 0; i < SAMPLE_COUNT; i++) {
        float result = sin(i * K) * level; // calculate buffer value

        // for each channel
        for (int j = 0; j < CHANNEL_COUNT; j++) {
            // get the location in the buffer and write the result
            short* p = &buffer[i * CHANNEL_COUNT + j]; 
            *p = (short)result; //... as short
        }
    }

    SDL_AudioSpec requestAs;
    SDL_AudioSpec actualAs;
    SDL_zero(actualAs);
    requestAs.freq = 48000;
    requestAs.format  = AUDIO_S16;
    requestAs.channels = CHANNEL_COUNT;
    requestAs.samples = 4096;
    requestAs.callback = NULL;
    const char* devName = SDL_GetAudioDeviceName(0, 0);
    SDL_AudioDeviceID device = SDL_OpenAudioDevice(devName , 0, &requestAs, &actualAs, 1);
    if (device == 0) {
        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "SDL ERROR", "Cannot open audio device", nullptr);
        SDL_Log("Something went wrong with SDL Audio device init %s", SDL_GetError());
        return 3;
    }

    SDL_PauseAudioDevice(device, 0);
    // one of these lasts less that .1 seconds!
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    SDL_QueueAudio(device, buffer, AUDIO_BUFFER_BYTES);
    
    SDL_Delay(2000);

    free(buffer);
    SDL_CloseAudioDevice(device);
    SDL_Quit();
    return 0;
}