doompanning/src/dp_doom/linuxdoom-1.10/ib_sound/ib_sound_nng.c

#include "../ib_sound.h"

#include <stddef.h>
#include <dp_common.h>

#include "SDL.h"

/* The function that actually produces the output audio */
static void (*audio_callback)(short* output_buffer, size_t frames_to_do, void *user_data);

static void dp_sdl_error(const char *const msg)
{
    log_error("%s: %s", msg, SDL_GetError());
}

static SDL_AudioDeviceID audio_device;

static void Callback(void *user_data, Uint8 *output_buffer, int bytes_to_do)
{
    const int frames_to_do = bytes_to_do / 2 / sizeof(short);

    audio_callback((short*)output_buffer, (size_t)frames_to_do, user_data);
}

int IB_StartupSound(void (*initial_callback)(unsigned int output_sample_rate, void *user_data), void (*_audio_callback)(short* output_buffer, size_t frames_to_do, void *user_data), void *user_data)
{
#if 0
    unsigned int freq = 48000;
    initial_callback(freq, user_data);
    return 1;
#endif

    SDL_AudioSpec desired_audio_specification;
    SDL_AudioSpec obtained_audio_specification;

    audio_callback = _audio_callback;

    if (SDL_Init(SDL_INIT_AUDIO))
    {
        dp_sdl_error("IB_StartupSound: SDL_INIT_AUDIO failed");
        return 0;
    }

    desired_audio_specification.freq = 48000;
    desired_audio_specification.format = AUDIO_S16;
    desired_audio_specification.channels = 2;
    desired_audio_specification.samples = 0x200; /* About 10ms at 48000Hz. */
    desired_audio_specification.callback = Callback;
    desired_audio_specification.userdata = user_data;

    audio_device = SDL_OpenAudioDevice(NULL,
        0, &desired_audio_specification, &obtained_audio_specification,
        SDL_AUDIO_ALLOW_FREQUENCY_CHANGE | SDL_AUDIO_ALLOW_SAMPLES_CHANGE);

    if (audio_device)
    {
        initial_callback(obtained_audio_specification.freq, user_data);
        SDL_PauseAudioDevice(audio_device, 0);
        return 1;
    }

    dp_sdl_error("IB_StartupSound: SDL_INIT_AUDIO failed");
    SDL_QuitSubSystem(SDL_INIT_AUDIO);
    return 0;
}

void IB_ShutdownSound(void)
{
    SDL_CloseAudioDevice(audio_device);
    SDL_QuitSubSystem(SDL_INIT_AUDIO);
}

void IB_LockSound(void)
{
    SDL_LockAudioDevice(audio_device);
}

void IB_UnlockSound(void)
{
    SDL_UnlockAudioDevice(audio_device);
}