#include <SDL2/SDL.h>
#include <SDL2/SDL_audio.h>
#include <SDL2/SDL_error.h>
#include <stddef.h>
#include <stdio.h>

#define PCM_BUF_SIZE (1024*2*2*2)

static Uint8 *s_audio_buf = NULL;
static Uint8 *s_audio_pos = NULL;
static Uint8 *s_audio_end = NULL;

void audo_pcm_callback(void *data, Uint8 *stream, int len) {
    SDL_memset(stream, 0, len);

    if (s_audio_pos >= s_audio_end) {
        return;
    }

    int remain_buffer_len = s_audio_end - s_audio_pos;
    len = (len < remain_buffer_len) ? len : remain_buffer_len;

    SDL_MixAudio(stream, s_audio_pos, len, SDL_MIX_MAXVOLUME/8);
    s_audio_pos += len;
}

#undef main
int main(int argc, char* argv[]) {
    int ret = -1;
    FILE *audio_fd = NULL;
    SDL_AudioSpec spec;
    const char *path = "44100_16bit_2ch.pcm";
    size_t read_buffer_len = 0;

    if (SDL_Init(SDL_INIT_AUDIO)) {
        fprintf(stderr, "SDL_Init(SDL_INIT_AUDIO) failed: %s\n", SDL_GetError());
        return ret;
    }

    audio_fd = fopen(path, "rb");
    if (!audio_fd) {
        fprintf(stderr, "fopen(path, \"rb\")\n");
        goto fail;
    }
}