space_game/src/audio.c

#include "audio.h"

void generate_audio(void);
struct game_sounds game_sounds;

Uint8 big_hum(unsigned int t); 
Uint8 func0(int t); 


 void fill_audio(void *func, Uint8 *stream, int len) {
     Uint8 (*wavegen)(int) = func;

    static int t = 1;
    for(int i = 0; i < len; i++,t++) {
        stream[i] = wavegen(t);
    }
}

void callbackfn3(void *unused, Uint8 *stream, int len) {
    static int t = 1;
    for(int i = 0; i < len; i++,t++) {
        stream[i] = big_hum(t);
        stream[i] = 0; 
    }
}

void start_audio(void) {
 
    //audio_format.callback = callbackfn3;
    /* just for playing background music 
    if (SDL_OpenAudio(&audio_format, NULL)) {
        fprintf(stderr, "Unable to open audio: %s\n", SDL_GetError());
        exit(1);
    }
    */
    //SDL_PauseAudio(0);
    if (Mix_OpenAudio(G_AUDIO_SFREQ,AUDIO_U8,1,G_AUDIO_BSIZE) < 0) {
        fprintf(stderr, "Unable to open audio: %s\n", SDL_GetError());
        exit(1);
    }
    generate_audio();
    Mix_Resume(-1);
}

void play_game_sound(Mix_Chunk *chunk, int len, int channel) {
    if (Mix_Playing(channel)) {
        return;
    }
    Mix_FadeInChannelTimed(channel, chunk, -1, 1, len);
}

void synthplay_now(Uint8 (*bbgen)(unsigned int t), int len) {
    static Mix_Chunk *new_chunk = NULL;

    if (Mix_Playing(1)) {
        return;
    }

    if (new_chunk)
        Mix_FreeChunk(new_chunk);

    int generate_len = len * (512) * 8;

    Uint8 raw_data[generate_len];
    fill_audio(bbgen, raw_data, generate_len);

    new_chunk = Mix_QuickLoad_RAW(raw_data, generate_len);
    Mix_PlayChannelTimed(1, new_chunk, -1, -1);
}



void callbackfn2(void *unused, Uint8 *stream, int len) {
    static int t = 1;
    int i;
    int yeet = rand();
    for(i=0; i < len; i++,t++) {
        stream[i] = func0(t);
    }
}


void callbackfn(void *unused, Uint8 *stream, int len)
{
    static int t = 0;
    int i;
    int yeet = rand();
    for( i=0; i < len; i++,t++) {
    /*
            stream[i] = (t*5&(t>>7))|(t*3&(t>>8));
    */
    //stream[i] = (( t >> 10 ) & 42) * t;
    stream[i] = (t & yeet) % 73;
    }
}

/* Waveform Generators */

Uint8 big_hum(unsigned int t) {
    return ( (sin(t*2*3.14159265/16000*200)+1) * 20) + ( (sin(t*2*3.14159265/16000*110)+1) * 20) + ( (sin(t*2*3.14159265/16000*230)+1) * 20) + ( (sin((t % 80)*2*3.14159265/16000 * 6)+1) * 12);
}

unsigned int sine_wave_sound(int t) {
    const double R=8000; // sample rate (samples per second)
    const double C=261.625565; // frequency of middle-C (hertz)
    const double F=R/256; // bytebeat frequency of 1*t due to 8-bit truncation (hertz)
    const double V=127; // a volume constant
    return (sin(t*2*M_PI/R*C)+1)*V;
}

unsigned int winch_sound(int t) {
    return (t % 80) | (t % 36) | (6 * (t % 6));
}

unsigned int beat_2(int t) {
    return ((((t % 250) / 2)) | (t % 129)) % 110;
}

Uint8 func0(int t) {
    int note = 18;
    if (t % 1240) {
        note = (1 + rand()) % 18 + 1;
    }

    fflush(stdout);
    return (t % note);
}

unsigned int func1(int t) {
    int note = 10;
    if (!(t % 8000)) {
        note = (1 + rand()) % 10 + 5;
        printf("%d %d\n", t, note);
    }
    return ((t & 110) % 73 | (t % 1711));
}


void generate_audio(void) {

    const int sfx_len_ms = 2000;
    unsigned int sfx_len = (G_AUDIO_SFREQ/1000) * G_AUDIO_BSIZE * sfx_len_ms;
    Uint8 raw_data[sfx_len]; // 10 seconds

    fill_audio(winch_sound, raw_data, sfx_len);
    game_sounds.rope_pull = Mix_QuickLoad_RAW(raw_data, sfx_len);
    fill_audio(beat_2, raw_data, sfx_len);
    game_sounds.collision = Mix_QuickLoad_RAW(raw_data, sfx_len);
}