Generates Mario Theme Song

mario.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define NUM_SAMPLES 44100
#define PI 3.14159265
// ------ NOTE IDS ------
#define C_ 0
#define CS 1
#define D_ 2
#define DS 3
#define E_ 4
#define F_ 5
#define FS 6
#define G_ 7
#define GS 8
#define A_ 9
#define AS 10
#define B_ 11

#define MKNOTE(oct, note, frac) ((Note){(oct)*12+(note),1.0/(frac)})

typedef struct {
    int note;
    float duration;
} Note;

// ------ EXAMPLE ------
Note SUPER_MARIO_THEME_SONG[] = {
    MKNOTE(4, E_, 4),
    MKNOTE(4, E_, 2),
    MKNOTE(4, E_, 2),
    MKNOTE(4, C_, 4),
    MKNOTE(4, E_, 2),
    MKNOTE(4, G_, 1),
    MKNOTE(3, G_, 1),
    MKNOTE(4, C_, 1.5),
    MKNOTE(3, G_, 1.5),
    MKNOTE(3, E_, 2),
    MKNOTE(3, A_, 2),
    MKNOTE(3, B_, 2),
    MKNOTE(3, AS, 4),
    MKNOTE(3, A_, 2),
    MKNOTE(3, G_, 4),
    MKNOTE(4, E_, 4),
    MKNOTE(4, G_, 4),
    MKNOTE(4, A_, 2),
    MKNOTE(4, F_, 4),
    MKNOTE(4, G_, 2),
    MKNOTE(4, E_, 2),
    MKNOTE(4, C_, 4),
    MKNOTE(4, D_, 4),
    MKNOTE(3, B_, 1),
    MKNOTE(4, C_, 1.5),
    MKNOTE(3, G_, 1.5),
    MKNOTE(3, E_, 2),
    MKNOTE(3, A_, 2),
    MKNOTE(3, B_, 2),
    MKNOTE(3, AS, 4),
    MKNOTE(3, A_, 2),
    MKNOTE(3, G_, 4),
    MKNOTE(4, E_, 4),
    MKNOTE(4, G_, 4),
    MKNOTE(4, A_, 2),
    MKNOTE(4, F_, 4),
    MKNOTE(4, G_, 2),
    MKNOTE(4, E_, 2),
    MKNOTE(4, C_, 4),
    MKNOTE(4, D_, 4),
    MKNOTE(3, B_, 1),
};

const double noteFrequencies[] = {
    261.63, 277.18, 293.66, 311.13, 329.63, 349.23, 369.99, 392.00, 415.30, 440.00, 466.16, 493.88
};

int convertNote(int noteNumber) {
    int octave = noteNumber/12;
    double freq = noteFrequencies[noteNumber%12]*pow(2, octave-4);
    return (int)(freq + 0.5);
}

void generateWaveFile(const char* filename, Note* notes, int numNotes, int bpm) {
    float bps = bpm/60.0f;
    int i, j, k = 0;
    int overallNumSamples = 0;
    for (i = 0; i < numNotes; i++) {
      overallNumSamples += (notes[i].duration/bps)*NUM_SAMPLES; 
    }

    short waveform[overallNumSamples];

    // Generate square wave
    for (i = 0; i < numNotes; i++) {
        int note = convertNote(notes[i].note);
        float duration = notes[i].duration/2.0;
        int samplesPerCycle = 44100 / note;
        int numSamples = (int)(duration * 44100);

        for (j = 0; j < numSamples; j++) {
            if (j % samplesPerCycle < samplesPerCycle / 2) {
                waveform[k++] = 32767/2;
            } else {
                waveform[k++] = -32767/2;
            }
        }
    }

    // Write the samples to a file in .wav format
    FILE *fp = fopen(filename, "wb");
    short format = 1;
    short numChannels = 1;
    short bitsPerSample = 16;
    int byteRate = NUM_SAMPLES * numChannels * bitsPerSample / 8;
    short blockAlign = numChannels * bitsPerSample / 8;
    int dataSize = overallNumSamples * 2;
    int chunkSize = 16;
    int sampleRate = NUM_SAMPLES;

    fwrite("RIFF", 4, 1, fp);
    int riffSize = 4 + (8 + chunkSize) + (8 + dataSize);
    fwrite(&riffSize, 4, 1, fp);
    fwrite("WAVE", 4, 1, fp);
    fwrite("fmt ", 4, 1, fp);
    fwrite(&chunkSize, 4, 1, fp);
    fwrite(&format, 2, 1, fp);
    fwrite(&numChannels, 2, 1, fp);
    fwrite(&sampleRate, 4, 1, fp);
    fwrite(&byteRate, 4, 1, fp);
    fwrite(&blockAlign, 2, 1, fp);
    fwrite(&bitsPerSample, 2, 1, fp);
    fwrite("data", 4, 1, fp);
    fwrite(&dataSize, 4, 1, fp);
    fwrite(waveform, 2, overallNumSamples, fp);
    fclose(fp);
}

int main() {
    int numNotes = sizeof(SUPER_MARIO_THEME_SONG) / sizeof(SUPER_MARIO_THEME_SONG[0]);
    generateWaveFile("mario.wav", SUPER_MARIO_THEME_SONG, numNotes, 108);
    return 0;
}