CS50 Exercise Music | Solution by Normantas

// Helper functions for music

#include <cs50.h>
#include <math.h>
#include "helpers.h"

int scaleCal(int _f, char _scale) //4+
{
    if (_scale == '#'){
        _f = round(_f * pow(2, 1/12));
    }
    else if(_scale == 'b'){
        _f = round(_f / pow(2, 1/12));
    }
    return _f;
}

int letterMov(char l, int _f) //2
{
    if(l == 'A')
        _f = 440;
    if(l == 'B')
        _f = round(_f * pow(2, 2/12));
    if(l == 'G')
        _f = round(_f / pow(2, 2/12));
    if(l == 'F')
        _f = round(_f / pow(2, 4/12));
    if(l == 'E')
        _f = round(_f / pow(2, 5/12));
    if(l == 'D')
        _f = round(_f / pow(2, 7/12));
    if(l == 'C')
        _f = round(_f / pow(2, 9/12));
    return _f;
}

int octaveFreq(int oct, int _f) //3
{
    double a = oct - 4;
    if (oct > 4)
    {
        _f = _f * pow(2, a);
    }
    else if(oct < 4 )
    {
        _f = round(_f / pow(2, a));
    }
    return _f;
}

char octaveCheck(char a, char b) //1
{
     if(a == '#' || a == 'b'){ //Checks for # or b;
        return b;
    }
    else{
        return a;
    }
}

// Converts a fraction formatted as X/Y to eighths
int duration(string fraction)
{
    int up = (int)fraction[0];
    int down = (int)fraction[2];
    return up * 8 / down;
}

// Calculates frequency (in Hz) of a note
int frequency(string note)
{
    int octave, f = 0; char letter, scale;
    octave = octaveCheck(note[1],note[2]);
    letter = note[0];
    scale = note[1];
    f = letterMov(letter, f);
    f = octaveFreq(octave, f);
    f = scaleCal(f, scale);
    return f;
}

// Determines whether a string represents a rest
bool is_rest(string s)
{
   if(s[0] == '\0')
   {
       return true;
   }
   else
   {
        return false;
   }
}