DtoAtable

#include <iostream>
#include <cmath>
#include <bitset>
#include <string>
#include <sstream>

using namespace std;

string DtoAeqn(int bits, double& maxNoGain);
void renderTable(int bits, double gain);
double voltageOut(bitset<128> bits, int length, double gain = 1);
double nthBitContrib(int bit, bool high, int length);

int main(void)
{
    bool run = 1;
    while(run)
    {
        cout << "Enter the full scale voltage of the DtoA device: ";
        double fs;
        cin >> fs;

        cout << "Enter the number of resolution bits (max 128): ";
        int bits = 129;
        while(bits > 128)
        {
            cin >> bits;
        }

        cout << "\nThe equation for the output voltage is: \nVo = G(";
        double maxNoGain = 0;
        string eqn(DtoAeqn(bits, maxNoGain));
        cout << eqn;

        double gain = fs/maxNoGain;
        cout << "Where G is the gain " << fs/maxNoGain << "\n\n";

        renderTable(bits, gain);

        cout << "\nRun again?(y/n): ";
        char runChar;
        cin >> runChar;
        if(runChar == 'n' || runChar == 'N')
        {
            run = 0;
        }
        cout << "\n";
    }
}

string DtoAeqn(int bits, double& maxNoGain)
{
    ostringstream eqn;
    for(int i = 0; i < bits; i++)
    {
        double A = 1/pow(2.0,i);
        maxNoGain += A;
        eqn << "(" << A << "*" << "b" << bits-i-1 << ")";
        if(i != bits-1)
        {
            eqn << "+";
        }
        else
        {
            eqn << ")\n\n";
        }
    }

    return eqn.str();
}

void renderTable(int bits, double gain)
{
    for(int i = 0; i < pow(2.0,bits); i++)
    {
        for(int k = 0; k < bits; k++)
        {
            cout << "b" << bits-k-1 << " ";
        }
        cout << " Vo";
        cout << "\n";

        bitset<128> binNumber(i);
        string binString(binNumber.to_string().substr(128-bits,bits));
        for(int k = 0; k < bits; k++)
        {
            cout << binString[k] << "  ";
        }
        cout << " " << gain*voltageOut(binNumber, bits, gain);

        cout << "\n";
    }
}

double voltageOut(bitset<128> bits, int length, double gain)
{
    double totalVolts = 0;
    for(int i = 0; i <= length; i++)
    {
        totalVolts += nthBitContrib(i, bits[i], length);
    }
    return totalVolts;
}

double nthBitContrib(int bit, bool high, int length)
{
    return high*(1.0/pow(2.0,length-bit-1));
}