#include "mbed.h"           //Include the mbed header file which contains the prototypes of the libraries used here (DigitalOut) as well as various syntax definitions.
#include "USBSerial.h"      //Include USBSerial library which allows for comms with PC.

void segout();              //Prototype declared above main function to avoid errors.

USBSerial pc;               //Create an instance of USBSerial called pc. Allows use of USBSerial library.

DigitalOut MUX(P1_25);      //Make the pin that controls which seven segment display is ON into an output pin.
                            //Create an instance for each segment piece to be a different output pin.
DigitalOut LEDA(P1_23);     //Seg A as output.
DigitalOut LEDB(P1_28);     //Seg B as output.
DigitalOut LEDC(P0_16);     //Seg C as output.
DigitalOut LEDD(P1_31);     //Seg D as output.
DigitalOut LEDE(P1_13);     //Seg E as output.
DigitalOut LEDF(P1_16);     //Seg F as output.
DigitalOut LEDG(P1_19);     //Seg G as output.
DigitalOut LEDDP(P0_23);    //Seg Decimal Point as output.

int num, temp;              //Declare variables for output number value (num) and a temporary value (temp) for holding the decimal value of input characters.

//Array of variables which correspond to the bit output required by the seven seg to display a number.
//i.e. a call to this array with a digit 0-9 will return the 7 bit data that will show that number on the segments.
int segNums[11] = {63, 6, 91, 79, 102, 109, 125, 7, 127, 103, 256};

int main()
{

    MUX = 1;                                                        //MUX is set to 1 to select the right display for the duration of the program.
    LEDA = LEDB = LEDC = LEDD = LEDE = LEDF = LEDG = LEDDP= 1;      //All segments set to 1 to turn off all segments initially.
    char buf[3];                                                    //Declare buffer to hold incoming data. Set to 3 as this is the longest length of string that is used.
                                                                    //Any extra characters will be ignored.

    while(1) {                                                      //Start while loop for start sequence. Repeat until user input is received.
        pc.printf("Press any key and then enter to begin.\r\n");    //Start message is repeatedly put to the screen so that it is there even if the terminal is not opened right away.
        if (pc.available()) {                                       //When there is a character available.
            pc.scanf("%s", buf);                                    //Read in string and place in buf array.
            break;                                                  //When start string has been read in the start sequence can be broken out of.
        }
    }

    //Print instructions for the program to the PC terminal.
    pc.printf("\r\nEnter a number to display and press enter.\r\nTyping a number will display that number.\r\nTyping . will toggle the Decimal point.\r\nTyping OFF will turn all LEDs off.\r\n\r\n");


    while(1) {

        pc.scanf("%s", buf);                                            //Hold program and wait until the user inputs a string into the terminal.

        temp = buf[0] - 48;                                             //Put the first character of the input buffer into temp and convert it to decimal by removing 48.
                                                                        //(Only works for chars 0-9)

        if (temp < 10 && temp >= 0) {                                   //If the first character of the input string is a digit between 0 and 9.
            num = temp;                                                 //Make equal to the input digit so the digit will be put to the seven seg display. 
            pc.printf("%d\r\n", num);                                   //Print the number back to the PC terminal to show that it has been received and displayed on seven seg.
            segout();                                                   //Call segout() to update the seven seg display with the new num.
        } 
        else if (temp == -2) {                                          //If the first character is a decimal point (46 in ASCII, -2 after 48 has been removed).
            LEDDP = !LEDDP;                                             //Toggle the LEDDP to toggle the decimal point.
            pc.printf("Decimal Point\r\n");                             //Print Decimal Point back to the PC terminal to show that it has been received and displayed on seven seg.
        } 
        else if (buf[0] == 'O' && buf[1] == 'F' && buf[2] == 'F') {     //If the first three characters in the incoming string are OFF.
            num = 10;                                                   //Make num = 10 which when used in the segNums array will turn all segments off (make all = 1).
            LEDDP = 1;                                                  //Turn off decimal point.
            pc.printf("OFF\r\n");                                       //Print OFF back to the PC terminal to show that it has been received and displayed on seven seg.
            segout();                                                   //Call segout() to update the seven seg display with the new num.
        }
    }
}


void segout()                       //Function to output digits to seven segment display.
{

    int bits = ~segNums[num];       //Call the array segNums with the number that wants to be displayed. Set bits to equal the bitwise inverted (~) number.
                                    //The Bitwise Inverter (~) is used because the LEDs in the seven seg are active low.

                                    //The next section uses Bitwise AND (&) to filter out the value of each bit using "bits" and a bitmask.
    LEDA = bits & 1;                //Set LEDA to the value of the first bit of bits.
    LEDB = bits & 2;                //Set LEDB to the value of the second bit of bits.
    LEDC = bits & 4;                //Set LEDC to the value of the third bit of bits.
    LEDD = bits & 8;                //Set LEDD to the value of the fourth bit of bits.
    LEDE = bits & 16;               //Set LEDE to the value of the fifth bit of bits.
    LEDF = bits & 32;               //Set LEDF to the value of the sixth bit of bits.
    LEDG = bits & 64;               //Set LEDG to the value of the seventh bit of bits.

}