accumulator++++

/*

  Adam An                    WOW!                                          * HOT *
  CSCI 304    | |_| |__   ___
  section 03  | __| '_ \ / _ \       edition 2.0             new look same great taste
     _        | |_| | | |  __/          _       _                      ___   ___   ___   ___
    / \   ___ _\__|_| |_|\___|__  _   _| | __ _| |_ _ __ ___  _ __    ( _ ) / _ \ / _ \ / _ \
   / _ \ / __/ __| | | | '_ ` _ \| | | | |/ _` | __| '__/ _ \| '_ \   / _ \| | | | | | | | | |
  / ___ \ (_| (__| |_| | | | | | | |_| | | (_| | |_| | | (_) | | | | | (_) | |_| | |_| | |_| |
 /_/   \_\___\___|\__,_|_| |_| |_|\__,_|_|\__,_|\__|_|  \___/|_| |_|  \___/ \___/ \___/ \___/

 */


#include <stdio.h>
#include <ctype.h>

unsigned short get_binary_op(char *bin) {
    short operand = 0;

    int length = 16;
    int i;
    for (i = 0; i <= 16; i++) {
        if (*(bin + i) == '\0') {
            length = i - 1;
            break;
        }
    }

    for (i = 0; i <= length; i++) {
        if (*(bin + i) == '1') {
            // operand += 2^(length - i)
            if (length - i == 0) {
                operand += 1;
            } else {
                int j;
                int powerOfTwo = 2;
                for (j = 1; j < length - i; j++) {
                    powerOfTwo *= 2;
                }
                operand += powerOfTwo;
            }
        }
    }

    return operand;
}

void convert_to_binary(short acc, char *bin) {
    int i;
    for (i = 0; i <= 15; i++) {
        // get the ith bit of acc.
       short bit = (acc >> (16 - i - 1)) & 1;

       if (bit == 0) {
           bin[i] = '0';
       } else if (bit == 1) {
           bin[i] = '1';
       }
    }
}

short get_operand(char mode) {
    short operand;
    switch(mode) {
        case 'B':
            printf("Enter binary value: ");
            char binaryString[17];

            int i;
            for (i = 0; i <= 16; i++) {
                binaryString[i] = '\0';
            }

            scanf("%16s", &binaryString);
            operand = get_binary_op(&binaryString);
            break;
        case 'O':
            printf("Enter octal value: ");
            scanf(" %ho", &operand);
            break;
        case 'H':
            printf("Enter hexadecimal value: ");
            scanf(" %hx", &operand);
            break;
        case 'D':
        default:
            printf("Enter decimal value: ");
            scanf(" %hd", &operand);
            break;
    }
    return operand;
}

void print_acc(short acc) {
    char binaryString[17];
    int i;
    for (i = 0; i <= 16; i++) {
        binaryString[i] = '0';
    }

    convert_to_binary(acc, &binaryString);

    printf("\n");
    printf("**************************************\n");
    printf("* Accumulator:                       *\n");

    printf("*   Binary  :  ");
    int digit;
    for (digit = 0; digit <= 3; digit++) {
        printf("%c", binaryString[digit]);
    }
    printf(" ");
    for (digit = 4; digit <= 7; digit++) {
        printf("%c", binaryString[digit]);
    }
    printf(" ");
    for (digit = 8; digit <= 11; digit++) {
        printf("%c", binaryString[digit]);
    }
    printf(" ");
    for (digit = 12; digit <= 15; digit++) {
        printf("%c", binaryString[digit]);
    }
    printf(" ");
    printf("  *\n");

    printf("*   Hex     :  %04hX                  *\n", acc);
    printf("*   Octal   :  %06ho                *\n", acc);
    printf("*   Decimal :  %-6d                *\n", acc);
    printf("**************************************\n");
}

char print_menu() {
    printf("\n");
    printf("Please enter your command:\n");
    printf("\n");
    printf("B   Binary Mode          &   AND with Accumulator     +   Add to Accumulator\n");
    printf("O   Octal Mode           |   OR with Accumulator      -   Subtract from Accumulator\n");
    printf("H   Hexadecimal Mode     ^   XOR with Accumulator     N   Negate Accumulator\n");
    printf("D   Decimal Mode         ~ Complement Accumulator\n");
    printf("C   Clear Accumulator    <   Shift Accumulator left\n");
    printf("S   Set Accumulator      >   Shift Accumulator right\n");
    printf("\n");
    printf("Q   Quit Accumulator\n");

    printf("\n");
    printf("Command: ");

    char choice[17];
    scanf(" %s", &choice);

    if (strlen(choice) != 1) {
        printf("Invalid option: %s\n", choice);
        return print_menu();
    }

    return choice[0];
}

void add(short * acc, char mode) {
    short operand = get_operand(mode);
    short result = * acc + operand;

    if (* acc > 0 && operand > 0 && result < 0) {
        printf("Overflow Error");
    }
    if (* acc < 0 && operand < 0 && result > 0) {
        printf("Negative Overflow Error");
    }

    * acc = result;
}

void subtract(short * acc, char mode) {
    short operand = get_operand(mode);
    short result = * acc - operand;

    if (* acc > 0 && operand < 0 && result < 0) {
        printf("Overflow Error");
    }

    if (* acc < 0 && operand > 0 && result > 0) {
        printf("Negative Overflow Error");
    }

    * acc = result;
}

int main() {
    short accumulator = 0;
    char mode = 'D';

    short operand;
    short result;

    while (1) {
        print_acc(accumulator);
        char input_char = toupper(print_menu());

        switch (input_char) {
            case '\n':
                break;
            case 'Q':
                return 0;
                break;
            case 'C':
                accumulator = 0;
                printf("accumulator cleared!\n");
                break;
            case 'S':
                accumulator = get_operand(mode);
                break;
            case 'B':
                mode = input_char;
                printf("Mode is binary!\n");
                break;
            case 'D':
                mode = input_char;
                printf("Mode is decimal!\n");
                break;
            case 'O':
                mode = input_char;
                printf("Mode is octal!\n");
                break;
            case 'H':
                mode = input_char;
                printf("Mode is hexadecimal!\n");
                break;
            case '&':
                accumulator &= get_operand(mode);
                break;
            case '|':
                accumulator |= get_operand(mode);
                break;
            case '^':
                accumulator ^= get_operand(mode);
                break;
            case '~':
                accumulator = ~accumulator;
                break;
            case '<':
                accumulator <<= get_operand(mode);
                break;
            case '>':
                accumulator >>= get_operand(mode);
                break;
            case '+':
                add(&accumulator, mode);
                break;
            case '-':
                subtract(&accumulator, mode);
                break;
            case 'N':
                accumulator *= -1;
                break;
            default:
                printf("Invalid option: %c\n", input_char);
                break;
        }
    }
    return 0;
}