AB.cpp

#include <cstdlib>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <csignal>
#define countof(a) ( sizeof(a) / sizeof(*(a)) )

using namespace std;

int Num_char = 0;
int Position = 0;
int NewPosition = 0;

int Character;
string Program;

string Result;
int Register1 = 0;
int Register2 = 0;
int Register3 = 0;
int Register4[] = { 0, 0 };
int Mode = 0;
int Memory[1024];
int Temp;

int ipow(int base, int exponent)
{
    int retval = 1;

    if ( exponent < 0 )
        raise(SIGFPE);

    while ( exponent )
    {
        retval *= ( exponent & 1 ) ? base : 1;
        exponent /= 2;
        base *= base;
    }

    return retval;
}

void error(const char* msg)
{
	puts(msg);
	exit(1);
}

void checkmem(int addr, const char* errormsg)
{
	if(!(addr >= 0 && addr < (int)countof(Memory))) error(errormsg);
}

int main(int argc, char *argv[])
{
    if ( argc != 2 )
	{
		fprintf(stderr, "Usage: %s FILE\n", argv[0]);
		return 1;
	}

    FILE * FileInd = fopen(argv[1], "r");

	if ( FileInd == NULL )
	{
		fprintf(stderr, "Could not open file '%s'.\n", argv[1]);
		return 1;
	}

    do {
        Character = getc(FileInd);
        Program.append(1, char(Character));
        Num_char ++;

        } while ( Character != EOF );

    fclose(FileInd);

    do {
        NewPosition = Position;
        if(!(Position >= 0 && Position < Num_char)) error("Invalid position");

        if ( Program[Position] == 'a' ) { Register1 += 1 ;}
        if ( Program[Position] == 'b' ) { Register1 -= 1 ;}
        if ( Program[Position] == 'c' ) { Register1 += 10 ;}
        if ( Program[Position] == 'd' ) { Register1 -= 10 ;}
        if ( Program[Position] == 'e' ) { Register1 += 100 ;}
        if ( Program[Position] == 'f' ) { Register1 -= 100 ;}
        if ( Program[Position] == 'g' ) { Register2 += 1 ;}
        if ( Program[Position] == 'h' ) { Register2 -= 1 ;}
        if ( Program[Position] == 'i' ) { Register2 += 10 ;}
        if ( Program[Position] == 'j' ) { Register2 -= 10 ;}
        if ( Program[Position] == 'k' ) { Register2 += 100 ;}
        if ( Program[Position] == 'l' ) { Register2 -= 100 ;}
        if ( Program[Position] == 'm' ) { Register3 = !Register1 ;}
        if ( Program[Position] == 'n' ) { Register3 = !Register2 ;}
        if ( Program[Position] == 'o' ) { Register3 = Register1 and Register2 ;}
        if ( Program[Position] == 'p' ) { Register3 = Register1 or Register2 ;}
        if ( Program[Position] == 'q' ) { Register3 = Register1 xor Register2 ;}
        if ( Program[Position] == 'r' ) { Register3 = Register1 + Register2 ;}
        if ( Program[Position] == 's' ) { Register3 = Register1 - Register2 ;}
        if ( Program[Position] == 't' ) { Register3 = Register1 * Register2 ;}
        if ( Program[Position] == 'u' ) { if(Register2 == 0) error("u: division by zero"); Register3 = Register1 / Register2 ;}
        if ( Program[Position] == 'v' ) { if(Register2 == 0) error("v: division by zero"); Register3 = Register1 % Register2 ;}
        if ( Program[Position] == 'w' ) { Register3 = ipow(Register1, Register2) ;}
        if ( Program[Position] == 'x' ) { Register1 = 0 ;}
        if ( Program[Position] == 'y' ) { Register2 = 0 ;}
        if ( Program[Position] == 'z' ) { Register3 = 0 ;}
        if ( Program[Position] == 'A' ) { Register2 = Register1 ;}
        if ( Program[Position] == 'B' ) { Register1 = Register2 ;}
        if ( Program[Position] == 'C' ) { Register3 = Register1 ;}
        if ( Program[Position] == 'D' ) { Register3 = Register2 ;}
        if ( Program[Position] == 'E' ) { Register1 = Register3 ;}
        if ( Program[Position] == 'F' ) { Register2 = Register3 ;}
        if ( Program[Position] == 'G' ) { checkmem(Register4[0], "G: invalid memory address"); Register1 = Memory[Register4[0]] ;}
        if ( Program[Position] == 'H' ) { checkmem(Register4[0], "H: invalid memory address"); Register2 = Memory[Register4[0]] ;}
        if ( Program[Position] == 'I' ) { checkmem(Register4[0], "I: invalid memory address"); Memory[Register4[0]] = Register3 ;}
        if ( Program[Position] == 'J' ) { if (( Temp = getchar()) != EOF ) Register1 = Temp ;}
        if ( Program[Position] == 'K' ) { if (( Temp = getchar()) != EOF ) Register2 = Temp ;}
        if ( Program[Position] == 'L' ) { cout << char(Register3) ;}
        if ( Program[Position] == 'M' ) { cout << int(Register3) ;}
        if ( Program[Position] == 'N' ) { if ( Register1 == Register2 ) NewPosition = Register4[1];}
        if ( Program[Position] == 'O' ) { if ( Register1 != Register2 ) NewPosition = Register4[1];}
        if ( Program[Position] == 'P' ) { if ( Register1 >= Register2 ) NewPosition = Register4[1];}
        if ( Program[Position] == 'Q' ) { if ( Register1 <= Register2 ) NewPosition = Register4[1];}
        if ( Program[Position] == 'R' ) { if ( Register3 == 0 ) NewPosition = Register4[1] - 1;}
        if ( Program[Position] == 'S' ) { Register4[Mode] += 1 ;}
        if ( Program[Position] == 'T' ) { Register4[Mode] -= 1 ;}
        if ( Program[Position] == 'U' ) { Register4[Mode] += 10 ;}
        if ( Program[Position] == 'V' ) { Register4[Mode] -= 10 ;}
        if ( Program[Position] == 'W' ) { Register4[Mode] += 100 ;}
        if ( Program[Position] == 'X' ) { Register4[Mode] -= 100 ;}
        if ( Program[Position] == 'Y' ) { Register4[Mode] = 0 ;}
        if ( Program[Position] == 'Z' ) { Mode = ( Mode + 1 ) % 2 ;}

        Position = (Position == NewPosition) ? Position + 1 : NewPosition;
        } while ( Position < Num_char );

    return 0;
}