hello-generator.cc

/**
 * Hello Generator
 *
 * Joe Vasquez <joe.vasquez@gmail.com>
 *
 * I wish I knew more assembly!
**/

#include <fstream>
#include <iostream>
#include <string>
#include <sstream>
#include <stdlib.h>
#include <stdlib.h>
#include <time.h>
using namespace std;

#define MAX_SIZE 64
#define MAX_JUNK_LINES 53
#define JUNK_GROUPS 5
#define NOP "nop"
#define ALPHABET "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz01234567890!@#$%&*."
#define NUM_FILES 10
#define NEWLINE "\n"
#define STR_TERMINATOR "$"
#define P_NOP 45

/**
 * add_nop
 *
 * based on current filesize and current junk lines, decide to add a nop
 * decicsion based on probability of nop (p_nop)
 *
 * returns nop
**/
string add_nop(int &currentFileSize, int &currentJunkLines) {
    if((currentJunkLines < MAX_JUNK_LINES) || (currentFileSize < MAX_SIZE)) {
        bool add_it = (rand() % 100) <= P_NOP;
        if(add_it) {
            currentFileSize++;
            currentJunkLines++;
            string newNop = NOP;
            return newNop.append(NEWLINE);
        }
    }
    return "";
}

/**
 * add_nops
 *
 * based on current file size and current junk lines, decide how many nops to try
 * number of nops to try is 0 to JUNK_GROUPS
 *
 * returns string of nops
**/
string add_nops(int &currentFileSize, int &currentJunkLines) {
    string nops = "";
    int numNops = rand() % JUNK_GROUPS;
    for(int i = 0; i < numNops; i++)
        nops.append(add_nop(currentFileSize, currentJunkLines));
    return nops;
}

/**
 * make_noise
 *
 * fill rest of file with random letters
 *
 * returns noise
**/
string make_noise(int currentFileSize) {
    string noise = "";
    string letter = "";
    for(int i = currentFileSize; i < MAX_SIZE -1 ; i++){
        letter = ALPHABET[rand() % (sizeof(ALPHABET) - 1)];
        noise.append(letter); 
    }
    noise.append(STR_TERMINATOR);
    return noise;
}

int main() {
    srand(time(NULL));
    string fileName;
    string command;
    int currentFileSize;
    int currentJunkLines;

    for(int i = 0; i < NUM_FILES; i++) {
        ostringstream number;
        number << i;
        fileName = "hello_";
        fileName.append(number.str());
        fileName.append(".asm");
        currentFileSize = 0;
        currentJunkLines = 0;

        command = "nasm -f bin ";
        ofstream fh(fileName.c_str());

        if(fh.is_open()){

            fh << "ORG 100h";
            fh << NEWLINE;
            fh << add_nops(currentFileSize, currentJunkLines);
            fh << "mov   ax, cs";
            fh << NEWLINE;
            currentFileSize += 2;
            fh << add_nops(currentFileSize, currentJunkLines);
            fh << "mov   ds, ax";
            fh << NEWLINE;
            currentFileSize += 2;
            fh << add_nops(currentFileSize, currentJunkLines);
            fh << "mov   dx, hel";
            fh << NEWLINE;
            currentFileSize += 3;
            fh << add_nops(currentFileSize, currentJunkLines);
            fh << "mov   ah, 09h";
            fh << NEWLINE;
            currentFileSize += 2;
            fh << add_nops(currentFileSize, currentJunkLines);
            fh << "int   21h";
            fh << NEWLINE;
            currentFileSize += 2;
            fh << add_nops(currentFileSize, currentJunkLines);
            fh << "mov   ax, 4C00h";
            fh << NEWLINE;
            currentFileSize += 3;
            fh << add_nops(currentFileSize, currentJunkLines);
            fh << "int   21h";
            fh << NEWLINE;
            currentFileSize += 2;
            fh << add_nops(currentFileSize, currentJunkLines);
            fh << "hel: db \"Hello World!$\"";
            fh << NEWLINE;
            currentFileSize += 13;
            fh << add_nops(currentFileSize, currentJunkLines);
            fh << "noise: db \"";
            fh << make_noise(currentFileSize);
            fh << "\"";
            fh << NEWLINE;

            fh.close();

            command.append(fileName);
            command.append(" -o hello_");
            command.append(number.str());
            command.append(".com");
            system(command.c_str());
            number.clear();

        } else {
            cout << "Could not open file " << fileName << NEWLINE;
        }
    }

    system("del *.asm");

    return 0;

}