컴공 일기229

요새는 운동을 하러 가는 것 이외엔, 공학과 수학에 집중하고 있습니다. 나도 모르게, 몰입이 되고 있다는 느낌을 많이 받고 있어요. 다만, 결과는 과정의 수려함들을 집어삼켜 먹는 습성이 있는 걸 잘 알아서, 큰 욕심은 내지 않고 있습니다.

과정에 주목하는 삶을 살고 있달까요. 뭐, 무엇인가를 크게 이뤄나가는 일상은 아닙니다만, 개인적으론 참 만족스럽습니다.

저번 일기에서 그려보았듯, Assembler를 제작하고 있어요. 재미있는 여정입니다.

Parser 모듈 : 입력 코드에 대한 접근을 캡슐화(Capsulation)합니다. 어셈블리 명령을 읽어 들여 구문을 분석하고, 명령 세부요소(필드/기호)에 편리하게 접근하도록 합니다. 추가적으로 모든 공백과 주석문을 제거합니다.

Parser.h

#pragma once

#ifndef HACK_ASSEMBLER_PARSER_H

#define HACK_ASSEMBLER_PARSER_H

#include <iostream>

#include <fstream>

#include <string>

#include <algorithm>

#include <map>

using namespace std;

class Parser

{

public:

    Parser(string& filename);

    //File is closed implicitly.

    bool hasMoreCommands();

    //Returns true if the file contains commands that still need to be parsed,

    //Return flase otherwise.

    void advance(unsigned long& lineNr);

    char commandType(unsigned long& lineNr);

    string symbol();

    //Returns the symbol or decimal value of the current command.

    //Should only be called if commandType() returns 'A' or 'L'.

    string destM();

    // Returns the destination mnemonic of the current command.

    string compM();

    string jumpM();

private:

    ifstream fin;

    string currentCommand;

    map <char, char> commandTable;

};

#endif

-Parser.cpp

#include "Parser.h"

using namespace std;

Parser::Parser(string& fileName)

{

    fin.open(fileName);

    if (fin.fail())

    {

        cout << fileName << "not found." << endl;

        exit(1);

    }

    //Populate the command map table.

    commandTable['@'] = 'A';

    commandTable['A'] = 'C';

    commandTable['D'] = 'C';

    commandTable['M'] = 'C';

    commandTable['0'] = 'C';

    commandTable['1'] = 'C';

    commandTable['-'] = 'C';

    commandTable['!'] = 'C';

    commandTable['('] = 'L';

}

bool Parser::hasMoreCommands()

{

    return !fin.eof();

}

void Parser::advance(unsigned long& lineNr)

{

    string currentLine;

    unsigned long commentPos;

    bool commandFound;

    commandFound = false;

    while (!commandFound && getline(fin, currentLine))

    {

        lineNr++;

        //Remove whitespace. 

        currentLine.erase(remove_if(currentLine.begin(), currentLine.end(), ::isspace), currentLine.end());

        //Remove comments.

        commentPos = currentLine.find("//");

        //if comments were found 

        if (commentPos != string::npos)

        {

            currentLine.erase(commentPos, currentLine.length() - commentPos);

        }

        commandFound = !currentLine.empty();

    }

    currentCommand = currentLine;

}

char Parser::commandType(unsigned long& lineNr)

{

    if (commandTable.find(currentCommand[0]) != commandTable.end())

    {

        return commandTable[currentCommand[0]];

    }

    cout << "Invalid syntax at line: " << lineNr << endl;

}

string Parser::symbol()

{

    unsigned long openBracketPos, closeBracketPos;

    openBracketPos = currentCommand.find('(');

    closeBracketPos = currentCommand.find(')');

    //A-instruction: return everything after the '@' character

    if (currentCommand[0] == '@')

    {

        return currentCommand.substr(1, currentCommand.length() - 1);

    }

    else if (openBracketPos != string::npos && closeBracketPos != string::npos) {

        return currentCommand.substr(openBracketPos + 1, closeBracketPos - openBracketPos - 1);

    }

    // If the function was called in error, return a blank string.

    return "";

}

string Parser::destM()

{

    unsigned long equalSignPos;

    //Return everything before the '=' character.

    if (equalSignPos != string::npos)

    {

        return currentCommand.substr(0, equalSignPos);

    }

    //If no destination was specified, return a blank string.

    return "";

}

string Parser::compM()

{

    unsigned long equalSignPos, semiColonPos;

    equalSignPos = currentCommand.find('=');

    semiColonPos = currentCommand.find(';');

    // Return the computation mnemonic based on three cases.

    if (equalSignPos != string::npos)

    {

        //Case 1: dest = comp ; jump

        if (semiColonPos != string::npos)

        {

            return currentCommand.substr(equalSignPos + 1, semiColonPos - equalSignPos - 1);

        }

        //Case 2: dest = comp

        return currentCommand.substr(equalSignPos + 1, currentCommand.length() - equalSignPos - 1);

    }

    else if (semiColonPos != string::npos)

    {

        //Case 3: comp ; jump

        return currentCommand.substr(0, semiColonPos);

    }

    return "";

}

string Parser::jumpM()

{

    unsigned long semiColonPos;

    //Return everything after the ';' character.

    if (semiColonPos != string::npos)

    {

        return currentCommand.substr(semiColonPos + 1, currentCommand.length() - semiColonPos - 1);

    }

    //If a jump was not specified, return a blank string.

}

CodeTranslator 모듈 : 어셈블리 언어의 연상기호를 2진 코드로 변환합니다. 

-CodeTranslator.h

#pragma once

#ifndef HACK_ASSEMBLER_CODE_H

#define HACK_ASSEMBLER_CODE_H

#include <iostream>

#include <map>

using namespace std;

class CodeTranslator

{

public:

    CodeTranslator();

    //Populates the code translation map tables

    // with the language specification.

    string dest(string destMenmonic, unsigned long& lineNr);

    //Returns the binary code of the destination mnemonic

    //as a string containing 3 bits.

    //Line number is passed for use in an error message.

    string comp(string compMnemonic, unsigned long& lineNr);

    //Returns the binary code of the computation mnemonic 

    //as a string containing 3 bits.

    //Line number is passed for use in an error message.

    string jump(string jumpMnemonic, unsigned long& lineNr);

    //Returns the binary code of the jump mnemonic

    //as a string containing 3 bits.

    //Line number is passed for use in an error meassage.

private:

    map<string, string> destTable;

    map<string, string> compTable;

    map<string, string> jumpTable;

};

#endif

-CodeTranslator.cpp