UJType.h

#include<iostream>
#include<vector>
#include<string>
#include<fstream>
#include<bitset>
#include<algorithm>
#include<ctype.h>

using namespace std;

class UJType{
	// instruction imm[20][10:1][11][19:12] | rd[11:7] | opcode[6:0]
	private:
		vector <string> instructions;
		vector <string> opcode;
	public:
		// initialise the vectors with their respective values from the input file
		void initialise (string filename);
		//checks if given command is present in the list of UJ Type instructions
		bool isPresent(string command);
		//Converts string instruction to 32 bit machine code
		bitset <32> decode (string instruction);

};

void UJType::initialise (string filename){
	ifstream ifile(filename.c_str());
	string instName, instOpcode;
	while(ifile >> instName >> instOpcode){
		instructions.push_back(instName);
		opcode.push_back(instOpcode);

	}
}

bool UJType::isPresent (string inst){
	int i=0;
	string instName;
	while(!isalnum(inst[i]))	i++;		//isalnum checks whether inst[i] is digit,lower or upper case letter
	while(isalpha(inst[i])){
		instName.push_back(inst[i]);
		i++;
	}
	vector <string> :: iterator itr = find(instructions.begin(), instructions.end(), instName) ;
	if(itr == instructions.end())	return false;
	return true;
}

bitset <32> UJType::decode (string instruction){
	bitset <32> machineCode;
	string instName, rdName, labelOffset;
	int offset = 0;
	bool isNegative = false;
	int error =0;
	//Splitting instruction into various parts, ignoring whitespaces and commas
	int rdNum, i=0;
	while(!isalnum(instruction[i]))	i++;
	while(isalnum(instruction[i])){
		instName.push_back(instruction[i]);
		i++;
	}
	while(!isalnum(instruction[i]))	i++;
	while(isalnum(instruction[i])){
		rdName.push_back(instruction[i]);
		i++;
	}
	while(!isdigit(instruction[i])){
		if( instruction[i] == '-')	isNegative = true;
		if(isalpha(instruction[i])){
			error=1;
			for(int i=0;i<32;i++)
				machineCode[i]=-1;
			error = 0;
			return machineCode;	
		}
		i++;
	}
	while(isdigit(instruction[i])){
		labelOffset.push_back(instruction[i]);
		i++;
	}

	//index for opcode
	int index = find(instructions.begin(), instructions.end(), instName) - instructions.begin();

	// Finding register no.
	if(rdName.size()==2)
		rdNum = rdName[1] - '0';
	else
		rdNum = 10*(rdName[1]-'0') + (rdName[2]-'0');

	bitset <5> rd(rdNum);

	// Finding offset
	for(i=0; labelOffset[i]!='\0'; i++)
		offset = offset*10 + (labelOffset[i] - '0');
	if(isNegative)
		offset *= -1;

	bitset <20> imm(offset);
	if(rdNum<0 || rdNum >31)
			{
				for(int i=0;i<32;i++)
					machineCode[i]=-1;
				return machineCode;
			}
	// Generatng machine code
	for(int i=0; i<7; i++)
		machineCode[i] = opcode[index][6-i] - '0';
	for(int i=0; i<5; i++)
		machineCode[7+i] = rd[i];
	for(int i=0; i<8; i++)
		machineCode[12+i] = imm [i+11];
	machineCode[20] = imm[10];
	machineCode[31] = imm[19];
	for(int i=0; i<11; i++)
		machineCode[21+i] = imm[i];
		   
	return machineCode;

}