Not declared in this scope

I'm in the process of implementing a MIPS instruction set simulator. But when I try compiling my code, I keep getting "out of scope" errors and it's getting to be very frustrating. I've tried all kinds of variations, but nothing seems to be helping.

Here's my MIPSsim.cpp file

#include <iostream>
#include <fstream>
#include <string>
#include <cassert>

using namespace std;
const int BITS = 32;

string inst_decode(string line);
void execute(string line, string instruction, int &registers[]);
void print(int cycle, int inst_address, int regs[]/*, int data[]*/);
int convert_5(string binary);
int convert_32(string binary);
void add(string line, int &registers[]);
void sub(string line, int &registers[]);
void mult(string line, int &registers[]);


string inst_decode(string line){
    string instruction; 
    if(line.compare(0,1,"0") == 0){
        if (line.compare(1,5,"00010") == 0){
            cout << "JUMP" << endl;
            instruction = "JUMP";
        }else if (line.compare(1,5,"00100") == 0){
        cout << "BEQ" << endl;
        instruction = "BEQ";
    }else if (line.compare(1,5,"00001") == 0){
        cout << "BLTZ" << endl;
        instruction = "BLTZ";
    }else if (line.compare(1,5,"00111") == 0){
        cout << "BGTZ" << endl;
        instruction = "BGTZ";
    }else if (line.compare(1,5,"01011") == 0){
        cout << "SW" << endl;
        instruction = "SW";
    }else if (line.compare(1,5,"00011") == 0){
        cout << "LW" << endl;
        instruction = "LW";
    }else if (line.compare(1,5,"00010") == 0){
        cout << "SRL" << endl;
        instruction = "SRL";
    }else if ((line.compare(1,5,"11100") == 0)&&(line.compare(26,6,"000010") == 0)){
        cout << "MUL" << endl;
        instruction = "MUL";
    }else if (line.compare(1,5,"00000") == 0){
        if (line.compare(26,6,"100000") == 0){
            cout << "ADD" << endl;
            instruction = "ADD";
        }else if (line.compare(26,6,"100010") == 0){
            cout << "SUB" << endl;
            instruction = "SUB";
        }else if (line.compare(26,6,"100100") == 0){
            cout << "AND" << endl;
            instruction = "AND";
        }else if (line.compare(26,6,"100101") == 0){
            cout << "OR" << endl;
            instruction = "OR";
        }else if (line.compare(26,6,"101010") == 0){
            cout << "SLT" << endl;
            instruction = "SLT";
        }else if (line.compare(26,6,"000000") == 0){
            cout << "SLL" << endl;
            instruction = "SLL";
        }else if (line.compare(6,26,"00000000000000000000000000") == 0){
            cout << "NOP" << endl;
            instruction = "NOP";
        }
    }
    }else{
        if (line.compare(26,6,"100100") == 0){
            cout << "ADDI" << endl;
            instruction = "ADDI";
        }else if (line.compare(26,6,"100010") == 0){
            cout << "ANDI" << endl;
            instruction = "ANDI";
        }
    }
    return instruction;
}

void execute(string line, string instruction, int& registers[]){
    if(instruction == "ADD"){
        add(line, registers);
    }else if(instruction == "ADDI"){
        addi(line, registers);
    }else if(instruction == "SUB"){
        sub(line, registers);
    }else if(instruction == "MUL"){
        mult(line, registers);
    }
}

void print(int cycle, int inst_address, int regs[]/*, int data[][]*/){
    cout << "---------------------------\n";
    cout << "Cycle: " << cycle << "\t" << inst_address << "\t" << "\n";
    cout << "\nRegisters\n";
    cout << "R00:\t";
    for(int i=0; i<=15; i++){
        cout << regs[i] << "\t";
    }
    cout << "\nR16:\t";
    for(int i=16; i<32; i++){
            cout << regs[i] << "\t";
    }
    cout << "\n\nData\n";
        //cout << "\n148:\t";
        //for(int i=0; i<8; i++){
        //  cout << data[i] << "\t";
        //}
        //cout << "\n180:\t";
        //for(int i=9; i<17; i++){
            //  cout << data[i] << "\t";
        //}
        //cout << "\n212:\t";
        //for(int i=18; i<26; i++){
        //  cout << data[i] << "\t";
    //}
    cout << "\n";
}


int main(){
    int registers[32] = {0};
        //  int data[2][32];
    string inst;
    //int cycle = 1;
    //int PC = 64;
    string binary_inst[64];

    ifstream inFile;
    inFile.open("sample.txt");
    if (!inFile) {
        cout << "Unable to open file sample.txt" << endl;
        return 0;
    }
    string x;
    while(!inFile.eof()){
        for(int i=0; i<64; i++){
            inFile >> x;
            binary_inst[i] = x;
            inst = inst_decode(binary_inst[i]);
            execute(binary_inst[i], inst, registers);
            //print(cycle, PC, registers);
        }
    } 
    //  print(cycle, PC, registers);

    return 0;
}



int convert_5(string binary) {
    long power = 32;
    long sum = 0;
    assert(binary.size() == 5);

    for ( int i=0; i<BITS; ++i) {
        if ( i==0 && binary[i]!='0') {
            sum = -32;
        }
        else {
            sum += (binary[i]-'0')*power;
        }
        power /= 2;
    }
    return sum;
}

int convert_32(string binary) {
    long power = 4294967296;
    long sum = 0;
    assert(binary.size() == 32);

    for ( int i=0; i<BITS; ++i) {
        if ( i==0 && binary[i]!='0') {
            sum = -4294967296;
        }
        else {
            sum += (binary[i]-'0')*power;
        }
        power /= 2;
    }
    return sum;
}



void add(string line, int& registers[]){
    int dest = convert_5(line.substr(17,5));
    cout << "Dest: " << dest << endl;

    int target = convert_5(line.substr(12,5));
    cout << "Target: " << target << endl;

    int source = convert_5(line.substr(7,5));
    cout << "Source: " << source << endl;

    registers[dest] = registers[source] + registers[target];
    cout << "Addition: " << registers[dest] << endl;
}

void sub(string line, int& registers[]){
    int dest = convert_5(line.substr(17,5));
    cout << "Dest: " << dest << endl;

    int target = convert_5(line.substr(12,5));
    cout << "Target: " << target << endl;

    int source = convert_5(line.substr(7,5));
    cout << "Source: " << source << endl;

    registers[dest] = registers[source] - registers[target];
    cout << "Subtraction: " << registers[dest] << endl;
}

void mult(string line, int& registers[]){
    int dest = convert_5(line.substr(17,5));
    cout << "Dest: " << dest << endl;

    int target = convert_5(line.substr(12,5));
    cout << "Target: " << target << endl;

    int source = convert_5(line.substr(7,5));
    cout << "Source: " << source << endl;

    registers[dest] = registers[source] * registers[target];
    cout << "Multiplication: " << registers[dest] << endl;
}

Here are the error messages I keep getting:

lin114-08:10% make all
g++ -Wall -o MIPSsim MIPSsim.cpp
MIPSsim.cpp:10: error: declaration of ‘registers’ as array of references
MIPSsim.cpp:14: e开发者_如何学编程rror: declaration of ‘registers’ as array of references
MIPSsim.cpp:15: error: declaration of ‘registers’ as array of references
MIPSsim.cpp:16: error: declaration of ‘registers’ as array of references
MIPSsim.cpp:85: error: declaration of ‘registers’ as array of references
MIPSsim.cpp: In function ‘void execute(...)’:
MIPSsim.cpp:86: error: ‘instruction’ was not declared in this scope
MIPSsim.cpp:87: error: ‘line’ was not declared in this scope
MIPSsim.cpp:87: error: ‘registers’ was not declared in this scope
MIPSsim.cpp:89: error: ‘line’ was not declared in this scope
MIPSsim.cpp:89: error: ‘registers’ was not declared in this scope
MIPSsim.cpp:89: error: ‘addi’ was not declared in this scope
MIPSsim.cpp:91: error: ‘line’ was not declared in this scope
MIPSsim.cpp:91: error: ‘registers’ was not declared in this scope
MIPSsim.cpp:93: error: ‘line’ was not declared in this scope
MIPSsim.cpp:93: error: ‘registers’ was not declared in this scope
MIPSsim.cpp: In function ‘int main()’:
MIPSsim.cpp:146: warning: cannot pass objects of non-POD type ‘struct std::string’     through ‘...’; call will abort at runtime
MIPSsim.cpp:146: warning: cannot pass objects of non-POD type ‘struct std::string’     through ‘...’; call will abort at runtime
MIPSsim.cpp: At global scope:
MIPSsim.cpp:193: error: declaration of ‘registers’ as array of references
MIPSsim.cpp: In function ‘void add(...)’:
MIPSsim.cpp:194: error: ‘line’ was not declared in this scope
MIPSsim.cpp:203: error: ‘registers’ was not declared in this scope
MIPSsim.cpp: At global scope:
MIPSsim.cpp:207: error: declaration of ‘registers’ as array of references
MIPSsim.cpp: In function ‘void sub(...)’:
MIPSsim.cpp:208: error: ‘line’ was not declared in this scope
MIPSsim.cpp:217: error: ‘registers’ was not declared in this scope
MIPSsim.cpp: At global scope:
MIPSsim.cpp:221: error: declaration of ‘registers’ as array of references
MIPSsim.cpp: In function ‘void mult(...)’:
MIPSsim.cpp:222: error: ‘line’ was not declared in this scope
MIPSsim.cpp:231: error: ‘registers’ was not declared in this scope
make: *** [MIPSsim] Error 1

Any help would be greatly appreciated

---

Always fix the first error the compiler gives you: int &registers[] won't work - use int * registers or int registers[].

If you really want a reference to an array, you need to specify the size:

void execute(string line, string instruction, int (&registers) [10]);

All of these approaches will let you modify the actual array you pass to the function - there's no copying.

Side note:

In MIPSsim.cpp line 146 you're trying to pass a std::string to a vararg function (e.g. sprintf or printf) - That won't work. Pass string.c_str() instead.

---

I can't say if there are other problems but I think your execute, add, sub, mult functions can just take registers as an array, not an array of references.

void add(string line, int registers[]);

---

You can't pass an array as an argument in C++. What you'd have to do is declare the parameters:

int (&registers)[32];

But registers aren't the only machine state which is likely to be changed by executing some code. A much better solution would be to define a struct with all of the machine state (except maybe the memory):

struct HWState
{
    int registers[32];
    unsigned cc;
    ??? pc;
    //  ...
};

Then pass that by reference, and you shouldn't have any problem. (In practice, C style arrays should only be used for static variables, with static initialization, and as members, when the count is constant and not too big.)

---

When you have a lot of functions that all take the same argument, that's usually a sign that they should be member functions. Here, you have add, sub and mult which all operate on your set of registers. And of course, most future instructions will too.

Therefore, define a class CPU with data members for each register (i.e. int r[32];float f[32];, and a method CPU::add(std::string line). Within add, you can just refer to r[4] if you need the first function argument register etc.