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Compile the source and then type the following in:
Or even simpler:+1007 ( read a )
+1008 ( read b )
+2007 ( load a )
+3008 ( add b )
+2109 ( store c )
+1109 ( write c )
+4300 ( halt )
It works correctly the first time it's run. However, run it a second time around and you'll see from the memory dump that there's a problem somewhere. However the answer is correct. I honestly don't have a clue where the problem could lie and believe me I've looked. Also, any code suggestions are welcome.+1099 ( read into 99 )
+1199 ( write from 99 )
I feel like I'm actually getting somewhere in this C++ world!Code:/* ################################################################################# ## Simpletron! Simulator ################################################################################# ## ## Written by : CC ## Email : cc@hardcor3.za.net ## Last modified : 25/02/2004 ## Description : Allows the user to execute code written in SML language. A ## memory dump is given if an error occurs. New SML instructions ## can be coded. Many checks are run to ensure proper running of ## programs. ################################################################################# ## TODO List (in order of priority) ################################################################################# ## ## Finish Mem Dump [ ] ## Add new features [ ] ## Code programs [ ] ## Write documentation [ ] ################################################################################# */ #include <iostream> using std::cout; using std::cin; using std::endl; using std::right; using std::left; #include <iomanip> using std::setw; using std::setfill; using std::showpos; using std::noshowpos; // Prototypes void loadProgram( int[] ); void executeProgram( int *const, int *const, int *const, int *const, int *const, int [] ); void accumulatorCheck( const int *const , int *const ); void dump( const int *const, const int *const, const int *const, const int *const, const int *const, int [] ); #define MEMSIZE 100 int main() { // Single subscripted array used for the memory int memory[ MEMSIZE ] = { 0 }; int accumulator = 0; // Keeps track of location in memory that contains current instruction int counter; // What operation to do (two left most digits) int operationCode; // Memory location of operation (two right most digits) int operand; // Copy of instruction from memory of what to do int instructionRegister; int again = 0; cout << "*** Welcome to Simpletron! ***\n\n" << "*** Please enter your program one instruction ***\n" << "*** (or data word) at a time. I will type the ***\n" << "*** location number and a quesion mark (?). ***\n" << "*** You then type the word for that location. ***\n" << "*** Type the sentinel -99999 to stop entering ***\n" << "*** your program. Don't forget to HALT! ***\n\n"; // Load user's program into Simpletron's memory loadProgram( memory ); while( again == 0 || again == 1 || again == 2 ) { counter = 0; operationCode = 0; instructionRegister = 0; if( again == 1 ) system( "cls" ); if( again == 2 ) { // Resets memory on new run for( int i = 0; i < MEMSIZE; i++) memory[ i ] = 0; system( "cls" ); loadProgram( memory ); } if( again == 1 ) cout << "\n*** Program execution begins ***\n"; else cout << "*** Program execution begins ***\n"; // Execute all instructions until the halt instruction is found (or an error occurs) while( (operationCode != 43) && (operationCode != 50) ) { executeProgram( &instructionRegister, &operationCode, &operand, &counter, &accumulator, memory ); // Ensures accumulator stays between -9999 and 9999 accumulatorCheck( &accumulator, &operationCode ); ++counter; } if( operationCode == 50 ) { dump( &accumulator, &counter, &instructionRegister, &operationCode, &operand, memory ); // Computer dump // Reset accumulator accumulator = 0; } dump( &accumulator, &counter, &instructionRegister, &operationCode, &operand, memory ); cout << "\n[1 to rerun program; 2 to input new program; 3 to quit] "; cin >> again; } return 0; // indicates successful termination } void loadProgram( int mem[] ) { int location = 0; for( int i = 0; i < MEMSIZE - 1; i++) { cout << setw( 2 ) << right << noshowpos << setfill( '0' ) << i << " ? "; cin >> mem[ location ]; while( (mem[ location ] < -9999) || (mem[ location ] > 9999) ) { if( mem[ location ] == -99999 ) break; cout << "Invalid data input!\n" << setw( 2 ) << i << " ? "; cin >> mem[ location ]; } if( mem[ location ] == -99999 ) break; location++; } cout << "\n*** Program loading completed ***\n"; } void executeProgram( int *const instructionRegister, int *const operationCode, int *const operand, int *const counter, int *const accumulator, int memory[] ) { *instructionRegister = memory[ *counter ]; *operationCode = *instructionRegister / MEMSIZE; *operand = *instructionRegister % MEMSIZE; switch( *operationCode ) { // Case 0 is placed here so no error is given when variables are specified mid-program case 0: break; // Outputs a new line case 1: cout << '\n'; break; // Read a word from the keyboard case 10: cin >> memory[ *operand ]; break; // Write a word from memory location case 11: cout << noshowpos << memory[ *operand ]; break; //--------------------------------------------------\\ // Load word into accumulator case 20: *accumulator = memory[ *operand ]; break; // Store a word from accumulator into memory case 21: memory[ *operand ] = *accumulator; break; //--------------------------------------------------\\ // addition case 30: *accumulator += memory[ *operand ]; break; // subtraction case 31: *accumulator -= memory[ *operand ]; break; // division with check for divide by zero case 32: if( memory[ *operand ] == 0 ) { cout << "\n*** Attempt to divide by zero ***\n" << "*** Simpletron execution abnormally terminated ***"; *operationCode = 50; } else *accumulator /= memory[ *operand ]; break; // multiplication case 33: *accumulator *= memory[ *operand ]; break; //--------------------------------------------------\\ // branch to memory location case 40: *counter = *operand - 1; // We -1 from the operand as the loop in main always increases int counter by one break; // branch to mem location if negative case 41: if( *accumulator < 0 ) *counter = *operand - 1; break; // branch to mem location if accumulator is negative case 42: if( *accumulator == 0 ) *counter = *operand - 1; break; // halt case 43: cout << "\n*** Simpletron execution terminated ***\n"; break; default: cout << "\n*** Error in code ***\n" << "*** Simpletron execution abnormally terminated ***"; *operationCode = 50; } } void accumulatorCheck( const int *const accumulator, int *const code ) { if( (*accumulator < -9999) || (*accumulator > 9999) ) { cout << "*** Incorrect accumulator size ***\n" << "*** Simpletron execution abnormally terminated ***"; *code = 50; } } void dump( const int *const accumulator, const int *const counter, const int *const instructionRegister, const int *const operationCode, const int *const operand, int mem[] ) { cout << "\n\nREGISTERS:\n"; if( *accumulator > 0 ) cout << setw( 4 ) << setfill( '0' ) << showpos << "accumulator\t\t" << *accumulator; else if( *accumulator == 0 ) cout << "accumulator\t\t" << "+0000"; else cout << "accumulator\t\t" << *accumulator; cout << "\ncounter\t\t\t" << setfill( '0' ) << setw( 2 ) << noshowpos << (*counter - 1) // counter - 1 to take a step back to the problem << "\ninstructionRegister\t" << showpos << *instructionRegister << "\noperationCode\t\t" << setw( 2 ) << noshowpos << (*instructionRegister / MEMSIZE) << "\noperand\t\t\t" << setw( 2 ) << *operand << "\n\n"; cout << "MEMORY:" << endl; // Display column header cout << " "; for (int col = 0; col < 10; col++) cout<< setfill( ' ' ) << setw(7) << col; cout << '\n'; // Display row: header-data-newline for (int row = 0; row < 10; row++) { cout << setw(2) << right << noshowpos << setfill(' ') << row << " "; for (int col = 0; col < 10; col++) { static int number = 0; if( mem[ number ] == -99999 ) mem[ number ] = 0; cout << setw(5) << left << showpos << setfill('0') << mem[ number ] << " "; number++; } cout << '\n'; } }
