void printStacktrace()
{
printStacktrace( std::cerr );
}
int main(int argc, char *argv[])
{
// Initialize read and write files
FILE *ifp = fopen(argv[1], "r");
FILE *ofp = fopen(argv[2], "w+");
// Exit program if a file was not opened
if(ifp == NULL) { printf("Input File Not Found\n"); return 0; }
if(ofp == NULL) { printf("Output File Not Found\n"); return 0; }
// Register architecture
int BP = 1; // Base Pointer
int SP = 0; // Stack Pointer
int PC = 0; // Program Counter
instruction *IR; // Instructions (Opcode, Lexi. Level, Parameter)
int prev;
// Initialize stack
int stack[MAX_STACK_HEIGHT];
memset(stack, 0, MAX_STACK_HEIGHT * sizeof(int));
// Create and intialize an array of structs
instruction instructions[MAX_CODE_LENGTH];
read(ifp, instructions);
// Close input file
fclose(ifp);
// Print the instructions to be executed
printInstructions(ofp, instructions);
// Print header for the stacktrace
fprintf(ofp, "\n\n\t\t\t\t\tPC\tBP\tSP\tStack \nInitial Values \t\t\t\t\t%d\t%d\t%d\n", 0, 1, stack[0]);
printf("Fetch -> Execute Cycle\n");
// Fetch -> Execute Cycle
bool halt = false;
while(halt == false)
{
// Get instruction
IR = &instructions[PC];
// Save last program counter
prev = PC;
// Set instructions for cleaner usage
int OP = IR->OP;
int L = IR->L;
int M = IR->M;
switch(OP)
{
// LIT - Push value M onto the stack
case 1:
SP++;
stack[SP] = M;
PC++;
break;
/* OPR - Return from a procedure call
* or do an ALU op, specified by M */
case 2:
switch(M)
{
// Return from a procedure call
case 0:
SP = BP - 1;
PC = stack[SP + 4];
BP = stack[SP + 3];
break;
// NEG - Pop once -> push the negation of the result
case 1:
stack[SP] = -stack[SP];
break;
// ADD - Pop twice -> add -> push
case 2:
SP--;
stack[SP] = stack[SP] + stack[SP + 1];
break;
// SUB - Pop twice -> subtract top value from bottom value -> push
case 3:
SP--;
stack[SP] = stack[SP] - stack[SP + 1];
break;
// MUL - Pop twice -> multiply -> push
case 4:
SP--;
stack[SP] = stack[SP] * stack[SP + 1];
break;
// DIV - Pop twice -> divide top value from bottom value -> push
case 5:
SP--;
stack[SP] = stack[SP] / stack[SP + 1];
break;
// ODD - Pop once -> push 1 if odd and 0 if even
case 6:
stack[SP] = stack[SP] % 2;
break;
// MOD - Pop twice -> mod top value from bottom value -> push
case 7:
SP--;
stack[SP] = stack[SP] % stack[SP + 1];
break;
// EQL - Pop twice -> push 1 if first = second, 0 otherwise
case 8:
SP--;
stack[SP] = stack[SP] == stack[SP + 1];
// NEQ - Pop twice -> push 1 if first does not equal second, 0 otherwise
case 9:
SP--;
stack[SP] = stack[SP] != stack[SP + 1];
break;
// LSS - Pop twice -> push 1 if second < first, 0 otherwise
case 10:
SP--;
stack[SP] = stack[SP] < stack[SP + 1];
break;
// LEQ - Pop twice -> push 1 if second <= first, 0 otherwise
case 11:
SP--;
stack[SP] = stack[SP] <= stack[SP + 1];
break;
// GTR - Pop twice -> push 1 if second > first, 0 otherwise
case 12:
SP--;
stack[SP] = stack[SP] > stack[SP + 1];
// GEQ - Pop twice -> push 1 if second >= first, 0 otherwise
case 13:
SP--;
stack[SP] = stack[SP] >= stack[SP + 1];
}
break;
// LOD - Read the value at offset M, L levels down, and push onto stack
case 3:
SP++;
stack[SP] = stack[base(L, BP, stack) + M];
PC++;
break;
// STO - Pop the stack and write value into offset M, L levels down
case 4:
stack[base(L, BP, stack) + M] = stack[SP];
stack[SP] = 0;
SP--;
PC++;
break;
// CAL - Call the procedure at M
case 5:
stack[SP + 1] = 0;
stack[SP + 2] = base(L, BP, stack);
stack[SP + 3] = BP;
stack[SP + 4] = PC + 1;
BP = SP + 1;
PC = M;
break;
// INC - Allocate space for M local variables, will always allocate atleast 4
case 6:
SP = SP + M;
PC++;
break;
// JMP - Branch to M
case 7:
PC = M;
break;
// JPC - Pop the stack and branch to M if result is 0
case 8:
if(stack[SP] == 0)
PC = M;
else
PC++;
SP--;
break;
// SIO 1 - Pop the stack and write result to screen
case 9:
printf("%d\n", stack[SP]);
SP--;
PC++;
break;
// SIO 2 - Take user input and push on the stack
case 10:
printf("Enter Value:\n");
SP++;
scanf("%d", &stack[SP]);
PC++;
break;
// SIO 3 - Terminate
case 11:
printf("Halt\n");
halt = true;
BP = 0;
PC = 0;
SP = 0;
break;
default:
printf("Invalid Opcode\n");
return 0;
}
// Print the stacktrace for the instructions that were just executed
printStacktrace(ofp, prev, IR, PC, BP, SP, stack);
}
// Close
fclose(ofp);
return 0;
}