int execute_command(char cmd_char, int reg[], int nreg,
int mem[], int memlen)
{
if (cmd_char == '?' || cmd_char == 'h')
help_message();
switch (cmd_char) {
case 'd':
dump_control_unit(pc, ir, running, reg, nreg);
dump_memory(mem, memlen);
return 0;
break;
case 'q':
return 1;
break;
case '\n':
one_instruction_cycle(reg, nreg, mem, memlen);
return 0;
break;
default:
printf("Please enter a valid character");
break;
}
return 0;
}
// Initialize the control registers (pc, ir, running flag) and
// the general-purpose registers
//
void initialize_control_unit(int reg[], int nreg) {
pc = 0;
ir = 0;
running = 1;
int i;
for(i=0;i<nreg;i++){
reg[i]=0;
}
printf("\nInitial control unit:\n");
dump_control_unit(pc, ir, running, reg, nreg);
printf("\n");
}
// Execute a nonnumeric command; complain if it's not 'h', '?', 'd', 'q' or '\n'
// Return true for the q command, false otherwise
//
int execute_command(char cmd_char, int reg[], int nreg, int mem[], int memlen) {
if (cmd_char == '?' || cmd_char == 'h') {
help_message();
} else if (cmd_char == 'd') {
printf("Dumping control and memory:\n");
dump_control_unit(pc, ir, running, reg, NREG);
dump_memory(mem, MEMLEN);
} else if (cmd_char == 'q') {
printf("Quitting\n");
exit(0);
} else if (cmd_char == '\n' || cmd_char == ' ') {
one_instruction_cycle(reg,nreg,mem,memlen);
} else {
printf("Unkown command: %c; Ignoring it.\n",cmd_char);
return 1;
}
return 0;
}
// Main program: Initialize the cpu, read initial memory values,
// and execute the read-in program starting at location 00.
//
int main(int argc, char *argv[]) {
printf("=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=\n");
printf("=-=-=-=-=-=-= SDC SIM lab06 CS350 Devanshu Bharel =-=-=-=-=-=-=\n");
printf("=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=\n");
initialize_control_unit(reg, NREG);
initialize_memory(argc, argv, mem, MEMLEN);
char *prompt = "> ";
printf("\nBeginning execution; type h for help\n%s", prompt);
int done = read_execute_command(reg, NREG, mem, MEMLEN);
while (!done) {
printf("%s", prompt);
done = read_execute_command(reg, NREG, mem, MEMLEN);
}
printf("At termination\n");
dump_control_unit(pc, ir, running, reg, NREG);
dump_memory(mem, MEMLEN);
return 0;
}
int main(int argc, char *argv[])
{
printf("SDC Simulator\n");
/* initialize everything */
initialize_control_unit(reg, NREG);
initialize_memory(argc, argv, mem, MEMLEN);
char *prompt = "> ";
printf("\nBeginning execution; type h for help\n%s", prompt);
int done = read_execute_command(reg, NREG, mem, MEMLEN);
while (!done) {
printf("%s", prompt);
done = read_execute_command(reg, NREG, mem, MEMLEN);
}
/* Dump everything when done */
printf("Termination\n");
dump_control_unit(pc, ir, running, reg, NREG);
printf("\n");
dump_memory(mem, MEMLEN);
return 0;
}
// print out control unit
void exec_DMP(int addr_MM, int reg[], int nreg, int mem[], int memlen) {
printf("I/O 3: Dump control unit:\n");
dump_control_unit(pc, ir, running, reg, NREG);
}
void one_instruction_cycle(int reg[], int nreg,
int mem[], int memlen)
{
int reg_R, addr_MM, instr_sign, opcode;
/* Check if CPU is running */
if (running == 0) {
printf("The CPU is not running");
return;
}
/* Make sure that we didn't hit any boundaries */
if (pc >= memlen) {
printf("Program counter out of range");
exec_HLT();
}
/* Get instruction and increment PC */
int instr_loc = pc;
ir = mem[pc++];
/* Check instruction sign */
if (ir < 0) {
instr_sign = -1;
ir *= -1;
} else if (ir > 0) {
instr_sign = 1;
}
/* Decode instruction into opcode, register, and memory address */
opcode = ir / 1000;
reg_R = (ir % 1000) / 100;
addr_MM = ir % 100;
printf("At %02d instr %d %d %02d: ",
instr_loc, opcode, reg_R, addr_MM);
switch (opcode) {
/* HALT */
case 0:
exec_HLT();
break;
/* LOAD */
case 1: {
reg[reg_R] = mem[addr_MM];
} break;
/* STORE */
case 2: {
mem[addr_MM] = reg[reg_R];
} break;
/* ADD-IM-MM */
case 3: {
reg[reg_R] += mem[addr_MM];
} break;
/* NOT */
case 4: {
reg[reg_R] = (-reg[reg_R]);
} break;
/* LOAD IMMEDIATE */
case 5: {
reg[reg_R] = addr_MM * instr_sign;
} break;
/* ADD IMMEDIATE */
case 6: {
reg[reg_R] += addr_MM * instr_sign;
} break;
/* JUMP */
case 7: {
pc = addr_MM;
} break;
/* BRANCH CONDITIONAL */
case 8: {
if (reg[reg_R] > 0 && instr_sign > 0) {
pc = addr_MM;
} else if (reg[reg_R] < 0 && instr_sign < 0)
pc = addr_MM;
} break;
/* I/O Subroutines */
case 9: {
switch (reg_R) {
/* GETCHAR */
case 0: {
printf("enter a character>> ");
int k = getchar();
reg[0] = k;
} break;
/* PRINTCHAR */
case 1: {
printf("%c\n", reg[0]);
} break;
/* PRINT-STRING */
case 2: {
while (mem[addr_MM] != 0) {
printf("%c \n", mem[addr_MM++]);
}
printf("\n");
} break;
/* DUMP CU */
case 3: {
dump_control_unit(pc, ir, running, reg, nreg);
} break;
/* DUMP MEM */
case 4: {
dump_memory(mem, memlen);
} break;
default:
return;
break;
}
} break;
default:
printf("Bad opcode!? %d\n", opcode);
}
}
