private void stage_issue() {
System.out.println("station " + id + " in ISSUE.");
// check operand 1
Message msg;
if (Qj != READY) {
msg = bus.search_station(Qj);
if (msg != null) { // found
Qj = READY;
Vj = msg.result;
}
} // endif
// check operand 2
if (Qk != READY) {
msg = bus.search_station(Qk);
if (msg != null) { // found
Qk = READY;
Vk = msg.result;
}
} // endif
// if both operands ready, do execution
if ((Qj == READY) && (Qk == READY)) {
stage = "EX";
stage_ex();
}
}
private void issue(ArrayList<String> instruction) {
System.out.println("station " + id + " being issued with one instruction.");
bus.issued = true;
bus.PC++;
Busy = true;
stage = "ISSUE";
Op = instruction.get(0);
if ((Op.equals("add.d"))
|| (Op.equals("sub.d"))
|| (Op.equals("mul.d"))
|| (Op.equals("div.d"))) {
if ((Op.equals("add.d")) || Op.equals("sub.d")) {
cycles_left = 3;
} else cycles_left = 6;
// check operand 1
int index = Integer.parseInt(instruction.get(4));
int depend = bus.freg.getFregFlag(index);
if (depend == READY) { // operand 1 ready
Qj = READY;
Vj = bus.freg.getFreg(index);
} else { // operand 1 depends on another station
// check bus
Message msg = bus.search_station(depend);
if (msg != null) {
Qj = READY;
Vj = msg.result;
} else Qj = depend; // wait on that station;
}
// check operand 2
index = Integer.parseInt(instruction.get(6));
depend = bus.freg.getFregFlag(index);
if (depend == READY) { // operand 1 ready
Qk = READY;
Vk = bus.freg.getFreg(index);
} else { // operand 1 depends on another station
// check bus
Message msg = bus.search_station(depend);
if (msg != null) {
Qk = READY;
Vk = msg.result;
} else Qk = depend; // wait on that station;
}
// if they are ready, enter stage EX
if ((Qj == READY) && (Qk == READY)) { // both operands ready
stage = "EX";
}
// set register dependency flag
int reg_dst = Integer.parseInt(instruction.get(2));
bus.freg.setFregFlag(reg_dst, id);
System.out.println("station " + id + ": F" + reg_dst + " now depends on it.");
} else if (Op.equals("daddi")) {
cycles_left = 2; // how many?
// check operand 1
int index = Integer.parseInt(instruction.get(4));
int depend = bus.reg.getRegFlag(index);
if (depend == READY) { // operand 1 ready
Qj = READY;
Vj = bus.reg.getReg(index);
} else { // operand 1 depends on another station
// check bus
Message msg = bus.search_station(depend);
if (msg != null) {
Qj = READY;
Vj = msg.result;
} else Qj = depend; // wait on that station;
}
// operand 2 always ready
Qk = READY;
Vk = Integer.parseInt(instruction.get(6));
// if they are ready, enter stage EX
if ((Qj == READY) && (Qk == READY)) { // both operands ready
stage = "EX";
}
// set register dependency flag
int reg_dst = Integer.parseInt(instruction.get(2));
bus.reg.setRegFlag(reg_dst, id);
System.out.println("station " + id + ": R" + reg_dst + " now depends on it.");
} else if (Op.equals("s.d")) {
cycles_left = 1;
// check operand 1
int index = Integer.parseInt(instruction.get(2));
int depend = bus.freg.getFregFlag(index);
if (depend == READY) { // operand ready
Qj = READY;
Vj = bus.freg.getFreg(index);
} else { // operand depends on another station
// check bus
Message msg = bus.search_station(depend);
if (msg != null) {
Qj = READY;
Vj = msg.result;
} else Qj = depend; // wait on that station;
}
// check operand 2
index = Integer.parseInt(instruction.get(6));
depend = bus.reg.getRegFlag(index);
if (depend == READY) { // operand 1 ready
Qk = READY;
Vk = bus.reg.getReg(index);
} else { // operand 1 depends on another station
// check bus
Message msg = bus.search_station(depend);
if (msg != null) {
Qk = READY;
Vk = msg.result;
} else Qk = depend; // wait on that station;
}
// if they are ready, enter stage EX
if ((Qj == READY) && (Qk == READY)) { // both operands ready
stage = "EX";
}
// no registers' value depend on s.d instruction
// but we have to calculation A, into which memory unit the bus stores result
// second part of A comes from Rx, which will accumulated to A in stage EX
A = Integer.parseInt(instruction.get(4));
} else if (Op.equals("l.d")) {
cycles_left = 1;
// check operand 1
Qj = READY;
Vj = Integer.parseInt(instruction.get(4));
// check operand 2
int index = Integer.parseInt(instruction.get(6));
int depend = bus.reg.getRegFlag(index);
if (depend == READY) { // operand 2 ready
Qk = READY;
Vk = bus.reg.getReg(index);
} else { // operand 2 depends on another station
// check bus
Message msg = bus.search_station(depend);
if (msg != null) {
Qk = READY;
Vk = msg.result;
} else Qk = depend; // wait on that station;
}
// if they are ready, enter stage EX
if ((Qj == READY) && (Qk == READY)) { // both operands ready
stage = "EX";
}
// set register dependency flag
int reg_dst = Integer.parseInt(instruction.get(2));
bus.freg.setFregFlag(reg_dst, id);
System.out.println("station " + id + ": F" + reg_dst + " now depends on it.");
} else {
System.out.println("== Station.is_match == this should not happen");
}
}