/* put things on the bus */
public void ClockCycleWrite(int clock) {
if (StatusChanged) ALUopstart = clock;
/* see if we can assert the result yet */
if (clock == ALUopstart + 60) {
int op;
long rightop = Rt_ALU;
if (!IRALU) /* ALUop from IR */ op = ir.getALUop();
else /* ALUop from microcode */ {
rightop = ALU_PLUS2 ? 2 : Rt_ALU;
op = MC_op;
}
/* do the operations: */
switch (op) {
default:
case 0: /* nop */
ALUresult = 0;
break;
case 1:
ALUresult = Lt_ALU + rightop;
break;
case 2:
ALUresult = Lt_ALU - rightop;
break;
case 3:
ALUresult = Lt_ALU & rightop;
break;
case 4:
ALUresult = Lt_ALU | rightop;
break;
case 5:
ALUresult = Lt_ALU ^ rightop;
break;
case 6:
ALUresult = (0xfffff) ^ rightop;
break;
}
/* set SR as appropriate. */
if (!sr.getSHFALU() && sr.getW_SR12()) {
sr.setSR1(ALUresult > 0);
sr.setSR2(ALUresult < 0);
}
ALUopstart = 0;
}
/* read from internal register */
if (R_ALU) {
if (W_LALU || (W_RALU && !ALU_PLUS2))
throw new IllegalOperation("Writing to ALU registers while reading ALU output");
bus.setValue(ALUresult);
}
}
