/**
* Writes the given instruction in assembly-code format.
*
* @param instr the instruction to display.
*/
private void writeInstruction(Instruction instr) {
String targetLabel = "***";
// get label of destination addr, if instr transfers control
if (instr.r == Machine.Reg.CB.ordinal()) targetLabel = addrToLabel.get(instr.d);
Machine.Op instruction = Machine.intToOp[instr.op];
asmWrite(String.format("%-7s", instruction.toString()));
switch (instruction) {
case LOAD:
blankN();
writeD(instr.d);
writeR('[', instr.r, ']');
break;
case LOADA:
blankN();
writeD(instr.d);
writeR('[', instr.r, ']');
break;
case LOADI:
break;
case LOADL:
blankN();
writeD(instr.d);
break;
case STORE:
blankN();
writeD(instr.d);
writeR('[', instr.r, ']');
break;
case STOREI:
break;
case CALL:
if (instr.r == Machine.Reg.PB.ordinal()) {
blankN();
writePrimitive(instr.d);
} else {
blankN();
asmWrite(targetLabel);
}
break;
case CALLI:
break;
case RETURN:
writeN(instr.n);
writeD(instr.d);
break;
case CALLD:
blankN();
writeD(instr.d);
break;
case PUSH:
blankN();
writeD(instr.d);
break;
case POP:
blankN();
writeD(instr.d);
break;
case JUMP:
blankN();
asmWrite(targetLabel);
break;
case JUMPI:
break;
case JUMPIF:
writeN(instr.n);
asmWrite(targetLabel);
break;
case HALT:
writeN(instr.n);
break;
default:
asmWrite("???? ");
writeN(instr.n);
writeD(instr.d);
writeR('[', instr.r, ']');
break;
}
}
/** disassembles program held in code store */
void disassembleProgram(String asmFileName) {
try {
asmOut = new FileWriter(asmFileName);
} catch (IOException e) {
System.out.println("Disassembler: can not create asm output file " + asmName);
error = true;
return;
}
// collect all addresses that may be the target of a jump instruction
SortedSet<Integer> targets = new TreeSet<Integer>();
for (int addr = Machine.CB; addr < Machine.CT; addr++) {
Instruction inst = Machine.code[addr];
Machine.Op op = Machine.intToOp[inst.op];
switch (op) {
case CALL:
// only consider calls (branches) within code memory (i.e. not primitives)
if (inst.r == Machine.Reg.CB.ordinal()) targets.add(inst.d);
break;
case JUMP:
// address following an unconditional branch is an implicit target
targets.add(addr + 1);
/* FALL THROUGH! */
case JUMPIF:
// a jump of any sort creates a branch target
targets.add(inst.d);
}
}
// map branch target addresses to unique labels
addrToLabel = new HashMap<Integer, String>();
int labelCounter = 10;
for (Integer addr : targets) {
String label = "L" + labelCounter++;
addrToLabel.put(addr, label);
}
// disassemble each instruction
for (int addr = Machine.CB; addr < Machine.CT; addr++) {
// generate instruction address
asmWrite(String.format("%3d ", addr));
// if this addr is a branch target, output label
if (addrToLabel.containsKey(addr))
asmWrite(String.format("%-7s", addrToLabel.get(addr) + ":"));
else asmWrite(" ");
// instruction
writeInstruction(Machine.code[addr]);
// newline
asmWrite("\n");
}
// close output file
try {
asmOut.close();
} catch (IOException e) {
error = true;
}
}
