public static void Emulator(int initPC, int codeLen, int initSP,
InFile data, OutFile results, bool tracing)
{
// Emulates action of the codeLen instructions stored in mem[0 .. codeLen-1], with
// program counter initialized to initPC, stack pointer initialized to initSP.
// data and results are used for I/O. Tracing at the code level may be requested
int pcNow; // current program counter
int loop; // internal loops
int tos, sos; // value popped from stack
int adr; // effective address for memory accesses
stackBase = initSP;
heapBase = codeLen; // initialize boundaries
cpu.hp = heapBase; // initialize registers
cpu.sp = stackBase;
cpu.gp = stackBase;
cpu.mp = stackBase;
cpu.fp = stackBase;
cpu.pc = initPC; // initialize program counter
ps = running; // prepare to execute
int ops = 0;
timer.Start();
do {
ops++;
pcNow = cpu.pc; // retain for tracing/postmortem
if (cpu.pc < 0 || cpu.pc >= codeLen) {
ps = badAdr;
break;
}
cpu.ir = Next(); // fetch
if (tracing) Trace(results, pcNow);
switch (cpu.ir) { // execute
case PVM.nop: // no operation
break;
case PVM.dsp: // decrement stack pointer (allocate space for variables)
int localSpace = Next();
cpu.sp -= localSpace;
if (InBounds(cpu.sp)) // initialize
for (loop = 0; loop < localSpace; loop++)
mem[cpu.sp + loop] = 0;
break;
case PVM.ldc: // push constant value
Push(Next());
break;
case PVM.lda: // push local address
adr = cpu.fp - 1 - Next();
if (InBounds(adr)) Push(adr);
break;
case PVM.ldv: // dereference
Push(mem[Pop()]);
break;
case PVM.sto: // store
tos = Pop(); adr = Pop();
if (InBounds(adr)) mem[adr] = tos;
break;
case PVM.ldxa: // heap array indexing
adr = Pop();
int heapPtr = Pop();
if (heapPtr == 0) ps = nullRef;
else if (heapPtr < heapBase || heapPtr >= cpu.hp) ps = badMem;
else if (adr < 0 || adr >= mem[heapPtr]) ps = badInd;
else Push(heapPtr + adr + 1);
break;
case PVM.inpi: // integer input
adr = Pop();
if (InBounds(adr)) {
mem[adr] = data.ReadInt();
if (data.Error()) ps = badData;
}
break;
case PVM.prni: // integer output
if (tracing) results.Write(padding);
results.Write(Pop(), 0);
if (tracing) results.WriteLine();
break;
case PVM.inpb: // boolean input
adr = Pop();
if (InBounds(adr)) {
mem[adr] = data.ReadBool() ? 1 : 0;
if (data.Error()) ps = badData;
}
break;
case PVM.prnb: // boolean output
if (tracing) results.Write(padding);
if (Pop() != 0) results.Write(" true "); else results.Write(" false ");
if (tracing) results.WriteLine();
break;
case PVM.prns: // string output
if (tracing) results.Write(padding);
loop = Next();
while (ps == running && mem[loop] != 0) {
results.Write((char) mem[loop]); loop--;
if (loop < stackBase) ps = badMem;
}
if (tracing) results.WriteLine();
break;
case PVM.prnl: // newline
results.WriteLine();
break;
case PVM.neg: // integer negation
Push(-Pop());
break;
case PVM.add: // integer addition
tos = Pop(); Push(Pop() + tos);
break;
case PVM.sub: // integer subtraction
tos = Pop(); Push(Pop() - tos);
break;
case PVM.mul: // integer multiplication
tos = Pop(); Push(Pop() * tos);
break;
case PVM.div: // integer division (quotient)
tos = Pop(); Push(Pop() / tos);
break;
case PVM.rem: // integer division (remainder)
tos = Pop(); Push(Pop() % tos);
break;
case PVM.not: // logical negation
Push(Pop() == 0 ? 1 : 0);
break;
case PVM.and: // logical and
tos = Pop(); Push(Pop() & tos);
break;
case PVM.or: // logical or
tos = Pop(); Push(Pop() | tos);
break;
case PVM.ceq: // logical equality
tos = Pop(); Push(Pop() == tos ? 1 : 0);
break;
case PVM.cne: // logical inequality
tos = Pop(); Push(Pop() != tos ? 1 : 0);
break;
case PVM.clt: // logical less
tos = Pop(); Push(Pop() < tos ? 1 : 0);
break;
case PVM.cle: // logical less or equal
tos = Pop(); Push(Pop() <= tos ? 1 : 0);
break;
case PVM.cgt: // logical greater
tos = Pop(); Push(Pop() > tos ? 1 : 0);
break;
case PVM.cge: // logical greater or equal
tos = Pop(); Push(Pop() >= tos ? 1 : 0);
break;
case PVM.brn: // unconditional branch
cpu.pc = Next();
if (cpu.pc < 0 || cpu.pc >= codeLen) ps = badAdr;
break;
case PVM.bze: // pop top of stack, branch if false
int target = Next();
if (Pop() == 0) {
cpu.pc = target;
if (cpu.pc < 0 || cpu.pc >= codeLen) ps = badAdr;
}
break;
case PVM.anew: // heap array allocation
int size = Pop();
if (size <= 0 || size + 1 > cpu.sp - cpu.hp - 2)
ps = badAll;
else {
mem[cpu.hp] = size;
Push(cpu.hp);
cpu.hp += size + 1;
}
break;
case PVM.halt: // halt
ps = finished;
break;
case PVM.stk: // stack dump (debugging)
StackDump(results, pcNow);
break;
case PVM.heap: // heap dump (debugging)
HeapDump(results, pcNow);
break;
case PVM.ldc_0: // push constant 0
case PVM.ldc_1: // push constant 1
case PVM.ldc_2: // push constant 2
case PVM.ldc_3: // push constant 3
case PVM.lda_0: // push local address 0
case PVM.lda_1: // push local address 1
case PVM.lda_2: // push local address 2
case PVM.lda_3: // push local address 3
case PVM.ldl: // push local value
case PVM.ldl_0: // push value of local variable 0
case PVM.ldl_1: // push value of local variable 1
case PVM.ldl_2: // push value of local variable 2
case PVM.ldl_3: // push value of local variable 3
case PVM.stl: // store local value
case PVM.stlc: // store local value
case PVM.stl_0: // pop to local variable 0
case PVM.stl_1: // pop to local variable 1
case PVM.stl_2: // pop to local variable 2
case PVM.stl_3: // pop to local variable 3
case PVM.stoc: // character checked store
case PVM.inpc: // character input
case PVM.prnc: // character output
case PVM.low: // toLowerCase
case PVM.islet: // isLetter
case PVM.inc: // ++
case PVM.dec: // --
default: // unrecognized opcode
ps = badOp;
break;
}
} while (ps == running);
TimeSpan ts = timer.Elapsed;
// Format and display the TimeSpan value.
string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}",
ts.Hours, ts.Minutes, ts.Seconds,
ts.Milliseconds / 10);
Console.WriteLine("\n\n" + ops + " operations. Run Time " + elapsedTime + "\n\n");
if (ps != finished) PostMortem(results, pcNow);
timer.Reset();
timer.Stop();
}
// The interpreters and utility methods
public static void Emulator(int initPC, int codeLen, int initSP,
InFile data, OutFile results, bool tracing)
{
// Emulates action of the codeLen instructions stored in mem[0 .. codeLen-1], with
// program counter initialized to initPC, stack pointer initialized to initSP.
// data and results are used for I/O. Tracing at the code level may be requested
int pcNow; // current program counter
int loop; // internal loops
int tos, sos; // value popped from stack
stackBase = initSP;
heapBase = codeLen; // initialize boundaries
cpu.hp = heapBase; // initialize registers
cpu.sp = stackBase;
cpu.gp = stackBase;
cpu.mp = stackBase;
cpu.fp = stackBase;
cpu.pc = initPC; // initialize program counter
ps = running; // prepare to execute
int ops = 0;
timer.Start();
do {
ops++;
pcNow = cpu.pc; // retain for tracing/postmortem
cpu.ir = mem[cpu.pc++]; // fetch
// if (tracing) Trace(results, pcNow);
switch (cpu.ir) { // execute
case PVM.nop: // no operation
break;
case PVM.dsp: // decrement stack pointer (allocate space for variables)
cpu.sp -= mem[cpu.pc++];
break;
case PVM.ldc: // push constant value
mem[--cpu.sp] = mem[cpu.pc++];
break;
case PVM.lda: // push local address
mem[--cpu.sp] = cpu.fp - 1 - mem[cpu.pc++];
break;
case PVM.ldv: // dereference
mem[cpu.sp] = mem[mem[cpu.sp]];
break;
case PVM.sto: // store
tos = mem[cpu.sp++]; mem[mem[cpu.sp++]] = tos;
break;
case PVM.ldxa: // heap array indexing
tos = mem[cpu.sp++]; mem[cpu.sp] = mem[cpu.sp] + tos;
break;
case PVM.inpi: // integer input
mem[mem[cpu.sp++]] = data.ReadInt();
break;
case PVM.prni: // integer output
// if (tracing) results.Write(padding);
results.Write(mem[cpu.sp++], 0);
// if (tracing) results.WriteLine();
break;
case PVM.inpb: // boolean input
mem[mem[cpu.sp++]] = data.ReadBool() ? 1 : 0;
break;
case PVM.prnb: // boolean output
// if (tracing) results.Write(padding);
if (mem[cpu.sp++] != 0) results.Write(" true "); else results.Write(" false ");
// if (tracing) results.WriteLine();
break;
case PVM.prns: // string output
// if (tracing) results.Write(padding);
loop = mem[cpu.pc++];
while (mem[loop] != 0) {
results.Write((char) mem[loop]); loop--;
}
// if (tracing) results.WriteLine();
break;
case PVM.prnl: // newline
results.WriteLine();
break;
case PVM.neg: // integer negation
mem[cpu.sp] = -mem[cpu.sp];
break;
case PVM.add: // integer addition
tos = mem[cpu.sp++]; mem[cpu.sp] += tos;
break;
case PVM.sub: // integer subtraction
tos = mem[cpu.sp++]; mem[cpu.sp] -= tos;
break;
case PVM.mul: // integer multiplication
tos = mem[cpu.sp++]; mem[cpu.sp] *= tos;
break;
case PVM.div: // integer division (quotient)
tos = mem[cpu.sp++]; mem[cpu.sp] /= tos;
break;
case PVM.rem: // integer division (remainder)
tos = mem[cpu.sp++]; mem[cpu.sp] %= tos;
break;
case PVM.not: // logical negation
mem[cpu.sp] = mem[cpu.sp] == 0 ? 1 : 0;
break;
case PVM.and: // logical and
tos = mem[cpu.sp++]; mem[cpu.sp] &= tos;
break;
case PVM.or: // logical or
tos = mem[cpu.sp++]; mem[cpu.sp] |= tos;
break;
case PVM.ceq: // logical equality
tos = mem[cpu.sp++]; mem[cpu.sp] = mem[cpu.sp] == tos ? 1 : 0;
break;
case PVM.cne: // logical inequality
tos = mem[cpu.sp++]; mem[cpu.sp] = mem[cpu.sp] != tos ? 1 : 0;
break;
case PVM.clt: // logical less
tos = mem[cpu.sp++]; mem[cpu.sp] = mem[cpu.sp] < tos ? 1 : 0;
break;
case PVM.cle: // logical less or equal
tos = mem[cpu.sp++]; mem[cpu.sp] = mem[cpu.sp] <= tos ? 1 : 0;
break;
case PVM.cgt: // logical greater
tos = mem[cpu.sp++]; mem[cpu.sp] = mem[cpu.sp] > tos ? 1 : 0;
break;
case PVM.cge: // logical greater or equal
tos = mem[cpu.sp++]; mem[cpu.sp] = mem[cpu.sp] >= tos ? 1 : 0;
break;
case PVM.brn: // unconditional branch
cpu.pc = mem[cpu.pc++];
break;
case PVM.bze: // pop top of stack, branch if false
int target = mem[cpu.pc++];
if (mem[cpu.sp++] == 0) cpu.pc = target;
break;
case PVM.anew: // heap array allocation
int size = mem[cpu.sp];
mem[cpu.sp] = cpu.hp;
cpu.hp += size;
break;
case PVM.halt: // halt
ps = finished;
break;
case PVM.stk: // stack dump (debugging)
StackDump(results, pcNow);
break;
case PVM.heap: // heap dump (debugging)
HeapDump(results, pcNow);
break;
case PVM.ldc_0: // push constant 0
case PVM.ldc_1: // push constant 1
case PVM.ldc_2: // push constant 2
case PVM.ldc_3: // push constant 3
case PVM.lda_0: // push local address 0
case PVM.lda_1: // push local address 1
case PVM.lda_2: // push local address 2
case PVM.lda_3: // push local address 3
case PVM.ldl: // push local value
case PVM.ldl_0: // push value of local variable 0
case PVM.ldl_1: // push value of local variable 1
case PVM.ldl_2: // push value of local variable 2
case PVM.ldl_3: // push value of local variable 3
case PVM.stl: // store local value
case PVM.stlc: // store local value
case PVM.stl_0: // pop to local variable 0
case PVM.stl_1: // pop to local variable 1
case PVM.stl_2: // pop to local variable 2
case PVM.stl_3: // pop to local variable 3
case PVM.stoc: // character checked store
case PVM.inpc: // character input
case PVM.prnc: // character output
case PVM.low: // toLowerCase
case PVM.islet: // isLetter
case PVM.inc: // ++
case PVM.dec: // --
default: // unrecognized opcode
ps = badOp;
break;
}
} while (ps == running);
TimeSpan ts = timer.Elapsed;
// Format and display the TimeSpan value.
string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}",
ts.Hours, ts.Minutes, ts.Seconds,
ts.Milliseconds / 10);
Console.WriteLine("\n\n" + ops + " operations. Run Time " + elapsedTime + "\n\n");
if (ps != finished) PostMortem(results, pcNow);
timer.Reset();
timer.Stop();
}