internal static void ForLoop(Instruction i, ILuaVM vm)
{
var(a, sBx) = i.AsBx();
a += 1;
// R(A)+=R(A+2)
vm.PushValue(a + 2);
vm.PushValue(a);
vm.Arith(ArithOp.Add);
vm.Replace(a);
// R(A)<?=R(A+1)
bool isPositiveStep = vm.ToNumber(a + 2) >= 0;
if ((isPositiveStep && vm.Compare(a, a + 1, CompareOp.Le)) ||
(!isPositiveStep && vm.Compare(a + 1, a, CompareOp.Le)))
{
vm.AddPC(sBx); // pc+=sBx
vm.Copy(a, a + 3); // R(A+3)=R(A)
}
}
private static void Compare(Instruction i, ILuaVM vm, CompareOp op)
{
var(a, b, c) = i.ABC();
vm.GetRK(b);
vm.GetRK(c);
if (vm.Compare(-2, -1, op) != (a != 0))
{
vm.AddPC(1);
}
vm.Pop(2);
}
/// <summary>
/// R(A) += R(A + 2)
/// if R(A) <?= R(A + 1) {
/// pc += sBx
/// R(A + 3) = R(A)
/// }
/// </summary>
public static void ForLoop(Instruction ins, ILuaVM vm)
{
ins.AsBx(out var a, out var sbx);
a += 1;
// R(A) += R(A + 2)
vm.PushValue(a + 2);
vm.PushValue(a);
vm.Arith(EArithOp.Add);
vm.Replace(a);
var isPositiveStep = vm.ToNumber(a + 2) >= 0;
if (isPositiveStep && vm.Compare(a, a + 1, ECompOp.Le) ||
!isPositiveStep && vm.Compare(a + 1, a, ECompOp.Le))
{
// pc += sBx
vm.AddPC(sbx);
// R(A + 3) = R(A)
vm.Copy(a, a + 3);
}
}
/// <summary>
/// if ((RK(B) op RK(C)) != A)
/// pc++
/// </summary>
private static void Compare(Instruction ins, ILuaVM vm, ECompOp op)
{
ins.ABC(out var a, out var b, out var c);
vm.GetRK(b);
vm.GetRK(c);
if (vm.Compare(-2, -1, op) != (a != 0))
{
vm.AddPC(1);
}
vm.Pop(2);
}
