private static Statement ExpandComplex(Statement s)
{
if(s is Instruction)
{
Instruction src = s as Instruction;
// TODO: is it complex?
Instruction dest = new Instruction();
dest.op = src.op.ToLower();
dest.srca = src.srca;
dest.srcb = src.srcb;
dest.dest = src.dest;
return dest;
}
return s;
}
private static void ExpandComplex(Statement s, List<Statement> next_pass)
{
if(s is Instruction)
{
Instruction src = s as Instruction;
string op_lower = src.op.ToLower();
// is it complex?
if (op_lower == "jl")
{
/* Jump with link
add PC, 4->LR
j x
*/
Instruction new_1 = new Instruction();
new_1.cond = src.cond;
new_1.op = "add";
new_1.srca = new RegisterOperand { val = "PC" };
new_1.srcb = new IntegerOperand { val = 4 };
new_1.dest = new RegisterOperand { val = "LR" };
next_pass.Add(new_1);
Instruction new_2 = new Instruction();
new_2.cond = src.cond;
new_2.op = "j";
new_2.srca = src.srca;
next_pass.Add(new_2);
}
else if (op_lower == "jrel")
{
/* Relative jump
only valid if srca is a label/integer
-> mov x -> pc (which is interpreted as an add to pc)
*/
Expression new_srca = null;
if (src.srca is IntegerOperand)
new_srca = src.srca;
else if (src.srca is LabelExpression)
{
new_srca = src.srca;
((LabelExpression)new_srca).addend = -4;
((LabelExpression)new_srca).is_pcrel = true;
}
else if (src.srca is RegisterOperand)
{
var r_srca = src.srca as RegisterOperand;
if (regs.ContainsKey(r_srca.val.ToUpper()))
{
throw new Exception("jrel must have an integer or label operand");
}
new_srca = src.srca;
((LabelExpression)new_srca).addend = -4;
((LabelExpression)new_srca).is_pcrel = true;
}
Instruction new_1 = new Instruction();
new_1.cond = src.cond;
new_1.op = "mov";
new_1.srca = new_srca;
new_1.dest = new RegisterOperand { val = "PC" };
next_pass.Add(new_1);
}
else if (op_lower == "jlrel")
{
/* Relative jump with link
only valid if srca is a label/integer
-> add pc, 4 -> lr
mov x -> pc (which is interpreted as an add to pc)
*/
Expression new_srca = null;
if (src.srca is IntegerOperand)
new_srca = src.srca;
else if (src.srca is LabelExpression)
{
new_srca = src.srca;
((LabelExpression)new_srca).addend = -4;
((LabelExpression)new_srca).is_pcrel = true;
}
else if (src.srca is RegisterOperand)
{
var r_srca = src.srca as RegisterOperand;
if (regs.ContainsKey(r_srca.val.ToUpper()))
{
throw new Exception("jrel must have an integer or label operand");
}
new_srca = src.srca;
((LabelExpression)new_srca).addend = -4;
((LabelExpression)new_srca).is_pcrel = true;
}
Instruction new_1 = new Instruction();
new_1.cond = src.cond;
new_1.op = "add";
new_1.srca = new RegisterOperand { val = "PC" };
new_1.srcb = new IntegerOperand { val = 4 };
new_1.dest = new RegisterOperand { val = "LR" };
next_pass.Add(new_1);
Instruction new_2 = new Instruction();
new_2.cond = src.cond;
new_2.op = "mov";
new_2.srca = new_srca;
new_2.dest = new RegisterOperand { val = "PC" };
next_pass.Add(new_2);
}
else if (op_lower == "ret")
{
/* Return
j LR
*/
Instruction new_1 = new Instruction();
new_1.cond = src.cond;
new_1.op = "j";
new_1.srca = new RegisterOperand { val = "LR" };
next_pass.Add(new_1);
}
else if (op_lower == "push")
{
/* Push x
sub SP, 4 -> SP
store x, 4 -> SP
*/
Instruction new_1 = new Instruction();
new_1.cond = src.cond;
new_1.op = "sub";
new_1.srca = new RegisterOperand { val = "SP" };
new_1.srcb = new IntegerOperand { val = 4 };
new_1.dest = new RegisterOperand { val = "SP" };
next_pass.Add(new_1);
Instruction new_2 = new Instruction();
new_2.cond = src.cond;
new_2.op = "store";
new_2.srca = src.srca;
new_2.srcb = new IntegerOperand { val = 4 };
new_2.dest = new RegisterOperand { val = "SP" };
next_pass.Add(new_2);
}
else if (op_lower == "pop")
{
/* Pop x
load SP, 4 -> x
add SP, 4 -> SP
*/
Instruction new_1 = new Instruction();
new_1.cond = src.cond;
new_1.op = "load";
new_1.srca = new RegisterOperand { val = "SP" };
new_1.srcb = new IntegerOperand { val = 4 };
new_1.dest = src.srca;
next_pass.Add(new_1);
Instruction new_2 = new Instruction();
new_2.cond = src.cond;
new_2.op = "add";
new_2.srca = new RegisterOperand { val = "SP" };
new_2.srcb = new IntegerOperand { val = 4 };
new_2.dest = new RegisterOperand { val = "SP" };
next_pass.Add(new_2);
}
else
{
Instruction dest = new Instruction();
dest.op = op_lower;
dest.srca = src.srca;
dest.srcb = src.srcb;
dest.dest = src.dest;
dest.cond = src.cond;
next_pass.Add(dest);
}
}
else
next_pass.Add(s);
}