//See general definition in parent(Instruction)
public override void DecodeInst()
{
cond = Memory.ExtractBits(Inst, 0, 3);
typ = Memory.ExtractBits(Inst, 4, 6);
bit7 = Memory.ExtractBits(Inst, 24, 24);
bit4 = Memory.ExtractBits(Inst, 27, 27);
if (typ == 0 && bit7 == 1 && bit4 == 1)
{
opcode = 0x10; //for convenience, I suppose.
Rd = Memory.ExtractBits(Inst, 12, 15);
Rs = Memory.ExtractBits(Inst, 20, 23);
Rm = Memory.ExtractBits(Inst, 28, 31);
}
else
{
regimm = Convert.ToBoolean(Memory.ExtractBits(typ, 31, 31)); //true == 1; false = 0;
opcode = Memory.ExtractBits(Inst, 7, 10);
sbit = Convert.ToBoolean(Memory.ExtractBits(Inst, 11, 11)); //same as regimm;
Rn = Memory.ExtractBits(Inst, 12, 15);
Rd = Memory.ExtractBits(Inst, 16, 19);
Oper2 = Operand2.GetOper2(regimm, Memory.ExtractBits(Inst, 20, 31));
Oper2.Oper2Regs = I_Reg;
}
}
//Update flags after Rn - shifter_operand
public override void Execute(uint Rn, uint Rd, Operand2 oper2)
{
uint rnval = (uint)CPU.GetRegr(I_Reg, (int)Rn), op2val = (uint)oper2.GetValue();
int val = (int)(rnval - op2val);
uint N = Memory.ExtractBits((uint)val, 0, 0);
int Z = val == 0 ? 1 : 0;
int C = op2val <= rnval ? 1 : 0; //May not be correctly handling C flag will need to modify
int rnv = (int)rnval, op2v = (int)op2val;
val = rnv - op2v;
int V = (rnv > 0 && op2v < 0 && val < 0) || (rnv < 0 && op2v > 0 && val > 0) ? 1 : 0;
bool[] flags = { Convert.ToBoolean(N), Convert.ToBoolean(Z), Convert.ToBoolean(C), Convert.ToBoolean(V) };
for (int i = 0; i < 4; ++i)
{
I_Reg.SetFlag(4 * 16, i, flags[i]);
}
}
//Rd := shifter_operand (no Rn)
public override void Execute(uint Rn, uint Rd, Operand2 oper2)
{
CPU.SetReg(I_Reg, (int)Rd, oper2.GetValue());
int mode = (int)Memory.ExtractBits((uint)CPU.GetRegr(I_Reg, 16), 27, 31);
if (sbit && Rd == 15)
{
int spsr = CPU.GetRegr(I_Reg, 16);
if (mode == 0b10010)
{
spsr = CPU.GetRegr(I_Reg, 19); //because I had to place them weirdly.
//CPU.SetReg(I_Reg, (int)Rd, oper2.GetValue() - 4); //adjust the LR for the PC when IRQ
}
else if (mode == 0b10011)
{
spsr = CPU.GetRegr(I_Reg, 22);
}
CPU.SetReg(I_Reg, 16, spsr);
}
}
//override for execute which all subclasses, except for MUL, use.
public virtual void Execute(uint Rn, uint Rd, Operand2 oper2)
{
;
}
//Rd := Rn AND NOT(shifter_operand)
public override void Execute(uint Rn, uint Rd, Operand2 oper2)
{
int val = CPU.GetRegr(I_Reg, (int)Rn) & (~oper2.GetValue());
CPU.SetReg(I_Reg, (int)Rd, val);
}
//Rd := NOT shifter_operand (no Rn)
public override void Execute(uint Rn, uint Rd, Operand2 oper2)
{
CPU.SetReg(I_Reg, (int)Rd, ~oper2.GetValue());
}