// FUNCTION:- execute RegAndImmShReg operand2
// - update field RmRegVal which contains the Rm register actual content value
public void execute_RegShReg()
{
// shift XReg by shiftNum accoding to shift type bits.
switch (shiftTypeUInt) // bits: 6 5
{
case 0:
shiftedRegUInt = BarrelShifter.lsl(RmRegVal, RsRegVal); // 0 0 = LSL
break;
case 1:
shiftedRegUInt = BarrelShifter.lsr(RmRegVal, RsRegVal); // 0 1 = LSR
break;
case 2:
shiftedRegUInt = BarrelShifter.asr(RmRegVal, RsRegVal); // 1 0 = ASR
break;
case 3:
/* if (_shiftNum == 0) TODO: this no supported for sim I
* XReg = BarrelShifter.lsl(XReg, this.shiftNum); // 1 1 = RRX
* else*/
shiftedRegUInt = BarrelShifter.ror(RmRegVal, RsRegVal); // 1 1 = ROR
break;
default:
Debug.WriteLine("ERROR in file 'Operand2' RegAndImmShReg.execute_Imm(): type is out of range.");
break;
}
//this.shiftedRegUInt = XReg;
// write back the copy into the register specified by Rm only if write back specified
// this.registers.updateRegisterN(this.Rm, XReg);
}
// FUNCTION:
// -Using instruction field update fields: rotNum, _8BitImmediate, rotatedImmediate
public void decode_Imm()
{
// update field rotNum
this.rotNum = (instruction >> 8) & 0xf;
// update field _8BitImmediate
this._8BitImmediate = instruction & 0xff;
// update field rotatedImmediate
this.rotatedImmediate = this._8BitImmediate;
this.rotatedImmediate = BarrelShifter.ror(this.rotatedImmediate, rotNum * 2); // rotate 8bit immediate in a 32 bit address
}