[파이썬] ror / rol 함수

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[파이썬] ror / rol 함수

Ally.Jin90 2016. 3. 16. 16:24

ROTATE_BITMASK = {
    8  : 0xff,
    16 : 0xffff,
    32 : 0xffffffff,
    64 : 0xffffffffffffffff,
}

# inVal 은 대상 값, numShifts 는 로테이트 할 수
# 예) ROR AL 1 
#      inVal : AL
#      numSHifts : 1
 
def ror(inVal, numShifts, dataSize=32):
    '''rotate right instruction emulation'''
    if numShifts == 0:
        return inVal
    if (numShifts < 0) or (numShifts > dataSize):
        raise ValueError('Bad numShifts')
    if (dataSize != 8) and (dataSize != 16) and (dataSize != 32) and (dataSize != 64):
        raise ValueError('Bad dataSize')
    bitMask = ROTATE_BITMASK[dataSize]
    return bitMask & ((inVal >> numShifts) | (inVal << (dataSize-numShifts)))

def rol(inVal, numShifts, dataSize=32):
    '''rotate left instruction emulation'''
    if numShifts == 0:
        return inVal
    if (numShifts < 0) or (numShifts > dataSize):
        raise ValueError('Bad numShifts')
    if (dataSize != 8) and (dataSize != 16) and (dataSize != 32) and (dataSize != 64):
        raise ValueError('Bad dataSize')
    bitMask = ROTATE_BITMASK[dataSize]
    currVal = inVal
    return bitMask & ((inVal << numShifts) | (inVal >> (dataSize-numShifts)))

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