Patent ID: 6567832
Filing Date: 2003-05-20
Classification: G06F

Abstract:
An exponent preprocessing unit in an exponentiation device in which the exponent preprocessing unit preprocesses an n-bit exponent k and an operating unit exponentiates a base A by the preprocessed exponent k to compute Ak, the exponent preprocessing unit comprising:bit string storing means for storing a bit string including a sign bit and the exponent k; reading means for reading from the bit string storing means a bit pattern composed of the sign bit and a bit sequence made up of a predetermined number of bits, the predetermined number being smaller than n; bit pattern generating means for generating a new bit pattern based on the bit pattern read by the reading means; operation pattern specifying means for specifying an operation pattern to be applied to the base A, based on the read bit pattern; instructing and changing means for instructing the operating unit to perform an operation according to the operation pattern specified by the operation pattern specifying means, and changing the read bit pattern to the new bit pattern and writing the new bit pattern back into the bit string storing means in bit positions from which the bit pattern was read; read position setting means for having the reading means read a next bit sequence starting from a different bit in the bit string in the bit string storing means; and repeat controlling means for having the reading means, the bit pattern generating means, the operation pattern specifying means, the instructing and changing means, and the read position setting means sequentially repeat respective procedures thereof n+1 times.