SHIFTER BASED ON LEFT SHIFT STRUCTURE

摘要

PURPOSE: A shifter based on the left shift structure is provided to prevent the error occurring when the amounts of shifts and the numbers of input of the left and right shifts are not the same. CONSTITUTION: A shifter(100) based on left shift structure includes an input buffer(20), a MASK decoder(30), a MASK generator(40), a shift array(50), an output buffer(60), a scale element decoder(70) and an option decoder(50). Here, the shift array(50) has a structure only for left shifting. And the shifting occurs after all other operations such as MASK generation are finished. The MASK generator(40) forms patterns to fill the remaining bits after shifting. The option decoder(80) decodes a control signal used for choosing among patterns formed by the MASK generator(40). And an extra array(54) can be added to prevent shifting error when the amounts of shifting and the number of input are not the same.