APPARATUS AND METHOD FOR SHIFTING PACKED QUADWORDS AND EXTRACTING PACKED WORDS

摘要

An apparatus and method for performing left-shifting operations on packed quadword data. For example, one embodiment of a processor comprises: a decoder to decode a left-shift instruction to generate a decoded left-shift instruction; a first source register to store a plurality of packed quadword data elements, each of the packed quadword data elements including a sign bit; execution circuitry to execute the decoded left-shift instruction, the execution circuitry comprising shift circuitry with sign preservation logic to left-shift first and second packed quadword data elements from first and second packed quadword data element locations, respectively, in the first source register by an amount specified in an immediate value or in a control value in a second source register, the left-shifting to generate first and second left-shifted quadwords, the shift circuitry to write zeroes into bit positions exposed by the left-shifting of the packed quadword data elements; the sign preservation logic to maintain a copy of the sign bit while the shift circuitry performs the left-shift operations; the execution circuitry to cause selection of 16 most significant bits of the first and second left-shifted quadwords, including the sign bit, to be written to 16 least significant bit regions of first and second quadword data element locations, respectively, of a destination register, writing the sign bit to the most significant bit position of each 16 least significant bit region.