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Instruction mmx - PSRAW/PSRAD—Packed Shift Right Arithmetic

Shifts the bits in the data elements (words or doublewords) in the destination operand (first operand) to the right by the amount of bits specified in the unsigned count operand (second operand). The result of the shift operation is written to the destination operand. The empty high-order bits of each element are filled with the initial value of the sign bit of the data element. If the value specified by the count operand is greater than 15 (for words) or 31 (for doublewords), each destination data element is filled with the initial value of the sign bit of the element. The destination operand must be an MMX technology register; the count operand (source operand) can be either an MMX technology register, a 64-bit memory location, or an 8-bit immediate. The PSRAW instruction shifts each of the four words in the destination operand to the right by the number of bits specified in the count operand; the PSRAD instruction shifts each of the two doublewords in the destination operand. As the individual data elements are shifted right, the empty high-order bit positions are filled with the sign value.