User Guide

128-Bit Media and Scientific Programming 147
24592—Rev. 3.15—November 2009 AMD64 Technology
The PADDUSB and PADDUSW instructions perform saturating-add operations analogous to the
PADDSB and PADDSW instructions, except on unsigned integer elements.
Subtraction.
• PSUBB—Packed Subtract Bytes
• PSUBW—Packed Subtract Words
• PSUBD—Packed Subtract Doublewords
• PSUBQ—Packed Subtract Quadword
• PSUBSB—Packed Subtract with Saturation Bytes
• PSUBSW—Packed Subtract with Saturation Words
• PSUBUSB—Packed Subtract Unsigned and Saturate Bytes
• PSUBUSW—Packed Subtract Unsigned and Saturate Words
The subtraction instructions perform operations analogous to the addition instructions.
The PSUBB, PSUBW, PSUBD, and PSUBQ instructions subtract each 8-bit (PSUBB), 16-bit
(PSUBW), 32-bit (PSUBD), or 64-bit (PSUBQ) integer element in the second operand from the
corresponding, same-sized integer element in the first operand and write the integer result to the
corresponding, same-sized element of the destination. For vectors of n number of elements, the
operation is:
operand1[i] = operand1[i] - operand2[i]
where: i = 0 to n – 1
These instructions operate on both signed and unsigned integers. However, if the result underflows, the
borrow is ignored and only the low-order byte, word, doubleword, or quadword of each result is
written to the destination.
The PSUBSB and PSUBSW instructions subtract each 8-bit (PSUBSB) or 16-bit (PSUBSW) signed
integer element in the second operand from the corresponding, same-sized signed integer element in
the first operand and write the signed integer result to the corresponding, same-sized element of the
destination. For each result in the destination, if the result is larger than the largest, or smaller than the
smallest, representable 8-bit (PSUBSB) or 16-bit (PSUBSW) signed integer, the result is saturated to
the largest or smallest representable value, respectively.
The PSUBUSB and PSUBUSW instructions perform saturating-add operations analogous to the
PSUBSB and PSUBSW instructions, except on unsigned integer elements.
Multiplication.
• PMULHW—Packed Multiply High Signed Word
• PMULLW—Packed Multiply Low Signed Word
• PMULHUW—Packed Multiply High Unsigned Word
• PMULUDQ—Packed Multiply Unsigned Doubleword and Store Quadword