Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1751

PSUBSB/PSUBSW—Packed Subtract with Saturation
Opcode
0F E8 /r
0F E9 /r
Description
Subtracts the individual signed data elements (bytes or words) of the source operand
(second operand) from the individual signed data elements of the destination operand
(first operand). (See
the specified data type, the result is saturated. The destination operand must be an
MMX technology register; the source operand can be either an MMX technology register
or a quadword memory location.
Figure 3-20.
mm
mm/m64
mm
The PSUBSB instruction subtracts the signed bytes of the source operand from the
signed bytes of the destination operand and stores the results to the destination
operand. When an individual result is beyond the range of a signed byte (that is,
greater than 7FH or less than 80H), the saturated byte value of 7FH or 80H,
respectively, is written to the destination operand.
The PSUBSW instruction subtracts the signed words of the source operand from the
signed words of the destination operand and stores the results to the destination
operand. When an individual result is beyond the range of a signed word (that is,
greater than 7FFFH or less than 8000H), the saturated word value of 7FFFH or 8000H,
respectively, is written to the destination operand.
®
Volume 4: IA-32 Intel MMX™ Technology Instruction Reference
Instruction
PSUBSB mm, mm/m64 Subtract signed packed bytes in mm/m64 from signed
PSUBSW mm, mm/m64 Subtract signed packed words in mm/m64 from signed
Figure 3-20.) If the result of a subtraction exceeds the range for
Operation of the PSUBSW Instruction
PSUBSW mm, mm/m64
–
Description
packed bytes in mm and saturate.
packed words in mm and saturate.
1000000000000000
– –
0000000000000001
1000000000000000
0111111100111000
–
1110100011111001
0111111111111111
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