Compaq ECQD2KCTE Laptop User Manual


 
Instruction Descriptions 4–151
4.13 Multimedia (Graphics and Video) Support
Alpha provides the following instructions that enhance support for graphics and video
algorithms:
The MIN and MAX instructions allow the clamping of pixel values to maximium values that
are allowed in different standards and stages of the CODECs.
The PERR instruction accelerates the macroblock search in motion estimation.
The pack and unpack (PKxB and UNPKBx) instructions accelerate the blocking of interleaved
YUV coordinates for processing by the CODEC.
Implementation Note:
Alpha processors for which the AMASK instruction returns bit 8 set implement these
instructions. Those processors for which AMASK does not return bit 8 set can take an
Illegal Instruction trap, and software can emulate their function, if required.
Mnemonic Operation
MINUB8 Vector Unsigned Byte Minimum
MINSB8 Vector Signed Byte Minimum
MINUW4 Vector Unsigned Word Minimum
MINSW4 Vector Signed Word Minimum
MAXUB8 Vector Unsigned Byte Maximum
MAXSB8 Vector Signed Byte Maximum
MAXUW4 Vector Unsigned Word Maximum
MAXSW4 Vector Signed Word Maximum
PERR Pixel Error
PKLB Pack Longwords to Bytes
PKWB Pack Words to Bytes
UNPKBL Unpack Bytes to Longwords
UNPKBW Unpack Bytes to Words