Technical: Hardware: G4
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Vector Unpack High

vec_unpackh(arg1)

The operation forms halfwords or words in the result by sign-extending each high byte or halfword, respectively, of arg1.
In the case of the vector pixel argument type, words are formed in the result by unpacking the corresponding high pixel of the argument.
A vector pixel is a 1/5/5/5-encoded aRGB halfword. It is unpacked into a word by setting the bits of the most significant byte to the alpha channel bit, and by placing the 5 bits for red, green and blue into the low-order bits of the remaining bytes (see diagram below.)

Result

arg1

Maps To

vector signed short

vector signed char

vupkhsb

vector bool short

vector bool char

vupkhsb

vector unsigned long

vector pixel

vupkhpx

vector signed long

vector signed short

vupkhsh

vector bool long

vector bool short

vupkhsh

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Copyright © 2004 Apple Computer, Inc.
All rights reserved. | Terms of use | Privacy Notice