Technical: Hardware: G4
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Vector Unpack Low

vec_unpackl(arg1)

The operation forms halfwords or words in the result by sign-extending each low 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 low 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

vupklsb

vector bool short

vector bool char

vupklsb

vector unsigned long

vector pixel

vupklpx

vector signed long

vector signed short

vupklsh

vector bool long

vector bool short

vupklsh

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