C/C++ and Fortran

Vector gather-bits-by-bytes function "vec_gbb"

By Archive User posted Fri August 29, 2014 05:32 AM

  

Originally posted by: TracyR


In IBM XL C/C++ for Linux, V13.1, we support a vector built-in function vec_gbb that can perform a gather-bits-by-bytes operation on the input.
NOTE: This built-in function is valid only when -qarch is set to target POWER8™ processors.


Syntax
d=vec_gbb(a)

The following table describes the types of the function returned value "d" and the argument "a".

d

a

 

The same type as the argument a

vector unsigned long long

vector signed long long


Result value:
For example, let x(i) (0 <= i < 8) denote the byte elements of the corresponding input doubleword element, with x(7) representing the most significant byte.
Rules for each doubleword element of the result: for each pair of i and j (0 <= i < 8; 0 <= j < 8), the jth bit of the ith byte element of the result is set to the value of the ith bit of the jth byte element of the input.


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