Packs information from each element of two vectors into the result vector, using saturated values.
Elemental function
If ARG1 is an INTEGER(2) vector or an UNSIGNED(2) vector, then the result is an UNSIGNED(1) vector. If ARG1 is an INTEGER(4) vector or an UNSIGNED(4) vector, then the result is an UNSIGNED(2) vector.
The value of each element of the result vector is the saturated value of the corresponding element of the result of concatenating ARG1 and ARG2.