=== IDISA Expansion Operations ===
The IDISA expansion operations produce vectors of 2''w'' bit fields
by operations on input vectors of ''w'' bit fields. Let ''N'' = ''W''/''w''
be the number of ''w'' bit fields in an input vector.
== Binary Expansion Operations ==
|| `mergeh(a, b)` || merge the high ''N''/2 fields of `a` and `b` ||
|| `mergel(a, b)` || merge the low ''N''/2 fields of `a` and `b` ||
|| `multh(a, b)` || multiply the high ''N''/2 fields of `a` and `b` ||
|| `multll(a, b)` || multiply the low ''N''/2 fields of `a` and `b` ||
== Unary Expansion Operations ==
|| `signextendh(a)` || sign-extend the high ''N''/2 fields of `a` ||
|| `signextendl(a)` || sign-extend the low ''N''/2 fields of `a` ||
|| `zeroextendh(a)` || zero-extend the high ''N''/2 fields of `a` ||
|| `zeroextendl(a)` || zero-extend the low ''N''/2 fields of `a` ||