OpenEuphoria

Bit-shifting

• Posted by Robert Craig <robert_craig at COMPUSERVE.COM> May 04, 1997
• 841 views

Pete Eberlein writes:
> I would much rather be able to
>        integer SHR 1   -- shift right
>        integer SAR 1   -- shift arithmetic right  (keeps the sign)
> instead of using
>        floor(integer / 2)

Thanks for the suggestions about shift operators.
Maybe some day. But I just want to point out that
Euphoria already optimizes floor(integer/2) into
a single right-shift machine instruction (plus a few instructions
of overhead needed by any interpretive language).

In general, floor(integer1/integer2) does NOT use
a floating-point divide instruction. It performs a machine-level
integer divide. The compiler portion of Euphoria is smart enough
to see that divide of 2 integers is followed
immediately by floor, so it generates an intermediate-language
op-code that performs a machine-level integer divide, and
then there's no need for a separate "floor" operation at all.

Regards,
  Rob Craig
  Rapid Deployment Software