Re: Shifts/Rotates: (cobweb-ridded) terminology clarification
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: Shifts/Rotates: (cobweb-ridded) terminology clarification
- From: Martin <eden_martin_fuhrspam@...>
- Date: 2017年5月15日 15:07:22 -0700
On 05/15/2017 03:31 AM, sur-behoffski wrote:
> This is a long message, so TL;DR:
>
> * Be careful to distinguish between LOGICAL shift right and ARITHMETIC
> shift right (assuming a twos-complement architecture).
>
> * Some of these machine-level operations are not natively available in
> "C89" (ANSI X3.159-1989) at the coder's level, although the
> compiler,
> the OS, and quite a number of associated libraries are likely to use
> them quite extensively internally. My understanding is that they
> can
> be emulated in Lua, although not as cheaply as directly executing
> native machine code.
>
Good post!
I think it'll benefit from mentioning related Intel microprocessor
instructions:
operation | left | right
-----------+------+-------
shift | SHL | SHR
.arithm | SAL | SAR
rotate | ROL | ROR
.via_carry| RCL | RCR
-- Martin