Re: [tlug] Assembly Language v C and Embedded Development: !gcc for PIC16F84

[Attila Kinali <attila@example.com>]

On Thu, 10 Mar 2011 19:13:59 +0900
Lewske Wada <ryu@example.com> wrote:

> How about
> 
> mov bx, ax
> shl bx, 3
> sub bx, ax
> 
> to get 7 times ax?

I'm actually not sure whether this is faster than a

mul ax, 7

on modern processors.
Please keep in mind that logic delay is virtually zero for
most functions, even complex ones like multiplies, while
codes like the one abve induce pipeline stals because the
result of the previous operation is used imediatly.


			Attila Kinali

-- 
It is the unknown we fear when we look
upon death and darkness, nothing more.
	-- Albus P. W. B. Dumbledore