Message-ID: <34F517C3.4190@post.comstar.ru>
Date: Thu, 26 Feb 1998 10:20:35 +0300
From: Dim Zegebart <zager AT post DOT comstar DOT ru>
Reply-To: zager AT post DOT comstar DOT ru
Organization: Comstar Ltd.
MIME-Version: 1.0
To: Javi <jap AT mundivia DOT es>
CC: DJGPP Mail List <djgpp AT delorie DOT com>
Subject: Re: Xpressions
References: <01bd41b1$f6ceb280$aeb537c3 AT omnia>
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Javi wrote:
> 
> Hi and thanks, but I don't know what does the '& 0x0f', what does it do? why
> do you get the offset with it.
> Thanks again

0x0f is hex notation of digit 15 or 00001111 in binary notation
Suppose you have 0x42 hex or 01000010 in binary notation
Lets look what '&' will do
0x0f & 0x42 
  00001111
& 01000010
----------
  00000010

This is socalled - 'masking'. 0x0f is a mask. Doing '&' with mask 0x0f
suppres all bits
in masked number exept last four ones.
 
-- 
____ ____ 
|   \   /   Dim Zegebart
____/____   

Moscow Russia
WWW - http://www.geocities.com/siliconvalley/pines/7817
DZcomm - comm library for Allegro
Palantir - multytasking kernel for Allegro (based on PDMLWP)