🚀 go-pugleaf

JRS:  In article <7naolk$5j$1@nnrp1.deja.com> of Fri, 23 Jul 1999
22:00:23 in news:comp.lang.pascal.borland, Robert AH Prins
<prinsra@williscorroon.com> wrote:
>
>Does anyone know, short of what I've done now, adding a constant with
>the required shift value, if there is a way to get the base-2 log of
>sizes of datastructures in BASM. (Obviously restricted to sizes that are
>powers of 2...)

I don't know enough (any) BASM - however :

You _want_ to arrange that the shift count will automatically be
correct, for the *easy* subsequent avoidance of error.

If that cannot be contrived, it *may* be possible to define the log as a
source-code constant, and arrange that assembly fails if the constant is
incorrect, thereby giving *reliable* avoidance of error, which will
suffice.  I've done this in Pascal/Delphi.  Perhaps you can use not a
log2 but a pow2, with some equivalent of
        const A = <log2?> ;
        B = 1 shl A ;
then    C = 1 div (Size-B) ;
or      type Ar = array [B..Size, Size..B] of byte ;

Or, maybe, some equivalent of
        const X = SizeOf(SizedType) ;
        A = <log2?> ;
...
        if X shr A <> 1 then HALT(234) ;
so that, if wrong, the program will fail immediately on test with a
specific message.


Note : you crossposted between "publicly" and "privately" owned
newsgroups.  I *think* that this reply will go only to public servers,
and be missed by TeamB.
 
-- 
 � John Stockton, Surrey, UK.  jrs@merlyn.demon.co.uk   Turnpike v4.00   MIME. �
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