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Date: Thu, 10 May 2012 20:02:46 +0200
Message-ID: <CAHYJk3SgFybFyof4CdmTXxUOcuQZBMHOPFOwPq8TnG7CGrSdyw@mail.gmail.com>
Subject: Re: logical NOT
From: Mikael Magnusson <mikachu@gmail.com>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: zsh-users@zsh.org
Content-Type: text/plain; charset=UTF-8

On 10/05/2012, Bart Schaefer <schaefer@brasslantern.com> wrote:
> On May 10,  1:59pm, Mark van Dijk wrote:
> }
> } Then I wondered about how to let zsh "reverse" a binary number and came
> } up with the logical NOT: simply flip each bit.
>
> As others have noted, that gives you the number what might be described
> as "upside down", rather than backward.
>
> mac2bin() {
>   setopt localoptions extendedglob
>   print ${(l:8::0:)${${(s.:.)1}//(#b)(*)/$(([#2]$match))}#2\#}
> }
>
> reverse() {
>   setopt localoptions noksharrays
>   local i a
>   a=( ${(s::)*} )
>   for i in {$#a..1}; print -n -- $a[$i]
>   print
> }
>
> torch% mac2bin AC:DE:48:00:00:80
> 00000000 00000000 00110000 00000000 00000000 01010000
> torch% reverse $(mac2bin AC:DE:48:00:00:80)
> 00001010 00000000 00000000 00001100 00000000 00000000

Reverse can also be implemented more confusingly with Oa,
reverse() {
  setopt localoptions noksharrays
  print -r -- "${(j::)${(@Oa)${(s::)*}}}"
}
-- 
Mikael Magnusson