From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <ee9e417a0609201320xe43c72ai4f7698476710ea39@mail.gmail.com>
Date: Wed, 20 Sep 2006 16:20:04 -0400
From: "Russ Cox" <rsc@swtch.com>
To: "Fans of the OS Plan 9 from Bell Labs" <9fans@cse.psu.edu>
Subject: Re: [9fans] awk: hex numbers? (and leak(1))
In-Reply-To: <82c890d00609200634u42901f17pb537f5b92a34c556@mail.gmail.com>
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References: <200609201034.k8KAY0w20632@zamenhof.cs.utwente.nl>
	<82c890d00609200634u42901f17pb537f5b92a34c556@mail.gmail.com>
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> define todec(str) {
>         hstr="1234567890ABDCEF";
>         res=0;
>         n=split(str,digit,"");
>
>         for(i=1;i<=n;i++) {
>                 num=index(hstr,digit[i])-1;
>                 res=res+(num*16^(n-i));
>          }
>
>         return res;
> }

Here's an alternate version.
Among other things my awk doesn't seem to know about "define".

BEGIN {
	for(i=0; i<16; i++)
		_unhex[sprintf("%x", i)] = _unhex[sprintf("%X", i)] = i
}

function unhex(s,  i, v) {
	v = 0
	for (i=1; i<=length(s); i++)
		v = v*16 + _unhex[substr(s,i,1)]
	return v
}

{print unhex($1)}

Russ