From mboxrd@z Thu Jan  1 00:00:00 1970
From: Laurent Vivier <lvivier@redhat.com>
Date: Thu, 03 Mar 2016 13:02:01 +0000
Subject: Re: [kvm-unit-tests PATCH] powerpc: Add tests for RTAS
Message-Id: <56D835C9.5060506@redhat.com>
List-Id: <kvm-ppc.vger.kernel.org>
References: <1457008099-29944-1-git-send-email-lvivier@redhat.com>
 <56D831E5.2030604@redhat.com>
In-Reply-To: <56D831E5.2030604@redhat.com>
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To: Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org
Cc: drjones@redhat.com, thuth@redhat.com, dgibson@redhat.com



On 03/03/2016 13:45, Paolo Bonzini wrote:
> 
> 
> On 03/03/2016 13:28, Laurent Vivier wrote:
>> +
>> +#define DAYS(y,m,d) (365UL * (y) + ((y) / 4) - ((y) / 100) + ((y) / 400) + \
>> +		     367UL * (m) / 12  + \
> 
> Out of curiosity, where did you take this from?  I knew the variant with
> 2447/80 instead of 367/12, but they give the same result, as checked
> with bc:

Some ideas from:
http://www.cantab.net/users/michael.behrend/algorithms/easter/pages/main.html

30*m + (7*(m+1) / 12)

reduced into

(360m + 7m + 7)/12 -> 367m/12

Laurent

> $ bc
> for (n=1;n<;n++)2447*n/80-367*n/12;
> 0
> 0
> 0
> 0
> 0
> 0
> 0
> 0
> 0
> 0
> 0
> 0
> 
> Paolo
> 
>> +		     (d))
>> +