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Date: Thu, 26 Dec 2013 22:41:00 -0500
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From: cherry <lunaria21@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: Re: [9fans] MIPS LE fp register ordering in MOVD
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On Thu, Dec 26, 2013 at 6:46 PM, cherry <lunaria21@gmail.com> wrote:

> Another issue is 0l/vl seems to output wrong bits for single precision
> floats in little endian mode, due to a similar reason: it used bytes 4-7
> instead of 0-3. This seems to fix it:
>
> % diff /sys/src/cmd/vl/asm.c asm.c
> 672c672,675
> <                     buf.dbuf[l] = cast[fnuxi8[i+4]];
> ---
> >                     if(little)
> >                         buf.dbuf[l] = cast[fnuxi8[i]];
> >                     else
> >                         buf.dbuf[l] = cast[fnuxi8[i+4]];
>
> An alternative fix would be simply use fnuxi4 instead of fnuxi8, so that
> both BE and LE would work (I guess, don't have BE machine to test).
>

Indeed I can test it, simply diff the output of vl before and after. Using,
fnuxi4 does NOT work for BE, as fnuxi4 is only set for LE
(obj.c:1385,1404), probably due to (the same or another) historical reason.

- cherry

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<div dir=3D"ltr"><br><div class=3D"gmail_extra"><br><br><div class=3D"gmail=
_quote">On Thu, Dec 26, 2013 at 6:46 PM, cherry <span dir=3D"ltr">&lt;<a hr=
ef=3D"mailto:lunaria21@gmail.com" target=3D"_blank">lunaria21@gmail.com</a>=
&gt;</span> wrote:<br>

<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex"><div dir=3D"ltr">Another issue is 0l/vl seem=
s to output wrong bits for single precision floats in little endian mode, d=
ue to a similar reason: it used bytes 4-7 instead of 0-3. This seems to fix=
 it:<br>

<br>% diff /sys/src/cmd/vl/asm.c asm.c<br>
672c672,675<br>&lt; =A0=A0=A0 =A0=A0=A0 =A0=A0=A0 =A0=A0=A0 =A0=A0=A0 buf.d=
buf[l] =3D cast[fnuxi8[i+4]];<br>---<br>&gt; =A0=A0=A0 =A0=A0=A0 =A0=A0=A0 =
=A0=A0=A0 =A0=A0=A0 if(little)<br>&gt; =A0=A0=A0 =A0=A0=A0 =A0=A0=A0 =A0=A0=
=A0 =A0=A0=A0 =A0=A0=A0 buf.dbuf[l] =3D cast[fnuxi8[i]];<br>&gt; =A0=A0=A0 =
=A0=A0=A0 =A0=A0=A0 =A0=A0=A0 =A0=A0=A0 else<br>&gt; =A0=A0=A0 =A0=A0=A0 =
=A0=A0=A0 =A0=A0=A0 =A0=A0=A0 =A0=A0=A0 buf.dbuf[l] =3D cast[fnuxi8[i+4]];<=
br>


<br>An alternative fix would be simply use fnuxi4 instead of fnuxi8, so tha=
t both BE and LE would work (I guess, don&#39;t have BE machine to test).</=
div></blockquote><div><br>Indeed I can test it, simply diff the output of v=
l before and after. Using, fnuxi4 does NOT work for BE, as fnuxi4 is only s=
et for LE (obj.c:1385,1404), probably due to (the same or another) historic=
al reason.<br>

<br>- cherry<br><br></div></div></div></div>

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