Re: [FFmpeg-devel] [PATCH] ac3dsp: RISC-V V float_to_fixed24

From: flow gg <hlefthleft@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] ac3dsp: RISC-V V float_to_fixed24
Date: Wed, 22 Nov 2023 22:35:24 +0800
Message-ID: <CAEa-L+t_ugUHwBQXeMSmDLYf4xo=ZcB_JnBs5PypZ2Pn=nx+Fg@mail.gmail.com> (raw)
In-Reply-To: <CAEa-L+tkx5FDob+ppJ0jgJuoyobtbHfatCAygZGXReym+zQ0QA@mail.gmail.com>

qemu-riscv64 -cpu rv64,v=true,g=true,c=true,zba=true,vlen=128 checkasm
--test=ac3dsp

flow gg <hlefthleft@gmail.com> 于2023年11月22日周三 22:30写道：

> > How did you test it?
>
> I wrote a test, but it was a bit rough, so I want to modify it before
> submitting. I've added it to this reply.
>
> > This does not seem according to the C ABI. AFAIK `unsigned` is
> sign-extended.
>
> I'm a bit confused... because this passed in the tests I wrote in qemu.
> Maybe there's a problem with my test？
>
> > ALU right before dependent conditional branch should be avoided.
>
> Should the sub be moved forward? I've modified it.
>
> > SHxADD can be used advantageously.
>
> Okay, I've made the modification
>
> Rémi Denis-Courmont <remi@remlab.net> 于2023年11月22日周三 21:41写道：
>
>> Hi,
>>
>> How did you test it? As per
>> http://ffmpeg.org/pipermail/ffmpeg-devel/2023-June/310720.html we still
>> don't have a FATE instance set up with the RISC-V Vector extension. The
>> only testing consists of my manual runs of checkasm on a K230 board. (We
>> *do* have Zba and Zbb now though, hence the existing extract_exponents()).
>>
>> Also:
>> - This does not seem according to the C ABI. AFAIK `unsigned` is
>> sign-extended.
>> - ALU right before dependent conditional branch should be avoided.
>> - SHxADD can be used advantageously.
>>
>>
>> Le 22 novembre 2023 14:00:07 GMT+02:00, flow gg <hlefthleft@gmail.com> a
>> écrit :
>> >c910
>> >    float_to_fixed24_c: 208.2
>> >    float_to_fixed24_rvv_f32: 71.5
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