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Groups > comp.lang.c++ > #84455
| From | Bonita Montero <Bonita.Montero@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c++, comp.lang.c, de.comp.lang.c |
| Subject | Re: Fast trunc() algorithm |
| Date | 2022-06-02 04:43 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <t7983b$ufs$1@dont-email.me> (permalink) |
| References | <t6va0v$eno$1@dont-email.me> <t742o0$pha$1@dont-email.me> <t782sg$qa4$1@dont-email.me> |
Cross-posted to 3 groups.
There's even a simpler way with SSE 4.1:
inline double ftrunc( double d )
{
__m128d mm;
mm.m128d_f64[0] = d;
_mm_round_sd( mm, mm, _MM_FROUND_FLOOR );
return mm.m128d_f64[0];
}
inline double ftrunc( float f )
{
__m128 mm;
mm.m128_f32[0] = f;
_mm_round_ss( mm, mm, _MM_FROUND_FLOOR );
return mm.m128_f32[0];
}
With that a simple double trunc() 11.6 times faster on my CPU.
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Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-05-29 10:14 +0200
Re: Fast trunc() algorithm Muttley@dastardlyhq.com - 2022-05-29 08:21 +0000
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-05-29 10:29 +0200
Re: Fast trunc() algorithm Freethinker <freethinker@mymail.com> - 2022-05-29 15:20 +0200
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-05-29 15:27 +0200
Re: Fast trunc() algorithm Freethinker <freethinker@mymail.com> - 2022-05-29 15:37 +0200
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-05-29 15:46 +0200
Re: Fast trunc() algorithm John McCue <jmccue@magnetar.hsd1.ma.comcast.net> - 2022-05-29 21:32 +0000
Re: Fast trunc() algorithm Christian Gollwitzer <auriocus@gmx.de> - 2022-05-29 23:36 +0200
Re: Fast trunc() algorithm Juha Nieminen <nospam@thanks.invalid> - 2022-05-30 06:22 +0000
Re: Fast trunc() algorithm David Brown <david.brown@hesbynett.no> - 2022-05-30 08:59 +0200
Re: Fast trunc() algorithm muttley@dastardlyhq.com - 2022-05-30 07:52 +0000
Re: Fast trunc() algorithm Paavo Helde <eesnimi@osa.pri.ee> - 2022-05-30 11:58 +0300
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-05-30 11:32 +0200
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-05-30 11:34 +0200
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-05-31 05:41 +0200
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-06-01 18:07 +0200
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-06-01 18:09 +0200
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-06-02 04:43 +0200
Re: Fast trunc() algorithm jak <nospam@please.ty> - 2022-06-02 07:44 +0200
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-06-02 08:14 +0200
Re: Fast trunc() algorithm jak <nospam@please.ty> - 2022-06-02 11:14 +0200
Re: Fast trunc() algorithm Bonita Montero <Bonita.Montero@gmail.com> - 2022-06-02 12:48 +0200
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