Sse roundss how get low parts?

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Roman

Joined: 21 Apr 2012
Posts: 1792

Roman 24 Apr 2023, 09:51

Xmm1= 4.982
I want get 0.982

But I try this

Code:

 
;xmm1 = 4.982 
roundss xmm1, xmm1, 1
;do xmm1 = 4.0

Yes I could do 4.982-4 and get 0.982

But roundss not have this variant to get number after point ?
I don't want do 3 asm commands, I expected do one roundss and get watch I want.

24 Apr 2023, 09:51

macomics

Joined: 26 Jan 2021
Posts: 949
Location: Russia

macomics 24 Apr 2023, 15:27

fxtract

24 Apr 2023, 15:27

Roman

Joined: 21 Apr 2012
Posts: 1792

Roman 24 Apr 2023, 15:31

Easy write three sse commands.
Fpu three too

fld value
fxtract
fstp outmem

Strange why roundss not have option as fxtract ?

24 Apr 2023, 15:31

macomics

Joined: 26 Jan 2021
Posts: 949
Location: Russia

macomics 24 Apr 2023, 16:39

Because round <> extract

24 Apr 2023, 16:39

Roman

Joined: 21 Apr 2012
Posts: 1792

Roman 24 Apr 2023, 19:28

But it could be Smile

24 Apr 2023, 19:28

bitRAKE

Joined: 21 Jul 2003
Posts: 4039
Location: vpcmpistri

bitRAKE 24 Apr 2023, 22:14

Did you try ...

Code:

;xmm0 = 4.982
roundss xmm1, xmm0, 0x3 ; truncate
subss xmm0, xmm1
;do xmm0 = 0.982

... or maybe I misunderstand?
(roundss is all about the integer part, it only helps with fractional part through subtraction)

_________________
¯\(°_o)/¯ “languages are not safe - uses can be” Bjarne Stroustrup

24 Apr 2023, 22:14

Roman

Joined: 21 Apr 2012
Posts: 1792

Roman 25 Apr 2023, 02:45

Yes i do this.

25 Apr 2023, 02:45

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