SSE or AVX convert float to string.

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Roman

Joined: 21 Apr 2012
Posts: 1617

Roman 18 Sep 2020, 08:40

I looking example convert float dd 1.0 or float dq 1.0 to asc2 string.

18 Sep 2020, 08:40

Roman

Joined: 21 Apr 2012
Posts: 1617

Roman 18 Sep 2020, 09:52

I try do this AVX in fasm 1.73. Code compiled but crash. My CPU Intel I5 2320

Code:

align 16
Abss dq 1.0,2.0,2.0,2.0
Start:
vcvtps2dq       ymm0, YWORD [Abss] ;ok
vpxor   xmm1, xmm1, xmm1             ;ok
vpackssdw       ymm0, ymm0, ymm1 ;this crash my program
vpermq  ymm0, ymm0, 216              ;this crash my program

This not crash

Code:

vpackssdw       xmm0, xmm0, xmm1

18 Sep 2020, 09:52

Furs

Joined: 04 Mar 2016
Posts: 2340

Furs 18 Sep 2020, 13:23

Your CPU only supports AVX, not AVX2. You can't use ymm registers. (the first one is probably treated as xmm0 or whatever by your CPU).

18 Sep 2020, 13:23

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8263
Location: Kraków, Poland

Tomasz Grysztar 18 Sep 2020, 18:52

Furs wrote:

Your CPU only supports AVX, not AVX2. You can't use ymm registers. (the first one is probably treated as xmm0 or whatever by your CPU).

AVX2 is not a requirement to use 256-bit registers (ymm). But AVX2 is needed for VPERMQ and a 256-bit variant of VPACKSSDW to be available.

You can test this with fasmg's instruction set packages:

Code:

        include 'align.inc'
        include 'cpu/x64.inc'

        include 'cpu/ext/avx.inc'
        ;include 'cpu/ext/avx2.inc'     ; try switching this

align 16
Abss dq 1.0,2.0,2.0,2.0
Start:
vcvtps2dq       ymm0, YWORD [Abss]
vpxor   xmm1, xmm1, xmm1            
vpackssdw       ymm0, ymm0, ymm1 
vpermq  ymm0, ymm0, 216

Code:

>fasmg test.asm -e10
flat assembler  version g.j1gh
test.asm [13]:
        vpackssdw ymm0, ymm0, ymm1
macro vpackssdw [1] macro basic_instruction [6]
Custom error: invalid operand size.
test.asm [14]:
        vpermq ymm0, ymm0, 216
Processed: vpermq ymm0, ymm0, 216
Error: illegal instruction.

18 Sep 2020, 18:52

Overclick

Joined: 11 Jul 2020
Posts: 635
Location: Ukraine

Overclick 25 Sep 2020, 17:28

Isn't fistp enough for that?

25 Sep 2020, 17:28

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