how to call vcvtqq2ph?

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Gto

Joined: 26 Jul 2023
Posts: 1

Gto 31 Jul 2023, 14:45

I want to transform 2 quadword in 2 half float and did not find the instruction vcvtqq2ph in the .inc files, there is vcvtqq2ps and vcvtqq2pd in avx512dq.inc but not ph.

this is smy first post there is something i can do beter?

31 Jul 2023, 14:45

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20537
Location: In your JS exploiting you and your system

revolution 31 Jul 2023, 14:51

It appears to be a missing instruction.

https://www.felixcloutier.com/x86/vcvtqq2ph

31 Jul 2023, 14:51

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8367
Location: Kraków, Poland

Tomasz Grysztar 31 Jul 2023, 15:04

This is not an AVX512DQ instruction, it belongs to later AVX512-FP16 extension, and I have not implemented this one yet.

31 Jul 2023, 15:04

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20537
Location: In your JS exploiting you and your system

revolution 31 Jul 2023, 18:56

If my reading of rhe instruction format is correct then this macro might do the job.

Code:

macro vcvtqq2ph args& {
        local ..a,..x
   ..a: vcvtqq2ps args
        load ..x from ..a + 1
        store ..x or 4 at ..a + 1  ; set m2 to change to map5
}
        vcvtqq2ps xmm0,xmm1     ; 0x62,0xf1,0xfc,0x08,0x5b,0xc1
        vcvtqq2ph xmm0,xmm1     ; 0x62,0xf5,0xfc,0x08,0x5b,0xc1

vcvtqq2ph uses map5, so it appears to simply be a one bit change from vcvtqq2ps.

31 Jul 2023, 18:56

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