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SSE in DOS under JEMM386 ?? (DOSX)

posted by Japheth Homepage, Germany (South), 10.01.2008, 17:19

> This is in contrast to
> Causeway/CW402's
> source:
>
> .586p
> mov        eax,1
> cpuid
> and       edx,3000000h    ; only want SSE and FXSR bit status
> cmp        edx,3000000h
> jne       nosse           ; both bits required
> mov       eax,cr0
> and    al,NOT 6        ; clear EM and MP bits
> mov     cr0,eax
> mov    eax,cr4
> or     ax,200h         ; set OSFXFR bit to allow SSE instructions
> mov cr4,eax


I tried it out today. Value of MP is irrelevant for SSE. EM must be cleared, though, else an Exc06 occurs. However, this bit is hardly set on any cpu running nowadays.

---
MS-DOS forever!

 

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