flat assembler - [Help] - Saving xmm register

Index > Main > [Help] - Saving xmm register

Author

Thread

ctl3d32

Joined: 30 Dec 2009
Posts: 206
Location: Brazil

ctl3d32 10 Jan 2011, 03:09

Hi Folks!

Need help to save xmm register state. Is it possible?

Something like:

Code:

push xmm3 ;save xmm3 value
stdcall something ;proc something will change xmm3 register value
pop xmm3 ;restore xmm3 value

Thanks in advance,
ctl3d32

10 Jan 2011, 03:09

idle

Joined: 06 Jan 2011
Posts: 440
Location: Ukraine

idle 10 Jan 2011, 07:15

Code:

movaps [esp] ;if destination aligned
movups [esp] ;if destination !aligned

10 Jan 2011, 07:15

ctl3d32

Joined: 30 Dec 2009
Posts: 206
Location: Brazil

ctl3d32 10 Jan 2011, 13:41

I can't do this:

Code:

proc LUsolve a,l,u
   locals
            lij dq ?
             i dd ?
             j dd ?
   endl
   mov     [i],1
   mov     [j],1
   stdcall getLij,[a],[l],[u],[i],[j]
   movsd   [lij],xmm0
   stdcall setMatrixElem,[l],[i],[j],lij
endp

Only works if lij is declared at .bss or .data section.

Code:

proc LUsolve a,l,u
   locals
             i dd ?
             j dd ?
   endl
   mov     [i],1
   mov     [j],1
   stdcall getLij,[a],[l],[u],[i],[j]
   movsd   [lij],xmm0
   stdcall setMatrixElem,[l],[i],[j],lij
endp

section '.bss' ...
align 16
lij dq ?

Why?

Thanks

10 Jan 2011, 13:41

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20303
Location: In your JS exploiting you and your system

revolution 12 Jan 2011, 08:13

ctl3d32 wrote:

I can't do this:

Code:

proc LUsolve a,l,u
   locals
            lij dq ?
             i dd ?
             j dd ?
   endl
   mov     [i],1
   mov     [j],1
   stdcall getLij,[a],[l],[u],[i],[j]
   movsd   [lij],xmm0
   stdcall setMatrixElem,[l],[i],[j],lij
endp

Only works if lij is declared at .bss or .data section.

Code:

proc LUsolve a,l,u
   locals
             i dd ?
             j dd ?
   endl
   mov     [i],1
   mov     [j],1
   stdcall getLij,[a],[l],[u],[i],[j]
   movsd   [lij],xmm0
   stdcall setMatrixElem,[l],[i],[j],lij
endp

section '.bss' ...
align 16
lij dq ?

Why?

Thanks

The reason is alignment. Use movupd to store to unaligned locations.

Also you need to use addr lij

Code:

stdcall setMatrixElem,[l],[i],[j],addr lij

12 Jan 2011, 08:13

ctl3d32

Joined: 30 Dec 2009
Posts: 206
Location: Brazil

ctl3d32 12 Jan 2011, 11:59

Can i make local variables aligned 16 like in .data or .bss section?

Thanks

12 Jan 2011, 11:59

edfed

Joined: 20 Feb 2006
Posts: 4330
Location: Now

edfed 12 Jan 2011, 12:27

yes, you can.

with align16 directive.

remember that every instructions and directives are designed to be alone, then, they can be inserted anywhere.

12 Jan 2011, 12:27

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20303
Location: In your JS exploiting you and your system

revolution 12 Jan 2011, 13:31

ctl3d32 wrote:

Can i make local variables aligned 16 like in .data or .bss section?

Thanks

Short answer: No.

Long answer: Yes, but ... it requires extra either 1) extra code at function entry to force stack alignment at runtime, or 2) your whole application must be made stack alignment compliant everywhere.

12 Jan 2011, 13:31

rugxulo

Joined: 09 Aug 2005
Posts: 2341
Location: Usono (aka, USA)

rugxulo 19 Jan 2011, 22:36

fxsave / fxrstor ??

19 Jan 2011, 22:36

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum