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Index > Main > Bug Report: fstenv

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madmatt



Joined: 07 Oct 2003
Posts: 1045
Location: Michigan, USA
madmatt
Having problems with fstenv instruction using local variables for storage, when I do this:

local fpuenvtemp[28]:BYTE
fstenv [fpuenvtemp]

I get an "invalid size of operand"
Post 15 Jul 2006, 10:51
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia
vid
try searching first next time
Post 15 Jul 2006, 12:55
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Hunter



Joined: 07 Jun 2006
Posts: 41
Hunter
Yes, madmatt is right, FASM generates error "invalid size of operand" for following code:
envdata db 28 dup (0)
fstenv [envdata]

but
label envdata_label
envdata db 28 dup (0)
fstenv [envdata_label]
is compiled successfully.

I think, the operand size isn't needed for fstenv, fnstenv, fldenv, fsave, fnsave, frstor, fxsave, fxrstor instructions in this situation.
Post 15 Jul 2006, 22:24
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Post 15 Jul 2006, 22:57
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madmatt



Joined: 07 Oct 2003
Posts: 1045
Location: Michigan, USA
madmatt
vid: Yeh, I should've checked the intel docs before I posted, it only accepts a global (static) memory reference to work.

locodelassembly: after reading the post, looks like a $66 prefix is all that is needed a make it work, I'll have to try and see what happens.
Post 15 Jul 2006, 23:18
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madmatt



Joined: 07 Oct 2003
Posts: 1045
Location: Michigan, USA
madmatt
Tried a direct approach: fstenv [esp + 48], also fstenv [ebp _48] and it compiled without error.
Why won't it work with the local variable?
Post 15 Jul 2006, 23:24
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Quote:

vid: Yeh, I should've checked the intel docs before I posted, it only accepts a global (static) memory reference to work.


But you can use the stack if you want
Code:
include 'win32axp.inc'

.code
proc start
local ..fpuenvtemp[28]:BYTE
label .fpuenvtemp at ..fpuenvtemp
  fstenv [.fpuenvtemp]

  ret
endp

.end start    


[edit]
Quote:
Tried a direct approach: fstenv [esp + 48], also fstenv [ebp _48] and it compiled without error.
Why won't it work with the local variable?

Because fstenv needs a label with no type[/edit]
Post 15 Jul 2006, 23:29
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia
vid
i meant searching the board, for that thread - i was too lazy to explain it or search for the thread myself Smile
Post 16 Jul 2006, 08:46
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