Related Projects > NASMX

Typo in nasmx.inc and issue with invoke on win64

(1/2) > >>

miz:
Hi,

while looking through the include file I noticed a typo (line 776)

--- Code: ---%elifidn __OUTPUT_FORAMT__,macho64
--- End code ---

Also, it seems that the invoke macro on win64 always writes the first four parameters to the stack, which is quite unnecessary.

Frank Kotler:
Good catch! Fixed in my version. Thanks, Miz!

Best,
Frank

Rob Neff:
Thanks for the feedback, Miz!  8)
I'll correct the typo, investigate the stack usage, and update sourceforge in the near future. 

Rob Neff:
I've updated the nasmx.inc file on sourceforge.net so the changes will be included in the next release.  I've also attached it to this message for your convenience.

The typo was obviously an easy fix.  However, the stack issue required some thought.  I don't recall the exact reasons for the current behavior but I'm pretty sure it involved possible portability issues between Win32 and Win64.  And given the fact that this framework has been out for years now we can't afford to break any existing programs which may rely on this feature.

I've added an option which is only necessary for Windows FastCall to prevent saving register parameters to shadow space ( ie: the MS definition of stack space reserved for registers ) during an INVOKE macro call.  The option can be specified on the nasm command line using a define to globally affect code generation, eg:


--- Code: ---nasm -f win64 -DDISABLE_FASTCALL_STACK_PRELOAD

--- End code ---

or it can be turned off and/or on again within your source code by using the syntax:

--- Code: ---NASMX_PRAGMA FASTCALL_STACK_PRELOAD, [ ENABLE | DISABLE ]

--- End code ---

The default INVOKE behavior on Windows is to save the register parameters to the stack before executing the call to ensure backward compatibility.  Specifying this option on BSD/Linux currently has no effect.

You may also simply remove the 3 lines in the nasmx.inc INVOKE macro where the option is located if you never want the old behavior.  Of course, you'll need to maintain your own personal copy.

Please experiment with it and share any comments you may have by replying in this thread.  I hope you find this a satisfactory solution.  Thanks again for the feedback.

miz:
Great, thanks for the quick fix :)

Navigation

[0] Message Index

[#] Next page