Re: Macro To Generate Inline Assembly
On Apr 27, 1:39 pm, Daniel Kr?gler <daniel.krueg...@googlemail.com>
wrote:
On 27 Apr., 15:29, Le Chaud Lapin <jaibudu...@gmail.com> wrote:
`> 1) IMO the x86 processor does not accept a literal
as argument of mul (B == 0). Only registers or
variables are allowed.
You're right. The example I gave was erroneous.
2) MS does not officially support _asm, it seems
to be a relict, which just may work. You will find
out that it does *not* work, if you disable language
extensions (/Za). I recommend to use the officially
supported __asm (double underscore) notation.
Fixed. :)
Naturally, I would like to understand not just how to do this for
VS2005, but for all systems/compilers, so that I am not left guessing
whether I got it right or not.
Unfortunately this seems an impossible task, because
no compiler I'm aware of uses the standardized syntax
for assembler declaration, which would change your code to
#define MULTIPLY(A, B, lower_word, upper_word)\
{\
asm("mov eax, A");\
asm("mul B");\
asm("mov upper_word, edx");\
asm("mov lower_word, eax");\
What I meant was to keep the interface seen by the pure C++ code the
same.
Back to your compiler/pre-processor problem: It seems
that you can solve your problem in this case by
removing the final semicola (according to the MS
documentation this is feasible). My recommended
syntax would be to write the code as follows (note
that I use __asm instead of _asm):
#define MULTIPLY(A, B, lower_word, upper_word)\
{\
__asm mov eax, A\
__asm mul B\
__asm mov upper_word, edx\
__asm mov lower_word, eax\
}
Changes made.
Thanks for comments,
-Le Chaud Lapin-
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