Author: Frank Phillips
Date: 09:27:31 10/22/00
Go up one level in this thread
On October 21, 2000 at 14:56:59, Robert Hyatt wrote:
>On October 21, 2000 at 12:30:39, Frank Phillips wrote:
>
>>[Bob Hyatt Wrote in response to how to use Eugene's FirstOne() etc assembly code
>>in Linux
>>
>>All you really need to do is compile the .s file separately, which produces
>>a .o file. Then use those procedures in your C program calls. IE there is a
>>FirstOne(), LastOne() function. You could change the names in the .s file if
>>you want, of course.
>>
>>Then just link that .o file in with your regular C and you should be ready to
>>rumble...]
>>
>>
>>Despite having read most HOWTOs I could find, I am still missing something
>>simple.
>>Linking X86.o to the rest of the program does not work, giving errors that seem
>>to
>>indicate the function cannot be found even though the function type is defined.
>>
>>int FirstOne(BITBOARD);
>>main()
>>{
>>FirstOne(1);
>>return;
>>}
>>
>>The above compiles with gcc -c -o main.o main.cpp
>>
>>The X86.s is compile with asm -o X86.o X86.s
>>But gcc -o prog main.o X86.o fails with the following type of error
>>main.o(.text+0x250): undefined reference to `FirstOne(unsigned long long)'
>>
>>Very strange because this _appears_ to be what is done in Crafty by the
>>Makefile.
>>
>>Frank
>
>
>You can't quite call it from c++ programs like that, due to the way the compiler
>mangles function names to handle overloading. If your code was pure C, what
>you have should work fine. If you compile it with c++, the compiler will cause
>trouble. You can declare the function as an extern C function to get around
>this...
>
>Not really doing much C/C++ interoperability stuff here, I can't tell you
>exactly what to do to fix this, but it ought to be easy..
Got it, finally. Thanks. Making allowance for name mangling and declaring the
functions as extern C did the trick. Gained around 10% in speed, which puts
Linux about 15 to 20 percent behind the W98 MS VC++ version.
Frank
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