c and assembly problem

[huh]

I write my os mostly in c, but sometimes I NEED to use assembly. if i define a variable in c:

Code: Select all

main()
{
  long var = 0;
}

and then i want to do something with it in assembly:

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asm("movl $1, var\n");

the gcc compiler gives me this error:

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/tmp/ccpKcN36.o: In function `main':
test.c:(.text+0xf): undefined reference to `var'
collect2: ld returned 1 exit status

why?

[bubach]

The wiki has a section about inline assembly, and examples of correct syntax:
http://wiki.osdev.org/Inline_Assembly

[qw]

This is GCC specific. In MSVC it is perfectly valid to use local variable names in inline assembly directly. This is mainly a matter of syntax.