Nasm and C??

[Rob Neff]

hmmm....documentation....that's probably the ONE key item missing from the package.  I've been busy trying to finish the full 64-bit Linux/Windows build ( rather tricky, but almost there! ) and should seriously consider adding some docs to the project.  After I get the next RC out ( and I don't hear anything negative ) I'll try and whip up something.  In the meantime you can peruse some of my postings both here and on asmcommunity.net where you'll catch a glimmer of ideas. 

[brethren]

i finally got C types working, thanks for the info Rob. Plus dynamic inclusion is working great, thanks Bryant

heres an example

Code: [Select]

%include "stdio.inc"
%include "stdlib.inc"
%include "time.inc"

SECTION .bss

        var1 reserve(time_t) 1

SECTION .text
cproc main

        ccall time, var1
        ccall printf, `Number of seconds since the epoch: %d\n`, time_t[var1]
        
        mov eax, EXIT_SUCCESS

cendproc



[brethren]

heres another question 

can you use a procedure that has the same name as an nasm keyword?

i'm just reading about a linux function called 'times' that returns the amount of CPU time a process has used in clock ticks (would be useful for timing code). obviously times is also an nasm directive

is it possible to use this function?

btw for anybody using linux the function prototype is in /usr/include/sys/times.h

[Keith Kanios]

can you use a procedure that has the same name as an nasm keyword?

For TIMES in particular, no, as it is handled at assemble time, so I don't think any amount of preprocessing or overloading voodoo will help.

This is where you'd want to prepend an underscore and treat it as _TIMES within NASM and during link phase.

However, and in hindsight, there should be some code within NASM to handle this corner case, e.g. "when TIMES is used as a MEMREF, and if EXTERN or LABEL, then don't ASSEMBLE as TIMES" or something like that.

[Frank Kotler]

"$times" for the external function?

Best,
Frank

[Frank Kotler]

I knew I'd seen it documented! Hard to find, though. There it is, in section 3.1!

"An identifier may also be prefixed with a $ to indicate that it is intended to be read as an identifier and not a reserved word; thus, if some other module you are linking with defines a symbol called eax, you can refer to $eax in NASM code to distinguish the symbol from the register."

Best,
Frank

[brethren]

just tested and then disassembled the code, worked perfectly:)

Code: [Select]

%include "sys/times.inc"
SECTION .bss

        buf resb tms_size

SECTION .text
cproc main
        ccall $times, buf
cendproc



Code: [Select]

    0x080483d0 <main+0>:    push   ebp
    0x080483d1 <main+1>:    mov    ebp,esp
    0x080483d3 <main+3>:    push   0x80495c4
    0x080483d8 <main+8>:    call   0x80482fc <times@plt>
    0x080483dd <main+13>:   add    esp,0x4
    0x080483e3 <main+19>:   mov    esp,ebp
    0x080483e5 <main+21>:   pop    ebp
    0x080483e6 <main+22>:   ret   
   
End of assembler dump.

[Keith Kanios]

I knew I'd seen it documented! Hard to find, though. There it is, in section 3.1!

Nice find, I'll have to remember that one.