compilers

There''s another asm compiler also called MASM, search for Icezillian, it lets you program windows in asm.

Compilers that create .exe create assembly code. All of C eventually falls back onto some asm routine. The compiler inserts some op codes to setup function calls and variables, then inserts the code for the functions that are called. You can load any .exe with VC and look at the op codes (and even step through the program, op code by op code).

Soo, an assembler and a C compiler won''t produce the exact same code; though it may produce the same results. There''s nothing to prevent you from linking to the C libraries using an assembler, and calling all the C functions ''manually''. Even then the code is likely to be slightly different.

//in a .cpp somewhere unsigned long RDTSC() { unsigned long ulTicks; __asm{ xor eax, eax xor ebx, ebx xor ecx, ecx xor edx, edx //This is how you use op codes that the compiler doesn''t know about _emit 0x0f // CPUID _emit 0xa2 _emit 0x0f // RDTSC _emit 0x31 mov [ulTicks], eax } return(ulTick); } BTW Sp5 is available now...

Magmai Kai Holmlor
- The disgruntled & disillusioned

hrrm....hang on a second here...
doesn''t compilers that create .exe files create opcodes (in som hexadecimal form or whatever) rather than assembly code??


--Spencer

I think they create ASM first. Translation from ASM to machine code is a relatively simple process.

~~~~~~~~~~
Martee
http://www.csc.uvic.ca/~mdill

Martee is correct. VC++ converts the code to assembler and stores it in .obj (or .ojb)files (i can''t remember offhand which file extension). From these files it creates the .exe file, which is in machine code. If you want to look at your program in asm, try opening an obj/ojb file. I have never tried this, so I don''t know if it will work.

The huge post above was me. It comes out as anonymous. >:|

"Simple is beautiful"

quote:

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Original post by amish1234

VC++ converts the code to assembler and stores it in .obj (or .ojb)files (i can''t remember offhand which file extension).

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.obj files does _not_ contain assembly. They basically contain compiled code and data which still has unresolved references. Its the linker''s job to link several .obj files together to resolve those references.
I believe, however, that there is a switch for VC++ to make it generate assembly output in addition to/instead of object files. At least other compilers have a switch like that.
gcc _does_ generate assembly at an intermediate stage, which it then feeds to gas, the gnu assembler.

For reference, the VC++ command line params to generate assembly are:

/FAs /Fa{listing filename}

That will generate an assembly listing with C/C++ code in comments. (I don't remember the modifications to generate machine code, or the other options.)

In the IDE, the options are found in the C/C++ tab of the Project Settings box, in the "Listing Files" section.

Edited by - Qoy on April 9, 2001 4:24:13 AM

Here is a link to a web site that contains a free book on compilers. It also gives a good intro to assembly languages. Check out chapters one through four.

Compilers and Compiler Generators