From: ams AT ludd DOT luth DOT se (Martin Str|mberg)
Newsgroups: comp.os.msdos.djgpp
Subject: Some assembly questions
Date: 16 Mar 1999 18:51:44 GMT
Organization: University of Lulea, Sweden
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To: djgpp AT delorie DOT com
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How do I set or clear the carry flag? I _think_ "andl %%eax, %%eax" 
clears it (and "orl %%eax, %%eax" too).

How do I inhibit the gcc generated pre- and postlude to c functions?

Like if I have:

int eax;

void my_interrupt_handler(void)
{
	/* Get eax. */
	asm(""
	    : "=a" (eax)
	    : /* No input. */
	    );

/* Do some c stuff. */

	asm("sti"
	 "\n iret"
	    : /* No output. */
	    : /* No input. */
	    );

}


This generates (-S switch to gcc):

pushl %ebp
movl %esp,%ebp
pushl %esi
pushl %ebx

/* Here comes my code from above.*/

movl %eax,_eax

/* The c stuff in assembly. */

sti
iret



If I am not completely misstaken my iret will probably wreck havoc on
the stack, won't it?


Shostakovich, String Quartet No. 15,

							MartinS