asm syntax in gcc?

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1 total messages Started by Jason Merrill Sat, 12 Dec 1992 16:36

#741

Author: Jason Merrill
Date: Sat, 12 Dec 1992 16:36

35 lines
1357 bytes

Some of the system headers on our machine (Sequent Symmetry, Dynix 3.1.2)
seem to use a different syntax for "asm" directives.  For instance:

asm void S_LOCK(laddr)
{
%reg laddr; lab loop, spin, done;
/PEEPOFF
loop:	movb	$L_LOCKED, %al
	xchgb	%al, (laddr)		/* an atomic "test and set" */
	cmpb	$L_UNLOCKED, %al
	je	done			/* if equal, we got the lock */
spin:	cmpb	$L_UNLOCKED, (laddr)	/* spin in cache until unlocked */
	je	loop			/* then, try get lock again */
	jmp	spin
done:
/PEEPON
%mem laddr; lab loop, spin, done;
/PEEPOFF
loop:	movb	$L_LOCKED, %al
	movl	laddr, %ecx
	xchgb	%al, (%ecx)		/* an atomic "test and set" */
	cmpb	$L_UNLOCKED, %al
	je	done			/* if equal, we got the lock */
spin:	cmpb	$L_UNLOCKED, (%ecx)	/* spin in cache until unlocked */
	je	loop			/* then, try get lock again */
	jmp	spin
done:
/PEEPON
}

How does this differ from the gcc asm syntax?  What would be equivalent
code that gcc would accept?

--
Jason Merrill					jason@jarthur.claremont.edu

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