xref: /titanic_44/usr/src/lib/libc/i386/gen/ldivide.s (revision 9a70fc3be3b1e966bf78825cdb8d509963a6f0a1)
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217257d1b4Sraf
227c478bd9Sstevel@tonic-gate/*
237257d1b4Sraf * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
247c478bd9Sstevel@tonic-gate * Use is subject to license terms.
257c478bd9Sstevel@tonic-gate */
267c478bd9Sstevel@tonic-gate
27*9a70fc3bSMark J. Nelson	.file	"ldivide.s"
287c478bd9Sstevel@tonic-gate
297c478bd9Sstevel@tonic-gate/ Double long divide routine.
307c478bd9Sstevel@tonic-gate
317c478bd9Sstevel@tonic-gate#include "SYS.h"
327c478bd9Sstevel@tonic-gate
337c478bd9Sstevel@tonic-gate	.set	lop,16
347c478bd9Sstevel@tonic-gate	.set	rop,24
357c478bd9Sstevel@tonic-gate	.set	ans,0
367c478bd9Sstevel@tonic-gate
377c478bd9Sstevel@tonic-gate	ENTRY(ldivide)
387c478bd9Sstevel@tonic-gate	popl	%eax
397c478bd9Sstevel@tonic-gate	xchgl	%eax,0(%esp)
407c478bd9Sstevel@tonic-gate	pushl	%eax
417c478bd9Sstevel@tonic-gate
427c478bd9Sstevel@tonic-gate	pushl	%esi
437c478bd9Sstevel@tonic-gate	pushl	%edi
447c478bd9Sstevel@tonic-gate
457c478bd9Sstevel@tonic-gate	movl	lop(%esp),%eax
467c478bd9Sstevel@tonic-gate	movl	lop+4(%esp),%edx
477c478bd9Sstevel@tonic-gate
487c478bd9Sstevel@tonic-gate/ the following code is only for compatibility with original ldivide code
497c478bd9Sstevel@tonic-gate	orl	%edx,%edx	/ force numerator positive
507c478bd9Sstevel@tonic-gate	jns	.ldiv1
517c478bd9Sstevel@tonic-gate	notl	%edx
527c478bd9Sstevel@tonic-gate	negl	%eax
537c478bd9Sstevel@tonic-gate	sbbl	$0xffffffff,%edx
547c478bd9Sstevel@tonic-gate.ldiv1:
557c478bd9Sstevel@tonic-gate	testl	$0x80000000,rop+4(%esp)
567c478bd9Sstevel@tonic-gate	jz	.ldiv2
577c478bd9Sstevel@tonic-gate	notl	rop+4(%esp)	/ force denominator positive
587c478bd9Sstevel@tonic-gate	negl	rop(%esp)
597c478bd9Sstevel@tonic-gate	sbbl	$0xffffffff,rop+4(%esp)
607c478bd9Sstevel@tonic-gate.ldiv2:
617c478bd9Sstevel@tonic-gate/ end of compatibility code
627c478bd9Sstevel@tonic-gate
637c478bd9Sstevel@tonic-gate	xorl	%esi,%esi	/ initialize remainder to 0
647c478bd9Sstevel@tonic-gate	movl	%esi,%edi
657c478bd9Sstevel@tonic-gate	movl	$64,%ecx	/ initialize counter for 64-bits
667c478bd9Sstevel@tonic-gate.div_mod_loop:
677c478bd9Sstevel@tonic-gate	shll	$1,%edi
687c478bd9Sstevel@tonic-gate	rcll	$1,%esi		/ remainder * 2
697c478bd9Sstevel@tonic-gate	shll	$1,%eax
707c478bd9Sstevel@tonic-gate	rcll	$1,%edx		/ numerator * 2 (also quotient)
717c478bd9Sstevel@tonic-gate	adcl	$0,%edi		/ add in any carry from the shift
727c478bd9Sstevel@tonic-gate	subl	rop(%esp),%edi	/ subtract denominator from remainder
737c478bd9Sstevel@tonic-gate	sbbl	rop+4(%esp),%esi
747c478bd9Sstevel@tonic-gate	incl	%eax		/ turn on quotient bit for now
757c478bd9Sstevel@tonic-gate	jnc	.inc_remainder	/ inc didn't affect carry flag
767c478bd9Sstevel@tonic-gate/ can't subtract the denominator from the remainder, add it back
777c478bd9Sstevel@tonic-gate	addl	rop(%esp),%edi
787c478bd9Sstevel@tonic-gate	adcl	rop+4(%esp),%esi
797c478bd9Sstevel@tonic-gate	decl	%eax		/ turn quotient bit off
807c478bd9Sstevel@tonic-gate.inc_remainder:
817c478bd9Sstevel@tonic-gate	loop	.div_mod_loop
827c478bd9Sstevel@tonic-gate
837c478bd9Sstevel@tonic-gate/ at this point, %edx:%eax has the quotient and %edi:%esi has the remainder
847c478bd9Sstevel@tonic-gate	popl	%edi
857c478bd9Sstevel@tonic-gate	popl	%esi
867c478bd9Sstevel@tonic-gate	movl	%eax,%ecx
877c478bd9Sstevel@tonic-gate	popl	%eax
887c478bd9Sstevel@tonic-gate	movl	%ecx,ans(%eax)
897c478bd9Sstevel@tonic-gate	movl	%edx,ans+4(%eax)
907c478bd9Sstevel@tonic-gate	ret
917c478bd9Sstevel@tonic-gate	SET_SIZE(ldivide)
92