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      1 /*-
      2  * Copyright (c) 1991, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * This code is derived from software contributed to Berkeley by
      6  * Donn Seeley at UUNET Technologies, Inc.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. Neither the name of the University nor the names of its contributors
     17  *    may be used to endorse or promote products derived from this software
     18  *    without specific prior written permission.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     30  * SUCH DAMAGE.
     31  */
     32 
     33 #include <machine/asm.h>
     34 
     35 	/* .asciz "@(#)urem.s	8.1 (Berkeley) 6/4/93" */
     36 RCSID("$NetBSD: urem.S,v 1.3 2011/01/25 04:45:28 matt Exp $")
     37 
     38 /*
     39  * Unsigned modulus, PCC flavor.
     40  * urem() takes an ordinary dividend/divisor pair;
     41  * aurem() takes a pointer to a dividend and an ordinary divisor.
     42  */
     43 
     44 #define	DIVIDEND	4(%ap)
     45 #define	DIVISOR		8(%ap)
     46 
     47 ASENTRY(__urem,0)
     48 	movl	DIVISOR,%r2
     49 	jlss	Leasy		# big divisor: settle by comparison
     50 	movl	DIVIDEND,%r0
     51 	jlss	Lhard		# big dividend: need extended division
     52 	divl3	%r2,%r0,%r1	# small divisor and dividend: signed modulus
     53 	mull2	%r2,%r1
     54 	subl2	%r1,%r0
     55 	ret
     56 Lhard:
     57 	clrl	%r1
     58 	ediv	%r2,%r0,%r1,%r0
     59 	ret
     60 Leasy:
     61 	subl3	%r2,DIVIDEND,%r0
     62 	jcc	Ldifference	# if divisor goes in once, return difference
     63 	movl	DIVIDEND,%r0	# if divisor is bigger, return dividend
     64 Ldifference:
     65 	ret
     66 END(__urem)
     67 
     68 ASENTRY(__aurem,0)
     69 	movl	DIVIDEND,%r3
     70 	movl	DIVISOR,%r2
     71 	jlss	La_easy		# big divisor: settle by comparison
     72 	movl	(%r3),%r0
     73 	jlss	La_hard		# big dividend: need extended division
     74 	divl3	%r2,%r0,%r1	# small divisor and dividend: signed modulus
     75 	mull2	%r2,%r1
     76 	subl2	%r1,%r0
     77 	movl	%r0,(%r3)		# leave the value of the assignment in %r0
     78 	ret
     79 La_hard:
     80 	clrl	%r1
     81 	ediv	%r2,%r0,%r1,%r0
     82 	movl	%r0,(%r3)
     83 	ret
     84 La_easy:
     85 	subl3	%r2,(%r3),%r0
     86 	jcs	La_dividend	# if divisor is bigger, leave dividend alone
     87 	movl	%r0,(%r3)		# if divisor goes in once, store difference
     88 	ret
     89 La_dividend:
     90 	movl	(%r3),%r0
     91 	ret
     92 END(__aurem)
     93