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      1 /*	$NetBSD: sdivsi3.S,v 1.12 2011/08/05 01:59:39 uwe Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990 The Regents of the University of California.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * William Jolitz.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  *
     34  *	from: @(#)udivsi3.s	5.1 (Berkeley) 5/15/90
     35  */
     36 
     37 #include <machine/asm.h>
     38 #if defined(LIBC_SCCS)
     39 	RCSID("$NetBSD: sdivsi3.S,v 1.12 2011/08/05 01:59:39 uwe Exp $")
     40 #endif
     41 
     42 /*
     43  * IMPOTANT: This function is special.
     44  *
     45  * This function is an auxiliary "millicode" function that is
     46  * referenced by the code generated by gcc for signed integer
     47  * division.  But gcc does NOT treat a call to this function as an
     48  * ordinary function call - it can clobber only R1, R2 and R3.
     49  *
     50  * See the definition of "divsi3_i1" in gcc/config/sh/sh.md
     51  *
     52  * As the consequence this function cannot be called via any
     53  * indirection that assumes normal calling convention:
     54  *
     55  * . cannot have _PROF_PROLOGUE
     56  * . cannot be called via PLT (not relevant for kernel)
     57  */
     58 
     59 
     60 #ifdef __ELF__
     61 	.hidden __sdivsi3
     62 #endif
     63 
     64 
     65 /* r0 <= r4 / r5 */
     66 NENTRY(__sdivsi3)
     67 	mov	r4, r0
     68 	mov	r5, r1
     69 
     70 	tst	r1, r1
     71 	bt	.L_div_by_zero
     72 
     73 	mov	#0, r2
     74 	div0s	r2, r0
     75 	subc	r3, r3
     76 	subc	r2, r0
     77 	div0s	r1, r3
     78 #define DIVSTEP	rotcl r0; div1 r1, r3
     79 	/* repeat 32 times */
     80 	DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
     81 	DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
     82 	DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
     83 	DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
     84 #undef DIVSTEP
     85 	rotcl	r0
     86 
     87 	rts
     88 	 addc	r2, r0
     89 
     90 .L_div_by_zero:
     91 	rts
     92 	 mov	#0, r0
     93