Home | History | Annotate | Line # | Download | only in sh3
udivsi3_i4i.S revision 1.2 
      1 /*	$NetBSD: udivsi3_i4i.S,v 1.2 2011/08/05 02:00:25 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: udivsi3_i4i.S,v 1.2 2011/08/05 02:00:25 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 unsigned integer
     47  * division.  But gcc does NOT treat a call to this function as an
     48  * ordinary function call - it can clobber only R1, MACL and MACH.
     49  *
     50  * See the definition of "udivsi3_i4_int" 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  * XXX: uwe: Older gcc used __udivsi3; newer uses __udivsi3_i4i - a
     59  * heavily tuned version that is NOT compatible with __udivsi3 because
     60  * it clobbers different registers.  We don't want to link the kernel
     61  * against libgcc and we don't have resources to write heavily tuned
     62  * version ourselves, so clone __udivsi3 but adjust the code to
     63  * conform to the __udivsi3_i4i clobber spec.
     64  */
     65 
     66 
     67 #ifdef __ELF__
     68 	.hidden __udivsi3_i4i
     69 #endif
     70 
     71 
     72 /* r0 <= r4 / r5 */
     73 NENTRY(__udivsi3_i4i)
     74 	tst	r5, r5
     75 	bt	.L_div_by_zero
     76 
     77 	mov	r4, r1		! cannot clobber r4 in this version
     78 	mov	#0, r0
     79 	div0u
     80 #define DIVSTEP	rotcl r1; div1 r5, r0
     81 	/* repeat 32 times */
     82 	DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
     83 	DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
     84 	DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
     85 	DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
     86 #undef DIVSTEP
     87 	rotcl	r1
     88 
     89 	rts
     90 	 mov	r1, r0
     91 
     92 .L_div_by_zero:
     93 	rts
     94 	 mov	#0, r0
     95