minix/sys/lib/libkern/arch/sh3/udivsi3_i4i.S
2012-02-09 18:48:13 +01:00

95 lines
3.4 KiB
ArmAsm

/* $NetBSD: udivsi3_i4i.S,v 1.2 2011/08/05 02:00:25 uwe Exp $ */
/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)udivsi3.s 5.1 (Berkeley) 5/15/90
*/
#include <machine/asm.h>
#if defined(LIBC_SCCS)
RCSID("$NetBSD: udivsi3_i4i.S,v 1.2 2011/08/05 02:00:25 uwe Exp $")
#endif
/*
* IMPOTANT: This function is special.
*
* This function is an auxiliary "millicode" function that is
* referenced by the code generated by gcc for unsigned integer
* division. But gcc does NOT treat a call to this function as an
* ordinary function call - it can clobber only R1, MACL and MACH.
*
* See the definition of "udivsi3_i4_int" in gcc/config/sh/sh.md
*
* As the consequence this function cannot be called via any
* indirection that assumes normal calling convention:
*
* . cannot have _PROF_PROLOGUE
* . cannot be called via PLT (not relevant for kernel)
*
* XXX: uwe: Older gcc used __udivsi3; newer uses __udivsi3_i4i - a
* heavily tuned version that is NOT compatible with __udivsi3 because
* it clobbers different registers. We don't want to link the kernel
* against libgcc and we don't have resources to write heavily tuned
* version ourselves, so clone __udivsi3 but adjust the code to
* conform to the __udivsi3_i4i clobber spec.
*/
#ifdef __ELF__
.hidden __udivsi3_i4i
#endif
/* r0 <= r4 / r5 */
NENTRY(__udivsi3_i4i)
tst r5, r5
bt .L_div_by_zero
mov r4, r1 ! cannot clobber r4 in this version
mov #0, r0
div0u
#define DIVSTEP rotcl r1; div1 r5, r0
/* repeat 32 times */
DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
#undef DIVSTEP
rotcl r1
rts
mov r1, r0
.L_div_by_zero:
rts
mov #0, r0