1/* $NetBSD: sdivsi3_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: sdivsi3_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 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, MACL and MACH. 49 * 50 * See the definition of "divsi3_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 __sdivsi3; newer uses __sdivsi3_i4i - a 59 * heavily tuned version that is NOT compatible with __sdivsi3 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 __sdivsi3 but adjust the code to 63 * conform to the __sdivsi3_i4i clobber spec. 64 */ 65 66 67#ifdef __ELF__ 68 .hidden __sdivsi3_i4i 69#endif 70 71 72/* r0 <= r4 / r5 */ 73NENTRY(__sdivsi3_i4i) 74 mov r4, r0 75 mov r5, r1 76 77 tst r1, r1 78 bt .L_div_by_zero 79 80 !! this version cannot clobber r2 and r3, but can clobber macl/mach 81 lds r2, macl 82 lds r3, mach 83 84 mov #0, r2 85 div0s r2, r0 86 subc r3, r3 87 subc r2, r0 88 div0s r1, r3 89#define DIVSTEP rotcl r0; div1 r1, r3 90 /* repeat 32 times */ 91 DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; 92 DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; 93 DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; 94 DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; 95#undef DIVSTEP 96 rotcl r0 97 98 addc r2, r0 99 100 sts mach, r3 101 sts macl, r2 102 103 rts 104 nop 105 106.L_div_by_zero: 107 rts 108 mov #0, r0 109