1/* $NetBSD: mulsi3.S,v 1.1 2014/09/03 19:34:25 matt Exp $ */ 2 3/*- 4 * Copyright (c) 2014 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Matt Thomas of 3am Software Foundry. 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 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32#include <machine/asm.h> 33 34__RCSID("$NetBSD: mulsi3.S,v 1.1 2014/09/03 19:34:25 matt Exp $") 35 36ENTRY(__mulsi3) 37 l.movhi r11, 0 38 39 l.sfeqi r3, 0 40 l.bf .Lret 41 l.nop 42 43 l.sfeqi r4, 0 44 l.bf .Lret 45 l.nop 46 47 l.sfleu r3, r4 # is r3 < r4 (unsigned) 48#if 0 49 l.ori r6, r3, 0 # move r3 to r6 50 l.bf .Lloop # yes, r6 already has smaller value, 51 l.nop 52 l.ori r6, r4, 0 # move r4 to r6 because it's smaller than r3 53#else 54 l.cmov r6, r3, r4 # choose lesser of r3 or r4 55#endif 56 57.Lloop: 58 l.andi r5, r6, 1 # get LSB 59 l.sub r8, r0, r5 # 0 -> 0, 1 -> 0xffffffff 60 l.and r8, r8, r4 # r8 = r6 & 1 ? r4 : 0 61 l.add r11, r11, r8 # add to result 62 l.srli r4, r4, 1 # discard LSB 63 l.slli r6, r6, 1 # multiply by 2 64.Lentry: 65 l.sfeqi r4, 0 # only 0 left? 66 l.bf .Lret # yes, we're done 67 l.nop 68 l.sfeqi r6, 0 # only 0 left? 69 l.bnf .Lloop # no, another round of long multiplication. 70 l.nop 71 72.Lret: l.jr lr 73 l.nop 74END(__mulsi3) 75