1/* $NetBSD: ffs.S,v 1.3 1996/10/17 03:08:13 cgd Exp $ */ 2 3/* 4 * Copyright (c) 1995 Christopher G. Demetriou 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by Christopher G. Demetriou 18 * for the NetBSD Project. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34#include <machine/asm.h> 35__FBSDID("$FreeBSD$"); 36 37ENTRY(ffs, 1) 38 sxt4 r14=in0 ;; 39 cmp.eq p6,p0=r14,r0 40(p6) br.dpnt.few Lallzero 41 42 /* 43 * Initialize return value (ret0), and set up r15 so that it 44 * contains the mask with only the lowest bit set. 45 */ 46 sub r15=r0,r14 47 mov ret0=1 ;; 48 and r15=r14,r15 ;; 49 50 extr.u r16=r15,0,8 ;; 51 cmp.ne p6,p0=r0,r16 52(p6) br.dptk.few Ldo8 53 54 /* 55 * If lower 16 bits empty, add 16 to result and use upper 16. 56 */ 57 extr.u r16=r15,0,16 ;; 58 cmp.ne p6,p0=r0,r16 59(p6) br.dptk.few Ldo16 60 extr.u r15=r15,16,16 61 add ret0=16,ret0 ;; 62 63Ldo16: 64 /* 65 * If lower 8 bits empty, add 8 to result and use upper 8. 66 */ 67 extr.u r16=r15,0,8 ;; 68 cmp.ne p6,p0=r0,r16 69(p6) br.dptk.few Ldo8 70 extr.u r15=r15,8,24 71 add ret0=8,ret0 ;; 72 73Ldo8: 74 and r16=0x0f,r15 /* lower 4 of 8 empty? */ 75 and r17=0x33,r15 /* lower 2 of each 4 empty? */ 76 and r18=0x55,r15 ;; /* lower 1 of each 2 empty? */ 77 cmp.ne p6,p0=r16,r0 78 cmp.ne p7,p0=r17,r0 79 cmp.ne p8,p0=r18,r0 80 81 /* If lower 4 bits empty, add 4 to result. */ 82(p6) br.dptk.few Ldo4 83 add ret0=4,ret0 ;; 84 85Ldo4: /* If lower 2 bits of each 4 empty, add 2 to result. */ 86(p7) br.dptk.few Ldo2 87 add ret0=2,ret0 ;; 88 89Ldo2: /* If lower bit of each 2 empty, add 1 to result. */ 90(p8) br.dptk.few Ldone 91 add ret0=1,ret0 92 93Ldone: 94 br.ret.sptk.few rp 95 96Lallzero: 97 mov ret0=0 98 br.ret.sptk.few rp 99END(ffs) 100