1/* $NetBSD: ffs.S,v 1.1 2016/08/05 15:06:02 scole 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 * __FBSDID("$FreeBSD: releng/10.1/lib/libc/ia64/string/ffs.S 111777 2003-03-03 01:09:46Z obrien $"); 34 * 35 */ 36 37#include <machine/asm.h> 38/* 39 40/* 41 * int 42 * ffs(int value); 43 */ 44ENTRY(ffs, 1) 45 sxt4 r14=in0 ;; 46 cmp.eq p6,p0=r14,r0 47(p6) br.dpnt.few Lallzero 48 49 /* 50 * Initialize return value (ret0), and set up r15 so that it 51 * contains the mask with only the lowest bit set. 52 */ 53 sub r15=r0,r14 54 mov ret0=1 ;; 55 and r15=r14,r15 ;; 56 57 extr.u r16=r15,0,8 ;; 58 cmp.ne p6,p0=r0,r16 59(p6) br.dptk.few Ldo8 60 61 /* 62 * If lower 16 bits empty, add 16 to result and use upper 16. 63 */ 64 extr.u r16=r15,0,16 ;; 65 cmp.ne p6,p0=r0,r16 66(p6) br.dptk.few Ldo16 67 extr.u r15=r15,16,16 68 add ret0=16,ret0 ;; 69 70Ldo16: 71 /* 72 * If lower 8 bits empty, add 8 to result and use upper 8. 73 */ 74 extr.u r16=r15,0,8 ;; 75 cmp.ne p6,p0=r0,r16 76(p6) br.dptk.few Ldo8 77 extr.u r15=r15,8,24 78 add ret0=8,ret0 ;; 79 80Ldo8: 81 and r16=0x0f,r15 /* lower 4 of 8 empty? */ 82 and r17=0x33,r15 /* lower 2 of each 4 empty? */ 83 and r18=0x55,r15 ;; /* lower 1 of each 2 empty? */ 84 cmp.ne p6,p0=r16,r0 85 cmp.ne p7,p0=r17,r0 86 cmp.ne p8,p0=r18,r0 87 88 /* If lower 4 bits empty, add 4 to result. */ 89(p6) br.dptk.few Ldo4 90 add ret0=4,ret0 ;; 91 92Ldo4: /* If lower 2 bits of each 4 empty, add 2 to result. */ 93(p7) br.dptk.few Ldo2 94 add ret0=2,ret0 ;; 95 96Ldo2: /* If lower bit of each 2 empty, add 1 to result. */ 97(p8) br.dptk.few Ldone 98 add ret0=1,ret0 99 100Ldone: 101 br.ret.sptk.few rp 102 103Lallzero: 104 mov ret0=0 105 br.ret.sptk.few rp 106END(ffs) 107