1 /* $NetBSD: ffs.S,v 1.3 1996/10/17 03:08:13 cgd Exp $ */
4 * Copyright (c) 1995 Christopher G. Demetriou
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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
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.
34 #include <machine/asm.h>
41 * Initialize return value (v0), and set up t1 so that it
42 * contains the mask with only the lowest bit set.
52 * If lower 16 bits empty, add 16 to result and use upper 16.
61 * If lower 8 bits empty, add 8 to result and use upper 8.
69 and t1, 0x0f, t5 /* lower 4 of 8 empty? */
70 and t1, 0x33, t6 /* lower 2 of each 4 empty? */
71 and t1, 0x55, t7 /* lower 1 of each 2 empty? */
73 /* If lower 4 bits empty, add 4 to result. */
77 Ldo4: /* If lower 2 bits of each 4 empty, add 2 to result. */
81 Ldo2: /* If lower bit of each 2 empty, add 1 to result. */