Annotation of sys/lib/libkern/arch/mips64/ffs.S, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: ffs.S,v 1.3 2004/09/09 15:41:18 pefo Exp $ */
! 2: /*-
! 3: * Copyright (c) 1991, 1993
! 4: * The Regents of the University of California. All rights reserved.
! 5: *
! 6: * This code is derived from software contributed to Berkeley by
! 7: * Ralph Campbell.
! 8: *
! 9: * Redistribution and use in source and binary forms, with or without
! 10: * modification, are permitted provided that the following conditions
! 11: * are met:
! 12: * 1. Redistributions of source code must retain the above copyright
! 13: * notice, this list of conditions and the following disclaimer.
! 14: * 2. Redistributions in binary form must reproduce the above copyright
! 15: * notice, this list of conditions and the following disclaimer in the
! 16: * documentation and/or other materials provided with the distribution.
! 17: * 3. Neither the name of the University nor the names of its contributors
! 18: * may be used to endorse or promote products derived from this software
! 19: * without specific prior written permission.
! 20: *
! 21: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 22: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 23: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 24: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 25: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 27: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 28: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 29: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 30: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 31: * SUCH DAMAGE.
! 32: */
! 33:
! 34: #include "DEFS.h"
! 35:
! 36:
! 37: /*
! 38: * bit = ffs(value)
! 39: */
! 40: LEAF(ffs, 0)
! 41: .set noreorder
! 42: beq a0, zero, 2f
! 43: move v0, zero
! 44: 1:
! 45: and v1, a0, 1 # bit set?
! 46: addu v0, v0, 1
! 47: beq v1, zero, 1b # no, continue
! 48: srl a0, a0, 1
! 49: 2:
! 50: j ra
! 51: nop
! 52: END(ffs)
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