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File: [cvs.NetBSD.org] / src / common / lib / libc / arch / mips / string / ffs.S (download)

Revision 1.4, Mon Jul 4 11:35:26 2011 UTC (10 years, 4 months ago) by mrg
Branch: MAIN
CVS Tags: yamt-pagecache-tag8, yamt-pagecache-base9, yamt-pagecache-base8, yamt-pagecache-base7, yamt-pagecache-base6, yamt-pagecache-base5, yamt-pagecache-base4, yamt-pagecache-base3, yamt-pagecache-base2, yamt-pagecache-base, yamt-pagecache, tls-maxphys-base, tls-maxphys-20171202, tls-maxphys, tls-earlyentropy-base, tls-earlyentropy, rmind-smpnet-nbase, rmind-smpnet-base, riastradh-xf86-video-intel-2-7-1-pre-2-21-15, riastradh-drm2-base3, riastradh-drm2-base2, riastradh-drm2-base1, riastradh-drm2-base, riastradh-drm2, prg-localcount2-base3, prg-localcount2-base2, prg-localcount2-base1, prg-localcount2-base, prg-localcount2, phil-wifi-base, phil-wifi-20200421, phil-wifi-20200411, phil-wifi-20200406, phil-wifi-20191119, phil-wifi-20190609, pgoyette-localcount-base, pgoyette-localcount-20170426, pgoyette-localcount-20170320, pgoyette-localcount-20170107, pgoyette-localcount-20161104, pgoyette-localcount-20160806, pgoyette-localcount-20160726, pgoyette-localcount, pgoyette-compat-merge-20190127, pgoyette-compat-base, pgoyette-compat-20190127, pgoyette-compat-20190118, pgoyette-compat-1226, pgoyette-compat-1126, pgoyette-compat-1020, pgoyette-compat-0930, pgoyette-compat-0906, pgoyette-compat-0728, pgoyette-compat-0625, pgoyette-compat-0521, pgoyette-compat-0502, pgoyette-compat-0422, pgoyette-compat-0415, pgoyette-compat-0407, pgoyette-compat-0330, pgoyette-compat-0322, pgoyette-compat-0315, pgoyette-compat, perseant-stdc-iso10646-base, perseant-stdc-iso10646, netbsd-9-base, netbsd-9-2-RELEASE, netbsd-9-1-RELEASE, netbsd-9-0-RELEASE, netbsd-9-0-RC2, netbsd-9-0-RC1, netbsd-9, netbsd-8-base, netbsd-8-2-RELEASE, netbsd-8-1-RELEASE, netbsd-8-1-RC1, netbsd-8-0-RELEASE, netbsd-8-0-RC2, netbsd-8-0-RC1, netbsd-8, netbsd-7-nhusb-base-20170116, netbsd-7-nhusb-base, netbsd-7-nhusb, netbsd-7-base, netbsd-7-2-RELEASE, netbsd-7-1-RELEASE, netbsd-7-1-RC2, netbsd-7-1-RC1, netbsd-7-1-2-RELEASE, netbsd-7-1-1-RELEASE, netbsd-7-1, netbsd-7-0-RELEASE, netbsd-7-0-RC3, netbsd-7-0-RC2, netbsd-7-0-RC1, netbsd-7-0-2-RELEASE, netbsd-7-0-1-RELEASE, netbsd-7-0, netbsd-7, netbsd-6-base, netbsd-6-1-RELEASE, netbsd-6-1-RC4, netbsd-6-1-RC3, netbsd-6-1-RC2, netbsd-6-1-RC1, netbsd-6-1-5-RELEASE, netbsd-6-1-4-RELEASE, netbsd-6-1-3-RELEASE, netbsd-6-1-2-RELEASE, netbsd-6-1-1-RELEASE, netbsd-6-1, netbsd-6-0-RELEASE, netbsd-6-0-RC2, netbsd-6-0-RC1, netbsd-6-0-6-RELEASE, netbsd-6-0-5-RELEASE, netbsd-6-0-4-RELEASE, netbsd-6-0-3-RELEASE, netbsd-6-0-2-RELEASE, netbsd-6-0-1-RELEASE, netbsd-6-0, netbsd-6, matt-nb8-mediatek-base, matt-nb8-mediatek, matt-nb6-plus-nbase, matt-nb6-plus-base, matt-nb6-plus, localcount-20160914, khorben-n900, is-mlppp-base, is-mlppp, cjep_sun2x-base1, cjep_sun2x-base, cjep_sun2x, cjep_staticlib_x-base1, cjep_staticlib_x-base, cjep_staticlib_x, bouyer-xenpvh-base2, bouyer-xenpvh-base1, bouyer-xenpvh-base, bouyer-xenpvh, bouyer-socketcan-base1, bouyer-socketcan-base, bouyer-socketcan, agc-symver-base, agc-symver, ad-namecache-base3, ad-namecache-base, ad-namecache, HEAD
Branch point for: phil-wifi
Changes since 1.3: +3 -2 lines

add a weak alias from ffs to __ffssi2.  newsmips kernels link now.

/*	$NetBSD: ffs.S,v 1.4 2011/07/04 11:35:26 mrg Exp $	*/

/*-
 * Copyright (c) 2010 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matt Thomas of 3am Software Foundry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <mips/asm.h>

RCSID("$NetBSD: ffs.S,v 1.4 2011/07/04 11:35:26 mrg Exp $")

/* bit = ffs(value) */

	.text
	.set	noreorder

WEAK_ALIAS(__ffssi2,ffs)
#if __mips == 64 || __mips == 32
LEAF(ffs)
#ifndef _LP64
XLEAF(ffsl)
#endif
	.set	push
	.set	mips32
	li	v1, 32
#if __mips == 64
	sll	a0, a0, 0
#endif
	negu	a1, a0
	and	a0, a1
	clz	v0, a0
	j	ra
	 subu	v0, v1, v0
	.set	pop
END(ffs)
#if defined(_LP64) && __mips == 64
LEAF(ffsl)
	li	v1, 64
	negu	a1, a0
	and	a0, a1
	dclz	v0, a0
	j	ra
	 subu	v0, v1, v0
END(ffsl)
#endif
#else /* __mips != 64 && __mips != 32 */

#ifdef _LP64
XLEAF(ffsl)
	beqz	a0, 6f			# fast escape if 0
	 li	v0, 0

	li	v0, 1
	li	a3, 0xffffffff		# initial mask
	b	1f
	 li	a2, 32			# bit count of mask
#endif /* _LP64 */
LEAF(ffs)
#ifndef _LP64
XLEAF(ffsl)
#endif /* !_LP64 */
	beqz	a0, 6f
	 li	v0, 0

	li	v0, 1
	li	a3, 0xffff		# initial mask
	li	a2, 16			# bit count of mask
1:
	and	v1, a0, a3		# focus no lower half of bits left
	bnez	v1, 2f			# any of the lower half set?
	 nop
	addu	v0, a2			# nope, then bit is in the upper half
#ifdef _LP64
	dsrlv	a0, a0, a2		# discard low bits
#else
	srlv	a0, a0, a2		# discard low bits
#endif
2:
	srl	a2, 1			# divide bit count by 2
	bnez	a2, 1b			# still bits left to text?
	 srlv	a3, a3, a2		# shrink mask in half
6:
	j	ra
	 nop
END(ffs)
#endif /* __mips == 64 || __mips == 32 */