31489a9a26
For setjmp() and longjmp(), put the signal mask where it's supposed to be, instead of in the space reserved for fp regs.
83 lines
3.2 KiB
ArmAsm
83 lines
3.2 KiB
ArmAsm
/* $NetBSD: ffs.S,v 1.5 2003/04/05 23:08:52 bjh21 Exp $ */
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/*
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* Copyright (c) 2001 Christopher Gilbert
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the company nor the name of the author may be used to
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* endorse or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <machine/asm.h>
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__FBSDID("$FreeBSD$");
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/*
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* ffs - find first set bit, this algorithm isolates the first set
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* bit, then multiplies the number by 0x0450fbaf which leaves the top
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* 6 bits as an index into the table. This algorithm should be a win
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* over the checking each bit in turn as per the C compiled version.
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*
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* under ARMv5 there's an instruction called CLZ (count leading Zero's) that
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* could be used
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*
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* This is the ffs algorithm devised by d.seal and posted to comp.sys.arm on
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* 16 Feb 1994.
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*/
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ENTRY(ffs)
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/* Standard trick to isolate bottom bit in r0 or 0 if r0 = 0 on entry */
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rsb r1, r0, #0
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ands r0, r0, r1
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#ifndef __XSCALE__
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/*
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* now r0 has at most one set bit, call this X
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* if X = 0, all further instructions are skipped
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*/
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adrne r2, .L_ffs_table
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orrne r0, r0, r0, lsl #4 /* r0 = X * 0x11 */
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orrne r0, r0, r0, lsl #6 /* r0 = X * 0x451 */
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rsbne r0, r0, r0, lsl #16 /* r0 = X * 0x0450fbaf */
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/* now lookup in table indexed on top 6 bits of r0 */
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ldrneb r0, [ r2, r0, lsr #26 ]
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RET
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.text;
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.type .L_ffs_table, _ASM_TYPE_OBJECT;
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.L_ffs_table:
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/* 0 1 2 3 4 5 6 7 */
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.byte 0, 1, 2, 13, 3, 7, 0, 14 /* 0- 7 */
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.byte 4, 0, 8, 0, 0, 0, 0, 15 /* 8-15 */
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.byte 11, 5, 0, 0, 9, 0, 0, 26 /* 16-23 */
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.byte 0, 0, 0, 0, 0, 22, 28, 16 /* 24-31 */
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.byte 32, 12, 6, 0, 0, 0, 0, 0 /* 32-39 */
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.byte 10, 0, 0, 25, 0, 0, 21, 27 /* 40-47 */
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.byte 31, 0, 0, 0, 0, 24, 0, 20 /* 48-55 */
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.byte 30, 0, 23, 19, 29, 18, 17, 0 /* 56-63 */
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#else
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clzne r0, r0
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rsbne r0, r0, #32
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RET
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#endif
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