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am c55f980d: am 4b832714: am 97288549: Merge "Let the compiler worry about implementing ffs(3)."

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* commit 'c55f980d23a62f2b9603c1dfdbc10d3698f9c1ed':
  Let the compiler worry about implementing ffs(3).
This commit is contained in:
Elliott Hughes 2013-10-24 16:46:19 -07:00 committed by Android Git Automerger
commit 9b22fc2d81
10 changed files with 40 additions and 179 deletions
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1
libc/Android.mk
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@ -223,6 +223,7 @@ libc_bionic_src_files := \
bionic/__errno.cpp \
bionic/eventfd_read.cpp \
bionic/eventfd_write.cpp \
bionic/ffs.cpp \
bionic/fork.cpp \
bionic/futimens.cpp \
bionic/getauxval.cpp \

1
libc/arch-arm/arm.mk
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@ -4,7 +4,6 @@ _LIBC_ARCH_COMMON_SRC_FILES := \
arch-arm/bionic/clone.S \
arch-arm/bionic/eabi.c \
arch-arm/bionic/_exit_with_stack_teardown.S \
arch-arm/bionic/ffs.S \
arch-arm/bionic/futex_arm.S \
arch-arm/bionic/__get_sp.S \
arch-arm/bionic/kill.S \

41
libc/arch-arm/bionic/ffs.S
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@ -1,41 +0,0 @@
/* $NetBSD: ffs.S,v 1.5 2003/04/05 23:08:52 bjh21 Exp $ */
/*
* Copyright (c) 2001 Christopher Gilbert
* All rights reserved.
*
* 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.
* 3. The name of the company nor the name of the author may be used to
* endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 <machine/asm.h>
#include <machine/cpu-features.h>
ENTRY(ffs)
/* Standard trick to isolate bottom bit in r0 or 0 if r0 = 0 on entry */
rsb r1, r0, #0
ands r0, r0, r1
clzne r0, r0
rsbne r0, r0, #32
bx lr
END(ffs)

92
libc/arch-mips/bionic/ffs.S
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@ -1,92 +0,0 @@
/* $NetBSD: ffs.S,v 1.5 2003/04/05 23:08:52 bjh21 Exp $ */
/*
* Copyright (c) 2001 Christopher Gilbert
* All rights reserved.
*
* 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.
* 3. The name of the company nor the name of the author may be used to
* endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
/*
* ffs - find first set bit, this algorithm isolates the first set
* bit, then multiplies the number by 0x0450fbaf which leaves the top
* 6 bits as an index into the table. This algorithm should be a win
* over the checking each bit in turn as per the C compiled version.
*
* This is the ffs algorithm devised by d.seal and posted to comp.sys.arm on
* 16 Feb 1994.
*/
.text
.ent ffs
.type ffs, @function
.global ffs
.align 4
.set noreorder
ffs:
#if (__mips==32)
subu $t0,$0,$a0
and $a0,$t0
clz $t0,$a0
li $v0,32
j $ra
subu $v0,$t0
#else
/* Size of the ffs routine in bytes
* This is used to index .L_ffs_table from $t9
* FIXME: there must be a better way to do this
*/
#define FFSSIZE 12*4
subu $t0,$0,$a0
and $a0,$t0
/*
* now a0 has at most one set bit, call this X
* if X = 0, all further instructions are skipped
*/
sll $t0,$a0,4 /* t0 = X * 0x00000010 */
or $a0,$t0 /* a0 = X * 0x00000011 */
sll $t0,$a0,6 /* t0 = X * 0x00000440 */
or $a0,$t0 /* a0 = X * 0x00000451 */
sll $t0,$a0,16 /* t0 = X * 0x04510000 */
subu $a0,$t0,$a0 /* a0 = X * 0x0450fbaf */
/* now lookup in table indexed on top 6 bits of a0 */
srl $a0,25
addu $t9,$a0
j $ra
lbu $v0,FFSSIZE($t9)
.L_ffs_table:
/* 0 1 2 3 4 5 6 7 */
.byte 0, 1, 2, 13, 3, 7, 0, 14 /* 0- 7 */
.byte 4, 0, 8, 0, 0, 0, 0, 15 /* 8-15 */
.byte 11, 5, 0, 0, 9, 0, 0, 26 /* 16-23 */
.byte 0, 0, 0, 0, 0, 22, 28, 16 /* 24-31 */
.byte 32, 12, 6, 0, 0, 0, 0, 0 /* 32-39 */
.byte 10, 0, 0, 25, 0, 0, 21, 27 /* 40-47 */
.byte 31, 0, 0, 0, 0, 24, 0, 20 /* 48-55 */
.byte 30, 0, 23, 19, 29, 18, 17, 0 /* 56-63 */
#endif
.end ffs

13
libc/arch-mips/mips.mk
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@ -1,20 +1,19 @@
_LIBC_ARCH_COMMON_SRC_FILES := \
arch-mips/bionic/__get_sp.S \
arch-mips/bionic/__set_tls.c \
arch-mips/bionic/_exit_with_stack_teardown.S \
arch-mips/bionic/_setjmp.S \
arch-mips/bionic/futex_mips.S \
arch-mips/bionic/bzero.S \
arch-mips/bionic/cacheflush.cpp \
arch-mips/bionic/clone.S \
arch-mips/bionic/ffs.S \
arch-mips/bionic/_exit_with_stack_teardown.S \
arch-mips/bionic/futex_mips.S \
arch-mips/bionic/__get_sp.S \
arch-mips/bionic/memcmp16.S \
arch-mips/bionic/memmove.c \
arch-mips/bionic/_setjmp.S \
arch-mips/bionic/setjmp.S \
arch-mips/bionic/__set_tls.c \
arch-mips/bionic/sigsetjmp.S \
arch-mips/bionic/vfork.S \
arch-mips/string/memset.S \
arch-mips/string/memcpy.S \
arch-mips/string/memset.S \
arch-mips/string/mips_strlen.c \
_LIBC_ARCH_STATIC_SRC_FILES := \

18
libc/arch-x86/string/ffs.S
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@ -1,18 +0,0 @@
/* $OpenBSD: ffs.S,v 1.3 2005/08/07 11:30:38 espie Exp $ */
/*
* Written by J.T. Conklin <jtc@netbsd.org>.
* Public domain.
*/
#include <machine/asm.h>
ENTRY(ffs)
bsfl 4(%esp),%eax
jz L1 /* ZF is set if all bits are 0 */
incl %eax /* bits numbered from 1, not 0 */
ret
.align 2
L1: xorl %eax,%eax /* clear result */
ret
END(ffs)

1
libc/arch-x86/x86.mk
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@ -9,7 +9,6 @@ _LIBC_ARCH_COMMON_SRC_FILES := \
arch-x86/bionic/sigsetjmp.S \
arch-x86/bionic/syscall.S \
arch-x86/bionic/vfork.S \
arch-x86/string/ffs.S
ifeq ($(ARCH_X86_HAVE_SSSE3),true)
_LIBC_ARCH_COMMON_SRC_FILES += \

18
libc/arch-x86_64/string/ffs.S
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@ -1,18 +0,0 @@
/* $OpenBSD: ffs.S,v 1.1 2004/01/28 01:44:45 mickey Exp $ */
/*
* Written by J.T. Conklin <jtc@netbsd.org>.
* Public domain.
* Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
*/
#include <machine/asm.h>
ENTRY(ffs)
bsfl %edi,%eax
jz L1 /* ZF is set if all bits are 0 */
incl %eax /* bits numbered from 1, not 0 */
ret
_ALIGN_TEXT
L1: xorl %eax,%eax /* clear result */
ret

1
libc/arch-x86_64/x86_64.mk
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@ -10,7 +10,6 @@ _LIBC_ARCH_COMMON_SRC_FILES := \
arch-x86_64/bionic/sigsetjmp.S \
arch-x86_64/bionic/syscall.S \
arch-x86_64/bionic/vfork.S \
arch-x86_64/string/ffs.S \
string/memcmp16.c \
_LIBC_ARCH_STATIC_SRC_FILES := \

33
libc/bionic/ffs.cpp Normal file
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@ -0,0 +1,33 @@
/*
* Copyright (C) 2013 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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 COPYRIGHT HOLDERS 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
* COPYRIGHT OWNER 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 <strings.h>
int ffs(int x) {
return __builtin_ffs(x);
}