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Add ffsl(), ffsll(), fls(), flsl(), flsll() and use GCC's __builtin_ctz/__builtin_clz for faster implementation of these

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This commit is contained in:
Jussi Kivilinna 2017-03-24 09:41:31 -06:00 committed by Gregory Nutt
parent 61ff3c6b84
commit d0c54039dc
9 changed files with 508 additions and 4 deletions
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12
include/nuttx/compiler.h
View file

@ -64,6 +64,18 @@
# define UNUSED(a) ((void)(a))
/* Built-in functions */
/* GCC 4.x have __builtin_ctz(|l|ll) and __builtin_clz(|l|ll). These count
* trailing/leading zeros of input number and typically will generate few
* fast bit-counting instructions. Inputting zero to these functions is
* undefined and needs to be taken care of by the caller. */
#if __GNUC__ >= 4
# define CONFIG_HAVE_BUILTIN_CTZ 1
# define CONFIG_HAVE_BUILTIN_CLZ 1
#endif
/* Attributes
*
* GCC supports weak symbols which can be used to reduce code size because

11
include/strings.h
View file

@ -114,6 +114,17 @@ static inline FAR char *rindex(FAR const char *s, int c)
****************************************************************************/
int ffs(int j);
int ffsl(long j);
#ifdef CONFIG_HAVE_LONG_LONG
int ffsll(long long j);
#endif
int fls(int j);
int flsl(long j);
#ifdef CONFIG_HAVE_LONG_LONG
int flsll(long long j);
#endif
int strcasecmp(FAR const char *, FAR const char *);
int strncasecmp(FAR const char *, FAR const char *, size_t);

3
libc/string/Make.defs
View file

@ -35,7 +35,8 @@
# Add the string C files to the build
CSRCS += lib_ffs.c lib_isbasedigit.c lib_memset.c lib_memchr.c
CSRCS += lib_ffs.c lib_ffsl.c lib_ffsll.c lib_fls.c lib_flsl.c
CSRCS += lib_flsll.c lib_isbasedigit.c lib_memset.c lib_memchr.c
CSRCS += lib_memccpy.c lib_memcmp.c lib_memmove.c lib_skipspace.c
CSRCS += lib_stpcpy.c lib_strcasecmp.c lib_strcat.c lib_strchr.c
CSRCS += lib_strcpy.c lib_strcmp.c lib_strcspn.c lib_strdup.c

12
libc/string/lib_ffs.c
View file

@ -33,11 +33,11 @@
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/compiler.h>
#include <strings.h>
/****************************************************************************
@ -55,11 +55,11 @@
*
* Description:
* The ffs() function will find the first bit set (beginning with the least
* significant bit) in i, and return the index of that bit. Bits are
* significant bit) in j, and return the index of that bit. Bits are
* numbered starting at one (the least significant bit).
*
* Returned Value:
* The ffs() function will return the index of the first bit set. If i is
* The ffs() function will return the index of the first bit set. If j is
* 0, then ffs() will return 0.
*
****************************************************************************/
@ -70,6 +70,11 @@ int ffs(int j)
if (j != 0)
{
#ifdef CONFIG_HAVE_BUILTIN_CTZ
/* Count trailing zeros function can be used to implement ffs. */
ret = __builtin_ctz(j) + 1;
#else
unsigned int value = (unsigned int)j;
int bitno;
@ -81,6 +86,7 @@ int ffs(int j)
break;
}
}
#endif
}
return ret;

93
libc/string/lib_ffsl.c Normal file
View file

@ -0,0 +1,93 @@
/****************************************************************************
* libc/string/lib_ffsl.c
*
* Copyright (C) 2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/compiler.h>
#include <strings.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define NBITS (8 * sizeof(unsigned long))
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: ffsl
*
* Description:
* The ffsl() function will find the first bit set (beginning with the least
* significant bit) in j, and return the index of that bit. Bits are
* numbered starting at one (the least significant bit).
*
* Returned Value:
* The ffsl() function will return the index of the first bit set. If j is
* 0, then ffsl() will return 0.
*
****************************************************************************/
int ffsl(long j)
{
int ret = 0;
if (j != 0)
{
#ifdef CONFIG_HAVE_BUILTIN_CTZ
/* Count trailing zeros function can be used to implement ffs. */
ret = __builtin_ctzl(j) + 1;
#else
unsigned long value = (unsigned long)j;
int bitno;
for (bitno = 1; bitno <= NBITS; bitno++, value >>= 1)
{
if ((value & 1) != 0)
{
ret = bitno;
break;
}
}
#endif
}
return ret;
}

97
libc/string/lib_ffsll.c Normal file
View file

@ -0,0 +1,97 @@
/****************************************************************************
* libc/string/lib_ffsll.c
*
* Copyright (C) 2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/compiler.h>
#include <strings.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define NBITS (8 * sizeof(unsigned long long))
/****************************************************************************
* Public Functions
****************************************************************************/
#ifdef CONFIG_HAVE_LONG_LONG
/****************************************************************************
* Name: ffsll
*
* Description:
* The ffsll() function will find the first bit set (beginning with the least
* significant bit) in i, and return the index of that bit. Bits are
* numbered starting at one (the least significant bit).
*
* Returned Value:
* The ffsll() function will return the index of the first bit set. If j is
* 0, then ffsll() will return 0.
*
****************************************************************************/
int ffsll(long long j)
{
int ret = 0;
if (j != 0)
{
#ifdef CONFIG_HAVE_BUILTIN_CTZ
/* Count trailing zeros function can be used to implement ffs. */
ret = __builtin_ctzll(j) + 1;
#else
unsigned long long value = (unsigned long long)j;
int bitno;
for (bitno = 1; bitno <= NBITS; bitno++, value >>= 1)
{
if ((value & 1) != 0)
{
ret = bitno;
break;
}
}
#endif
}
return ret;
}
#endif

93
libc/string/lib_fls.c Normal file
View file

@ -0,0 +1,93 @@
/****************************************************************************
* libc/string/lib_fls.c
*
* Copyright (C) 2017 Haltian Ltd. All rights reserved.
* Author: Jussi Kivilinna <jussi.kivilinna@haltian.com>
*
* 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. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/compiler.h>
#include <strings.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define NBITS (8 * sizeof(unsigned int))
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: fls
*
* Description:
* The fls() function will find the last bit set in value and return
* the index of that bit. Bits are numbered starting at one (the least
* significant bit).
*
* Returned Value:
* The fls() function will return the index of the last bit set. If j is
* 0, then fls() will return 0.
*
****************************************************************************/
int fls(int j)
{
int ret = 0;
if (j != 0)
{
#ifdef CONFIG_HAVE_BUILTIN_CLZ
/* Count leading zeros function can be used to implement fls. */
ret = NBITS - __builtin_clz(j);
#else
unsigned int value = (unsigned int)j;
int bitno;
for (bitno = 1; bitno <= NBITS; bitno++, value >>= 1)
{
if (value == 1)
{
ret = bitno;
break;
}
}
#endif
}
return ret;
}

93
libc/string/lib_flsl.c Normal file
View file

@ -0,0 +1,93 @@
/****************************************************************************
* libc/string/lib_fls.c
*
* Copyright (C) 2017 Haltian Ltd. All rights reserved.
* Author: Jussi Kivilinna <jussi.kivilinna@haltian.com>
*
* 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. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/compiler.h>
#include <strings.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define NBITS (8 * sizeof(unsigned long))
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: flsl
*
* Description:
* The flsl() function will find the last bit set in value and return
* the index of that bit. Bits are numbered starting at one (the least
* significant bit).
*
* Returned Value:
* The flsl() function will return the index of the last bit set. If j is
* 0, then flsl() will return 0.
*
****************************************************************************/
int flsl(long j)
{
int ret = 0;
if (j != 0)
{
#ifdef CONFIG_HAVE_BUILTIN_CLZ
/* Count leading zeros function can be used to implement fls. */
ret = NBITS - __builtin_clzl(j);
#else
unsigned long value = (unsigned long)j;
int bitno;
for (bitno = 1; bitno <= NBITS; bitno++, value >>= 1)
{
if (value == 1)
{
ret = bitno;
break;
}
}
#endif
}
return ret;
}

98
libc/string/lib_flsll.c Normal file
View file

@ -0,0 +1,98 @@
/****************************************************************************
* libc/string/lib_fls.c
*
* Copyright (C) 2017 Haltian Ltd. All rights reserved.
* Author: Jussi Kivilinna <jussi.kivilinna@haltian.com>
*
* 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. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/compiler.h>
#include <strings.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define NBITS (8 * sizeof(unsigned long long))
/****************************************************************************
* Public Functions
****************************************************************************/
#ifdef CONFIG_HAVE_LONG_LONG
/****************************************************************************
* Name: flsll
*
* Description:
* The flsll() function will find the last bit set in value and return
* the index of that bit. Bits are numbered starting at one (the least
* significant bit).
*
* Returned Value:
* The flsll() function will return the index of the last bit set. If j is
* 0, then flsll() will return 0.
*
****************************************************************************/
int flsll(long long j)
{
int ret = 0;
if (j != 0)
{
#ifdef CONFIG_HAVE_BUILTIN_CLZ
/* Count leading zeros function can be used to implement fls. */
ret = NBITS - __builtin_clzll(j);
#else
unsigned long long value = (unsigned long long)j;
int bitno;
for (bitno = 1; bitno <= NBITS; bitno++, value >>= 1)
{
if (value == 1)
{
ret = bitno;
break;
}
}
#endif
}
return ret;
}
#endif