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libc: implement C23 <stdbit.h> functions

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This new header complies with ISO/IEC 9899:2024 (C23).

Contrary to glibc, we do not provide inline definitions in
<stdbit.h> as we expect our system compiler to soon recognise
these as builtins anyway.

Relnotes:	yes
MFC after:	1 month
Reviewed by:	adrian
Approved by:	markj (mentor)
Differential Revision:	https://reviews.freebsd.org/D53657
This commit is contained in:
Robert Clausecker 2025-11-18 18:32:53 +01:00
parent 4a1c7529c9
commit 6296500a85
19 changed files with 973 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
include/Makefile
View file

@ -29,8 +29,8 @@ INCS= a.out.h ar.h assert.h bitstring.h byteswap.h \
pthread_np.h pwd.h ranlib.h readpassphrase.h regex.h \
res_update.h resolv.h runetype.h sched.h \
search.h semaphore.h setjmp.h \
signal.h spawn.h stab.h stdalign.h stdbool.h stdckdint.h stddef.h \
stdnoreturn.h stdio.h stdlib.h string.h stringlist.h \
signal.h spawn.h stab.h stdalign.h stdbit.h stdbool.h stdckdint.h \
stddef.h stdnoreturn.h stdio.h stdlib.h string.h stringlist.h \
strings.h sysexits.h tar.h termios.h tgmath.h \
time.h timeconv.h timers.h ttyent.h \
uchar.h ulimit.h unistd.h utime.h utmpx.h uuid.h varargs.h \

124
include/stdbit.h Normal file
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@ -0,0 +1,124 @@
/*-
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#ifndef __STDC_VERSION_STDBIT_H__
#define __STDC_VERSION_STDBIT_H__ 202311L
#include <sys/cdefs.h>
/* byte order */
#define __STDC_ENDIAN_LITTLE__ __ORDER_LITTLE_ENDIAN__
#define __STDC_ENDIAN_BIG__ __ORDER_BIG_ENDIAN__
#define __STDC_ENDIAN_NATIVE__ __BYTE_ORDER__
#define __generic_bitfunc(func, x) (_Generic(x, \
unsigned char: func ## _uc, \
unsigned short: func ## _us, \
unsigned int: func ## _ui, \
unsigned long: func ## _ul, \
unsigned long long: func ## _ull)(x))
__BEGIN_DECLS
unsigned int stdc_leading_zeros_uc(unsigned char) __pure2;
unsigned int stdc_leading_zeros_us(unsigned short) __pure2;
unsigned int stdc_leading_zeros_ui(unsigned int) __pure2;
unsigned int stdc_leading_zeros_ul(unsigned long) __pure2;
unsigned int stdc_leading_zeros_ull(unsigned long long) __pure2;
#define stdc_leading_zeros(x) __generic_bitfunc(stdc_leading_zeros, x)
unsigned int stdc_leading_ones_uc(unsigned char) __pure2;
unsigned int stdc_leading_ones_us(unsigned short) __pure2;
unsigned int stdc_leading_ones_ui(unsigned int) __pure2;
unsigned int stdc_leading_ones_ul(unsigned long) __pure2;
unsigned int stdc_leading_ones_ull(unsigned long long) __pure2;
#define stdc_leading_ones(x) __generic_bitfunc(stdc_leading_ones, x)
unsigned int stdc_trailing_zeros_uc(unsigned char) __pure2;
unsigned int stdc_trailing_zeros_us(unsigned short) __pure2;
unsigned int stdc_trailing_zeros_ui(unsigned int) __pure2;
unsigned int stdc_trailing_zeros_ul(unsigned long) __pure2;
unsigned int stdc_trailing_zeros_ull(unsigned long long) __pure2;
#define stdc_trailing_zeros(x) __generic_bitfunc(stdc_trailing_zeros, x)
unsigned int stdc_trailing_ones_uc(unsigned char) __pure2;
unsigned int stdc_trailing_ones_us(unsigned short) __pure2;
unsigned int stdc_trailing_ones_ui(unsigned int) __pure2;
unsigned int stdc_trailing_ones_ul(unsigned long) __pure2;
unsigned int stdc_trailing_ones_ull(unsigned long long) __pure2;
#define stdc_trailing_ones(x) __generic_bitfunc(stdc_trailing_ones, x)
unsigned int stdc_first_leading_zero_uc(unsigned char) __pure2;
unsigned int stdc_first_leading_zero_us(unsigned short) __pure2;
unsigned int stdc_first_leading_zero_ui(unsigned int) __pure2;
unsigned int stdc_first_leading_zero_ul(unsigned long) __pure2;
unsigned int stdc_first_leading_zero_ull(unsigned long long) __pure2;
#define stdc_first_leading_zero(x) __generic_bitfunc(stdc_first_leading_zero, x)
unsigned int stdc_first_leading_one_uc(unsigned char) __pure2;
unsigned int stdc_first_leading_one_us(unsigned short) __pure2;
unsigned int stdc_first_leading_one_ui(unsigned int) __pure2;
unsigned int stdc_first_leading_one_ul(unsigned long) __pure2;
unsigned int stdc_first_leading_one_ull(unsigned long long) __pure2;
#define stdc_first_leading_one(x) __generic_bitfunc(stdc_first_leading_one, x)
unsigned int stdc_first_trailing_zero_uc(unsigned char) __pure2;
unsigned int stdc_first_trailing_zero_us(unsigned short) __pure2;
unsigned int stdc_first_trailing_zero_ui(unsigned int) __pure2;
unsigned int stdc_first_trailing_zero_ul(unsigned long) __pure2;
unsigned int stdc_first_trailing_zero_ull(unsigned long long) __pure2;
#define stdc_first_trailing_zero(x) __generic_bitfunc(stdc_first_trailing_zero, x)
unsigned int stdc_first_trailing_one_uc(unsigned char) __pure2;
unsigned int stdc_first_trailing_one_us(unsigned short) __pure2;
unsigned int stdc_first_trailing_one_ui(unsigned int) __pure2;
unsigned int stdc_first_trailing_one_ul(unsigned long) __pure2;
unsigned int stdc_first_trailing_one_ull(unsigned long long) __pure2;
#define stdc_first_trailing_one(x) __generic_bitfunc(stdc_first_trailing_one, x)
unsigned int stdc_count_zeros_uc(unsigned char) __pure2;
unsigned int stdc_count_zeros_us(unsigned short) __pure2;
unsigned int stdc_count_zeros_ui(unsigned int) __pure2;
unsigned int stdc_count_zeros_ul(unsigned long) __pure2;
unsigned int stdc_count_zeros_ull(unsigned long long) __pure2;
#define stdc_count_zeros(x) __generic_bitfunc(stdc_count_zeros, x)
unsigned int stdc_count_ones_uc(unsigned char) __pure2;
unsigned int stdc_count_ones_us(unsigned short) __pure2;
unsigned int stdc_count_ones_ui(unsigned int) __pure2;
unsigned int stdc_count_ones_ul(unsigned long) __pure2;
unsigned int stdc_count_ones_ull(unsigned long long) __pure2;
#define stdc_count_ones(x) __generic_bitfunc(stdc_count_ones, x)
_Bool stdc_has_single_bit_uc(unsigned char) __pure2;
_Bool stdc_has_single_bit_us(unsigned short) __pure2;
_Bool stdc_has_single_bit_ui(unsigned int) __pure2;
_Bool stdc_has_single_bit_ul(unsigned long) __pure2;
_Bool stdc_has_single_bit_ull(unsigned long long) __pure2;
#define stdc_has_single_bit(x) __generic_bitfunc(stdc_has_single_bit, x)
unsigned int stdc_bit_width_uc(unsigned char) __pure2;
unsigned int stdc_bit_width_us(unsigned short) __pure2;
unsigned int stdc_bit_width_ui(unsigned int) __pure2;
unsigned int stdc_bit_width_ul(unsigned long) __pure2;
unsigned int stdc_bit_width_ull(unsigned long long) __pure2;
#define stdc_bit_width(x) __generic_bitfunc(stdc_bit_width, x)
unsigned char stdc_bit_floor_uc(unsigned char) __pure2;
unsigned short stdc_bit_floor_us(unsigned short) __pure2;
unsigned stdc_bit_floor_ui(unsigned int) __pure2;
unsigned long stdc_bit_floor_ul(unsigned long) __pure2;
unsigned long long stdc_bit_floor_ull(unsigned long long) __pure2;
#define stdc_bit_floor(x) __generic_bitfunc(stdc_bit_floor, x)
unsigned char stdc_bit_ceil_uc(unsigned char) __pure2;
unsigned short stdc_bit_ceil_us(unsigned short) __pure2;
unsigned int stdc_bit_ceil_ui(unsigned int) __pure2;
unsigned long stdc_bit_ceil_ul(unsigned long) __pure2;
unsigned long long stdc_bit_ceil_ull(unsigned long long) __pure2;
#define stdc_bit_ceil(x) __generic_bitfunc(stdc_bit_ceil, x)
__END_DECLS
#endif /* __STDC_VERSION_STDBIT_H__ */

1
lib/libc/Makefile
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@ -118,6 +118,7 @@ NOASM=
.endif
.include "${LIBC_SRCTOP}/regex/Makefile.inc"
.include "${LIBC_SRCTOP}/resolv/Makefile.inc"
.include "${LIBC_SRCTOP}/stdbit/Makefile.inc"
.include "${LIBC_SRCTOP}/stdio/Makefile.inc"
.include "${LIBC_SRCTOP}/stdlib/Makefile.inc"
.include "${LIBC_SRCTOP}/stdtime/Makefile.inc"

19
lib/libc/stdbit/Makefile.inc Normal file
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@ -0,0 +1,19 @@
# sources for <stdbit.h>
.PATH: ${LIBC_SRCTOP}/stdbit
SRCS+= stdc_bit_ceil.c \
stdc_bit_floor.c \
stdc_bit_width.c \
stdc_count_ones.c \
stdc_count_zeros.c \
stdc_first_leading_one.c \
stdc_first_leading_zero.c \
stdc_first_trailing_one.c \
stdc_first_trailing_zero.c \
stdc_has_single_bit.c \
stdc_leading_ones.c \
stdc_leading_zeros.c \
stdc_trailing_ones.c \
stdc_trailing_zeros.c
SYM_MAPS+=${LIBC_SRCTOP}/stdbit/Symbol.map

85
lib/libc/stdbit/Symbol.map Normal file
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@ -0,0 +1,85 @@
FBSD_1.9 {
stdc_leading_zeros_uc;
stdc_leading_zeros_us;
stdc_leading_zeros_ui;
stdc_leading_zeros_ul;
stdc_leading_zeros_ull;
stdc_leading_ones_uc;
stdc_leading_ones_us;
stdc_leading_ones_ui;
stdc_leading_ones_ul;
stdc_leading_ones_ull;
stdc_trailing_zeros_uc;
stdc_trailing_zeros_us;
stdc_trailing_zeros_ui;
stdc_trailing_zeros_ul;
stdc_trailing_zeros_ull;
stdc_trailing_ones_uc;
stdc_trailing_ones_us;
stdc_trailing_ones_ui;
stdc_trailing_ones_ul;
stdc_trailing_ones_ull;
stdc_first_leading_zero_uc;
stdc_first_leading_zero_us;
stdc_first_leading_zero_ui;
stdc_first_leading_zero_ul;
stdc_first_leading_zero_ull;
stdc_first_leading_one_uc;
stdc_first_leading_one_us;
stdc_first_leading_one_ui;
stdc_first_leading_one_ul;
stdc_first_leading_one_ull;
stdc_first_trailing_zero_uc;
stdc_first_trailing_zero_us;
stdc_first_trailing_zero_ui;
stdc_first_trailing_zero_ul;
stdc_first_trailing_zero_ull;
stdc_first_trailing_one_uc;
stdc_first_trailing_one_us;
stdc_first_trailing_one_ui;
stdc_first_trailing_one_ul;
stdc_first_trailing_one_ull;
stdc_count_zeros_uc;
stdc_count_zeros_us;
stdc_count_zeros_ui;
stdc_count_zeros_ul;
stdc_count_zeros_ull;
stdc_count_ones_uc;
stdc_count_ones_us;
stdc_count_ones_ui;
stdc_count_ones_ul;
stdc_count_ones_ull;
stdc_has_single_bit_uc;
stdc_has_single_bit_us;
stdc_has_single_bit_ui;
stdc_has_single_bit_ul;
stdc_has_single_bit_ull;
stdc_bit_width_uc;
stdc_bit_width_us;
stdc_bit_width_ui;
stdc_bit_width_ul;
stdc_bit_width_ull;
stdc_bit_floor_uc;
stdc_bit_floor_us;
stdc_bit_floor_ui;
stdc_bit_floor_ul;
stdc_bit_floor_ull;
stdc_bit_ceil_uc;
stdc_bit_ceil_us;
stdc_bit_ceil_ui;
stdc_bit_ceil_ul;
stdc_bit_ceil_ull;
};

71
lib/libc/stdbit/stdc_bit_ceil.c Normal file
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@ -0,0 +1,71 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <assert.h>
#include <limits.h>
#include <stdbit.h>
/* Ensure we don't shift 1U out of range. */
static_assert(UCHAR_WIDTH < UINT_WIDTH,
"stdc_bit_ceil_uc needs UCHAR_WIDTH < UINT_WIDTH");
unsigned char
stdc_bit_ceil_uc(unsigned char x)
{
if (x <= 1)
return (1);
return (1U << (UINT_WIDTH - __builtin_clz(x - 1)));
}
/* Ensure we don't shift 1U out of range. */
static_assert(USHRT_WIDTH < UINT_WIDTH,
"stdc_bit_ceil_us needs USHRT_WIDTH < UINT_WIDTH");
unsigned short
stdc_bit_ceil_us(unsigned short x)
{
if (x <= 1)
return (1);
return (1U << (UINT_WIDTH - __builtin_clz(x - 1)));
}
unsigned int
stdc_bit_ceil_ui(unsigned int x)
{
if (x <= 1)
return (1);
if (x > UINT_MAX/2 + 1)
return (0);
return (1U << (UINT_WIDTH - __builtin_clz(x - 1)));
}
unsigned long
stdc_bit_ceil_ul(unsigned long x)
{
if (x <= 1)
return (1);
if (x > ULONG_MAX/2 + 1)
return (0);
return (1UL << (ULONG_WIDTH - __builtin_clzl(x - 1)));
}
unsigned long long
stdc_bit_ceil_ull(unsigned long long x)
{
if (x <= 1)
return (1);
if (x > ULLONG_MAX/2 + 1)
return (0);
return (1ULL << (ULLONG_WIDTH - __builtin_clzll(x - 1)));
}

53
lib/libc/stdbit/stdc_bit_floor.c Normal file
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@ -0,0 +1,53 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <limits.h>
#include <stdbit.h>
unsigned char
stdc_bit_floor_uc(unsigned char x)
{
if (x == 0)
return (0);
return (1U << (UINT_WIDTH - __builtin_clz(x) - 1));
}
unsigned short
stdc_bit_floor_us(unsigned short x)
{
if (x == 0)
return (0);
return (1U << (UINT_WIDTH - __builtin_clz(x) - 1));
}
unsigned int
stdc_bit_floor_ui(unsigned int x)
{
if (x == 0)
return (0);
return (1U << (UINT_WIDTH - __builtin_clz(x) - 1));
}
unsigned long
stdc_bit_floor_ul(unsigned long x)
{
if (x == 0)
return (0);
return (1UL << (ULONG_WIDTH - __builtin_clzl(x) - 1));
}
unsigned long long
stdc_bit_floor_ull(unsigned long long x)
{
if (x == 0)
return (0);
return (1ULL << (ULLONG_WIDTH - __builtin_clzll(x) - 1));
}

53
lib/libc/stdbit/stdc_bit_width.c Normal file
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@ -0,0 +1,53 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <limits.h>
#include <stdbit.h>
unsigned int
stdc_bit_width_uc(unsigned char x)
{
if (x == 0)
return (0);
return (UINT_WIDTH - __builtin_clz(x));
}
unsigned int
stdc_bit_width_us(unsigned short x)
{
if (x == 0)
return (0);
return (UINT_WIDTH - __builtin_clz(x));
}
unsigned int
stdc_bit_width_ui(unsigned int x)
{
if (x == 0)
return (0);
return (UINT_WIDTH - __builtin_clz(x));
}
unsigned int
stdc_bit_width_ul(unsigned long x)
{
if (x == 0)
return (0);
return (ULONG_WIDTH - __builtin_clzl(x));
}
unsigned int
stdc_bit_width_ull(unsigned long long x)
{
if (x == 0)
return (0);
return (ULLONG_WIDTH - __builtin_clzll(x));
}

38
lib/libc/stdbit/stdc_count_ones.c Normal file
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@ -0,0 +1,38 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <limits.h>
#include <stdbit.h>
unsigned int
stdc_count_ones_uc(unsigned char x)
{
return (__builtin_popcount(x));
}
unsigned int
stdc_count_ones_us(unsigned short x)
{
return (__builtin_popcount(x));
}
unsigned int
stdc_count_ones_ui(unsigned int x)
{
return (__builtin_popcount(x));
}
unsigned int
stdc_count_ones_ul(unsigned long x)
{
return (__builtin_popcountl(x));
}
unsigned int
stdc_count_ones_ull(unsigned long long x)
{
return (__builtin_popcountll(x));
}

38
lib/libc/stdbit/stdc_count_zeros.c Normal file
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@ -0,0 +1,38 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <limits.h>
#include <stdbit.h>
unsigned int
stdc_count_zeros_uc(unsigned char x)
{
return (__builtin_popcount(x ^ UCHAR_MAX));
}
unsigned int
stdc_count_zeros_us(unsigned short x)
{
return (__builtin_popcount(x ^ USHRT_MAX));
}
unsigned int
stdc_count_zeros_ui(unsigned int x)
{
return (__builtin_popcount(~x));
}
unsigned int
stdc_count_zeros_ul(unsigned long x)
{
return (__builtin_popcountl(~x));
}
unsigned int
stdc_count_zeros_ull(unsigned long long x)
{
return (__builtin_popcountll(~x));
}

57
lib/libc/stdbit/stdc_first_leading_one.c Normal file
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@ -0,0 +1,57 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <limits.h>
#include <stdbit.h>
unsigned int
stdc_first_leading_one_uc(unsigned char x)
{
const int offset = UINT_WIDTH - UCHAR_WIDTH;
if (x == 0)
return (0);
return (__builtin_clz(x << offset) + 1);
}
unsigned int
stdc_first_leading_one_us(unsigned short x)
{
const int offset = UINT_WIDTH - USHRT_WIDTH;
if (x == 0)
return (0);
return (__builtin_clz(x << offset) + 1);
}
unsigned int
stdc_first_leading_one_ui(unsigned int x)
{
if (x == 0)
return (0);
return (__builtin_clz(x) + 1);
}
unsigned int
stdc_first_leading_one_ul(unsigned long x)
{
if (x == 0)
return (0);
return (__builtin_clzl(x) + 1);
}
unsigned int
stdc_first_leading_one_ull(unsigned long long x)
{
if (x == 0)
return (0);
return (__builtin_clzll(x) + 1);
}

57
lib/libc/stdbit/stdc_first_leading_zero.c Normal file
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@ -0,0 +1,57 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <limits.h>
#include <stdbit.h>
unsigned int
stdc_first_leading_zero_uc(unsigned char x)
{
const int offset = UINT_WIDTH - UCHAR_WIDTH;
if (x == UCHAR_MAX)
return (0);
return (__builtin_clz(~(unsigned int)x << offset) + 1);
}
unsigned int
stdc_first_leading_zero_us(unsigned short x)
{
const int offset = UINT_WIDTH - USHRT_WIDTH;
if (x == USHRT_MAX)
return (0);
return (__builtin_clz(~(unsigned int)x << offset) + 1);
}
unsigned int
stdc_first_leading_zero_ui(unsigned int x)
{
if (x == ~0U)
return (0);
return (__builtin_clz(~x) + 1);
}
unsigned int
stdc_first_leading_zero_ul(unsigned long x)
{
if (x == ~0UL)
return (0);
return (__builtin_clzl(~x) + 1);
}
unsigned int
stdc_first_leading_zero_ull(unsigned long long x)
{
if (x == ~0ULL)
return (0);
return (__builtin_clzll(~x) + 1);
}

52
lib/libc/stdbit/stdc_first_trailing_one.c Normal file
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@ -0,0 +1,52 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <stdbit.h>
unsigned int
stdc_first_trailing_one_uc(unsigned char x)
{
if (x == 0)
return (0);
return (__builtin_ctz(x) + 1);
}
unsigned int
stdc_first_trailing_one_us(unsigned short x)
{
if (x == 0)
return (0);
return (__builtin_ctz(x) + 1);
}
unsigned int
stdc_first_trailing_one_ui(unsigned int x)
{
if (x == 0)
return (0);
return (__builtin_ctz(x) + 1);
}
unsigned int
stdc_first_trailing_one_ul(unsigned long x)
{
if (x == 0)
return (0);
return (__builtin_ctzl(x) + 1);
}
unsigned int
stdc_first_trailing_one_ull(unsigned long long x)
{
if (x == 0)
return (0);
return (__builtin_ctzll(x) + 1);
}

53
lib/libc/stdbit/stdc_first_trailing_zero.c Normal file
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@ -0,0 +1,53 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <limits.h>
#include <stdbit.h>
unsigned int
stdc_first_trailing_zero_uc(unsigned char x)
{
if (x == UCHAR_MAX)
return (0);
return (__builtin_ctz(~x) + 1);
}
unsigned int
stdc_first_trailing_zero_us(unsigned short x)
{
if (x == USHRT_MAX)
return (0);
return (__builtin_ctz(~x) + 1);
}
unsigned int
stdc_first_trailing_zero_ui(unsigned int x)
{
if (x == ~0U)
return (0);
return (__builtin_ctz(~x) + 1);
}
unsigned int
stdc_first_trailing_zero_ul(unsigned long x)
{
if (x == ~0UL)
return (0);
return (__builtin_ctzl(~x) + 1);
}
unsigned int
stdc_first_trailing_zero_ull(unsigned long long x)
{
if (x == ~0ULL)
return (0);
return (__builtin_ctzll(~x) + 1);
}

38
lib/libc/stdbit/stdc_has_single_bit.c Normal file
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@ -0,0 +1,38 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <stdbit.h>
#include <stdbool.h>
bool
stdc_has_single_bit_uc(unsigned char x)
{
return (x != 0 && (x & x - 1) == 0);
}
bool
stdc_has_single_bit_us(unsigned short x)
{
return (x != 0 && (x & x - 1) == 0);
}
bool
stdc_has_single_bit_ui(unsigned int x)
{
return (x != 0 && (x & x - 1) == 0);
}
bool
stdc_has_single_bit_ul(unsigned long x)
{
return (x != 0 && (x & x - 1) == 0);
}
bool
stdc_has_single_bit_ull(unsigned long long x)
{
return (x != 0 && (x & x - 1) == 0);
}

60
lib/libc/stdbit/stdc_leading_ones.c Normal file
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@ -0,0 +1,60 @@
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <assert.h>
#include <limits.h>
#include <stdbit.h>
/* Avoid triggering undefined behavior if x == 0. */
static_assert(UCHAR_WIDTH < UINT_WIDTH,
"stdc_leading_ones_uc needs UCHAR_WIDTH < UINT_WIDTH");
unsigned int
stdc_leading_ones_uc(unsigned char x)
{
const int offset = UINT_WIDTH - UCHAR_WIDTH;
return (__builtin_clz(~(x << offset)));
}
/* Avoid triggering undefined behavior if x == 0. */
static_assert(USHRT_WIDTH < UINT_WIDTH,
"stdc_leading_ones_us needs USHRT_WIDTH < UINT_WIDTH");
unsigned int
stdc_leading_ones_us(unsigned short x)
{
const int offset = UINT_WIDTH - USHRT_WIDTH;
return (__builtin_clz(~(x << offset)));
}
unsigned int
stdc_leading_ones_ui(unsigned int x)
{
if (x == ~0U)
return (UINT_WIDTH);
return (__builtin_clz(~x));
}
unsigned int
stdc_leading_ones_ul(unsigned long x)
{
if (x == ~0UL)
return (ULONG_WIDTH);
return (__builtin_clzl(~x));
}
unsigned int
stdc_leading_ones_ull(unsigned long long x)
{
if (x == ~0ULL)
return (ULLONG_WIDTH);
return (__builtin_clzll(~x));
}

60
lib/libc/stdbit/stdc_leading_zeros.c Normal file
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/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <assert.h>
#include <limits.h>
#include <stdbit.h>
/* Offset must be greater than zero. */
static_assert(UCHAR_WIDTH < UINT_WIDTH,
"stdc_leading_zeros_uc needs UCHAR_WIDTH < UINT_WIDTH");
unsigned int
stdc_leading_zeros_uc(unsigned char x)
{
const int offset = UINT_WIDTH - UCHAR_WIDTH;
return (__builtin_clz((x << offset) + (1U << (offset - 1))));
}
/* Offset must be greater than zero. */
static_assert(USHRT_WIDTH < UINT_WIDTH,
"stdc_leading_zeros_us needs USHRT_WIDTH < UINT_WIDTH");
unsigned int
stdc_leading_zeros_us(unsigned short x)
{
const int offset = UINT_WIDTH - USHRT_WIDTH;
return (__builtin_clz((x << offset) + (1U << (offset - 1))));
}
unsigned int
stdc_leading_zeros_ui(unsigned int x)
{
if (x == 0)
return (UINT_WIDTH);
return (__builtin_clz(x));
}
unsigned int
stdc_leading_zeros_ul(unsigned long x)
{
if (x == 0)
return (ULONG_WIDTH);
return (__builtin_clzl(x));
}
unsigned int
stdc_leading_zeros_ull(unsigned long long x)
{
if (x == 0)
return (ULLONG_WIDTH);
return (__builtin_clzll(x));
}

56
lib/libc/stdbit/stdc_trailing_ones.c Normal file
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/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <assert.h>
#include <limits.h>
#include <stdbit.h>
/* Avoid triggering undefined behavior if x == ~0. */
static_assert(UCHAR_WIDTH < UINT_WIDTH,
"stdc_trailing_ones_uc needs UCHAR_WIDTH < UINT_WIDTH");
unsigned int
stdc_trailing_ones_uc(unsigned char x)
{
return (__builtin_ctz(~x));
}
/* Avoid triggering undefined behavior if x == ~0. */
static_assert(USHRT_WIDTH < UINT_WIDTH,
"stdc_trailing_ones_uc needs USHRT_WIDTH < UINT_WIDTH");
unsigned int
stdc_trailing_ones_us(unsigned short x)
{
return (__builtin_ctz(~x));
}
unsigned int
stdc_trailing_ones_ui(unsigned int x)
{
if (x == ~0U)
return (UINT_WIDTH);
return (__builtin_ctz(~x));
}
unsigned int
stdc_trailing_ones_ul(unsigned long x)
{
if (x == ~0UL)
return (ULONG_WIDTH);
return (__builtin_ctzl(~x));
}
unsigned int
stdc_trailing_ones_ull(unsigned long long x)
{
if (x == ~0ULL)
return (ULLONG_WIDTH);
return (__builtin_ctzll(~x));
}

56
lib/libc/stdbit/stdc_trailing_zeros.c Normal file
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/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <assert.h>
#include <limits.h>
#include <stdbit.h>
/* Ensure we do not shift 1U out of range. */
static_assert(UCHAR_WIDTH < UINT_WIDTH,
"stdc_trailing_zeros_uc needs UCHAR_WIDTH < UINT_WIDTH");
unsigned int
stdc_trailing_zeros_uc(unsigned char x)
{
return (__builtin_ctz(x | 1U << UCHAR_WIDTH));
}
/* Ensure we do not shift 1U out of range. */
static_assert(USHRT_WIDTH < UINT_WIDTH,
"stdc_trailing_zeros_uc needs USHRT_WIDTH < UINT_WIDTH");
unsigned int
stdc_trailing_zeros_us(unsigned short x)
{
return (__builtin_ctz(x | 1U << USHRT_WIDTH));
}
unsigned int
stdc_trailing_zeros_ui(unsigned int x)
{
if (x == 0U)
return (UINT_WIDTH);
return (__builtin_ctz(x));
}
unsigned int
stdc_trailing_zeros_ul(unsigned long x)
{
if (x == 0UL)
return (ULONG_WIDTH);
return (__builtin_ctzl(x));
}
unsigned int
stdc_trailing_zeros_ull(unsigned long long x)
{
if (x == 0ULL)
return (ULLONG_WIDTH);
return (__builtin_ctzll(x));
}