* [PATCH v2 0/2] Add C23 stdbit.h functionality
@ 2026-04-10 19:21 Joel Sherrill
2026-04-10 19:21 ` [PATCH v2 1/2] newlib/libc: Add C23 stdbit.h from FreeBSD Joel Sherrill
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Joel Sherrill @ 2026-04-10 19:21 UTC (permalink / raw)
To: newlib; +Cc: Joel Sherrill
In response to comments on the previous version of this patch,
I submitted my first Cygwin patch to add the missing _WIDTH
constants to the Cygwin limits.h. That patch is now merged
which hopefully removes the barrier for merging this.
Note that a limits.h implementation can "include_next" the
GCC limits.h and it will provide many constants. Cygwin
had a self-contained version and they had to be added.
Two patches:
- 0001 - adds the files
- 0002 - regenerates
--joel
Joel Sherrill (2):
newlib/libc: Add C23 stdbit.h from FreeBSD
Makefile.inc, stdbit/Makefile.inc: Add stdbit
newlib/libc/Makefile.inc | 1 +
newlib/libc/include/stdbit.h | 124 ++++++++++++++++++
newlib/libc/stdbit/Makefile.inc | 15 +++
newlib/libc/stdbit/stdc_bit_ceil.3 | 81 ++++++++++++
newlib/libc/stdbit/stdc_bit_ceil.c | 71 ++++++++++
newlib/libc/stdbit/stdc_bit_floor.3 | 83 ++++++++++++
newlib/libc/stdbit/stdc_bit_floor.c | 53 ++++++++
newlib/libc/stdbit/stdc_bit_width.3 | 104 +++++++++++++++
newlib/libc/stdbit/stdc_bit_width.c | 53 ++++++++
newlib/libc/stdbit/stdc_count_ones.3 | 85 ++++++++++++
newlib/libc/stdbit/stdc_count_ones.c | 38 ++++++
newlib/libc/stdbit/stdc_count_zeros.3 | 84 ++++++++++++
newlib/libc/stdbit/stdc_count_zeros.c | 38 ++++++
newlib/libc/stdbit/stdc_first_leading_one.3 | 93 +++++++++++++
newlib/libc/stdbit/stdc_first_leading_one.c | 57 ++++++++
newlib/libc/stdbit/stdc_first_leading_zero.3 | 92 +++++++++++++
newlib/libc/stdbit/stdc_first_leading_zero.c | 57 ++++++++
newlib/libc/stdbit/stdc_first_trailing_one.3 | 110 ++++++++++++++++
newlib/libc/stdbit/stdc_first_trailing_one.c | 52 ++++++++
newlib/libc/stdbit/stdc_first_trailing_zero.3 | 93 +++++++++++++
newlib/libc/stdbit/stdc_first_trailing_zero.c | 53 ++++++++
newlib/libc/stdbit/stdc_has_single_bit.3 | 98 ++++++++++++++
newlib/libc/stdbit/stdc_has_single_bit.c | 38 ++++++
newlib/libc/stdbit/stdc_leading_ones.3 | 86 ++++++++++++
newlib/libc/stdbit/stdc_leading_ones.c | 60 +++++++++
newlib/libc/stdbit/stdc_leading_zeros.3 | 86 ++++++++++++
newlib/libc/stdbit/stdc_leading_zeros.c | 60 +++++++++
newlib/libc/stdbit/stdc_trailing_ones.3 | 86 ++++++++++++
newlib/libc/stdbit/stdc_trailing_ones.c | 56 ++++++++
newlib/libc/stdbit/stdc_trailing_zeros.3 | 87 ++++++++++++
newlib/libc/stdbit/stdc_trailing_zeros.c | 56 ++++++++
31 files changed, 2150 insertions(+)
create mode 100644 newlib/libc/include/stdbit.h
create mode 100644 newlib/libc/stdbit/Makefile.inc
create mode 100644 newlib/libc/stdbit/stdc_bit_ceil.3
create mode 100644 newlib/libc/stdbit/stdc_bit_ceil.c
create mode 100644 newlib/libc/stdbit/stdc_bit_floor.3
create mode 100644 newlib/libc/stdbit/stdc_bit_floor.c
create mode 100644 newlib/libc/stdbit/stdc_bit_width.3
create mode 100644 newlib/libc/stdbit/stdc_bit_width.c
create mode 100644 newlib/libc/stdbit/stdc_count_ones.3
create mode 100644 newlib/libc/stdbit/stdc_count_ones.c
create mode 100644 newlib/libc/stdbit/stdc_count_zeros.3
create mode 100644 newlib/libc/stdbit/stdc_count_zeros.c
create mode 100644 newlib/libc/stdbit/stdc_first_leading_one.3
create mode 100644 newlib/libc/stdbit/stdc_first_leading_one.c
create mode 100644 newlib/libc/stdbit/stdc_first_leading_zero.3
create mode 100644 newlib/libc/stdbit/stdc_first_leading_zero.c
create mode 100644 newlib/libc/stdbit/stdc_first_trailing_one.3
create mode 100644 newlib/libc/stdbit/stdc_first_trailing_one.c
create mode 100644 newlib/libc/stdbit/stdc_first_trailing_zero.3
create mode 100644 newlib/libc/stdbit/stdc_first_trailing_zero.c
create mode 100644 newlib/libc/stdbit/stdc_has_single_bit.3
create mode 100644 newlib/libc/stdbit/stdc_has_single_bit.c
create mode 100644 newlib/libc/stdbit/stdc_leading_ones.3
create mode 100644 newlib/libc/stdbit/stdc_leading_ones.c
create mode 100644 newlib/libc/stdbit/stdc_leading_zeros.3
create mode 100644 newlib/libc/stdbit/stdc_leading_zeros.c
create mode 100644 newlib/libc/stdbit/stdc_trailing_ones.3
create mode 100644 newlib/libc/stdbit/stdc_trailing_ones.c
create mode 100644 newlib/libc/stdbit/stdc_trailing_zeros.3
create mode 100644 newlib/libc/stdbit/stdc_trailing_zeros.c
--
2.47.3
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 1/2] newlib/libc: Add C23 stdbit.h from FreeBSD
2026-04-10 19:21 [PATCH v2 0/2] Add C23 stdbit.h functionality Joel Sherrill
@ 2026-04-10 19:21 ` Joel Sherrill
2026-04-10 19:21 ` [PATCH v2 2/2] Makefile.inc, stdbit/Makefile.inc: Add stdbit Joel Sherrill
2026-04-13 10:51 ` [PATCH v2 0/2] Add C23 stdbit.h functionality Corinna Vinschen
2 siblings, 0 replies; 7+ messages in thread
From: Joel Sherrill @ 2026-04-10 19:21 UTC (permalink / raw)
To: newlib; +Cc: Joel Sherrill
FreeBSD git hash: 80b4129bef8b908eb19fe47853cb6e45e4513d76
---
newlib/libc/include/stdbit.h | 124 ++++++++++++++++++
newlib/libc/stdbit/stdc_bit_ceil.3 | 81 ++++++++++++
newlib/libc/stdbit/stdc_bit_ceil.c | 71 ++++++++++
newlib/libc/stdbit/stdc_bit_floor.3 | 83 ++++++++++++
newlib/libc/stdbit/stdc_bit_floor.c | 53 ++++++++
newlib/libc/stdbit/stdc_bit_width.3 | 104 +++++++++++++++
newlib/libc/stdbit/stdc_bit_width.c | 53 ++++++++
newlib/libc/stdbit/stdc_count_ones.3 | 85 ++++++++++++
newlib/libc/stdbit/stdc_count_ones.c | 38 ++++++
newlib/libc/stdbit/stdc_count_zeros.3 | 84 ++++++++++++
newlib/libc/stdbit/stdc_count_zeros.c | 38 ++++++
newlib/libc/stdbit/stdc_first_leading_one.3 | 93 +++++++++++++
newlib/libc/stdbit/stdc_first_leading_one.c | 57 ++++++++
newlib/libc/stdbit/stdc_first_leading_zero.3 | 92 +++++++++++++
newlib/libc/stdbit/stdc_first_leading_zero.c | 57 ++++++++
newlib/libc/stdbit/stdc_first_trailing_one.3 | 110 ++++++++++++++++
newlib/libc/stdbit/stdc_first_trailing_one.c | 52 ++++++++
newlib/libc/stdbit/stdc_first_trailing_zero.3 | 93 +++++++++++++
newlib/libc/stdbit/stdc_first_trailing_zero.c | 53 ++++++++
newlib/libc/stdbit/stdc_has_single_bit.3 | 98 ++++++++++++++
newlib/libc/stdbit/stdc_has_single_bit.c | 38 ++++++
newlib/libc/stdbit/stdc_leading_ones.3 | 86 ++++++++++++
newlib/libc/stdbit/stdc_leading_ones.c | 60 +++++++++
newlib/libc/stdbit/stdc_leading_zeros.3 | 86 ++++++++++++
newlib/libc/stdbit/stdc_leading_zeros.c | 60 +++++++++
newlib/libc/stdbit/stdc_trailing_ones.3 | 86 ++++++++++++
newlib/libc/stdbit/stdc_trailing_ones.c | 56 ++++++++
newlib/libc/stdbit/stdc_trailing_zeros.3 | 87 ++++++++++++
newlib/libc/stdbit/stdc_trailing_zeros.c | 56 ++++++++
29 files changed, 2134 insertions(+)
create mode 100644 newlib/libc/include/stdbit.h
create mode 100644 newlib/libc/stdbit/stdc_bit_ceil.3
create mode 100644 newlib/libc/stdbit/stdc_bit_ceil.c
create mode 100644 newlib/libc/stdbit/stdc_bit_floor.3
create mode 100644 newlib/libc/stdbit/stdc_bit_floor.c
create mode 100644 newlib/libc/stdbit/stdc_bit_width.3
create mode 100644 newlib/libc/stdbit/stdc_bit_width.c
create mode 100644 newlib/libc/stdbit/stdc_count_ones.3
create mode 100644 newlib/libc/stdbit/stdc_count_ones.c
create mode 100644 newlib/libc/stdbit/stdc_count_zeros.3
create mode 100644 newlib/libc/stdbit/stdc_count_zeros.c
create mode 100644 newlib/libc/stdbit/stdc_first_leading_one.3
create mode 100644 newlib/libc/stdbit/stdc_first_leading_one.c
create mode 100644 newlib/libc/stdbit/stdc_first_leading_zero.3
create mode 100644 newlib/libc/stdbit/stdc_first_leading_zero.c
create mode 100644 newlib/libc/stdbit/stdc_first_trailing_one.3
create mode 100644 newlib/libc/stdbit/stdc_first_trailing_one.c
create mode 100644 newlib/libc/stdbit/stdc_first_trailing_zero.3
create mode 100644 newlib/libc/stdbit/stdc_first_trailing_zero.c
create mode 100644 newlib/libc/stdbit/stdc_has_single_bit.3
create mode 100644 newlib/libc/stdbit/stdc_has_single_bit.c
create mode 100644 newlib/libc/stdbit/stdc_leading_ones.3
create mode 100644 newlib/libc/stdbit/stdc_leading_ones.c
create mode 100644 newlib/libc/stdbit/stdc_leading_zeros.3
create mode 100644 newlib/libc/stdbit/stdc_leading_zeros.c
create mode 100644 newlib/libc/stdbit/stdc_trailing_ones.3
create mode 100644 newlib/libc/stdbit/stdc_trailing_ones.c
create mode 100644 newlib/libc/stdbit/stdc_trailing_zeros.3
create mode 100644 newlib/libc/stdbit/stdc_trailing_zeros.c
diff --git a/newlib/libc/include/stdbit.h b/newlib/libc/include/stdbit.h
new file mode 100644
index 000000000..a529676be
--- /dev/null
+++ b/newlib/libc/include/stdbit.h
@@ -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__ */
diff --git a/newlib/libc/stdbit/stdc_bit_ceil.3 b/newlib/libc/stdbit/stdc_bit_ceil.3
new file mode 100644
index 000000000..470b255f4
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_bit_ceil.3
@@ -0,0 +1,81 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_BIT_CEIL 3
+.Os
+.Sh NAME
+.Nm stdc_bit_ceil
+.Nd round up to the next power of\~2
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned char
+.Fn stdc_bit_ceil_uc "unsigned char value"
+.Ft unsigned short
+.Fn stdc_bit_ceil_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_bit_ceil_ui "unsigned int value"
+.Ft unsigned long
+.Fn stdc_bit_ceil_ul "unsigned long value"
+.Ft unsigned long long
+.Fn stdc_bit_ceil_ull "unsigned long long value"
+.Ft typeof Ns Pq Em value
+.Fn stdc_bit_ceil "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_bit_ceil_ Ns Em type Ns ()
+family of functions rounds
+.Fa value
+up to the next power of\~2, where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_bit_ceil "value"
+type-generic macro picks the appropriate
+.Nm stdc_bit_ceil_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns
+.Fa value
+round up to the next power of\~2.
+If this value is not representable,
+0\~is returned.
+.Sh SEE ALSO
+.Xr stdbit 3 ,
+.Xr stdc_bit_floor 3
+.Sh STANDARDS
+The
+.Nm stdc_bit_ceil_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_bit_ceil
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_bit_ceil_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_bit_ceil
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_bit_ceil.c b/newlib/libc/stdbit/stdc_bit_ceil.c
new file mode 100644
index 000000000..2dfd7bbcb
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_bit_ceil.c
@@ -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)));
+}
diff --git a/newlib/libc/stdbit/stdc_bit_floor.3 b/newlib/libc/stdbit/stdc_bit_floor.3
new file mode 100644
index 000000000..3e90c34f0
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_bit_floor.3
@@ -0,0 +1,83 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_BIT_FLOOR 3
+.Os
+.Sh NAME
+.Nm stdc_bit_floor
+.Nd round down to the previous power of\~2
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned char
+.Fn stdc_bit_floor_uc "unsigned char value"
+.Ft unsigned short
+.Fn stdc_bit_floor_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_bit_floor_ui "unsigned int value"
+.Ft unsigned long
+.Fn stdc_bit_floor_ul "unsigned long value"
+.Ft unsigned long long
+.Fn stdc_bit_floor_ull "unsigned long long value"
+.Ft typeof Ns Pq Em value
+.Fn stdc_bit_floor "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_bit_floor_ Ns Em type Ns ()
+family of functions rounds
+.Fa value
+down to the previous power of\~2, where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_bit_floor "value"
+type-generic macro picks the appropriate
+.Nm stdc_bit_floor_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns
+.Fa value
+round down to the previous power of\~2.
+If
+.Fa value
+is equal to zero,
+zero is returned.
+.Sh SEE ALSO
+.Xr stdbit 3 ,
+.Xr stdc_bit_ceil 3
+.Sh STANDARDS
+The
+.Nm stdc_bit_floor_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_bit_floor
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_bit_floor_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_bit_floor
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_bit_floor.c b/newlib/libc/stdbit/stdc_bit_floor.c
new file mode 100644
index 000000000..0a491d6ec
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_bit_floor.c
@@ -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));
+}
diff --git a/newlib/libc/stdbit/stdc_bit_width.3 b/newlib/libc/stdbit/stdc_bit_width.3
new file mode 100644
index 000000000..68c41d896
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_bit_width.3
@@ -0,0 +1,104 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_BIT_WIDTH 3
+.Os
+.Sh NAME
+.Nm stdc_bit_width
+.Nd find the first trailing one in an intege
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_bit_width_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_bit_width_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_bit_width_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_bit_width_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_bit_width_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_bit_width "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_bit_width_ Ns Em type Ns ()
+family of functions returns the number of bits needed to represent
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_bit_width "value"
+type-generic macro picks the appropriate
+.Nm stdc_bit_width_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Pp
+Functions
+.Fn stdc_bit_width_ui ,
+.Fn stdc_bit_width_ul ,
+and
+.Fn stdc_bit_width_ull
+are identical to
+.Bx 4.3
+functions
+.Xr fls 3 ,
+.Xr flsl 3 ,
+and
+.Xr flsll 3
+respectively, except for operating on unsigned instead of signed values.
+.Sh RETURN VALUES
+Returns the least number of bits needed to represent
+.Fa value .
+If
+.Fa value
+is zero, the return value is zero.
+Otherwise it is
+.EQ
+1 + \(lf log sub 2 italic value \(rf .
+.EN
+.Sh SEE ALSO
+.Xr bit_fls 3 ,
+.Xr fls 3 ,
+.Xr flsl 3 ,
+.Xr flsll 3 ,
+.Xr stdbit 3 ,
+.Xr stdc_count_leading_zeros 3 ,
+.Xr stdc_first_leading_one 3
+.Sh STANDARDS
+The
+.Nm stdc_bit_width_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_bit_width
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_bit_width_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_bit_width
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_bit_width.c b/newlib/libc/stdbit/stdc_bit_width.c
new file mode 100644
index 000000000..e248fae48
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_bit_width.c
@@ -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));
+}
diff --git a/newlib/libc/stdbit/stdc_count_ones.3 b/newlib/libc/stdbit/stdc_count_ones.3
new file mode 100644
index 000000000..fa3a2aa36
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_count_ones.3
@@ -0,0 +1,85 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_COUNT_ONES 3
+.Os
+.Sh NAME
+.Nm stdc_count_ones
+.Nd count the ones in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_count_ones_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_count_ones_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_count_ones_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_count_ones_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_count_ones_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_count_ones "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_count_ones_ Ns Em type Ns ()
+family of functions returns the number of bits set to\~1 in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+This is also known as the
+.Dq population count
+(popcount) or
+.Dq Hamming weight
+operation.
+The
+.Fn stdc_count_ones "value"
+type-generic macro picks the appropriate
+.Nm stdc_count_ones_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns the number of bits set to\~1 in
+.Fa value .
+.Sh SEE ALSO
+.Xr bit_count 3 ,
+.Xr stdbit 3 ,
+.Xr stdc_count_zeros 3 ,
+.Xr stdc_has_single_bit 3
+.Sh STANDARDS
+The
+.Nm stdc_count_ones_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_count_ones
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_count_ones_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_count_ones
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_count_ones.c b/newlib/libc/stdbit/stdc_count_ones.c
new file mode 100644
index 000000000..c5198dca8
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_count_ones.c
@@ -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));
+}
diff --git a/newlib/libc/stdbit/stdc_count_zeros.3 b/newlib/libc/stdbit/stdc_count_zeros.3
new file mode 100644
index 000000000..eef7a9e88
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_count_zeros.3
@@ -0,0 +1,84 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_COUNT_ZEROS 3
+.Os
+.Sh NAME
+.Nm stdc_count_zeros
+.Nd count the zeros in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_count_zeros_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_count_zeros_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_count_zeros_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_count_zeros_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_count_zeros_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_count_zeros "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_count_zeros_ Ns Em type Ns ()
+family of functions returns the number of bits set to\~0 in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+This is also known as the
+.Dq population count
+(popcount) or
+.Dq Hamming weight
+of the complement of
+.Fa value .
+The
+.Fn stdc_count_zeros "value"
+type-generic macro picks the appropriate
+.Nm stdc_count_zeros_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns the number of bits set to\~0 in
+.Fa value .
+.Sh SEE ALSO
+.Xr stdbit 3 ,
+.Xr stdc_count_ones 3
+.Sh STANDARDS
+The
+.Nm stdc_count_zeros_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_count_zeros
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_count_zeros_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_count_zeros
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_count_zeros.c b/newlib/libc/stdbit/stdc_count_zeros.c
new file mode 100644
index 000000000..35db965af
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_count_zeros.c
@@ -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));
+}
diff --git a/newlib/libc/stdbit/stdc_first_leading_one.3 b/newlib/libc/stdbit/stdc_first_leading_one.3
new file mode 100644
index 000000000..c2dd423bf
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_first_leading_one.3
@@ -0,0 +1,93 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_FIRST_LEADING_ONE 3
+.Os
+.Sh NAME
+.Nm stdc_first_leading_one
+.Nd find the first leading one in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_first_leading_one_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_first_leading_one_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_first_leading_one_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_first_leading_one_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_first_leading_one_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_first_leading_one "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_first_leading_one_ Ns Em type Ns ()
+family of functions returns the index of the most significant set bit in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_first_leading_one "value"
+type-generic macro picks the appropriate
+.Nm stdc_first_leading_one_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns the index of the most significant set bit in
+.Fa value .
+The bits are numbered such that the most significant bit has number\~1,
+and the least significant bit has number
+.Ms w
+where
+.Ms w
+is the number of bits in the type of
+.Fa value .
+If no bits are set in
+.Fa value
+(i.\^e.\&
+.Fa value
+is zero), zero is returned.
+.Sh SEE ALSO
+.Xr fls 3 ,
+.Xr stdbit 3 ,
+.Xr stdc_leading_zeros 3 ,
+.Xr stdc_first_leading_zero 3 ,
+.Xr stdc_first_trailing_one 3
+.Sh STANDARDS
+The
+.Nm stdc_first_leading_one_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_first_leading_one
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_first_leading_one_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_first_leading_one
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_first_leading_one.c b/newlib/libc/stdbit/stdc_first_leading_one.c
new file mode 100644
index 000000000..de4368565
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_first_leading_one.c
@@ -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);
+}
diff --git a/newlib/libc/stdbit/stdc_first_leading_zero.3 b/newlib/libc/stdbit/stdc_first_leading_zero.3
new file mode 100644
index 000000000..7c2a8e7f4
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_first_leading_zero.3
@@ -0,0 +1,92 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_FIRST_LEADING_ZERO 3
+.Os
+.Sh NAME
+.Nm stdc_first_leading_zero
+.Nd find the first leading zero in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_first_leading_zero_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_first_leading_zero_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_first_leading_zero_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_first_leading_zero_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_first_leading_zero_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_first_leading_zero "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_first_leading_zero_ Ns Em type Ns ()
+family of functions returns the index of the most significant clear bit in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_first_leading_zero "value"
+type-generic macro picks the appropriate
+.Nm stdc_first_leading_zero_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns the index of the most significant clear bit in
+.Fa value .
+The bits are numbered such that the most significant bit has number\~1,
+and the least significant bit has number
+.Ms w
+where
+.Ms w
+is the number of bits in the type of
+.Fa value .
+If no bits are clear in
+.Fa value
+(i.\^e.\&
+.Fa value
+is the bitwise complement of zero), zero is returned.
+.Sh SEE ALSO
+.Xr stdbit 3 ,
+.Xr stdc_leading_ones 3 ,
+.Xr stdc_first_leading_ones 3 ,
+.Xr stdc_first_trailing_zero 3
+.Sh STANDARDS
+The
+.Nm stdc_first_leading_zero_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_first_leading_zero
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_first_leading_zero_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_first_leading_zero
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_first_leading_zero.c b/newlib/libc/stdbit/stdc_first_leading_zero.c
new file mode 100644
index 000000000..e6609b51b
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_first_leading_zero.c
@@ -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);
+}
diff --git a/newlib/libc/stdbit/stdc_first_trailing_one.3 b/newlib/libc/stdbit/stdc_first_trailing_one.3
new file mode 100644
index 000000000..71d7025ff
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_first_trailing_one.3
@@ -0,0 +1,110 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_FIRST_TRAILING_ONE 3
+.Os
+.Sh NAME
+.Nm stdc_first_trailing_one
+.Nd find the first trailing one in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_first_trailing_one_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_first_trailing_one_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_first_trailing_one_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_first_trailing_one_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_first_trailing_one_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_first_trailing_one "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_first_trailing_one_ Ns Em type Ns ()
+family of functions returns the index of the least significant set bit in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_first_trailing_one "value"
+type-generic macro picks the appropriate
+.Nm stdc_first_trailing_one_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Pp
+Functions
+.Fn stdc_first_trailing_one_ui ,
+.Fn stdc_first_trailing_one_ul ,
+and
+.Fn stdc_first_trailing_one_ull
+are identical to
+.Bx 4.3
+functions
+.Xr ffs 3 ,
+.Xr ffsl 3 ,
+and
+.Xr ffsll 3
+respectively, except for operating on unsigned instead of signed values.
+.Sh RETURN VALUES
+Returns the index of the least significant set bit in
+.Fa value .
+The bits are numbered such that the least significant bit has number\~1,
+and the most significant bit has number
+.Ms w
+where
+.Ms w
+is the number of bits in the type of
+.Fa value .
+If no bits are set in
+.Fa value
+(i.\^e.\&
+.Fa value
+is zero), one is returned.
+.Sh SEE ALSO
+.Xr bit_ffs 3 ,
+.Xr ffs 3 ,
+.Xr ffsl 3 ,
+.Xr ffsll 3 ,
+.Xr stdbit 3 ,
+.Xr stdc_trailing_zeros 3 ,
+.Xr stdc_first_trailing_zero 3 ,
+.Xr stdc_first_leading_one 3
+.Sh STANDARDS
+The
+.Nm stdc_first_trailing_one_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_first_trailing_one
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_first_trailing_one_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_first_trailing_one
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_first_trailing_one.c b/newlib/libc/stdbit/stdc_first_trailing_one.c
new file mode 100644
index 000000000..22972758d
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_first_trailing_one.c
@@ -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);
+}
diff --git a/newlib/libc/stdbit/stdc_first_trailing_zero.3 b/newlib/libc/stdbit/stdc_first_trailing_zero.3
new file mode 100644
index 000000000..2ee41cb3e
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_first_trailing_zero.3
@@ -0,0 +1,93 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_FIRST_TRAILING_ZERO 3
+.Os
+.Sh NAME
+.Nm stdc_first_trailing_zero
+.Nd find the first trailing zero in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_first_trailing_zero_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_first_trailing_zero_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_first_trailing_zero_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_first_trailing_zero_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_first_trailing_zero_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_first_trailing_zero "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_first_trailing_zero_ Ns Em type Ns ()
+family of functions returns the index of the least significant clear bit in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_first_trailing_zero "value"
+type-generic macro picks the appropriate
+.Nm stdc_first_trailing_zero_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns the index of the least significant clear bit in
+.Fa value .
+The bits are numbered such that the least significant bit has number\~1,
+and the most significant bit has number
+.Ms w
+where
+.Ms w
+is the number of bits in the type of
+.Fa value .
+If no bits are clear in
+.Fa value
+(i.\^e.\&
+.Fa value
+is the bitwise complement of zero), zero is returned.
+.Sh SEE ALSO
+.Xr bit_ffc 3 ,
+.Xr stdbit 3 ,
+.Xr stdc_trailing_ones 3 ,
+.Xr stdc_first_trailing_ones 3 ,
+.Xr stdc_first_leading_zero 3
+.Sh STANDARDS
+The
+.Nm stdc_first_trailing_zero_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_first_trailing_zero
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_first_trailing_zero_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_first_trailing_zero
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_first_trailing_zero.c b/newlib/libc/stdbit/stdc_first_trailing_zero.c
new file mode 100644
index 000000000..27395c697
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_first_trailing_zero.c
@@ -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);
+}
diff --git a/newlib/libc/stdbit/stdc_has_single_bit.3 b/newlib/libc/stdbit/stdc_has_single_bit.3
new file mode 100644
index 000000000..8f82c5522
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_has_single_bit.3
@@ -0,0 +1,98 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_HAS_SINGLE_BIT 3
+.Os
+.Sh NAME
+.Nm stdc_has_single_bit
+.Nd check for single bit set
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft bool
+.Fn stdc_has_single_bit_uc "unsigned char value"
+.Ft bool
+.Fn stdc_has_single_bit_us "unsigned short value"
+.Ft bool
+.Fn stdc_has_single_bit_ui "unsigned int value"
+.Ft bool
+.Fn stdc_has_single_bit_ul "unsigned long value"
+.Ft bool
+.Fn stdc_has_single_bit_ull "unsigned long long value"
+.Ft bool
+.Fn stdc_has_single_bit "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_has_single_bit_ Ns Em type Ns ()
+family of functions checks if there is exactly one bit
+set in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_has_single_bit "value"
+type-generic macro picks the appropriate
+.Nm stdc_has_single_bit_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Pp
+The functions in this family behave similarly to the
+.Fn powerof2 "value"
+macro of
+.In sys/param.h ,
+but differ when
+.Fa value
+is zero: while
+.Fn powerof2
+considers zero to be a power of two,
+.Fn stdc_has_single_bit
+does not.
+.Sh RETURN VALUES
+Returns
+.Sy true
+if exactly one bit is set in
+.Fa value ,
+otherwise returns
+.Sy false .
+I.\^e. the function determines if
+.Fa value
+is a power of two.
+.Sh SEE ALSO
+.Xr stdbit 3 ,
+.Xr stdc_count_ones 3
+.Sh STANDARDS
+The
+.Nm stdc_has_single_bit_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_has_single_bit
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_has_single_bit_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_has_single_bit
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_has_single_bit.c b/newlib/libc/stdbit/stdc_has_single_bit.c
new file mode 100644
index 000000000..a448464b0
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_has_single_bit.c
@@ -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);
+}
diff --git a/newlib/libc/stdbit/stdc_leading_ones.3 b/newlib/libc/stdbit/stdc_leading_ones.3
new file mode 100644
index 000000000..bdcbe95d7
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_leading_ones.3
@@ -0,0 +1,86 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_LEADING_ONES 3
+.Os
+.Sh NAME
+.Nm stdc_leading_ones
+.Nd find the number of leading ones in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_leading_ones_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_leading_ones_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_leading_ones_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_leading_ones_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_leading_ones_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_leading_ones "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_leading_ones_ Ns Em type Ns ()
+family of functions returns the number of leading ones in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_leading_ones "value"
+type-generic macro picks the appropriate
+.Nm stdc_leading_ones_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns the number of leading ones in
+.Fa value .
+If
+.Fa value
+is all ones,
+the total number of bits in the type of
+.Fa value
+is returned.
+.Sh SEE ALSO
+.Xr stdbit 3 ,
+.Xr stdc_leading_zeros 3 ,
+.Xr stdc_trailing_ones 3 ,
+.Xr stdc_first_leading_zero 3
+.Sh STANDARDS
+The
+.Nm stdc_leading_ones_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_leading_ones
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_leading_ones_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_leading_ones
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_leading_ones.c b/newlib/libc/stdbit/stdc_leading_ones.c
new file mode 100644
index 000000000..79d3ec7f2
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_leading_ones.c
@@ -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));
+}
diff --git a/newlib/libc/stdbit/stdc_leading_zeros.3 b/newlib/libc/stdbit/stdc_leading_zeros.3
new file mode 100644
index 000000000..985a6fa58
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_leading_zeros.3
@@ -0,0 +1,86 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_LEADING_ZEROS 3
+.Os
+.Sh NAME
+.Nm stdc_leading_zeros
+.Nd find the number of leading zeros in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_leading_zeros_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_leading_zeros_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_leading_zeros_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_leading_zeros_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_leading_zeros_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_leading_zeros "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_leading_zeros_ Ns Em type Ns ()
+family of functions returns the number of leading zeros in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_leading_zeros "value"
+type-generic macro picks the appropriate
+.Nm stdc_leading_zeros_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns the number of leading zeros in
+.Fa value .
+If
+.Fa value
+is all zeros,
+the total number of bits in the type of
+.Fa value
+is returned.
+.Sh SEE ALSO
+.Xr stdbit 3 ,
+.Xr stdc_leading_ones 3 ,
+.Xr stdc_trailing_zeros 3 ,
+.Xr stdc_first_leading_one 3
+.Sh STANDARDS
+The
+.Nm stdc_leading_zeros_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_leading_zeros
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_leading_zeros_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_leading_zeros
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_leading_zeros.c b/newlib/libc/stdbit/stdc_leading_zeros.c
new file mode 100644
index 000000000..2fdf64ec9
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_leading_zeros.c
@@ -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>
+
+/* 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));
+}
diff --git a/newlib/libc/stdbit/stdc_trailing_ones.3 b/newlib/libc/stdbit/stdc_trailing_ones.3
new file mode 100644
index 000000000..0548a7564
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_trailing_ones.3
@@ -0,0 +1,86 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_TRAILING_ONES 3
+.Os
+.Sh NAME
+.Nm stdc_trailing_ones
+.Nd find the number of trailing ones in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_trailing_ones_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_trailing_ones_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_trailing_ones_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_trailing_ones_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_trailing_ones_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_trailing_ones "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_trailing_ones_ Ns Em type Ns ()
+family of functions returns the number of trailing ones in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_trailing_ones "value"
+type-generic macro picks the appropriate
+.Nm stdc_trailing_ones_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns the number of trailing ones in
+.Fa value .
+If
+.Fa value
+is all ones,
+the total number of bits in the type of
+.Fa value
+is returned.
+.Sh SEE ALSO
+.Xr stdbit 3 ,
+.Xr stdc_leading_ones 3 ,
+.Xr stdc_trailing_zeros 3 ,
+.Xr stdc_first_trailing_zero 3
+.Sh STANDARDS
+The
+.Nm stdc_trailing_ones_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_trailing_ones
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_trailing_ones_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_trailing_ones
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_trailing_ones.c b/newlib/libc/stdbit/stdc_trailing_ones.c
new file mode 100644
index 000000000..c1a0e6b99
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_trailing_ones.c
@@ -0,0 +1,56 @@
+/*
+ * 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));
+}
diff --git a/newlib/libc/stdbit/stdc_trailing_zeros.3 b/newlib/libc/stdbit/stdc_trailing_zeros.3
new file mode 100644
index 000000000..833a164d4
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_trailing_zeros.3
@@ -0,0 +1,87 @@
+.\"
+.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.Dd November 9, 2025
+.Dt STDC_TRAILING_ZEROS 3
+.Os
+.Sh NAME
+.Nm stdc_trailing_zeros
+.Nd find the number of trailing zeros in an integer
+.Sh SYNOPSIS
+.Lb libc
+.In stdbit.h
+.Ft unsigned int
+.Fn stdc_trailing_zeros_uc "unsigned char value"
+.Ft unsigned int
+.Fn stdc_trailing_zeros_us "unsigned short value"
+.Ft unsigned int
+.Fn stdc_trailing_zeros_ui "unsigned int value"
+.Ft unsigned int
+.Fn stdc_trailing_zeros_ul "unsigned long value"
+.Ft unsigned int
+.Fn stdc_trailing_zeros_ull "unsigned long long value"
+.Ft unsigned int
+.Fn stdc_trailing_zeros "value"
+.Sh DESCRIPTION
+The
+.Nm stdc_trailing_zeros_ Ns Em type Ns ()
+family of functions returns the number of trailing zeros in
+.Fa value ,
+where
+.Fa value
+is of type
+.Va unsigned char ,
+.Va unsigned short ,
+.Va unsigned int ,
+.Va unsigned long ,
+or
+.Va unsigned long long
+for
+.Em type
+being
+.Sy uc ,
+.Sy us ,
+.Sy ui ,
+.Sy ul ,
+or
+.Sy ull
+respectively.
+The
+.Fn stdc_trailing_zeros "value"
+type-generic macro picks the appropriate
+.Nm stdc_trailing_zeros_ Ns Em type Ns ()
+function based on the type of
+.Fa value .
+.Sh RETURN VALUES
+Returns the number of trailing zeros in
+.Fa value .
+If
+.Fa value
+is all zeros,
+the total number of bits in the type of
+.Fa value
+is returned.
+.Sh SEE ALSO
+.Xr ffs 3 ,
+.Xr stdbit 3 ,
+.Xr stdc_leading_zeros 3 ,
+.Xr stdc_trailing_ones 3 ,
+.Xr stdc_first_trailing_one 3
+.Sh STANDARDS
+The
+.Nm stdc_trailing_zeros_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_trailing_zeros
+type-generic macro conform to
+.St -isoC-2023 .
+.Sh HISTORY
+The
+.Nm stdc_trailing_zeros_ Ns Em type Ns ()
+family of functions and the
+.Fn stdc_trailing_zeros
+type-generic macro were added in
+.Fx 15.1.
+.Sh AUTHOR
+.An Robert Clausecker Aq Mt fuz@FreeBSD.org
diff --git a/newlib/libc/stdbit/stdc_trailing_zeros.c b/newlib/libc/stdbit/stdc_trailing_zeros.c
new file mode 100644
index 000000000..6213f62cf
--- /dev/null
+++ b/newlib/libc/stdbit/stdc_trailing_zeros.c
@@ -0,0 +1,56 @@
+/*
+ * 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));
+}
--
2.47.3
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 2/2] Makefile.inc, stdbit/Makefile.inc: Add stdbit
2026-04-10 19:21 [PATCH v2 0/2] Add C23 stdbit.h functionality Joel Sherrill
2026-04-10 19:21 ` [PATCH v2 1/2] newlib/libc: Add C23 stdbit.h from FreeBSD Joel Sherrill
@ 2026-04-10 19:21 ` Joel Sherrill
2026-04-13 10:51 ` [PATCH v2 0/2] Add C23 stdbit.h functionality Corinna Vinschen
2 siblings, 0 replies; 7+ messages in thread
From: Joel Sherrill @ 2026-04-10 19:21 UTC (permalink / raw)
To: newlib; +Cc: Joel Sherrill
---
newlib/libc/Makefile.inc | 1 +
newlib/libc/stdbit/Makefile.inc | 15 +++++++++++++++
2 files changed, 16 insertions(+)
create mode 100644 newlib/libc/stdbit/Makefile.inc
diff --git a/newlib/libc/Makefile.inc b/newlib/libc/Makefile.inc
index d07eed764..39e98338d 100644
--- a/newlib/libc/Makefile.inc
+++ b/newlib/libc/Makefile.inc
@@ -56,6 +56,7 @@ include %D%/misc/Makefile.inc
include %D%/unix/Makefile.inc
include %D%/posix/Makefile.inc
include %D%/syscalls/Makefile.inc
+include %D%/stdbit/Makefile.inc
include %D%/iconv/Makefile.inc
include %D%/xdr/Makefile.inc
include %D%/ssp/Makefile.inc
diff --git a/newlib/libc/stdbit/Makefile.inc b/newlib/libc/stdbit/Makefile.inc
new file mode 100644
index 000000000..0f91f6797
--- /dev/null
+++ b/newlib/libc/stdbit/Makefile.inc
@@ -0,0 +1,15 @@
+libc_a_SOURCES += \
+ %D/stdc_bit_ceil.c \
+ %D/stdc_bit_floor.c \
+ %D/stdc_bit_width.c \
+ %D/stdc_count_ones.c \
+ %D/stdc_count_zeros.c \
+ %D/stdc_first_leading_one.c \
+ %D/stdc_first_leading_zero.c \
+ %D/stdc_first_trailing_one.c \
+ %D/stdc_first_trailing_zero.c \
+ %D/stdc_has_single_bit.c \
+ %D/stdc_leading_ones.c \
+ %D/stdc_leading_zeros.c \
+ %D/stdc_trailing_ones.c \
+ %D/stdc_trailing_zeros.c
--
2.47.3
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 0/2] Add C23 stdbit.h functionality
2026-04-10 19:21 [PATCH v2 0/2] Add C23 stdbit.h functionality Joel Sherrill
2026-04-10 19:21 ` [PATCH v2 1/2] newlib/libc: Add C23 stdbit.h from FreeBSD Joel Sherrill
2026-04-10 19:21 ` [PATCH v2 2/2] Makefile.inc, stdbit/Makefile.inc: Add stdbit Joel Sherrill
@ 2026-04-13 10:51 ` Corinna Vinschen
2026-04-16 20:55 ` Joel Sherrill
2 siblings, 1 reply; 7+ messages in thread
From: Corinna Vinschen @ 2026-04-13 10:51 UTC (permalink / raw)
To: Joel Sherrill; +Cc: newlib
Hi Joel,
is that your original patchset, rather than the fixed one?
Your stdbit/Makefile.inc is still using the incorrect %D, rather than
%D%.
The new files in the stdbit subdir don't build on Cygwin, because you're
including limits.h without defining __STDC_WANT_IEC_60559_BFP_EXT__.
This will only work if you set __ISO_C_VISIBLE >= 2023, which is NOT the
default when building newlib. You have to make sure this stuff builds
even if __ISO_C_VISIBLE >= 2023 is NOT defined while building newlib.
Next, these functions would be better also defined as macros in
stdbit.h, so the (in all cases trivial) functionality would be inlined
rather than adding the function calling overhead.
Last but not least, the new functions should be exported by Cygwin.
I. e., winsup/cygwin/cygwin.din needs to add them (in alphabetic order)
and CYGWIN_VERSION_API_MINOR in winsup/cygwin/include/cygwin/version.h
needs to be bumped. If this part of the patch isn't quite correct, it's
not much of a problem, but it would be nice to at least make an effort.
Thanks,
Corinna
On Apr 10 14:21, Joel Sherrill wrote:
> In response to comments on the previous version of this patch,
> I submitted my first Cygwin patch to add the missing _WIDTH
> constants to the Cygwin limits.h. That patch is now merged
> which hopefully removes the barrier for merging this.
>
> Note that a limits.h implementation can "include_next" the
> GCC limits.h and it will provide many constants. Cygwin
> had a self-contained version and they had to be added.
>
> Two patches:
> - 0001 - adds the files
> - 0002 - regenerates
>
> --joel
>
> Joel Sherrill (2):
> newlib/libc: Add C23 stdbit.h from FreeBSD
> Makefile.inc, stdbit/Makefile.inc: Add stdbit
>
> newlib/libc/Makefile.inc | 1 +
> newlib/libc/include/stdbit.h | 124 ++++++++++++++++++
> newlib/libc/stdbit/Makefile.inc | 15 +++
> newlib/libc/stdbit/stdc_bit_ceil.3 | 81 ++++++++++++
> newlib/libc/stdbit/stdc_bit_ceil.c | 71 ++++++++++
> newlib/libc/stdbit/stdc_bit_floor.3 | 83 ++++++++++++
> newlib/libc/stdbit/stdc_bit_floor.c | 53 ++++++++
> newlib/libc/stdbit/stdc_bit_width.3 | 104 +++++++++++++++
> newlib/libc/stdbit/stdc_bit_width.c | 53 ++++++++
> newlib/libc/stdbit/stdc_count_ones.3 | 85 ++++++++++++
> newlib/libc/stdbit/stdc_count_ones.c | 38 ++++++
> newlib/libc/stdbit/stdc_count_zeros.3 | 84 ++++++++++++
> newlib/libc/stdbit/stdc_count_zeros.c | 38 ++++++
> newlib/libc/stdbit/stdc_first_leading_one.3 | 93 +++++++++++++
> newlib/libc/stdbit/stdc_first_leading_one.c | 57 ++++++++
> newlib/libc/stdbit/stdc_first_leading_zero.3 | 92 +++++++++++++
> newlib/libc/stdbit/stdc_first_leading_zero.c | 57 ++++++++
> newlib/libc/stdbit/stdc_first_trailing_one.3 | 110 ++++++++++++++++
> newlib/libc/stdbit/stdc_first_trailing_one.c | 52 ++++++++
> newlib/libc/stdbit/stdc_first_trailing_zero.3 | 93 +++++++++++++
> newlib/libc/stdbit/stdc_first_trailing_zero.c | 53 ++++++++
> newlib/libc/stdbit/stdc_has_single_bit.3 | 98 ++++++++++++++
> newlib/libc/stdbit/stdc_has_single_bit.c | 38 ++++++
> newlib/libc/stdbit/stdc_leading_ones.3 | 86 ++++++++++++
> newlib/libc/stdbit/stdc_leading_ones.c | 60 +++++++++
> newlib/libc/stdbit/stdc_leading_zeros.3 | 86 ++++++++++++
> newlib/libc/stdbit/stdc_leading_zeros.c | 60 +++++++++
> newlib/libc/stdbit/stdc_trailing_ones.3 | 86 ++++++++++++
> newlib/libc/stdbit/stdc_trailing_ones.c | 56 ++++++++
> newlib/libc/stdbit/stdc_trailing_zeros.3 | 87 ++++++++++++
> newlib/libc/stdbit/stdc_trailing_zeros.c | 56 ++++++++
> 31 files changed, 2150 insertions(+)
> create mode 100644 newlib/libc/include/stdbit.h
> create mode 100644 newlib/libc/stdbit/Makefile.inc
> create mode 100644 newlib/libc/stdbit/stdc_bit_ceil.3
> create mode 100644 newlib/libc/stdbit/stdc_bit_ceil.c
> create mode 100644 newlib/libc/stdbit/stdc_bit_floor.3
> create mode 100644 newlib/libc/stdbit/stdc_bit_floor.c
> create mode 100644 newlib/libc/stdbit/stdc_bit_width.3
> create mode 100644 newlib/libc/stdbit/stdc_bit_width.c
> create mode 100644 newlib/libc/stdbit/stdc_count_ones.3
> create mode 100644 newlib/libc/stdbit/stdc_count_ones.c
> create mode 100644 newlib/libc/stdbit/stdc_count_zeros.3
> create mode 100644 newlib/libc/stdbit/stdc_count_zeros.c
> create mode 100644 newlib/libc/stdbit/stdc_first_leading_one.3
> create mode 100644 newlib/libc/stdbit/stdc_first_leading_one.c
> create mode 100644 newlib/libc/stdbit/stdc_first_leading_zero.3
> create mode 100644 newlib/libc/stdbit/stdc_first_leading_zero.c
> create mode 100644 newlib/libc/stdbit/stdc_first_trailing_one.3
> create mode 100644 newlib/libc/stdbit/stdc_first_trailing_one.c
> create mode 100644 newlib/libc/stdbit/stdc_first_trailing_zero.3
> create mode 100644 newlib/libc/stdbit/stdc_first_trailing_zero.c
> create mode 100644 newlib/libc/stdbit/stdc_has_single_bit.3
> create mode 100644 newlib/libc/stdbit/stdc_has_single_bit.c
> create mode 100644 newlib/libc/stdbit/stdc_leading_ones.3
> create mode 100644 newlib/libc/stdbit/stdc_leading_ones.c
> create mode 100644 newlib/libc/stdbit/stdc_leading_zeros.3
> create mode 100644 newlib/libc/stdbit/stdc_leading_zeros.c
> create mode 100644 newlib/libc/stdbit/stdc_trailing_ones.3
> create mode 100644 newlib/libc/stdbit/stdc_trailing_ones.c
> create mode 100644 newlib/libc/stdbit/stdc_trailing_zeros.3
> create mode 100644 newlib/libc/stdbit/stdc_trailing_zeros.c
>
> --
> 2.47.3
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 0/2] Add C23 stdbit.h functionality
2026-04-13 10:51 ` [PATCH v2 0/2] Add C23 stdbit.h functionality Corinna Vinschen
@ 2026-04-16 20:55 ` Joel Sherrill
2026-04-17 11:26 ` Corinna Vinschen
2026-04-18 5:17 ` Brian Inglis
0 siblings, 2 replies; 7+ messages in thread
From: Joel Sherrill @ 2026-04-16 20:55 UTC (permalink / raw)
To: newlib, Joel Sherrill
[-- Attachment #1: Type: text/plain, Size: 6958 bytes --]
On Mon, Apr 13, 2026 at 5:51 AM Corinna Vinschen <corinna@vinschen.de>
wrote:
> Hi Joel,
>
>
> is that your original patchset, rather than the fixed one?
>
> Your stdbit/Makefile.inc is still using the incorrect %D, rather than
> %D%.
>
> The new files in the stdbit subdir don't build on Cygwin, because you're
> including limits.h without defining __STDC_WANT_IEC_60559_BFP_EXT__.
> This will only work if you set __ISO_C_VISIBLE >= 2023, which is NOT the
> default when building newlib. You have to make sure this stuff builds
> even if __ISO_C_VISIBLE >= 2023 is NOT defined while building newlib.
>
I addressed this by adding "stdbit_internal.h" which provides definitions
or the _WIDTH symbols used if they aren't already defined. I checked
this by building with -std equal to gnu99, gnu11, and the default for the
GCC head which is C23. This minimized changes to the FreeBSD code.
I don't think we want to define __STDC_WANT_IEC_60559_BFP_EXT__
because I am pretty sure newlib is missing most of these.
https://en.cppreference.com/w/c/experimental/fpext1.html
>
> Next, these functions would be better also defined as macros in
> stdbit.h, so the (in all cases trivial) functionality would be inlined
> rather than adding the function calling overhead.
>
The implementation is unmodified from FreeBSD. I don't see the value
of deviating from their implementation at this time. If someone wants to
do that, OK but we cannot just copy it from glibc.
Also if you end up with all macros and inline functions, wouldn't that
make it impossible to export them?
>
> Last but not least, the new functions should be exported by Cygwin.
> I. e., winsup/cygwin/cygwin.din needs to add them (in alphabetic order)
> and CYGWIN_VERSION_API_MINOR in winsup/cygwin/include/cygwin/version.h
> needs to be bumped. If this part of the patch isn't quite correct, it's
> not much of a problem, but it would be nice to at least make an effort.
>
Done.
Patch set coming. Fingers crossed.
--joel
>
>
> Thanks,
> Corinna
>
>
> On Apr 10 14:21, Joel Sherrill wrote:
> > In response to comments on the previous version of this patch,
> > I submitted my first Cygwin patch to add the missing _WIDTH
> > constants to the Cygwin limits.h. That patch is now merged
> > which hopefully removes the barrier for merging this.
> >
> > Note that a limits.h implementation can "include_next" the
> > GCC limits.h and it will provide many constants. Cygwin
> > had a self-contained version and they had to be added.
> >
> > Two patches:
> > - 0001 - adds the files
> > - 0002 - regenerates
> >
> > --joel
> >
> > Joel Sherrill (2):
> > newlib/libc: Add C23 stdbit.h from FreeBSD
> > Makefile.inc, stdbit/Makefile.inc: Add stdbit
> >
> > newlib/libc/Makefile.inc | 1 +
> > newlib/libc/include/stdbit.h | 124 ++++++++++++++++++
> > newlib/libc/stdbit/Makefile.inc | 15 +++
> > newlib/libc/stdbit/stdc_bit_ceil.3 | 81 ++++++++++++
> > newlib/libc/stdbit/stdc_bit_ceil.c | 71 ++++++++++
> > newlib/libc/stdbit/stdc_bit_floor.3 | 83 ++++++++++++
> > newlib/libc/stdbit/stdc_bit_floor.c | 53 ++++++++
> > newlib/libc/stdbit/stdc_bit_width.3 | 104 +++++++++++++++
> > newlib/libc/stdbit/stdc_bit_width.c | 53 ++++++++
> > newlib/libc/stdbit/stdc_count_ones.3 | 85 ++++++++++++
> > newlib/libc/stdbit/stdc_count_ones.c | 38 ++++++
> > newlib/libc/stdbit/stdc_count_zeros.3 | 84 ++++++++++++
> > newlib/libc/stdbit/stdc_count_zeros.c | 38 ++++++
> > newlib/libc/stdbit/stdc_first_leading_one.3 | 93 +++++++++++++
> > newlib/libc/stdbit/stdc_first_leading_one.c | 57 ++++++++
> > newlib/libc/stdbit/stdc_first_leading_zero.3 | 92 +++++++++++++
> > newlib/libc/stdbit/stdc_first_leading_zero.c | 57 ++++++++
> > newlib/libc/stdbit/stdc_first_trailing_one.3 | 110 ++++++++++++++++
> > newlib/libc/stdbit/stdc_first_trailing_one.c | 52 ++++++++
> > newlib/libc/stdbit/stdc_first_trailing_zero.3 | 93 +++++++++++++
> > newlib/libc/stdbit/stdc_first_trailing_zero.c | 53 ++++++++
> > newlib/libc/stdbit/stdc_has_single_bit.3 | 98 ++++++++++++++
> > newlib/libc/stdbit/stdc_has_single_bit.c | 38 ++++++
> > newlib/libc/stdbit/stdc_leading_ones.3 | 86 ++++++++++++
> > newlib/libc/stdbit/stdc_leading_ones.c | 60 +++++++++
> > newlib/libc/stdbit/stdc_leading_zeros.3 | 86 ++++++++++++
> > newlib/libc/stdbit/stdc_leading_zeros.c | 60 +++++++++
> > newlib/libc/stdbit/stdc_trailing_ones.3 | 86 ++++++++++++
> > newlib/libc/stdbit/stdc_trailing_ones.c | 56 ++++++++
> > newlib/libc/stdbit/stdc_trailing_zeros.3 | 87 ++++++++++++
> > newlib/libc/stdbit/stdc_trailing_zeros.c | 56 ++++++++
> > 31 files changed, 2150 insertions(+)
> > create mode 100644 newlib/libc/include/stdbit.h
> > create mode 100644 newlib/libc/stdbit/Makefile.inc
> > create mode 100644 newlib/libc/stdbit/stdc_bit_ceil.3
> > create mode 100644 newlib/libc/stdbit/stdc_bit_ceil.c
> > create mode 100644 newlib/libc/stdbit/stdc_bit_floor.3
> > create mode 100644 newlib/libc/stdbit/stdc_bit_floor.c
> > create mode 100644 newlib/libc/stdbit/stdc_bit_width.3
> > create mode 100644 newlib/libc/stdbit/stdc_bit_width.c
> > create mode 100644 newlib/libc/stdbit/stdc_count_ones.3
> > create mode 100644 newlib/libc/stdbit/stdc_count_ones.c
> > create mode 100644 newlib/libc/stdbit/stdc_count_zeros.3
> > create mode 100644 newlib/libc/stdbit/stdc_count_zeros.c
> > create mode 100644 newlib/libc/stdbit/stdc_first_leading_one.3
> > create mode 100644 newlib/libc/stdbit/stdc_first_leading_one.c
> > create mode 100644 newlib/libc/stdbit/stdc_first_leading_zero.3
> > create mode 100644 newlib/libc/stdbit/stdc_first_leading_zero.c
> > create mode 100644 newlib/libc/stdbit/stdc_first_trailing_one.3
> > create mode 100644 newlib/libc/stdbit/stdc_first_trailing_one.c
> > create mode 100644 newlib/libc/stdbit/stdc_first_trailing_zero.3
> > create mode 100644 newlib/libc/stdbit/stdc_first_trailing_zero.c
> > create mode 100644 newlib/libc/stdbit/stdc_has_single_bit.3
> > create mode 100644 newlib/libc/stdbit/stdc_has_single_bit.c
> > create mode 100644 newlib/libc/stdbit/stdc_leading_ones.3
> > create mode 100644 newlib/libc/stdbit/stdc_leading_ones.c
> > create mode 100644 newlib/libc/stdbit/stdc_leading_zeros.3
> > create mode 100644 newlib/libc/stdbit/stdc_leading_zeros.c
> > create mode 100644 newlib/libc/stdbit/stdc_trailing_ones.3
> > create mode 100644 newlib/libc/stdbit/stdc_trailing_ones.c
> > create mode 100644 newlib/libc/stdbit/stdc_trailing_zeros.3
> > create mode 100644 newlib/libc/stdbit/stdc_trailing_zeros.c
> >
> > --
> > 2.47.3
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 0/2] Add C23 stdbit.h functionality
2026-04-16 20:55 ` Joel Sherrill
@ 2026-04-17 11:26 ` Corinna Vinschen
2026-04-18 5:17 ` Brian Inglis
1 sibling, 0 replies; 7+ messages in thread
From: Corinna Vinschen @ 2026-04-17 11:26 UTC (permalink / raw)
To: Joel Sherrill; +Cc: newlib
Hi Joel,
On Apr 16 15:55, Joel Sherrill wrote:
> On Mon, Apr 13, 2026 at 5:51 AM Corinna Vinschen <corinna@vinschen.de>
> wrote:
>
> > Hi Joel,
> >
> >
> > is that your original patchset, rather than the fixed one?
> >
> > Your stdbit/Makefile.inc is still using the incorrect %D, rather than
> > %D%.
> >
> > The new files in the stdbit subdir don't build on Cygwin, because you're
> > including limits.h without defining __STDC_WANT_IEC_60559_BFP_EXT__.
> > This will only work if you set __ISO_C_VISIBLE >= 2023, which is NOT the
> > default when building newlib. You have to make sure this stuff builds
> > even if __ISO_C_VISIBLE >= 2023 is NOT defined while building newlib.
> >
>
> I addressed this by adding "stdbit_internal.h" which provides definitions
> or the _WIDTH symbols used if they aren't already defined. I checked
> this by building with -std equal to gnu99, gnu11, and the default for the
> GCC head which is C23. This minimized changes to the FreeBSD code.
>
> I don't think we want to define __STDC_WANT_IEC_60559_BFP_EXT__
> because I am pretty sure newlib is missing most of these.
>
> https://en.cppreference.com/w/c/experimental/fpext1.html
That wasn't the point. The point was to set this *while building newlib*.
The most simple way would have been to add a line
#define __STDC_WANT_IEC_60559_BFP_EXT__
to the files in stdbit.
Corinna
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 0/2] Add C23 stdbit.h functionality
2026-04-16 20:55 ` Joel Sherrill
2026-04-17 11:26 ` Corinna Vinschen
@ 2026-04-18 5:17 ` Brian Inglis
1 sibling, 0 replies; 7+ messages in thread
From: Brian Inglis @ 2026-04-18 5:17 UTC (permalink / raw)
To: newlib
On 2026-04-16 14:55, Joel Sherrill wrote:
> On Mon, Apr 13, 2026 at 5:51 AM Corinna Vinschen wrote:
> The new files in the stdbit subdir don't build on Cygwin, because you're
> including limits.h without defining __STDC_WANT_IEC_60559_BFP_EXT__.
> This will only work if you set __ISO_C_VISIBLE >= 2023, which is NOT the
> default when building newlib. You have to make sure this stuff builds
> even if __ISO_C_VISIBLE >= 2023 is NOT defined while building newlib.
>
> Next, these functions would be better also defined as macros in
> stdbit.h, so the (in all cases trivial) functionality would be inlined
> rather than adding the function calling overhead.
>
> The implementation is unmodified from FreeBSD. I don't see the value
> of deviating from their implementation at this time. If someone wants to
> do that, OK but we cannot just copy it from glibc.
>
> Also if you end up with all macros and inline functions, wouldn't that
> make it impossible to export them?
FreeBSD may be assuming using whatever their current compilers are and which
will automatically inline trivial leaf functions of this sort, whereas newlib
and your build variants can not usually assume much compiler capability nor much
memory available on targets.
--
Take care. Thanks, Brian Inglis Calgary, Alberta, Canada
La perfection est atteinte Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add
mais lorsqu'il n'y a plus rien à retrancher but when there is no more to cut
-- Antoine de Saint-Exupéry
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2026-04-18 5:18 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2026-04-10 19:21 [PATCH v2 0/2] Add C23 stdbit.h functionality Joel Sherrill
2026-04-10 19:21 ` [PATCH v2 1/2] newlib/libc: Add C23 stdbit.h from FreeBSD Joel Sherrill
2026-04-10 19:21 ` [PATCH v2 2/2] Makefile.inc, stdbit/Makefile.inc: Add stdbit Joel Sherrill
2026-04-13 10:51 ` [PATCH v2 0/2] Add C23 stdbit.h functionality Corinna Vinschen
2026-04-16 20:55 ` Joel Sherrill
2026-04-17 11:26 ` Corinna Vinschen
2026-04-18 5:17 ` Brian Inglis
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