libc: Add C23 stdbit.h with optional Kconfig and generic implementation #18347
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That was fast, nice work! Please squash the commits ideally into two - one implementing stdbit and other updating the documentation. Also fix long lines in stdbit.h causing CI to fail.
We definitely need proper tests before merging this. These should go to app repository. I can write some, but won't get to it until next week probably.
include/nuttx/lib/stdbit.h
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| /* Leading zeros: result is width when x == 0 (C23). */ | ||
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| #define stdc_leading_zeros_uc(x) ((x) ? (unsigned int)(__builtin_clz((unsigned int)(x)) - (_STDBIT_WIDTH_UI - _STDBIT_WIDTH_UC)) : _STDBIT_WIDTH_UC) |
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NuttX still supports builds with older GNUC where __builtin_clz and others might not be defined (look at nuttx/compiler.h). We get CONFIG_HAVE_BUILTIN_CTZ and other defines that tell us if the builtin is available.
We probably don't have to support older GNUC right away, but I think at least some compilation time error could be raised here.
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sure, I have applied the changes, could you please review the changes
Kconfig
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| ARCH_HAVE_STDBIT_H. Otherwise a generic C23 implementation is | ||
| used. | ||
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| config LIBC_STDBIT_GENERIC |
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I am not sure if this belongs here. I suppose it's ok to make stdbit.h not mandatory, but maybe it could be done similarly to libm and put the configuration option to libs/libc/stdbit/ directory?
tools/Unix.mk
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| # CONFIG_LIBC_STDBIT_GENERIC is defined, copy stdbit.h to include/ for C23 | ||
| # bit utilities. | ||
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| ifeq ($(CONFIG_ARCH_STDBIT_H),y) |
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You could do something like
ifeq ($(firstword $(filter y,$(CONFIG_ARCH_STDBIT_H) $(CONFIG_LIBC_STDBIT_GENERIC))),y)
to get logical OR and avoid unnecessary code duplication.
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Include nuttx/kmalloc.h in arm64_arch_timer.c to fix missing header dependency. This ensures proper memory allocation functions are available for the architecture timer implementation. Signed-off-by: hongfengchen <hongfengchen@xiaomi.com>
Add DEBUGASSERT in nxsem_wait_slow() to catch illegal mutex recursion attempts. This helps identify bugs where a task tries to lock a mutex it already holds, which is not allowed. Signed-off-by: anjiahao <anjiahao@xiaomi.com>
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Seems the merge request now contains completely different commits unrelated to the title and previous changes. |
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Fixes: #18311
Summary
Add optional C23
stdbit.hsupport so builds can provide<stdbit.h>when the toolchain does not. Follows the same pattern asstdarg.h/math.h: redirect atinclude/nuttx/lib/stdbit.h, copied toinclude/stdbit.hwhen enabled.ARCH_HAVE_STDBIT_H,ARCH_STDBIT_H(arch-specific),LIBC_STDBIT_GENERIC(generic on any arch).__builtin_clz/__builtin_ctz/__builtin_popcountfor all C23 stdbit macros; archs may providearch/<arch>/include/stdbit.h.libs/libc/stdbit/stdbit_verify.c(compile-time check when stdbit enabled).Documentation/legacy_README.mdandDocumentation/components/libs/libc/index.rst.