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f6ecf80ebb
The documentation grew one page at a time, so the tree follows the
history of who wrote what and not the shape of NuttX. Scheduling is
spread over three places, a driver page can sit above the subsystem
that owns it, and the front page lists everything at the same level.
That is a lot to face when all you want to know is where the scheduler
lives.
This change files every page under the code it describes. It is a move,
not a rewrite: outside the ten pages named below, every page keeps the
text that is already in master, and no page's text is deleted.
What it does:
* Groups the table of contents into nine chapters.
* Moves the OS subsystems under os/: scheduling, memory, drivers,
filesystem, networking, IPC, interrupts, libs, time.
* Renames the platform pages to the names the source tree uses, and
derives their tags from the tree instead of by hand.
* Splits guides/ by subject.
* Adds Documentation/redirects.py, with a rule for every page that left
its old path, so old URLs keep working. The redirect page also carries
a link's #anchor across to the new page.
Ten pages have text that is new or rewritten. Nine of them are the
landing page of a chapter, which has to exist for the new structure:
index the front page
os/index OS Design
os/scheduling/index Scheduling
os/interrupts/index Interrupts
os/ipc/index IPC
os/time/index Time and timers
about/index About
developing/index Developing NuttX
ReleaseNotes/index Release notes
The tenth is os/libs/libbuiltin, the only page here with technical
content: libs/libbuiltin/ had no page at all. Five SVG diagrams come
with these pages, hand-written XML with no editor metadata.
Nothing outside Documentation/ is touched.
How it was checked:
* Sphinx builds with -W: no warnings, and no document left outside a
toctree.
* A script, offered in the PR, proves the narrow claim this rests on.
For every page outside the ten named above it erases what a move
touches -- link target, path, tag line, toctree block, table border --
from the whole old text and the whole new text, and requires the two
to be byte for byte identical. It also requires every sentence of a
deleted page to turn up somewhere, and every page that left its old
path to have a redirect, from a URL that existed, to where its content
went. It exits non-zero and names the page if any of that is not true,
and it tests added pages too, so forgetting to declare one cannot make
it pass.
* An independent audit checked 133 factual claims on these ten pages
against the tree, one shell command per claim: 130 confirmed, 1
refuted and fixed here, 2 not checkable.
* tools/checkpatch.sh is clean over the range.
The diff is large because moving a page changes every link that points
to it. Most of it is pure renames, and board pages that gained one tag
line.
Assisted-by: Claude:claude-opus-5
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========
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stdbit.h
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========
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The optional C23 ``stdbit.h`` header provides bit manipulation macros
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(endianness, leading/trailing zeros and ones, count, single-bit test,
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bit width, bit floor, bit ceil). NuttX provides this header only when
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explicitly enabled via Kconfig.
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Configuration
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=============
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- **CONFIG_ARCH_HAVE_STDBIT_H** (bool, selected by arch)
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Architecture indicates it provides ``arch/<arch>/include/stdbit.h``.
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- **CONFIG_ARCH_STDBIT_H** (bool "stdbit.h", depends on ARCH_HAVE_STDBIT_H)
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Use the redirecting header. The build copies
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``include/nuttx/lib/stdbit.h`` to ``include/stdbit.h``; that header
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then includes ``<arch/stdbit.h>`` when this option is set.
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- **CONFIG_LIBC_STDBIT_GENERIC** (bool "stdbit.h (generic C23)")
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Use the generic C23 implementation. The same redirecting file
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``include/nuttx/lib/stdbit.h`` is copied to ``include/stdbit.h``,
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and the generic implementation is used (no arch header). Requires
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compiler builtins (e.g. ``__builtin_clz``, ``__builtin_ctz``,
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``__builtin_popcount``); see ``CONFIG_HAVE_BUILTIN_*`` in
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``nuttx/compiler.h``.
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Either **CONFIG_ARCH_STDBIT_H** or **CONFIG_LIBC_STDBIT_GENERIC** may be
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enabled so that ``#include <stdbit.h>`` is available.
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