9ab05ec3f5
The mask computation introduced by "fix infinite loop in up_timer_getmask when maxticks == CLOCK_MAX" has two problems: 1. If maxticks == 0, flsx(0) expands to __builtin_clz(0), which is undefined behavior, and the shift count becomes 8 * sizeof(clock_t) = 64 for a 64-bit clock_t, which is undefined behavior as well. The loop-based code that was replaced kept *mask = 0 in this case. 2. CLOCK_MAX is INT64_MAX, i.e. 63 one bits, not a full-width bit pattern. The resulting mask is always one bit narrower than the one produced by the original loop; e.g. a 32-bit timer got 0x7fffffff instead of 0xffffffff, so counter deltas >= 2^31 were truncated in the clock timekeeping code. Fix this by keeping *mask = 0 when maxticks == 0 and by deriving the mask from the full-width unsigned constant (uint64_t)-1, which restores the all-ones semantics of the original loop and still covers the maxticks == CLOCK_MAX case. Also initialize maxticks in arch_timer.c: if the lower half does not implement the maxtimeout ops, the value is left untouched and would otherwise be read uninitialized. Assisted-by: Zhipu GLM-5.3 Signed-off-by: ouyangxiangzhen <ouyangxiangzhen@xiaomi.com> |
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| binfmt | ||
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| cmake | ||
| crypto | ||
| Documentation | ||
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| dummy | ||
| fs | ||
| graphics | ||
| include | ||
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| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
| syscall | ||
| tools | ||
| video | ||
| wireless | ||
| .asf.yaml | ||
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| .pre-commit-config.yaml | ||
| .yamllint | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
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| README.md | ||
| ReleaseNotes | ||
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.