pkg/mpaland-printf: Add alternative stdio as package #20664
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maribu
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Area: doc
This packs the stdio implementation from [1] as alternative to what the used standard C lib provides with the intent to provide a thread-safe, smaller, and more feature-complete alternative on newlib targets. Compared to `newlib_nano` this reduces `.text` by a bit more than 200 B while adding support for standard format specifiers such as `RPIu8`, `PRIu16`, `PRIu64`, `%z`, and `%t`. Note that `newlib_nano`'s stdio can be thread-safe in reentrant mode at the cost of RAM (per thread) and latency. Especially the increase in latency can be prohibitive when real time requirements need to be met. [1]: https://github.com/mpaland/printf
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aabadie and
MichelRottleuthner
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This adds a simple test applications that runs snprintf on standard format specifiers and compares the output with the expected output. The assumption is that internally every stdio implementation uses the same formatting code for each member of the printf functions family, so testing snprintf only is sufficient.
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Contribution description
This packs the stdio implementation from 1 as alternative to what the used standard C lib provides with the intent to provide a thread-safe, smaller, and more feature-complete alternative on newlib targets.
Compared to
newlib_nanothis reduces.textby a bit more than 200 B while adding support for standard format specifiers such asRPIu8,PRIu16,PRIu64,%z, and%t.Note that
newlib_nano's stdio can be thread-safe in reentrant mode at the cost of RAM (per thread) and latency. Especially the increase in latency can be prohibitive when real time requirements need to be met.Testing procedure
A test application has been added in
tests/sys/snprintf. This will use the package ifnewlibis used. It should pass, but removingMakefile.board.dep(which pulls in thempaland-printfpackage) should a failing test.Issues/PRs references
#20361