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newlib: update newlib nano documentation for C6

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C6 ROM has the the full IO formatting functions included.
This commit is contained in:
Marius Vikhammer
2023-02-02 17:24:31 +08:00
parent 990c6f58a6
commit 65a4058e8c
19 changed files with 68 additions and 15 deletions
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13
docs/en/api-guides/performance/size.rst
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@@ -352,6 +352,7 @@ lwIP IPv6
IPv6 is required by some components such as ``coap`` and :doc:`/api-reference/protocols/asio`, These components will not be available if IPV6 is disabled.
.. _newlib-nano-formatting:
Newlib nano formatting
@@ -359,11 +360,17 @@ Newlib nano formatting
By default, ESP-IDF uses newlib "full" formating for I/O (printf, scanf, etc.)
Enabling the config option :ref:`CONFIG_NEWLIB_NANO_FORMAT` will switch newlib to the "nano" formatting mode. This both smaller in code size and a large part of the implementation is compiled into the {IDF_TARGET_NAME} ROM, so it doesn't need to be included in the binary at all.
.. only:: CONFIG_ESP_ROM_HAS_NEWLIB_NANO_FORMAT
The exact difference in binary size depends on which features the firmware uses, but 25 KB ~ 50 KB is typical.
Enabling the config option :ref:`CONFIG_NEWLIB_NANO_FORMAT` will switch newlib to the "nano" formatting mode. This both smaller in code size and a large part of the implementation is compiled into the {IDF_TARGET_NAME} ROM, so it doesn't need to be included in the binary at all.
Enabling Nano formatting also reduces the stack usage of each function that calls printf() or another string formatting function, see :ref:`optimize-stack-sizes`.
The exact difference in binary size depends on which features the firmware uses, but 25 KB ~ 50 KB is typical.
.. only:: CONFIG_ESP_ROM_HAS_NEWLIB_NORMAL_FORMAT
Disabling the config option :ref:`CONFIG_NEWLIB_NANO_FORMAT` will switch newlib to the "full" formatting mode. This will reduce the binary size, as {IDF_TARGET_NAME} has the full formatting version of the functions in ROM, so it doesn't need to be included in the binary at all.
Enabling Nano formatting reduces the stack usage of each function that calls printf() or another string formatting function, see :ref:`optimize-stack-sizes`.
"Nano" formatting doesn't support 64-bit integers, or C99 formatting features. For a full list of restrictions, search for ``--enable-newlib-nano-formatted-io`` in the `Newlib README file`_.