mbed_minimal_putchar assumed that buffer being NULL meant that it
should print to a file. This caused a system crash when calling
snprintf with both buffer and stream set to NULL.
It is valid to call snprintf with a NULL buffer; nothing should
be outputted, but the string length should be measured.
As the ARM compiler is in GNU compatible mode, it defines __GNU__ which
(based on pre-processor condition in mbed_printf_implentation.h)
causes the printf functions to be wrapped using _wrap_* instead of
$Sub$$*.
This commit modifies the pre-processor
conditions to check for __GNUC__last in order to correctly
substitute the printf functions depending on the toolchain in use.
It also gets rid of $Super$$* substitution as it is not needed. $Super$$
is used to identify the original unpatched functions.
Missing substitutions for ARM compiler internal optimized "printfs" are
also added.
The two character sequence %% is used in standard implementations of
printf to print a single %. This is because % is essentially printf's
escape character for format specifiers and as \% cannot work printf
uses %%.
Therefore to be compatible with string buffers containing
%%, minimal-printf also needs to only print a single %.
Ensure the file descriptor stdout is passed to `fputc` when the high
level C functions to print to the console are referenced.
This issue fixed only affected binaries built with the ARM toolchain.
* Fixed wrapper functions for IAR
* Fixed and renamed profile to minimal-printf.json
* Moved minimal-printf under platform
* Removed minimal-printf/mbed_lib.json
* Modified exporter template to work with partial profile
* Prevented optimization of printf to avoid compiler function substitution
Evelyne Donnaes
Anna Bridge
Martin Kojtal
Bartek Szatkowski
David Lin
Rajkumar Kanagaraj
Hugues Kamba