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ARM GNU Toolchain 13.2Rel1 newlib issue with sprintf and floating point

vix

I need to use sprintf with floating point numbers (%f format specifier) in a project based on rpmsg_lite_str_echo_rtos on the cortex-M (NXP Processor).
I use the recommended arm-gnu-toolchain-12.3.rel1-mingw-w64-i686-arm-none-eabi
I see that when I call

sprintf(str, "%d" 3);

the number 3 is printed to the string str.

But if I have a floating point number and I use "%f" format specifier

sprintf(str, "%f" 3.5);

I get
ASSERT ERROR " Balloc succeeded ": file "/data/jenkins/workspace/GNU-toolchain/arm-12/src/newlib-cygwin/newlib/libc/stdlib/mprec.c" Line "783" function name ""

It seems similar to this error
forum.pjrc.com/index.php
that points to this fix
github.com/.../f88aece242178ff0c187d56e34a79645fbc44a23

Is there a way to have sprintf working with floating point numbers?

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  • 0
    Hi there,

    I haven't been able to replicate this on my side, yet (compiling for a Cortex-M0 and running on a FastModel).

    Is this with --specs=nano.specs? I believe newlib-nano does not contain floating-point support out-of-the-box. You can include some limited support by manually pulling in two symbols. You can do this by adding `-u _scanf_float -u _printf_float` to your command line, but if you are planning on using floating-point numbers more than just printf/scanf, you would be better off switching to the standard newlib (i.e.: remove --specs=nano.specs from your command line and the compiler will link with the standard newlib instead)

    If that doesn't help your situation, are you able to share more information on:
    * Does that error happen when actually running the code on the target, or at compile-time?
    * How have you defined the "str" pointer here? Is global or local, or is it malloc-ed on the heap?
    * What is your full compiler command line when you are seeing this issue?

    With those I should be able to replicate your issue to investigate further

    Thank you,
    Stam
Reply
  • 0
    Hi there,

    I haven't been able to replicate this on my side, yet (compiling for a Cortex-M0 and running on a FastModel).

    Is this with --specs=nano.specs? I believe newlib-nano does not contain floating-point support out-of-the-box. You can include some limited support by manually pulling in two symbols. You can do this by adding `-u _scanf_float -u _printf_float` to your command line, but if you are planning on using floating-point numbers more than just printf/scanf, you would be better off switching to the standard newlib (i.e.: remove --specs=nano.specs from your command line and the compiler will link with the standard newlib instead)

    If that doesn't help your situation, are you able to share more information on:
    * Does that error happen when actually running the code on the target, or at compile-time?
    * How have you defined the "str" pointer here? Is global or local, or is it malloc-ed on the heap?
    * What is your full compiler command line when you are seeing this issue?

    With those I should be able to replicate your issue to investigate further

    Thank you,
    Stam
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