printf and float

[jagauthier]

So, I'm having an issue getting the printf() function suite to work with floating point values.

First, understand that I am not using STM32CubeIDE. It's a good tool, but I've had too many issues/complications using it. I use a custom Makefile and VScode for my development environment.

That said: With STM32CubeIDE I *can* go into the options and select "Use float with printf from newlib-nano (-u _printf_float)"

This adds "-u _printf_float" to the linker flags and floating point values work.

In My Makefile, I've added "-u _printf_float" to the linker arguments and floating point values are always "0.0".

I'm not sure what else would be causing this.

STM32's linker line versus mine:

arm-none-eabi-gcc -o "CT_ReadG431.elf" @"objects.list"   
-mcpu=cortex-m4 -TSTM32G431KBTx_FLASH.ld
--specs=nosys.specs -Wl,-Map="CT_ReadG431.map" -Wl,--gc-sections -static --specs=nano.specs
 -mfpu=fpv4-sp-d16 -mfloat-abi=hard -mthumb -u _printf_float -Wl,--start-group -lc -lm -Wl,--end-group

Mine:

arm-none-eabi-gccm [Object list omitted for brevity] -mthumb -mfpu=fpv4-sp-d16 -mfloat-abi=hard
 -specs=nano.specs -TSTM32G431KBTx_FLASH.ld  -lc -lm -lnosys 
 -Wl,-Map=build/CT_ReadG431.map,--cref -Wl,--gc-sections  -u _printf_float  
 -o build/CT_ReadG431.elf

Could it be something else?

[jagauthier]

Well, as far as "buffer", that's how vasprintf() works..

"The functions asprintf() and vasprintf() are analogs of sprintf(3) and vsprintf(3), except that they allocate a string large enough to hold the output including the terminating null byte, and return a pointer to it via the first argument. This pointer should be passed to free(3) to release the allocated storage when it is no longer needed."

As for your other links... I will definitely read those and take them under advisement. I saw you had other posts with similar complaints so I can tell this is a sore spot for you!

Thanks!