I'm writing a serial interface for an MCU, and I want to know how one would create a printf-like function to write to the serial UART. I can write to the UART, but to save memory and stack space, and avoid temp string buffers, I would prefer to do that write directly instead of doing sprintf() to a string and then writing the string via serial. There is no kernel and no file handling, so FILE* writes like those from fprintf() won't work (but sprintf() does).
Is there something that processes formatted strings for each char, so I can print char-by-char as it parses the format string, and applies the related arguments?
We are using newlib as part of the efm32-base project.
I would like to note that ultimately we implemented the _write() function because thats all newlib needs to light up printf.
depending on your standard library implementation you need to write your own versions of fputc or _write functions.