FDEV_SETUP_STREAM - not working as docs say or my error?

Using Arduino Programming Questions
11

westfw:
There was a recent discussion on AVRfreaks, the upshot of which was that the FDEV_SETUP_STREAM macro uses features that don't work in C++ (but work fine in C.)

http://www.avrfreaks.net/forum/stdio-setup-printf-and-pulling-my-hair-out

Well, that's interesting. The "lowercase" version (that takes 4 parameters) works fine. In fact, I made a little library that HardwareSerial calls to automatically provide me stdin/out/err for the serial port. And, it sets up the proper one (for example, If, on a MEGA, I do "Serial1.begin()", it correctly associates Serial1 to the stdin/out streams.

Stdinout.cpp

#include <Stdinout.h>

// connect stdio to stream
void STDINOUT::open (Stream &str)
{
	if (_std_init) {
		close ();
	}
	_stream_pointer = &str;
	fdev_setup_stream (&_fp, _putchar, _getchar, _FDEV_SETUP_RW);
	stdin = stdout = stderr = &_fp;
	_std_init = true;
}

void STDINOUT::close (void)
{
	if (_std_init) {
		_stream_pointer->flush ();
		fdev_close ();
		_stream_pointer = NULL;
		_std_init = false;
	}
}

// Function that printf and related will use to print
int STDINOUT::_putchar (char c, FILE *stream)
{
	if (_stream_pointer) {
		if (c == '\n') { // \n sends crlf
			_putchar ((char) '\r', stream);
		}
		return (_stream_pointer->write (c));
	} else {
		return 0;
	}
}

// Function that scanf and related will use to read
int STDINOUT::_getchar (FILE *stream)
{
	if (_stream_pointer) {
		while (!(_stream_pointer->available ()));
		return (_stream_pointer->read ());
	} else {
		return 0;
	}
}

// end of stdinout.cpp

Stdinout.h

#ifndef STD_IN_OUT_H
#define STD_IN_OUT_H

#include <Stream.h>

static Stream *_stream_pointer;

class STDINOUT
{
	public:
		void open (Stream &);
		void close (void);
	private:
		FILE _fp;
		static int _putchar (char, FILE *);
		static int _getchar (FILE *);
		int _std_init = false;
};

#endif

// end of Stdinout.h

Then, in HardwareSerial, at the end of both begin() functions, I have this:

    STDIO.open (*this); // connect stdin/out/err to current serial stream

...and at the end of end():

    STDIO.close (); // flush, close and disconnect std streams

Lastly, what I didn't show is that there's a [b]static STDINOUT STDIO;[/b] in the HardwareSerial.h file.

It works like a charm