stdio/Read_me 11/12/92
steve's notes on ANSI-compliant iBCS2-compatible stdio library

To make the stdio library ANSI compliant and iBCS-2 compliant,
steve hacked old ANSI stdio sources (not the COHERENT stdio sources) 11/92.
To make the bits line up with Unix bits, split the flags into _ff1 and _ff2
and rearranged them accordingly.  To make FILE the same size as under Unix,
split it into two parts, FILE as in Unix and _FILE2 with additional fields.
This makes some of the code obscure and requires some additional code.


The FILE _mode field contains the i/o mode:
	_MODE_FBUF	fully buffered
	_MODE_LBUF	line buffered
	_MODE_NBUF	unbuffered
	_MODE_STR	string (for sscanf() and sprintf())
	_MODE_UNINIT	uninitialized
A stream is uninitialized before the buffering mode is determined,
i.e. before the first read or write to the stream or the first setvbuf() call.

The _gt field contains the appropriate getc() function, one of the following:
	_fginit		uninitialized
	_fgetb		buffered
	_fgetc		unbuffered
	_fgete		error (read on write-only stream)
	_fgetstr	string (for sscanf())
	_fungotc	get ungotten character

The _pt field contains the appropriate putc() function, one of the following:
	_fpinit		uninitialized
	_fputa		append (used on first write after seek on append stream)
	_fputb		fully buffered
	_fputc		unbuffered
	_fpute		error (write on read-only stream)
	_fputt		line buffered
	_funungetc	undo ungetc
