NAME
        UnGetC -- Makes a char available for reading again. (buffered) (V36)

   SYNOPSIS
        value = UnGetC(fh, character)
        D0             D1      D2

        long ungetc(bptr, long)

   FUNCTION
        Pushes the character specified back into the input buffer.  Every
        time you use a buffered read routine, you can always push back 1
        character.  You may be able to push back more, though it is not
        recommended, since there is no guarantee on how many can be
        pushed back at a given moment.

        Passing -1 for the character will cause the last character read to
        be pushed back.  If the last character read was an EOF, the next
        character read will be an EOF.

        Note: UnGetC can be used to make sure that a filehandle is set up
        as a read filehandle.  This is only of importance if you are writing
        a shell, and must manipulate the filehandle's buffer.

   INPUTS
        fh        - filehandle to use for buffered I/O
        character - character to push back or -1

   RESULT
        value     - character pushed back, or FALSE if the character cannot
                    be pushed back.

   BUGS
        In V36, UnGetC(fh,-1) after an EOF would not cause the next character
        read to be an EOF.  This was fixed for V37.

   SEE ALSO
        fgetc(), fputc(), flush()