include ratfor.def
/************************************************************************
*	doback	-do the C style backslash processing			*
*									*
*	usage:	foo = doback(string,size)				*
*	where:	string	=the string to convert, does not include	*
*			 backslash					*
*		size	=th number of characters in the symbol.		*
*		doback	=byte, the resulting character.			*
*			 or -1 if an error.				*
*									*
*	note:	Doback recognizes the following constructs		*
*		'\b'	back space					*
*		'\e'	escape						*
*		'\f'	form feed					*
*		'\l'	line feed					*
*		'\n'	newline (CR then LF)				*
*		'\r'	carriage return					*
*		'\t'	tab						*
*		'\\'	\						*
*		'\^*'	control-*					*
*		'\ddd'	ddd, ddd is in OCTAL.				*
*									*
*		The value of the function is an integer, not character.	*
*		This is done to allow the user to distinguish between	*
*		an error and a legal character.				*
*									*
*		Sometimes doback returns a -2, which is the code for	*
*		\n.							*
************************************************************************/
integer function doback(str,size)
character str(1)
integer size
integer i

size = 1
if(str(1) == 'b')			#backspace
	doback = BACKWARDS
else if(str(1) == 'e')		#escape
	doback = ESC
else if(str(1) == 'f')		#form feed
	doback = FF
else if(str(1) == 'l')		#line feed
	doback = newline
else if(str(1) == 'n')		#new line
	doback = -2				#magic value
else if(str(1) == 'r')		#carriage return
	doback = cr
else if(str(1) == 't')		#tab
	doback = tab
else if(str(1) >= '0' & str(1) <= '7') {	#\ddd
	doback = 0
	for(i = 1;str(i) >= '0' & str(i) <= '7' & i <= 3;i = i + 1)
		doback = doback*8 + (str(i) - '0')
	size = i - 1
	}
else if(str(1) == '^') {		#this is a control character
	size = 2
	i = str(2)			#convert to integer
	doback = i .and. 31		# and mask off top bits
	}
else if(str(1) == 0) {
	doback = 0
	size = 0
	}
else
	doback = str(1)
return
end