/*
	This C language subroutine returns non-zero
	if the input is alpha-numeric, zero otherwise.

	The Run Time Library for the C Language.

	Gordon A. Sterling	(617) 461 - 3076
	DSP Development Tools Engineering

	Updated on 5/94 by AS

	#include <ctype.h>			<Header>
	int isalnum(int c);			<Prototype>
*/

#include "lib_glob.h"
#include "cty_glob.h"

.SEGMENT/CODE	Code_Space_Name;
.FILE 		RTL_FILENAME;

.GLOBAL	    	_isalnum;

_isalnum:			
test_for_lowera:R2=122;			/* 122 == ASC('z')	*/
		COMP(R4,R2), FETCH_RETURN /* test c > ASC('z'), defl ret val*/
		IF GT JUMP (PC, return_false); /* must not be alnum*/
		R2=97;			/*  97 == ASC('a')	*/
		COMP(R4,R2), R0=dm_1;	/* test c >= ASC('a')	*/
		IF GE JUMP (PC, restore_state); /* is lower case alpha*/

test_for_uppera:R2=90;			/*  90 == ASC('Z')	*/
		COMP(R4,R2);		/* test c > ASC('z')	*/
		IF GT JUMP (PC, return_false);/* must not be alnum*/
		R2=65;			/*  65 == ASC('A')	*/
		COMP(R4,R2);		/* test c >= ASC('A')	*/
		IF GE JUMP (PC, restore_state);/* is upper case alpha*/

test_for_digit:	R2=57;			/*  57 = ASC('9')	*/
		COMP(R4,R2);		/* test c > ASC('9')	*/
		IF GT JUMP (PC, return_false);/* must not be alnum*/
		R2=48;			/*  48 = ASC('0')	*/
		COMP(R4,R2);		/* test c >= ASC('0')	*/
		IF GE JUMP (PC, restore_state); /* is digit	*/

return_false:	R0=R0-R0;		/* Set return false	*/

restore_state:	RETURN (DB);
		RESTORE_STACK
		RESTORE_FRAME
.ENDSEG;