*****************************************

* See if character in "B" is a hexdigit 0..9, A..F or a..f

* OTHER MODULES NEEDED: IS_DIGIT

* ENTRY: B=character to test

* EXIT: CC zero=1 if hex digit, 0 if not

 nam Is Char a Hex Digit?
 ttl Assembler Library Module


 psect IS_XDIGIT,0,0,0,0,0


IS_XDIGIT:
 pshs b
 lbsr IS_DIGIT 
 beq exit digits are okay
 cmpb #'A 
 blo exit exit, zero not set
 cmpb #'f
 bhi exit zero not set
 cmpb #'a 
 bhs yes
 cmpb #'F
 bhi exit
 
yes
 orcc #%00000100 set zero

exit
 puls b,pc

 endsect