;
;	NAME:  CMPCRC
;
	OBJNAM	.SBR
;
;	FUNCTION:  This module computes a CRC total for its input 
;	argument and returns it.
;
;	CALLING SEQUENCE:
;	XCALL CMPCRC,BUFFER,CRC  where
;	BUFFER is the data on which the CRC is to be computed
;	CRC is the returned total (should be length=1)
;
;	AUTHOR:  Tom Dahlquist
;
;	HISTORY:
;	  WHEN   WHO WHAT
;	05/09/85 TAD Written.
;
	SEARCH	SYS
	SEARCH	SYSSYM
;
;	BASIC parameter list
;
	ASECT
ARGCNT:	BLKW	1			; # of args
TYPE1:	BLKW	1			; arg type
ADDR1:	BLKL	1			; address
LEN1:	BLKL	1			; length
TYPE2:	BLKW	1
ADDR2:	BLKL	1
LEN2:	BLKL	1
	PSECT

CMPCRC:	PHDR	-1,0,PH$REU!PH$REE
	CMPW	@A3,#2			; must be 2 args...
	BNE	RETURN

	MOV	ADDR1(A3),A0		; A0 -> data bytes
	MOV	LEN1(A3),D0		; D0 = length of string
	DEC	D0			; decrement for DBF...
	CLR	D1			; to accumulate CRC...

LOOP:	ADDB	(A0)+,D1
	DBF	D0,LOOP

	MOV	ADDR2(A3),A0		; A0 -> return argument
	MOVB	D1,@A0			; return CRC...
RETURN:	RTN
	END


.