;This Intel(r) Pentium(r) code calculates a simple CRC by
;successively XOR-ing all data within the specified block

;following parameters assumed to be passed
;	EBP = Start Address of Data Block
;     EDI = Address of last Word to be checked (End address minus 4 bytes)

;other registers used during algorithm:
;     EAX = Calculated CRC returned
;	ECX =transfer register
;     EBX  =address increment (flash bus width in bytes)

.386P
CODE_SEG    SEGMENT  USE32
	
		ASSUME CS:CODE_SEG,DS:CODE_SEG

;setup usercode breakpoint
BreakPoint:
	JMP	BreakPoint

;set address increment to be 4 (4 bytes bus width)
	MOV	EBX, 4
	XOR	EAX, EAX

;copy from source location and calculate CRC by XOR
Loops:
	MOV	ECX, [EBP]
	XOR	EAX, ECX

	ADD	EBP, EBX
	CMP	EDI, EBP
	JGE	Loops

      JMP	BreakPoint
	
;******************************************************
;CODE ENDS HERE.
;******************************************************
CODE_SEG 	ENDS
     		END	BreakPoint