; ***************** SHIFT SUBROUTINE *****************
; SHIFTS CONTENTS OF (DE,HL) ONE BIT LEFT.
; SHIFTING CONTENTS TO THE LEFT IS MULTIPLICATION.
; EACH BIT SHIFT LEFT IS DOUBLING OR MULTIPLYING BY 2.
;
;	ENTRY:	NUMBER TO BE SHIFTED IS IN (DE,HL).
;	EXIT:	(DE,HL) SHIFTED LEFT ONE BIT, LOGICAL.
;			CHECK FLAGS REGISTER FOR CARRY BIT.
;           ALL REGISTERS SAVED EXCEPT DE,HL.
;	
; ****************************************************

.ORG	0000h
		
		LD	SP,	0080h	; ADDED FOR TESTING PURPOSES.
		LD	DE,	8111h	; ADDED FOR TESTING PURPOSES.
		LD	HL,	8222h	; ADDED FOR TESTING PURPOSES.
		CALL SHIFT		; ADDED FOR TESTING PURPOSES.
		HALT			; ADDED FOR TESTING PURPOSES.
		
SHIFT:	ADD	HL,	HL		; SHIFT HL BYTES.
		EX	DE,	HL		; GET MOST SIGNIFICANT BYTES.
		ADC	HL,	HL		; SHIFT MS BYTES AND CARRY.
		EX	DE,	HL		; NOW THE ORIGINAL IS DOUBLED.
		RET				; RETURN

.END