; SUBROUTINE TO COMPUTE SINE AND COSINE
; AS SINGLE-BYTE INTEGERS (SIGNED)
; STEP SIZE OF 1/16 RADIAN, OR 3.58 DEGREES
; ACCURACY OF ABOUT 1% FOR RANGE 0
;   THROUGH 90 DEGREES
;
	ENTRY	SINCOS,THETA

.THE	EQU	0
.SIN	EQU	1
.COS	EQU	2

THETA:	DS	1		; ARGUMENT TO FUNCTION
SINE:	DS	1		; SINE OF THETA
COSINE:	DS	1		; COSINE OF THETA

SINCOS:
START:
	LD	IX,THETA
	LD	A,126		; BEGIN INITIALIZATION
	LD	(IX+.COS),A
	LD	(IX+.SIN),0
	LD	B,(IX+.THE)
	INC	B
CYCLE:
	SRA	A		; COMPUTE NEW SINE
	SRA	A
	SRA	A
	SRA	A
	ADD	A,(IX+.SIN)
	LD	(IX+.SIN),A
	SRA	A		; COMPUTE NEW COSINE
	SRA	A
	SRA	A
	SRA	A
	SUB	(IX+.COS)
	NEG
	LD	(IX+.COS),A
	DJNZ	CYCLE		; LOOP UNTIL DONE
	RET

	END