Multiply Code

PLA
       LDA $04              ;\ multiply the cosine...
       STA $4202            ; |
       LDA !1594,x          ; |
       LDY $05              ; |\ if $05 is 1, no need to do the multiplication
       BNE .NoMultCos       ; |/
       STA $4203            ; | ...with radius of circle (!1594,x)
       NOP #4               ;/ waste some cycles while the result is calculated
       ASL $4216            ; Product/Remainder Result (Low Byte)
       LDA $4217            ; Product/Remainder Result (High Byte)
       ADC #$00
.NoMultCos
       LSR $01              ;\ if the high byte of the angle was set...
       BCC .NotInvertCos    ; |
       EOR #$FF             ; | ...then invert the cosine
       INC                  ;/
.NotInvertCos
       STA $04

       LDA $06              ;\ multiply the sine...
       STA $4202            ; |
       LDA !1594,x          ; |
       LDY $07              ; |\ if $07 is 1, no need to do the multiplication
       BNE .NoMultSin       ; |/
       STA $4203            ; | ...with raidus of circle (!1594,x)
       NOP #4               ;/ waste some cycles while the result is calculated
       ASL $4216            ; Product/Remainder Result (Low Byte)
       LDA $4217            ; Product/Remainder Result (High Byte)
       ADC #$00
.NoMultSin
       LSR $03              ;\ if the high byte of the angle was set...
       BCC .NotInvertSin    ; |
       EOR #$FF             ; | ...then invert the sine
       INC                  ;/
.NotInvertSin
       STA $06