Routines
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48648: Negate Number
Used by the routines at ApplyPlayerCollision, BounceShip, ReverseObjectSpeed, StartCrystalObject, ReverseAndHalveSpeed, CheckTerrainCollision and DrawShipTop.
Changes the sign of a signed number.
Input
HL Number
Output
HL Number with the sign changed
NegateNumber 48648 LD A,H A=H.
48649 CPL Invert A.
48650 LD H,A H=A.
48651 LD A,L A=L.
48652 CPL Invert A.
48653 LD L,A L=A.
48654 INC HL Advance HL.
48655 RET Return.
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