Routines
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B18C: Next Sprite Number
Used by the routines at HandleRemoteControlRobot, HandleValveGhostSparkle and HandleHomingSparkle.
Steps on to the next of the four animation frames of the object, by adding one to the lowest two bits of its sprite number (wrapping from three to zero).
Input
IX The address of the object
Output
A The new sprite number
Keep the upper bits and step the frame.
NextSpriteNumber B18C LD A,(IX+$00) Fetch the sprite number.
B18F LD C,A Keep it in C.
B190 AND %11111100 Keep bits 2 to 7.
B192 LD B,A Keep them in B.
B193 LD A,C Fetch it again and add one.
B194 INC A
B195 AND %00000011 Keep bits 0 and 1.
B197 OR B Combine them with the upper bits.
This entry point is used by the routine at ToggleSpriteNumber.
NextSpriteNumber_StoreSpriteNumber B198 LD (IX+$00),A Store the sprite number.
B19B RET Return.
View the equivalent code in;
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