Routines
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C319: Get Facing Direction
Used by the routines at HandleTurning and SetPlayerSpeed.
Works out the direction that an object is facing from the horizontal flip flag and bit 2 of the sprite number: bit 6 of the flags of the object is made into bit 1 of the direction, and bit 2 of the sprite number into bit 0. The direction is 00 west, 01 east, 02 north and 03 south.
Input
IX The address of the object
Output
A The direction
Bit 6 of the flags to bit 1.
GetFacingDirection C319 PUSH HL Stash HL on the stack.
C31A LD A,(IX+$07) Fetch the flags of the object.
C31D RRCA Rotate bit 6 into bit 3.
C31E RRCA
C31F RRCA
C320 AND %00001000 Keep only bit 3.
C322 LD L,A Copy it to L.
Bit 2 of the sprite to bit 0.
C323 LD A,(IX+$00) Fetch the sprite number of the object.
C326 AND %00000100 Keep only bit 2.
C328 OR L Merge L.
C329 RRCA Rotate the two bits into place.
C32A RRCA
C32B AND %00000011 Keep only bits 0 and 1.
C32D POP HL Restore HL from the stack.
C32E RET Return.
View the equivalent code in;
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