.HookFlipAbsolute EOR directionFacing \ Flip the sign bit of A if we are facing backwards \ along the track \ \ The Absolute8Bit routine does the following: \ \ * If A is positive leave it alone \ \ * If A is negative, set A= -A \ \ So if bit 7 of directionFacing is set (i.e. we are \ facing backwards along the track), this flips bit 7 of \ A, which changes the Absolute8Bit routine to the \ following (if we consider the original value of A): \ \ * If A is negative leave it alone \ \ * If A is positive, set A= -A \ \ So this sets set A= -|A| instead of A= |A| JSR Absolute8Bit \ Set A= |A|, unless we are facing backwards along the \ track, in which case set A= -|A| RTS \ Return from the subroutineName: HookFlipAbsolute [Show more] Type: Subroutine Category: Extra tracks Summary: Set the sign of A according to the direction we are facing along the track Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine in context in the source code References: This subroutine is called as follows: * newContentHi calls HookFlipAbsolute * newContentLo calls HookFlipAbsolute
This routine is called from MovePlayerOnTrack so that the yaw angle of the closest segment retains the correct sign, like this: * If we are facing forwards along the track, set A= |A| * If we are facing backwards along the track, set A= -|A|
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Configuration variable Absolute8Bit = &3450
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Configuration variable directionFacing = &0025