Routines
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36736: Get Whole Pixels
Used by the routine at UpdateVelocity.
Converts a velocity, which has four bits after the point, to the number of whole pixels to move. This is the velocity divided by sixteen, rounded towards zero.
Input
A The velocity (signed)
Output
A The whole pixels
GetWholePixels 36736 AND A Test the sign of the velocity.
36737 JP P,GetWholePixels_Positive Jump to GetWholePixels_Positive if it is positive.
36740 NEG Make the velocity positive.
36742 RRCA Shift the velocity right four times, to drop the bits after the point.
36743 RRCA
36744 RRCA
36745 RRCA
36746 AND %00001111 Keep only bits 0-3.
36748 NEG Make the result negative.
36750 RET Return.
GetWholePixels_Positive 36751 RRCA Shift the velocity right four times, to drop the bits after the point.
36752 RRCA
36753 RRCA
36754 RRCA
36755 AND %00001111 Keep only bits 0-3.
36757 RET Return.
View the equivalent code in;
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