Xform_Rise ($F663)
Xform_Rise_a ($F661)
These two routines generate a rise value, using the rise index pair in $C839-$C83A. For Xform_Rise_a the scalar value is passed in the A register, while for Xform_Rise, the scalar value must already be in $C83B. The transformed value is return in the A register.
ENTRY:
DP = $C8
A-reg = length for rise/run (Xform_Run_a only)
EXIT:
A-reg = rise value
B-reg trashed