Draw_Pat_VL_d ($F439)

This routine draws a series of patterned vectors. The pattern to use must already be specified in $C829. The number of vectors to draw minus 1 must be specified in $C823. The vector list, pointed to by the X register, has the following format:

rel y, rel x, rel y, rel x, ...

The routine starts at the (y,x) coordinates specified in the D register and ignores the first pair of coordinates in the vector list.

ENTRY:

DP = $D0

X-reg points to the vector list

D-reg = start (Y,X) coordinate

$C829 contains the line pattern.

EXIT:

X-reg points to next byte after list

D-reg trashed

Source