Routines
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F565: Step Pen Left
Used by the routines at DrawingFill and DrawingLine.
Moves the pen one pixel left. The top bit stays set while X is on the picture, and is clear once the pen has passed the left edge.
StepPenLeft F565 DEC D Move the pen left and return when it is still on the picture.
F566 BIT 7,D
F568 RET NZ
F569 INC D The pen passed the left edge, so step back and tell the caller it did not move.
F56A LD H,A
F56B XOR A
F56C LD A,H
F56D RET Return.
View the equivalent code in;
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