Routines
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50215: Step Up Right
Used by the routine at DrawStripsLeftToRight.
Moves the draw position up by eight pixels and right by sixteen pixels, and moves on to the next two bytes of the list of tiles.
Input
IY The address of the tile in its list
Move up and to the right, and on to the next tile.
StepUpRight 50215 LD DE,8 Set the vertical step to eight pixels up.
Move on to the next two bytes of the list.
AdvanceListStepRight 50218 INC IY Move on to the next two bytes of the list.
50220 INC IY
This entry point is used by the routine at StepUpRightKeepList.
Move the position.
StepRight 50222 LD HL,(41552) Add the vertical step to ScreenVerticalPosition.
50225 ADD HL,DE
50226 LD (41552),HL
50229 LD HL,(41550) Move ScreenHorizontalPosition sixteen pixels to the right.
50232 LD DE,16
50235 ADD HL,DE
50236 LD (41550),HL
50239 RET Return.
This entry point is used by the routine at DrawStripsLeftToRight.
Move down and to the right, and on to the next tile.
StepDownRight 50240 LD DE,65528 Set the vertical step to eight pixels down.
50243 JR AdvanceListStepRight Jump to AdvanceListStepRight.
This entry point is used by the routine at DrawCellWithWalls.
Move down and to the right.
StepDownRightKeepList 50245 LD DE,65528 Set the vertical step to eight pixels down.
50248 JR StepRight Jump to StepRight.
This entry point is used by the routine at DrawCell.
Move up and to the left, and on to the next tile.
StepUpLeft 50250 LD DE,8 Set the vertical step to eight pixels up.
Move on to the next two bytes of the list.
AdvanceListStepLeft 50253 INC IY Move on to the next two bytes of the list.
50255 INC IY
50257 LD HL,(41552) Add the vertical step to ScreenVerticalPosition.
50260 ADD HL,DE
50261 LD (41552),HL
50264 LD HL,(41550) Move ScreenHorizontalPosition sixteen pixels to the left.
50267 LD DE,65520
50270 ADD HL,DE
50271 LD (41550),HL
50274 RET Return.
This entry point is used by the routine at DrawCell.
Move down and to the left, and on to the next tile.
StepDownLeft 50275 LD DE,65528 Set the vertical step to eight pixels down.
50278 JR AdvanceListStepLeft Jump to AdvanceListStepLeft.
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