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Routines |
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Used by the routine at LocatePicture.
Adjusts the number of rows of a piece that is near the top of the screen so that it does not go above the top, and, for a sloped piece, limits the number of steps left in the segment to two. The screen address is loaded from SegmentScreenAddress.
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| AdjustPiece | 55003 | LD B,A | B=A. | |||||
| 55004 | LD A,(52826) | The vertical step copy. | ||||||
| 55007 | NEG | Negate A. | ||||||
| 55009 | ADD A,B | A gains B. | ||||||
| 55010 | SUB 24 | Subtract 24 from A. | ||||||
| 55012 | JP NC,AdjustPiece_Address | Jump to AdjustPiece_Address if the carry flag is clear. | ||||||
| 55015 | CPL | Invert A. | ||||||
| 55016 | SRL A | Shift A right. | ||||||
| 55018 | NEG | Negate A. | ||||||
| 55020 | ADD A,E | A gains E. | ||||||
| 55021 | LD E,A | E=A. | ||||||
| 55022 | LD A,(52791) | The vertical step. | ||||||
| 55025 | AND A | Jump to AdjustPiece_Address if A is zero. | ||||||
| 55026 | JR Z,AdjustPiece_Address | |||||||
| 55028 | EXX | Switch to the alternate registers. | ||||||
| 55029 | LD A,C | A=C. | ||||||
| 55030 | CP 1 | Jump to AdjustPiece_Columns if A is 1. | ||||||
| 55032 | JR Z,AdjustPiece_Columns | |||||||
| 55034 | LD C,2 | C=2. | ||||||
| AdjustPiece_Columns | 55036 | EXX | Switch to the alternate registers. | |||||
| AdjustPiece_Address | 55037 | LD HL,(52809) | Fetch the word at SegmentScreenAddress into HL. | |||||
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Continue on to JumpToDrawingRoutine.
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| Prev: 54898 | Up: Map | Next: 55040 |