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Routines |
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Used by the routine at NextStep.
Used when the ship is on the same row as a step of a segment in the bottom half of the tile. It sets bit 7 of the contact flags at ContactFlags. If the vertical speed is negative it also sets bit 1 (clearing bit 7) and copies the flags into LastContactFlags. It carries on at NextStep_Column.
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| FlagCeilingContact | 52887 | LD A,(23601) | The contact flags. | |
| 52890 | OR %10000000 | Set the bits of A that are set in 128. | ||
| 52892 | LD (23601),A | Update the contact flags. | ||
| 52895 | LD A,(52410) | The vertical scroll speed. | ||
| 52898 | BIT 7,A | Jump to NextStep_Column if bit 7 of A is clear. | ||
| 52900 | JP Z,NextStep_Column | |||
| 52903 | LD A,(23601) | The contact flags. | ||
| 52906 | XOR %10000010 | Flip the bits of A that are set in 130. | ||
| 52908 | LD (23601),A | Update the contact flags. | ||
| 52911 | LD (23602),A | Update the last contact flags. | ||
| 52914 | JP NextStep_Column | Jump to NextStep_Column. | ||
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