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Routines |
| Prev: B8FC | Up: Map | Next: B936 |
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Used by the routine at LaunchShot.
Gives a new shot the position of the ship, and a horizontal speed of 08 if bit 7 of its type is set or 18 if not. Its vertical speed is the value at ShipRow less the vertical position of the ship.
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| StartShotAtShip | B90A | LD A,($C903) | The row the ship was drawn on. | |||||
| B90D | LD B,A | B=A. | ||||||
| B90E | LD A,($5C38) | The ship row. | ||||||
| B911 | SUB B | Subtract B from A. | ||||||
| B912 | LD (IX+$09),A | Write the high byte of the vertical speed. | ||||||
| B915 | LD HL,($C8E6) | Fetch the word at C8E6 into HL. | ||||||
| B918 | LD DE,($C8E9) | Fetch the word at C8E9 into DE. | ||||||
| B91C | LD (IX+$01),L | Write the map column. | ||||||
| B91F | LD (IX+$02),H | Write the horizontal position. | ||||||
| B922 | LD (IX+$04),E | Write the map zone. | ||||||
| B925 | LD (IX+$05),D | Write the vertical position. | ||||||
| B928 | LD (IX+$07),$08 | Store 08 at offset 07 of IX. | ||||||
| B92C | BIT 7,(IX+$00) | Return if bit 7 of offset 00 of IX is set. | ||||||
| B930 | RET NZ | |||||||
| B931 | LD (IX+$07),$18 | Store 18 at offset 07 of IX. | ||||||
| B935 | RET | Return. | ||||||
| Prev: B8FC | Up: Map | Next: B936 |