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Routines |
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Used by the routine at FireWeapons.
Used when the extra key is pressed. If there is no special shot at 47154 and the ship has part 7 and is moving slowly in both directions, launches one. If there is one already, goes to DetonateSpecialShot.
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| CheckSpecialShot | 47155 | LD A,(47154) | The special-shot flag. | |
| 47158 | AND A | Jump to DetonateSpecialShot if A is not zero. | ||
| 47159 | JR NZ,DetonateSpecialShot | |||
| 47161 | LD A,(23607) | The controls. | ||
| 47164 | BIT 5,A | Return if bit 5 of A is clear. | ||
| 47166 | RET Z | |||
| 47167 | LD A,(62964) | The seventh part, which makes a special shot. | ||
| 47170 | AND A | Return if A is zero. | ||
| 47171 | RET Z | |||
| 47172 | LD HL,(51454) | Fetch the word at 51454 into HL. | ||
| 47175 | LD A,H | A=H. | ||
| 47176 | LD H,L | H=L. | ||
| 47177 | LD L,A | L=A. | ||
| 47178 | CALL ZeroSmallSpeed | Call ZeroSmallSpeed. | ||
| 47181 | LD A,H | A=H. | ||
| 47182 | OR L | Set the bits of A that are set in L. | ||
| 47183 | RET NZ | Return if the zero flag is clear. | ||
| 47184 | LD HL,(51456) | Fetch the word at 51456 into HL. | ||
| 47187 | LD A,H | A=H. | ||
| 47188 | LD H,L | H=L. | ||
| 47189 | LD L,A | L=A. | ||
| 47190 | CALL ZeroSmallSpeed | Call ZeroSmallSpeed. | ||
| 47193 | LD A,H | A=H. | ||
| 47194 | OR L | Set the bits of A that are set in L. | ||
| 47195 | RET NZ | Return if the zero flag is clear. | ||
| 47196 | LD A,(46896) | The weapon toggle. | ||
| 47199 | XOR %00000100 | Flip the bits of A that are set in 4. | ||
| 47201 | LD (46896),A | Update the weapon toggle. | ||
| 47204 | CALL LaunchShot | Call LaunchShot. | ||
| 47207 | LD A,(46896) | The weapon toggle. | ||
| 47210 | AND %00000001 | Keep the bits of A that are set in 1. | ||
| 47212 | LD (46896),A | Update the weapon toggle. | ||
| 47215 | RET | Return. | ||
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This entry point is used by the routine at CheckObjectHitByShot.
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| FindShot | 47216 | LD IY,45946 | The shot slots. | |
| 47220 | LD DE,24 | DE=24. | ||
| 47223 | LD B,3 | B=3. | ||
| CheckSpecialShot_Loop | 47225 | BIT 7,(IY+22) | Jump to CheckSpecialShot_Next if bit 7 of offset 22 of IY is set. | |
| 47229 | JR NZ,CheckSpecialShot_Next | |||
| 47231 | BIT 7,(IY+21) | Return if bit 7 of offset 21 of IY is set. | ||
| 47235 | RET NZ | |||
| CheckSpecialShot_Next | 47236 | ADD IY,DE | IY gains DE. | |
| 47238 | DJNZ CheckSpecialShot_Loop | Decrease B and jump to CheckSpecialShot_Loop until none remain. | ||
| 47240 | RET | Return. | ||
| DetonateSpecialShot | 47241 | LD A,(23607) | The controls. | |
| 47244 | BIT 5,A | Return if bit 5 of A is set. | ||
| 47246 | RET NZ | |||
| 47247 | CALL FindShot | Call FindShot. | ||
| 47250 | SET 7,(IY+16) | Set bit 7 of offset 16 of IY. | ||
| 47254 | RET | Return. | ||
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