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Routines |
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Used by the routine at UpdateBeams.
Plays the noise of a beam, using clicks that depend on the first three bytes of the object of the beam.
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| PlayBeamSound | 29391 | LD A,(IX+0) | Read offset 0 of IX. | |||||
| 29394 | XOR (IX+1) | Flip the bits of A that are set in the byte at offset 1 of IX. | ||||||
| 29397 | AND %00001111 | Keep the bits of A that are set in 15. | ||||||
| 29399 | ADD A,8 | Add 8 to A. | ||||||
| 29401 | LD C,A | That is the number of clicks in the beam. | ||||||
| 29402 | LD A,(IX+2) | Read offset 2 of IX. | ||||||
| 29405 | AND %00011111 | Keep the bits of A that are set in 31. | ||||||
| 29407 | LD E,A | The third byte is the click pattern. | ||||||
| PlayBeamSound_Loop | 29408 | LD A,C | Mix the clicks still left with the pattern. | |||||
| 29409 | ADD A,E | A gains E. | ||||||
| 29410 | AND %00001111 | Keep the bits of A that are set in 15. | ||||||
| 29412 | ADD A,A | Double the mixed value. | ||||||
| 29413 | LD B,A | Keep it as the on-time. | ||||||
| 29414 | LD A,E | The off-time starts from the pattern. | ||||||
| 29415 | ADD A,B | A gains B. | ||||||
| 29416 | ADD A,A | Double the sum. | ||||||
| 29417 | SUB B | Subtract B from A. | ||||||
| 29418 | LD D,A | That is the off-time of this click. | ||||||
| 29419 | CALL MakeClick | Call MakeClick. | ||||||
| 29422 | DEC C | One click of the beam has been played. | ||||||
| 29423 | JR NZ,PlayBeamSound_Loop | Jump to PlayBeamSound_Loop if the zero flag is clear. | ||||||
| 29425 | RET | Return. | ||||||
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