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Routines |
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Used by the routines at Controls_CheckRight, Controls_CheckLeft, Controls_CheckDown, Controls_CheckUp and Controls_CheckLeftUp.
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| Handler_CursorMovement | E53C | CALL FetchTileObject | Call FetchTileObject. | |
| E53F | LD A,($D82C) | Write *DestinationCursor_Y_Position to *StorageCursor_Y_Position. | ||
| E542 | LD ($D830),A | |||
| E545 | LD A,($D82D) | Write *DestinationCursor_X_Position to *StorageCursor_X_Position. | ||
| E548 | LD ($D831),A | |||
| E54B | LD A,R | A=the contents of the Memory Refresh Register. | ||
| E54D | RLCA | Multiply A by 02 and store the result in L. | ||
| E54E | LD L,A | |||
| E54F | LD H,$00 | H=00. | ||
| E551 | LD B,$46 | Set a counter in B for the first outer loop. | ||
| E553 | LD D,$05 | Set a counter in D for the first inner loop. | ||
| CursorMovement_SoundLoop_01 | E555 | LD A,(HL) | Fetch a byte from the ZX Spectrum ROM and store it in A. | |
| E556 | AND %00011000 | Keep only bits 3-4. | ||
| E558 | OR %00000101 | Set bits 0, 2. | ||
| E55A | OUT ($FE),A | Send to the speaker. | ||
| E55C | INC HL | Increment the ROM pointer by one. | ||
| E55D | PUSH BC | Stash the outer loop counter on the stack. | ||
| E55E | LD B,D | Set B to the inner loop counter held by D. | ||
| CursorMovement_DelayLoop_01 | E55F | DJNZ CursorMovement_DelayLoop_01 | Decrease the inner loop counter by one and loop back to CursorMovement_DelayLoop_01 until the counter is zero. | |
| E561 | POP BC | Restore the outer loop counter from the stack. | ||
| E562 | DJNZ CursorMovement_SoundLoop_01 | Decrease the outer loop counter by one and loop back to CursorMovement_SoundLoop_01 until the counter is zero. | ||
| E564 | HALT | Halt operation (suspend CPU until the next interrupt). | ||
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Update the cursor position.
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| E565 | LD A,($D82C) | Jump to Handler_CursorMovement_1 if *DestinationCursor_Y_Position is equal to *CurrentCursor_Y_Position. | ||
| E568 | LD HL,$D82E | |||
| E56B | CP (HL) | |||
| E56C | JR Z,Handler_CursorMovement_1 | |||
| E56E | JP P,Handler_CursorMovement_0 | Jump to Handler_CursorMovement_0 if *DestinationCursor_Y_Position is greater than or equal to *CurrentCursor_Y_Position. | ||
| E571 | DEC (HL) | Decrease *CurrentCursor_Y_Position by one. | ||
| E572 | JR Handler_CursorMovement_1 | Jump to Handler_CursorMovement_1. | ||
| Handler_CursorMovement_0 | E574 | INC (HL) | Increment *HL by one. | |
| Handler_CursorMovement_1 | E575 | LD A,($D82D) | Jump to Handler_CursorMovement_3 if *DestinationCursor_X_Position is equal to *CurrentCursor_X_Position. | |
| E578 | LD HL,$D82F | |||
| E57B | CP (HL) | |||
| E57C | JR Z,Handler_CursorMovement_3 | |||
| E57E | JP P,Handler_CursorMovement_2 | Jump to Handler_CursorMovement_2 if *DestinationCursor_X_Position is greater than or equal to *CurrentCursor_X_Position. | ||
| E581 | DEC (HL) | Decrease *CurrentCursor_X_Position by one. | ||
| E582 | JR Handler_CursorMovement_3 | Jump to Handler_CursorMovement_3. | ||
| Handler_CursorMovement_2 | E584 | INC (HL) | Increment *HL by one. | |
| Handler_CursorMovement_3 | E585 | LD A,($D82E) | Jump to Handler_CursorMovement if *CurrentCursor_Y_Position is not equal to *DestinationCursor_Y_Position. | |
| E588 | LD HL,$D82C | |||
| E58B | CP (HL) | |||
| E58C | JR NZ,Handler_CursorMovement | |||
| E58E | LD A,($D82F) | Jump to Handler_CursorMovement if *CurrentCursor_X_Position is not equal to *DestinationCursor_X_Position. | ||
| E591 | LD HL,$D82D | |||
| E594 | CP (HL) | |||
| E595 | JR NZ,Handler_CursorMovement | |||
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The final sound effect when the cursor reaches its destination.
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| E597 | LD A,R | Set the lower byte in L, which for randomness is the contents of the Memory Refresh Register. | ||
| E599 | LD L,A | |||
| E59A | LD H,$0A | Set the upper byte of the sound data address (00A00-00AFF). | ||
| E59C | LD B,$23 | Set a counter in B for the second outer loop. | ||
| E59E | LD C,$64 | Set a counter in C for the second inner loop. | ||
| CursorMovement_SoundLoop_02 | E5A0 | LD A,(HL) | Fetch a byte from the ZX Spectrum ROM and store it in A. | |
| E5A1 | INC HL | Increment the ROM pointer by one. | ||
| E5A2 | AND %00011000 | Keep only bits 3-4. | ||
| E5A4 | OR %00000101 | Set bits 0, 2. | ||
| E5A6 | OUT ($FE),A | Send to the speaker. | ||
| E5A8 | PUSH BC | Stash the outer loop counter on the stack. | ||
| E5A9 | LD B,C | Set B to the inner loop counter held by C. | ||
| CursorMovement_DelayLoop_02 | E5AA | DJNZ CursorMovement_DelayLoop_02 | Decrease the inner loop counter by one and loop back to CursorMovement_DelayLoop_02 until counter is zero. | |
| E5AC | POP BC | Restore the outer loop counter from the stack. | ||
| E5AD | DJNZ CursorMovement_SoundLoop_02 | Decrease the outer loop counter by one and loop back to CursorMovement_SoundLoop_02 until the counter is zero. | ||
| E5AF | RET | Return. | ||
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