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Routines |
| Prev: 57706 | Up: Map | Next: 57817 |
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Used by the routine at 57817.
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| 57761 | CALL CalculateScreenAddress | Call CalculateScreenAddress. | ||
| 57764 | PUSH DE | Stash DE on the stack. | ||
| 57765 | LD A,D | A=D. | ||
| 57766 | RRCA | RRCA. | ||
| 57767 | RRCA | |||
| 57768 | RRCA | |||
| 57769 | AND %00000011 | Keep only bits 0-1. | ||
| 57771 | OR %01011000 | Set bits 3-4, 6. | ||
| 57773 | LD D,A | D=A. | ||
| 57774 | LD BC,(57758) | BC=*57758. | ||
| 57778 | LD A,(DE) | A=*DE. | ||
| 57779 | XOR C | Flip the bits according to C. | ||
| 57780 | AND B | Merge the bits from B. | ||
| 57781 | XOR C | Flip the bits according to C. | ||
| 57782 | LD (DE),A | Write A to *DE. | ||
| 57783 | POP DE | Restore DE from the stack. | ||
| 57784 | LD A,H | A=H. | ||
| 57785 | AND %00000111 | Keep only bits 0-2. | ||
| 57787 | LD B,A | B=A. | ||
| 57788 | INC B | Increment B by one. | ||
| 57789 | LD A,254 | A=254. | ||
| 57791 | RRCA | RRCA. | ||
| 57792 | DJNZ 57791 | Decrease counter by one and loop back to 57791 until counter is zero. | ||
| 57794 | LD B,A | B=A. | ||
| 57795 | LD A,(57760) | C=*57760. | ||
| 57798 | LD C,A | |||
| 57799 | LD A,(DE) | A=*DE. | ||
| 57800 | BIT 1,C | Jump to 57805 if bit 1 of C is set. | ||
| 57802 | JR NZ,57805 | |||
| 57804 | AND B | Merge the bits from B. | ||
| 57805 | BIT 3,C | Jump to 57811 if bit 3 of C is set. | ||
| 57807 | JR NZ,57811 | |||
| 57809 | XOR B | Flip the bits according to B. | ||
| 57810 | CPL | Invert the bits in A. | ||
| 57811 | LD (DE),A | Write A to *DE. | ||
| 57812 | RET | Return. | ||
| 57813 | DEFW 1 | |||
| 57815 | DEFW 1 | |||
| Prev: 57706 | Up: Map | Next: 57817 |