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Routines |
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Used by the routine at BuildTables.
Builds the table at F900 of every byte with its bits in reverse order, indexed by the byte. The drawing routines use it to draw tiles back to front. The table overwrites the routine at F8FD onwards, which is no longer needed once the shape tables have been built.
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| BuildReverseTable | F856 | LD C,$00 | Clear C. | |
| F858 | LD HL,$F900 | The next shifted shape. | ||
| BuildReverseTable_Loop | F85B | LD B,$08 | B=08. | |
| F85D | LD D,C | D=C. | ||
| F85E | XOR A | Clear A. | ||
| BuildReverseTable_Bits | F85F | SLA D | Shift D left. | |
| F861 | RR A | Rotate A right through the carry. | ||
| F863 | DJNZ BuildReverseTable_Bits | Decrease B and jump to BuildReverseTable_Bits until none remain. | ||
| F865 | LD (HL),A | Write A where HL points. | ||
| F866 | INC HL | Advance HL. | ||
| F867 | INC C | Advance C. | ||
| F868 | JR NZ,BuildReverseTable_Loop | Jump to BuildReverseTable_Loop if the zero flag is clear. | ||
| F86A | RET | Return. | ||
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