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Routines |
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F1BA | LD A,($7FFE) | 7FFE holds X, the x-coordinate of the leftmost column of the play area on screen | ||||||
F1BD | SUB $38 | A=0x00, 0x08, 0x10, 0x18, 0x20, 0x28 or 0x30 (depending on the value of X) | ||||||
F1BF | JR NC,$F1BD | |||||||
F1C1 | ADD A,$38 | |||||||
F1C3 | RRCA | A=0xD7-0xDD | ||||||
F1C4 | RRCA | |||||||
F1C5 | RRCA | |||||||
F1C6 | ADD A,$D7 | |||||||
F1C8 | LD H,A | Point HL at the first byte of the first buffer in the group | ||||||
F1C9 | LD L,$00 | |||||||
F1CB | LD DE,$7F60 | Copy the first buffer in the group (buffer 1) to 7F60 temporarily | ||||||
F1CE | LD BC,$0019 | |||||||
F1D1 | LDIR | |||||||
F1D3 | LD E,B | Point DE at the first byte of the first buffer in the group | ||||||
F1D4 | LD D,H | |||||||
F1D5 | LD C,$64 | Move buffers 2-5 down into slots 1-4 (thus overwriting buffer 1) | ||||||
F1D7 | LDIR | |||||||
F1D9 | LD HL,$7F60 | Copy buffer 1 from its temporary storage location into slot 5 | ||||||
F1DC | LD C,$19 | |||||||
F1DE | LDIR | |||||||
F1E0 | JP $E80E | Scroll the screen left 8 columns (the routine at 7866 replaces this instruction with a RET) |
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