| Gyruss | Routines |
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Take a pattern pointed to by pattern_address and flip it vertically (upside down). Returns address of result in pattern_address. Used by the routine at upload_sprite_patterns.
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| flip_vertical | AFAE | LD DE,(pattern_address) | DE = source address | |
| AFB2 | LD HL,$0010 | HL = right after end of destination buffer | ||
| AFB5 | ADD HL,DE | ... | ||
| AFB6 | LD B,$08 | 8 bytes in pattern | ||
| flip_vertical_0 | AFB8 | LD A,(DE) | Get source byte | |
| AFB9 | DEC HL | Destination address moves backwards | ||
| AFBA | LD (HL),A | Store result | ||
| AFBB | INC DE | Next source | ||
| AFBC | DJNZ flip_vertical_0 | Repeat 8 times | ||
| AFBE | LD (pattern_address),HL | Store destination | ||
| AFC1 | RET | |||
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