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Routines |
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Used by the routine at 61B0. Sets the bits in the screen refresh buffer (SRB) that correspond to the four tiles in the left, middle or right column of a sprite.
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| 6980 | LD B,$04 | There are 4 rows (and 3 columns) in a sprite | ||||||||
| 6982 | LD A,(DE) | Pick up a sprite UDG reference | ||||||||
| 6983 | INC D | Next row of the sprite | ||||||||
| 6984 | AND A | Is this the blank UDG? | ||||||||
| 6985 | JR Z,$6989 | Jump if so (no need to update this SRB byte) | ||||||||
| 6987 | SET 0,(HL) | Set the appropriate bit in the SRB byte; this instruction is modified by the routine at 61B0 before this routine is called | ||||||||
| 6989 | LD A,$04 | Point HL at the byte of the SRB corresponding to the next row of the screen | ||||||||
| 698B | ADD A,L | |||||||||
| 698C | LD L,A | |||||||||
| 698D | DJNZ $6982 | Jump back until all 4 squares in the column are done | ||||||||
| 698F | BIT 3,D | Return with the zero flag reset if we have just updated the SRB for the rightmost column of the sprite | ||||||||
| 6991 | RET | |||||||||
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