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Routines |
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| EBE0 | LD A,($ECDE) | Get the X co-ordinate at ECDE. | ||
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Get the position and work out what frame number should be used, shifting the bits to the desired location.
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| EBE3 | AND $07 | Take the first three bits to get the frame number. | ||
| EBE5 | CP $04 | Is it greater than 4? | ||
| EBE7 | JR C,$EBEE | Skip the next bit if it is. | ||
| EBE9 | CALL $ECA2 | Shift the sprite to the left and move forward. | ||
| EBEC | JR $EBF5 | |||
| EBEE | CP $00 | Is the frame 0? | ||
| EBF0 | JR Z,$EBE9 | Skip the next bit if it is. | ||
| EBF2 | CALL $EC6F | Shift the sprite to the right. | ||
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Now work out where on screen should be updated.
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| EBF5 | LD A,($ECDE) | Get the co-ordinates | ||
| EBF8 | DEC A | Put the top five bits in HL. | ||
| EBF9 | AND $F8 | |||
| EBFB | SRL A | |||
| EBFD | SRL A | |||
| EBFF | SRL A | |||
| EC01 | LD L,A | |||
| EC02 | LD H,$00 | |||
| EC04 | LD ($ED14),HL | Store this as the next offset to use. | ||
| EC07 | LD A,($ECDF) | Get the Y co-ordinate at ECDF. | ||
| EC0A | LD D,$00 | Store this in DE. | ||
| EC0C | LD E,A | |||
| EC0D | LD HL,$EA60 | Add the base offset for the screen address table in EA60. | ||
| EC10 | ADD HL,DE | |||
| EC11 | ADD HL,DE | |||
| EC12 | LD ($ECE2),HL | Store this as the pointer to the screen that should be updated. | ||
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Copy the bytes from the working buffer onto screen.
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| EC15 | LD DE,$ECE4 | Point DE at the working buffer at ECE4. | ||
| EC18 | LD B,$10 | 16 cells to copy. | ||
| EC1A | PUSH BC | |||
| EC1B | LD HL,($ECE2) | Get the pointer to the screen address to update. | ||
| EC1E | LD A,(HL) | Get the actual screen address in HL. | ||
| EC1F | INC HL | |||
| EC20 | LD H,(HL) | |||
| EC21 | LD L,A | |||
| EC22 | PUSH DE | Remember DE which points at the working buffer. | ||
| EC23 | LD DE,($ED14) | Get the offset to use. | ||
| EC27 | ADD HL,DE | Add this to get the actual screen address to use in HL. | ||
| EC28 | POP DE | Restore DE. | ||
| EC29 | LD B,$03 | 3 cells to copy. | ||
| EC2B | EX DE,HL | Copy the cells from the buffer to screen. | ||
| EC2C | LD A,(HL) | |||
| EC2D | EX DE,HL | |||
| EC2E | LD (HL),A | |||
| EC2F | CALL $EC59 | Merge the bytes. | ||
| EC32 | INC HL | Move to the next cell. | ||
| EC33 | INC DE | |||
| EC34 | DJNZ $EC2B | Loop back if there is more to do. | ||
| EC36 | LD HL,($ECE2) | Move to the previous screen address. | ||
| EC39 | DEC HL | |||
| EC3A | DEC HL | |||
| EC3B | LD ($ECE2),HL | |||
| EC3E | POP BC | Loop back if there are more cells to copy. | ||
| EC3F | DJNZ $EC1A | |||
| EC41 | LD A,($ECDF) | Point HL at the next pointer to the screen address table. | ||
| EC44 | AND $F8 | |||
| EC46 | SRL A | |||
| EC48 | SRL A | |||
| EC4A | SRL A | |||
| EC4C | SUB $17 | |||
| EC4E | NEG | |||
| EC50 | LD L,A | |||
| EC51 | LD H,$00 | |||
| EC53 | LD B,$05 | |||
| EC55 | ADD HL,HL | |||
| EC56 | DJNZ $EC55 | Loop back until all the cells have been copied. | ||
| EC58 | RET | |||
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