quill | Routines |
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Used by the routine at LINE_ROUTINE.
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DRAW_LINE | 64544 | CALL SET_INVERSE_AND_OVER | Set over and inverse flags | |
64547 | CALL GET_OFFSETS | Read offsets into D and E | ||
64550 | LD B,D | B=Y offset | ||
64551 | LD C,E | C=X offset | ||
64552 | LD E,1 | E=X direction (positive) | ||
64554 | BIT 6,(IX+0) | Is this line left-to-right? | ||
64558 | JR Z,DRAW_LINE_0 | If, so keep positive X direction | ||
64560 | LD E,255 | E=negative X direction | ||
DRAW_LINE_0 | 64562 | LD D,1 | D=positive Y direction | |
64564 | BIT 7,(IX+0) | Is this line bottom-to-top? | ||
64568 | JR Z,DRAW_LINE_1 | If so, keep positive Y direction | ||
64570 | LD D,255 | D=negative Y direction | ||
DRAW_LINE_1 | 64572 | EXX | ||
64573 | PUSH HL | |||
64574 | EXX | |||
64575 | CALL 9402 | Line-drawing routines | ||
64578 | EXX | |||
64579 | POP HL | |||
64580 | EXX | |||
This entry point is used by the routine at PLOT_ROUTINE.
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NEXT_INSTRUCTION | 64581 | RES 0,(IY+87) | Clear temporary 'over' bit | |
64585 | RES 2,(IY+87) | Clear temporary 'inverse' bit | ||
64589 | JP SKIP_3_THEN_NEXT | Skip three bytes and execute next instruction |
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