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Routines |
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Used by the routine at CheckItemDelivery.
Draws one of the two pieces that are next to the ship, if there is one. The position of the piece is at IX and its sprite is in DE. Pieces that are being delivered are drawn directly to the screen with DrawSpritesDirectly.
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| DrawPiece | 49791 | PUSH DE | Stash DE on the stack. | |||||||
| 49792 | LD A,(49785) | The piece flags. | ||||||||
| 49795 | BIT 6,A | Jump to DrawPiece_Draw if bit 6 of A is set. | ||||||||
| 49797 | JR NZ,DrawPiece_Draw | |||||||||
| 49799 | AND A | Jump to DrawPiece_Done if A is zero. | ||||||||
| 49800 | JR Z,DrawPiece_Done | |||||||||
| 49802 | LD B,A | B=A. | ||||||||
| 49803 | LD A,(49786) | A piece has already been drawn. | ||||||||
| 49806 | AND A | Jump to DrawPiece_Draw if A is not zero. | ||||||||
| 49807 | JR NZ,DrawPiece_Draw | |||||||||
| 49809 | LD A,(51453) | The ship's facing. | ||||||||
| 49812 | XOR B | Flip the bits of A that are set in B. | ||||||||
| 49813 | BIT 7,A | Jump to DrawPiece_Done if bit 7 of A is clear. | ||||||||
| 49815 | JR Z,DrawPiece_Done | |||||||||
| DrawPiece_Draw | 49817 | LD A,(23581) | The height of the piece. | |||||||
| 49820 | LD (23580),A | Keep the height of the piece. | ||||||||
| 49823 | LD L,(IX+0) | Read offset 0 of IX into L. | ||||||||
| 49826 | LD H,(IX+1) | Read offset 1 of IX into H. | ||||||||
| 49829 | LD A,H | A=H. | ||||||||
| 49830 | LD (41609),A | Update the row offsets. | ||||||||
| 49833 | LD A,(23580) | The height of the piece. | ||||||||
| 49836 | CALL LimitHeight | Call LimitHeight. | ||||||||
| 49839 | LD A,B | A=B. | ||||||||
| 49840 | LD (23580),A | The height, kept below the top of the playfield. | ||||||||
| 49843 | LD (49027),HL | The position of the piece. | ||||||||
| 49846 | LD IY,42543 | The second aligned-row erase. | ||||||||
| 49850 | LD A,(23592) | The piece width in bytes. | ||||||||
| 49853 | CP 5 | Jump to DrawPiece_Draw2 if A is 5. | ||||||||
| 49855 | JR Z,DrawPiece_Draw2 | |||||||||
| 49857 | LD IY,42555 | The fourth aligned-row erase. | ||||||||
| DrawPiece_Draw2 | 49861 | LD A,(49785) | The piece flags. | |||||||
| 49864 | CALL SelectMirroredErase_Entry | Call SelectMirroredErase_Entry. | ||||||||
| 49867 | LD HL,(49027) | Fetch the word at 49027 into HL. | ||||||||
| 49870 | CALL GetScreenAddress | Call GetScreenAddress. | ||||||||
| 49873 | EXX | Switch to the alternate registers. | ||||||||
| DrawPiece_Done | 49874 | POP DE | Bring DE back off the stack. | |||||||
| 49875 | LD A,(49785) | The piece flags. | ||||||||
| 49878 | BIT 6,A | Jump to DrawPiece_Ship if bit 6 of A is clear. | ||||||||
| 49880 | JR Z,DrawPiece_Ship | |||||||||
| 49882 | XOR A | Clear A. | ||||||||
| 49883 | LD (23581),A | Draw the piece straight to the screen. | ||||||||
| 49886 | JP DrawSpritesDirectly | Jump to DrawSpritesDirectly. | ||||||||
| DrawPiece_Ship | 49889 | LD (IX+0),104 | Store 104 at offset 0 of IX. | |||||||
| 49893 | LD A,(23608) | The ship row. | ||||||||
| 49896 | SUB 13 | Subtract 13 from A. | ||||||||
| 49898 | LD (IX+1),A | Write A to offset 1 of IX. | ||||||||
| 49901 | LD HL,42621 | The second aligned-row draw. | ||||||||
| 49904 | LD A,(23593) | The piece width in bytes. | ||||||||
| 49907 | CP 5 | Jump to DrawPiece_Mask if A is 5. | ||||||||
| 49909 | JR Z,DrawPiece_Mask | |||||||||
| 49911 | LD (IX+0),120 | Store 120 at offset 0 of IX. | ||||||||
| 49915 | LD A,(IX+1) | Read offset 1 of IX. | ||||||||
| 49918 | SUB 35 | Subtract 35 from A. | ||||||||
| 49920 | LD (IX+1),A | Write A to offset 1 of IX. | ||||||||
| 49923 | LD HL,42631 | The fourth aligned-row draw. | ||||||||
| DrawPiece_Mask | 49926 | LD A,(51453) | The ship's facing. | |||||||
| 49929 | BIT 7,A | Jump to DrawPiece_Position if bit 7 of A is clear. | ||||||||
| 49931 | JR Z,DrawPiece_Position | |||||||||
| 49933 | LD (IX+0),96 | Store 96 at offset 0 of IX. | ||||||||
| DrawPiece_Position | 49937 | PUSH HL | Stash HL on the stack. | |||||||
| 49938 | LD L,(IX+0) | Read offset 0 of IX into L. | ||||||||
| 49941 | LD H,(IX+1) | Read offset 1 of IX into H. | ||||||||
| 49944 | LD A,H | A=H. | ||||||||
| 49945 | LD (41610),A | The row the piece is drawn on. | ||||||||
| 49948 | LD A,(23581) | The height of the piece. | ||||||||
| 49951 | CALL LimitHeight | Call LimitHeight. | ||||||||
| 49954 | LD A,B | A=B. | ||||||||
| 49955 | LD (23581),A | The height of the piece. | ||||||||
| 49958 | CALL GetScreenAddress | Call GetScreenAddress. | ||||||||
| 49961 | POP IX | Bring IX back off the stack. | ||||||||
| 49963 | CALL SelectMirroredDraw | Call SelectMirroredDraw. | ||||||||
| 49966 | JP DrawSpritesDirectly | Jump to DrawSpritesDirectly. | ||||||||
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