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Routines |
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Used by the routine at Draw_Room.
Draws the top right corner of the frame of the room if bit 1 of the frame flags is set, or clears its area if it is not.
The corner is three bytes wide and 32 lines high and is drawn at x position 232 y position 16. The shape depends on whether the ceiling (bit 0) and the right wall (bit 2) are present, and on the room x and y: the table at Top_Right_Corner_Table has a set of four shapes for each of four combinations of the room coordinates. The routine also draws the other corners, which jump to Draw_Corner_Shape.
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| Draw_Top_Right_Corner | 39507 | PUSH DE | Stash the frame flags on the stack. | |||||||
| 39508 | LD HL,4328 | Set the x position to 232 and the y position to 16 (4328). | ||||||||
| 39511 | LD A,E | Copy the frame flags to A. | ||||||||
| 39512 | LD DE,39574 | Point at the table of corner shapes (Top_Right_Corner_Table). | ||||||||
| 39515 | BIT 1,A | Jump to 39522 to clear the area if the corner is not present. | ||||||||
| 39517 | JP Z,Clear_Panel | |||||||||
| 39519 | SBC A,C | |||||||||
| Draw_Corner | 39520 | PUSH HL | Stash the position on the stack. | |||||||
| 39521 | EX DE,HL | Exchange the registers so that HL holds the address of the table. | ||||||||
| 39522 | BIT 0,A | Jump to Draw_Top_Right_Corner_Check_Right_Wall if the ceiling is not present. | ||||||||
| 39524 | JR Z,Draw_Top_Right_Corner_Check_Right_Wall | |||||||||
| 39526 | INC HL | Skip the shapes for a ceiling. | ||||||||
| 39527 | INC HL | |||||||||
| Draw_Top_Right_Corner_Check_Right_Wall | 39528 | BIT 2,A | Jump to Draw_Corner_Shape if the right wall is not present. | |||||||
| 39530 | JR Z,Draw_Corner_Shape | |||||||||
| 39532 | INC HL | Skip the shapes for a right wall. | ||||||||
| 39533 | INC HL | |||||||||
| 39534 | INC HL | |||||||||
| 39535 | INC HL | |||||||||
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This entry point is used by the routines at Draw_Bottom_Right_Corner, Draw_Bottom_Left_Corner and Draw_Top_Left_Corner.
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| Draw_Corner_Shape | 39536 | LD A,(IX+2) | Fetch the room x of Sabreman. | |||||||
| 39539 | ADD A,(IX+4) | Add the room y of Sabreman. | ||||||||
| 39542 | ADD A,A | Multiply the sum by eight. | ||||||||
| 39543 | ADD A,A | |||||||||
| 39544 | ADD A,A | |||||||||
| 39545 | AND %00011000 | Keep only bits 3 and 4. | ||||||||
| 39547 | LD C,A | Store the offset in C. | ||||||||
| 39548 | LD B,0 | Clear the high byte of the offset. | ||||||||
| 39550 | ADD HL,BC | Add the offset to the address in the table. | ||||||||
| 39551 | LD A,(HL) | Fetch the low byte of the address of the shape. | ||||||||
| 39552 | INC HL | Move on to the high byte. | ||||||||
| 39553 | LD H,(HL) | Fetch the high byte of the address of the shape. | ||||||||
| 39554 | LD L,A | Copy the low byte to L. | ||||||||
| 39555 | EX DE,HL | Exchange the registers so that DE holds the address of the shape. | ||||||||
| 39556 | LD BC,800 | Set the size of the area to three bytes wide, 32 lines high (800). | ||||||||
| 39559 | CALL ScreenAddress | Convert the position into a screen address. | ||||||||
| 39562 | CALL Draw_Tile_Without_Header | Draw the shape. | ||||||||
| 39565 | POP HL | Restore the position from the stack. | ||||||||
| 39566 | LD BC,800 | Set the size of the area to 800. | ||||||||
| 39569 | CALL Set_Area_Attributes | Set the attributes of the area. | ||||||||
| 39572 | POP DE | Restore the frame flags from the stack. | ||||||||
| 39573 | RET | Return. | ||||||||
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