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Routines |
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Used by the routine at Draw_Special_Room_Parts.
Draws a picture of a corner of the frame of a special room at x position 0 and y position 16 which is the top left corner. The picture is three bytes wide and 32 lines high, and starts with its attributes (see Room_Graphics).
The entries at Draw_Top_Right_Corner_Picture, Draw_Bottom_Left_Corner_Picture and Draw_Bottom_Right_Corner_Picture draw the other three corners, using the shared code from Draw_Corner_Picture onwards.
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| Draw_Top_Left_Corner_Picture | 40178 | LD HL,4096 | Set the x position to 0 and the y position to 16 (4096). | |||||
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This entry point is used by the routines at Draw_Top_Right_Corner_Picture, Draw_Bottom_Left_Corner_Picture and Draw_Bottom_Right_Corner_Picture.
Copy the attributes of the picture, four rows of three cells.
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| Draw_Corner_Picture | 40181 | PUSH HL | Stash the position on the stack. | |||||
| 40182 | CALL AttributeAddress | Convert the position into an attribute buffer address. | ||||||
| 40185 | LD C,4 | Set the number of rows to 4. | ||||||
| Draw_Top_Left_Corner_Picture_Row_Loop | 40187 | PUSH HL | Stash the address of the start of the row on the stack. | |||||
| 40188 | LD B,3 | Set the number of cells in a row to 3. | ||||||
| Draw_Top_Left_Corner_Picture_Cell_Loop | 40190 | LD A,(DE) | Fetch an attribute from the picture. | |||||
| 40191 | LD (HL),A | Write it to the cell. | ||||||
| 40192 | INC DE | Move on to the next attribute of the picture. | ||||||
| 40193 | INC L | Move on to the next cell. | ||||||
| 40194 | DJNZ Draw_Top_Left_Corner_Picture_Cell_Loop | Decrease the cell counter and loop back until the row is copied. | ||||||
| 40196 | POP HL | Restore the address of the start of the row. | ||||||
| 40197 | LD A,L | Fetch the low byte of the address. | ||||||
| 40198 | ADD A,32 | Add the size of a row of cells. | ||||||
| 40200 | LD L,A | Store the low byte of the address. | ||||||
| 40201 | LD A,H | Fetch the high byte of the address. | ||||||
| 40202 | ADC A,0 | Add the carry. | ||||||
| 40204 | LD H,A | Store the high byte of the address. | ||||||
| 40205 | DEC C | Decrease the row counter and loop back until all of the rows of attributes are copied. | ||||||
| 40206 | JR NZ,Draw_Top_Left_Corner_Picture_Row_Loop | |||||||
| 40208 | POP HL | Restore the position from the stack. | ||||||
| 40209 | CALL ScreenAddress | Convert the position into a screen address. | ||||||
| 40212 | LD C,32 | Set the number of lines to 32. | ||||||
| 40214 | JP Draw_Three_Byte_Lines | Jump to Draw_Three_Byte_Lines to copy the pixels. | ||||||
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