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Routines |
| Prev: E842 | Up: Map | Next: E879 |
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Used by the routine at F18E.
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| E845 | LD HL,$E7EC | Set the instruction at E7EB to 'LD BC,$001F' | ||
| E848 | LD (HL),$1F | |||
| E84A | LD L,$EF | Set the instruction at E7EE to 'LDDR' | ||
| E84C | LD (HL),$B8 | |||
| E84E | LD B,$08 | There are 8 columns to scroll on | ||
| E850 | PUSH BC | Save the column counter | ||
| E851 | LD B,$14 | There are 20 rows to be scrolled right | ||
| E853 | LD HL,$581E | Point HL at the attribute byte for the cell at screen coordinates (0,0) | ||
| E856 | LD D,H | Point DE at the attribute byte for the adjacent cell on the right | ||
| E857 | LD E,L | |||
| E858 | INC E | |||
| E859 | PUSH BC | Save the row counter | ||
| E85A | PUSH HL | Save the source attribute file address | ||
| E85B | CALL $E7E8 | Shift this row of the screen right | ||
| E85E | POP HL | Restore the source attribute file address to HL | ||
| E85F | LD C,$20 | Point HL at the next row down in the attribute file | ||
| E861 | ADD HL,BC | |||
| E862 | POP BC | Restore the row counter to B | ||
| E863 | DJNZ $E856 | Jump back until all 20 rows have been scrolled right | ||
| E865 | LD HL,$7FFE | 7FFE holds the x-coordinate of the leftmost column of the play area on screen | ||
| E868 | DEC (HL) | Decrement this x-coordinate | ||
| E869 | LD HL,$1300 | L=0 (leftmost screen column), H=19 (bottom row of the screen) | ||
| E86C | PUSH HL | Save the screen coordinates | ||
| E86D | CALL $E70C | Print a tile at screen coordinates (0,H) | ||
| E870 | POP HL | Restore the screen coordinates to HL | ||
| E871 | DEC H | Have we printed every tile in the column yet? | ||
| E872 | JP P,$E86C | Jump back if not | ||
| E875 | POP BC | Restore the column counter to B | ||
| E876 | DJNZ $E850 | Jump back until 8 columns have been scrolled on | ||
| E878 | RET | |||
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