Prev: E80D Up: Map Next: E842
E80E: Scroll the screen left 8 columns
Used by the routine at F1BA.
E80E LD HL,$E7EC Set the instruction at E7EB to 'LD BC,$001F'
E811 LD (HL),$1F
E813 LD L,$EF Set the instruction at E7EE to 'LDIR'
E815 LD (HL),$B0
E817 LD B,$08 There are 8 columns to scroll on
E819 PUSH BC Save the column counter
E81A LD B,$14 There are 20 rows to be scrolled left
E81C LD HL,$5801 Point HL at the attribute byte for the cell at screen coordinates (1,0)
E81F LD D,H Point DE at the attribute byte for the adjacent cell on the left
E820 LD E,L
E821 DEC E
E822 PUSH BC Save the row counter
E823 PUSH HL Save the source attribute file address
E824 CALL $E7E8 Shift this row of the screen left
E827 POP HL Restore the source attribute file address to HL
E828 LD C,$20 Point HL at the next row down in the attribute file
E82B POP BC Restore the row counter to B
E82C DJNZ $E81F Jump back until all 20 rows have been scrolled left
E82E LD HL,$7FFE 7FFE holds the x-coordinate of the leftmost column of the play area on screen
E831 INC (HL) Increment this x-coordinate
E832 LD HL,$131F L=31 (rightmost screen column), H=19 (bottom row of the screen)
E835 PUSH HL Save the screen coordinates
E836 CALL $E70C Print a tile at screen coordinates (31,H)
E839 POP HL Restore the screen coordinates to HL
E83A DEC H Have we printed every tile in the column yet?
E83B JP P,$E835 Jump back if not
E83E POP BC Restore the column counter to B
E83F DJNZ $E819 Jump back until 8 columns have been scrolled on
E841 RET
Prev: E80D Up: Map Next: E842