| Routines

59461: Scroll the screen right 8 columns

Used by the routine at 61838.
59461 | LD HL,59372 | Set the instruction at 59371 to 'LD BC,31'
59464 | LD (HL),31
59466 | LD L,239 | Set the instruction at 59374 to 'LDDR'
59468 | LD (HL),184
59470 | LD B,8 | There are 8 columns to scroll on
59472 | PUSH BC | Save the column counter
59473 | LD B,20 | There are 20 rows to be scrolled right
59475 | LD HL,22558 | Point HL at the attribute byte for the cell at screen coordinates (0,0)
59478 | LD D,H | Point DE at the attribute byte for the adjacent cell on the right
59479 | LD E,L
59480 | INC E
59481 | PUSH BC | Save the row counter
59482 | PUSH HL | Save the source attribute file address
59483 | CALL 59368 | Shift this row of the screen right
59486 | POP HL | Restore the source attribute file address to HL
59487 | LD C,32 | Point HL at the next row down in the attribute file
59489 | ADD HL,BC
59490 | POP BC | Restore the row counter to B
59491 | DJNZ 59478 | Jump back until all 20 rows have been scrolled right
59493 | LD HL,32766 | 32766 holds the x-coordinate of the leftmost column of the play area on screen
59496 | DEC (HL) | Decrement this x-coordinate
59497 | LD HL,4864 | L=0 (leftmost screen column), H=19 (bottom row of the screen)
59500 | PUSH HL | Save the screen coordinates
59501 | CALL 59148 | Print a tile at screen coordinates (0,H)
59504 | POP HL | Restore the screen coordinates to HL
59505 | DEC H | Have we printed every tile in the column yet?
59506 | JP P,59500 | Jump back if not
59509 | POP BC | Restore the column counter to B
59510 | DJNZ 59472 | Jump back until 8 columns have been scrolled on
59512 | RET |