| Routines

59406: Scroll the screen left 8 columns

Used by the routine at 61882.
59406 | LD HL,59372 | Set the instruction at 59371 to 'LD BC,31'
59409 | LD (HL),31
59411 | LD L,239 | Set the instruction at 59374 to 'LDIR'
59413 | LD (HL),176
59415 | LD B,8 | There are 8 columns to scroll on
59417 | PUSH BC | Save the column counter
59418 | LD B,20 | There are 20 rows to be scrolled left
59420 | LD HL,22529 | Point HL at the attribute byte for the cell at screen coordinates (1,0)
59423 | LD D,H | Point DE at the attribute byte for the adjacent cell on the left
59424 | LD E,L
59425 | DEC E
59426 | PUSH BC | Save the row counter
59427 | PUSH HL | Save the source attribute file address
59428 | CALL 59368 | Shift this row of the screen left
59431 | POP HL | Restore the source attribute file address to HL
59432 | LD C,32 | Point HL at the next row down in the attribute file
59434 | ADD HL,BC
59435 | POP BC | Restore the row counter to B
59436 | DJNZ 59423 | Jump back until all 20 rows have been scrolled left
59438 | LD HL,32766 | 32766 holds the x-coordinate of the leftmost column of the play area on screen
59441 | INC (HL) | Increment this x-coordinate
59442 | LD HL,4895 | L=31 (rightmost screen column), H=19 (bottom row of the screen)
59445 | PUSH HL | Save the screen coordinates
59446 | CALL 59148 | Print a tile at screen coordinates (31,H)
59449 | POP HL | Restore the screen coordinates to HL
59450 | DEC H | Have we printed every tile in the column yet?
59451 | JP P,59445 | Jump back if not
59454 | POP BC | Restore the column counter to B
59455 | DJNZ 59417 | Jump back until 8 columns have been scrolled on
59457 | RET |