Routines
Prev: 7CBE Up: Map Next: 7CE9
7CD4: Screen wipe
Wipe an area of the screen.
Used by the routine at draw_item.
Input
BC Dimensions (B x C == width x height, where width is specified in bytes).
HL Destination address.
screen_wipe 7CD4 LD A,B Set A to the byte width of the area to wipe
7CD5 LD ($7CD9),A Self modify the width counter at $7CD8 to set B to the byte width
screen_wipe_row 7CD8 LD B,$02 Set the column counter to the bitmap width in bytes
7CDA PUSH HL Save the destination address
screen_wipe_column 7CDB LD (HL),$00 Wipe a byte
7CDD INC L Step destination address
7CDE DJNZ screen_wipe_column Decrement the column counter then loop for every column
7CE0 POP HL Restore the destination address
7CE1 CALL next_scanline_down Move the destination address down a scanline
7CE4 DEC C Decrement the row counter
7CE5 JP NZ,screen_wipe_row ...loop for every row
7CE8 RET Return
Prev: 7CBE Up: Map Next: 7CE9