Routines
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50453: Fill Window
Used by the routines at DisplayObjectsCarried, DisplaySunMoonFrame, SetBorderAttributes, ColourSunMoon and DrawChangedObjects.
Fills a rectangle of the screen buffer, or of the attribute file, with one byte. The rows of the rectangle are 32 bytes apart.
Input
A Byte to fill the rectangle with
B Width of the rectangle in bytes
C Height of the rectangle in lines
HL Address of the first byte
Fill each line of the rectangle, then move down a row.
FillWindow 50453 LD DE,32 Set DE to the length of a line.
FillWindow_Line 50456 PUSH BC Stash the width and height on the stack.
50457 PUSH HL Stash the address of the start of the line on the stack.
FillWindow_Byte 50458 LD (HL),A Fill a byte.
50459 INC HL Move on to the next byte.
50460 DJNZ FillWindow_Byte Jump to FillWindow_Byte until the line is filled.
50462 POP HL Restore the address of the start of the line from the stack.
50463 ADD HL,DE Move on to the next line.
50464 POP BC Restore the width and height from the stack.
50465 DEC C Decrease the number of lines left.
50466 JR NZ,FillWindow_Line Jump to FillWindow_Line until all of the lines have been filled.
50468 RET Return.
View the equivalent code in;
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