| Routines

20709: Populate a row of the screen with machine code

Used by the routine at 33204. Copies 256 bytes of machine code from the source (either the top row of the screen, or character buffers 183-190) to the destination (the second or third row from the bottom of the screen), in eight 32-byte blocks.
Input
HL | Source (16384 or 46848)
DE | Destination display file address (20640 or 20672)
20709 | LD BC,32 | There are 32 bytes per row of pixels
20712 | PUSH DE |
20713 | LDIR | Copy 32 bytes to the display file
20715 | LD L,B | L=0
20716 | POP DE |
20717 | INC D | Point DE at the start of the next row of pixels
20718 | INC H | Point HL at the next batch of 32 bytes to copy
20719 | BIT 3,D | Have we copied 8 rows of bytes yet?
20721 | JR Z,20709 | Jump back if not
20723 | RET |