| Routines

44520: Insert a pixel column into the message graphic buffer

Used by the routines at 44776 and 45937. Slides the current contents of the message graphic buffer (at 23296) one pixel to the left, and places the new pixel column into the slot freed up on the right.
Input
A | Pixel column byte
44520 | EXX |
44521 | LD HL,23551 | Point HL' at the end of the graphic buffer at 23296
44524 | LD C,8 | There are 8 pixel rows in the graphic buffer
44526 | LD B,32 | Append a pixel to the row and slide all the other pixels one space to the left
44528 | RRCA
44529 | RL (HL)
44531 | DEC HL
44532 | DJNZ 44529
44534 | DEC C | Next pixel row
44535 | JR NZ,44526 | Jump back until all 8 pixels rows are done
44537 | EXX |
44538 | RET |