| Routines

75B4: Draw the left and right edges of a lines bubble

Used by routines at 75CC and 7600. Draws the left and right edges of the lines bubble against the lines of text just written into the graphic buffer (at EB00 or EC00).
Input
DE | Graphic buffer address
75B4 | LD HL,$FFC1 | Point HL at the top left corner of the text that was just written into the graphic buffer
75B7 | ADD HL,DE
75B8 | LD DE,$0007 | This is the 'distance' (in bytes) between the left and right edges of the graphic buffer
75BB | LD BC,$75A3 | Point BC at the graphic data table at 75A3
75BE | LD A,(BC) | Pick up a bubble left-edge graphic byte in A
75BF | INC C | Move BC along in the graphic data table
75C0 | INC A | Have we finished drawing the edges?
75C1 | RET Z | Return if so
75C2 | OR (HL) | Superimpose the bubble left-edge graphic byte
75C3 | LD (HL),A
75C4 | ADD HL,DE | Move over to the right edge
75C5 | LD A,(BC) | Pick up a bubble right-edge graphic byte in A
75C6 | INC C | Move BC along in the graphic data table
75C7 | OR (HL) | Superimpose the bubble right-edge graphic byte
75C8 | LD (HL),A
75C9 | INC HL | Move back to the left edge, one pixel row down
75CA | JR $75BE | Jump back to superimpose another edge graphic byte