Routines
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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
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