Preliminary setup: The line goes from (x1,y1) to (x2,y2). dx = max(abs(x2 - x1), abs(y2 - y1)) ; dy = min(abs(x2 - x1), abs(y2 - y1)) ; Register setup: BLTADAT = $8000 BLTBDAT = line texture pattern ($FFFF for a solid line) BLTAFWM = $FFFF BLTALWM = $FFFF BLTAMOD = 4 * (dy - dx) BLTBMOD = 4 * dy BLTCMOD = width of the bitplane in bytes BLTDMOD = width of the bitplane in bytes BLTAPT = (4 * dy) - (2 * dx) BLTBPT = unused BLTCPT = word containing the first pixel of the line BLTDPT = word containing the first pixel of the line BLTCON0 bits 15-12 = x1 modulo 15 BLTCON0 bits SRCA, SRCC, and SRCD = 1 BLTCON0 bit SRCB = 0 If exclusive-or line mode: _ _ then BLTCON0 LF control byte = ABC + AC _ else BLTCON0 LF control byte = AB + AC BLTCON1 bit LINEMODE = 1 BLTCON1 bit OVFLAG = 0 BLTCON1 bits 4-2 = octant number from table BLTCON1 bits 15-12 = start bit for line texture (0 = last significant If (((4 * dy) - (2 * dx)) < 0): bit) then BLTCON1 bit SIGNFLAG = 1 else BLTCON1 bit SIGNFLAG = 0 If one pixel/row: then BLTCON1 bit ONEDOT = 1 else BLTCON1 bit ONEDOT = 0 BLTSIZE bits 15-6 = dx + 1 BLTSIZE bits 5-0 = 2 Warning: -------- You must set the BLTSIZE register last as it starts the blit.

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