Difference between revisions of "84PCSE:BCALLs:54AF"

Latest revision as of 19:23, 4 October 2013

Synopsis

Unofficial Name: DispHorizDottedLine

BCALL Address: 54AFh

Displays a horizontal dotted line (in the style of the home screen) across the full screen.

Inputs

• A = Y coordinate to display the line
• H = foreground color (RBG-323)
• L = background color (RBG-323)
• DE = address of a 40-byte pattern to copy to pixelShadow
• LCD window registers must be set to full screen

Outputs

• Line drawn to LCD and to pixelShadow (or pixelShadow2)

Destroys

• AF, BC, DE, HL
• Interrupts enabled

Comments

H and L are "RBG-323" colors (i.e., the same value is used for both high and low bytes of the 16-bit color.) The line drawn is a repeating pattern (LL, LL, HH, HH, LL, LL, LL, LL, HH, HH, ...) and is two pixels high.

The 40 bytes at address DE will be copied to the appropriate location in pixelShadow/pixelShadow2, twice (once for each pixel row.) (Why a three-byte pattern would not suffice is perhaps a question best left unasked.) Note that the putmapUsePixShad2 flag is honored, but appTextSave and textDisplayOnly are ignored. Also, note that the data pointed to by DE must either be in the OS or must already be stored on RAM pages 83/82. Nevertheless, if you don't actually care about pixelShadow contents, you can ignore DE and let the OS use whatever 40 bytes of garbage it wants.