Epson Research and Development
Page 89
Vancouver Design Center
The Move BitBLT with Color Expansion is used to accelerate text drawing on the screen.
A monochrome bitmap of a font in off-screen memory occupies very little space and takes
advantage of the hardware acceleration. Since the foreground and background colors are
programmable, text of any color can be created.
The Move BitBLT with Color Expansion may move data from one rectangular area to
another, or it may be specified as linear. The linear configuration may be applied to the
source or destination. Defining the Move BitBLT as linear allows each line of the Move
BitBLT area to be placed directly after the previous line, rather than requiring a complete
row of address space for each line.
Note
The BitBLT ROP Code/Color Expansion Register must be programmed to value 07h
because in the first word in a line color expansion is started with the most significant bit
of the low byte.
Example 18: Color expand a 9 x 16 rectangle using the pattern in off-screen memory
at 10 0000h and move it to the screen coordinates x = 200, y = 20. As-
sume a 640x480 display at a color depth of 16 bpp, Foreground color of
black, and background color of white.
1. Calculate the destination and source addresses (upper left corner of the destination and
source rectangles), using the formula.
DestinationAddress = (y × ScreenStride) + (x × BytesPerPixel)
= (20 × (640 × 2)) + (200 × 2)
= 26000
= 6590h
where:
BytesPerPixel = 1 for 8 bpp
BytesPerPixel = 2 for 15/16 bpp
ScreenStride = DisplayWidthInPixels × BytesPerPixels = 1280 for 16 bpp
SourceAddress
= 1M
= 100000h
Program the BitBLT Destination Start Address Registers. REG[10Ah] is set to 00h,
REG[109h] is set to 65h, and REG[108h] is set to 90h.
Program the BitBLT Source Start Address Registers. REG[106h] is set to 10h,
REG[105h] is set to 00h, and REG[104h] is set to 00h.
2. Program the BitBLT Width Registers to 9 - 1. REG[111h] is set to 00h and
REG[110h] is set to 08h.
3. Program the BitBLT Height Registers to 16 - 1. REG[113h] is set to 00h and
REG[112h] is set to 0Fh.
4. Program the BitBLT ROP Code/Color Expansion Register. REG[102h] is set to
07h.
Programming Notes and Examples
Issue Date: 01/02/06
S1D13506
X25B-G-003-03
EPSON [ EPSON COMPANY ]
