Cirrus Logic EP93xx User Manual

Page 296

8-32

DS785UM1

Graphics Accelerator
EP93xx User’s Guide

‘1’ - Pixel Expansion Mapping Function enabled

‘0’ - Pixel Expansion Mapping Function disabled

The Pixel Expansion Mapping Function converts single bit
pixels in the source image to defined pixel-depth (see

Table 8-23

) pixels in the destination image.

When BG = ‘0’, source image pixels are unaffected
(transparent) when they are copied to the destination
image. When BG = ‘1’, source image pixels that have a
value of ‘0’ are copied to the destination image with the
color value in the BG field of the

BACKGROUND

and source image pixels that have a value of ‘1’ are copied
to the destination image with the color value in the MASK
field of the

BLOCKMASK

Destination Mode - Read/Write

The value in the this field specifies the destination mode:
‘00’ - Disabled
‘01’ - Destination AND Mode
‘10’ - Destination OR Mode
‘11’ - Destination XOR Mode

Mask Mode - Read/Write

The value in the this field specifies the mask mode:
‘00’ - Disabled
‘01’ - Mask AND Mode
‘10’ - Mask OR Mode
‘11’ - Mask XOR Mode

SYDIR, SXDIR: Counter/Accumulator Direction - Read/Write

Write the values of the DYDIR and DXDIR bits to the
SYDIR and DXDIR bits, respectively.

DYDIR, DXDIR:

Counter/Accumulator and Line Direction - Read/Write

The value of these bits specifies the general direction that
the current Graphics Acceleration function places pixels
on the display:

For a Block Fill or Block Copy function:

DXDIR = ‘1’ - Left in X

DXDIR = ‘0’ - Right in X

DYDIR = ‘1’ - Up in Y