GXM Datasheet, PDF (122/244 Pages) National Semiconductor (TI) – Geode™ GXm Processor Integrated x86 Solution with MMX Support

Integrated Functions (Continued)
4.4.3.1 Monochrome Patterns
Monochrome patterns are selected by setting the pattern
mode to 01b in the GP_RASTER_MODE register
(GX_BASE+ 8200h). Those pixels corresponding to a
clear bit (0) in the pattern are rendered using the color
specified in the GP_PAT_COLOR_0 register, and those
pixels corresponding to a set bit (1) in the pattern are ren-
dered using the color specified in the GP_PAT_COLOR_1
register (GX_BASE+8112h).
If the pattern transparency bit is set high in the
GP_RASTER_MODE register, those pixels corresponding
to a clear bit in the pattern data are not drawn.
Monochrome patterns use bits [63:0] of the pattern data.
Bits [7:0] correspond to the first row of the pattern, and bit
7 corresponds to the leftmost pixel on the screen. This is
illustrated in Figure 4-12.
GP_PAT_DATA_0 = 0x80412214
GP_PAT_DATA_1 = 0x08142241
14
22
41
80
41
22
14
08
4.4.3.2 Dither Patterns
Dither patterns are selected by setting the pattern mode
to 10 b in the GP_RASTER_MODE register (Table 4-25
on page 125). Two bits of pattern data are used for each
pixel, allowing color expansion to four colors. The colors
are specified in the GP_PAT_COLOR_0 through
GP_PAT_COLOR_3 registers (Table 4-25 on page 125).
Dither patterns use all 128 bits of pattern data. Bits [15:0]
correspond to the first row of the pattern (the lower byte
contains the LSB of the pattern color and the upper byte
contains the MSB of the pattern color). This is illustrated
in Figure 4-13.
GP_PAT_DATA_0 = 0x441100AA
GP_PAT_DATA_1 = 0x115500AA
GP_PAT_DATA_2 = 0x441100AA
GP_PAT_DATA_3 = 0x115500AA
00AA
4411
00AA
1155
00AA
4411
00AA
1155
Figure 4-12. Example of Monochrome Patterns
Figure 4-13. Example of Dither Patterns
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