Tadpole SPARCbook 3 series, Reference Manual

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11-10
Display Interface
Power 9100 User Interface Controller
Bit 25 Reserved
Bit 24 Drive Load 2
0 = Normal drive load
1 = Double drive load
Bit 23 Clocking – should be zero
Bits 22:20 Shift control 0
Bits 19:17 Shift control 1
bits 16:14 Shift control 2
The four shift control fields are used to define the resolution,
in bytes, of the horzontal display.
To determine which values to place in these feilds: first
determine the number of pixels in a horizontal scan line;
next, multiply this by the number of bytes per pixel (set in
Pixel Size field); finaly, set the shift control fields so that the
total adds up to the number of bytes per scan line. There are
many possible combinations of which four examples are
shown below:
Bits 13:11 Endian swapping for frame buffer access– set as follows:
Use 000 for 8 bits per pixel mode
Use 010 for 16 bits per pixel mode
Use 110 for 24 and 32 bits per pixel modes
Bit 10 Buffer select for read
0 = buffer 0
1 = buffer 1
Bit 9 Buffer select for write
0 = buffer 0
1 = buffer 1
Horizontal
Resolution
Bits per
Pixel
Horizontal
Bytes
Shift 0 Shift 1 Shift 2 Shift 3
640 8 64
101 011 000 00
011 000 101 00
1280 24 3840
110 101 100 10
111 100 101 01
Table 11-4 Example Horizontal Resolution Settings
S3GX_TRMBook Page 10 Friday, September 19, 1997 11:39 am