
141
7.1.6 Triangle Draw Registers
Each register is used by the drawing commands. The registers cannot be
accessed from the CPU or by using the SetRegister command.
(XY-coordinate register)
Register
Address
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Ys
Xs
dXdy
XUs
dXUdy
XLs
dXLdy
USN
LSN
0000h
0004h
0008h
000ch
0010h
0014h
0018h
001bh
0020h
S
S
S
S
S
S
S
0
0
S
S
S
S
S
S
S
0
0
S
S
S
S
S
S
S
0
0
S
S
S
S
S
S
S
0
0
Int
Int
Int
Int
Int
Int
Int
Int
Int
0
Frac
Frac
Frac
Frac
Frac
Frac
0
0
Address
Offset from DrawBaseAddress
S
Sign bit or sign extension
0
Not used or 0 extension
Int
Integer or integer part of fixed point data
Frac
Fraction part of fixed point data
Sets (X, Y) coordinates for triangle drawing
Ys
Y-coordinate start position of long side
Xs
X-coordinate start position of long side
dXdy
X DDA value of long side
XUs
X-coordinate start position of top side
dXUdy
X DDA value of top side
XLs
X-coordinate start position of bottom side
dXLdy
X DDA value of lower side
USN
Number of spans (rasters) of top triangle. If this value is 0, the top triangle is not drawn.
LSN
Number of spans (rasters) of bottom triangle. If this value is 0, the bottom triangle is not
drawn.
(Color register)
Register
Address
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Rs
dRdx
dRdy
Gs
dGdx
dGdy
Bs
dBdx
dBdy
0040h
0044h
0048h
004Ch
0050h
0054h
0058h
005ch
0060h
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
0
S
S
Int
Int
Int
Int
Int
Int
Int
Int
Int
Frac
Frac
Frac
Frac
Frac
Frac
Frac
Frac
Frac
Address
Offset from DrawBaseAddress
S
Sign bit or sign extension
0
Not used or 0 extension
Int
Integer or integer part of fixed point data
Frac
Fraction part of fixed point data