Motorola DSP96002 - Manual (Page 582)

MOTOROLA DSP96002 USER’S MANUAL B-63
If the A bit is set, the line can be accepted. If the R bit is cleared, the line can be rejected.
B.1.33.4 Four Point Polygon Accept/Reject
This determines if the polygon consisting of the points (x0,y0,z0), (x1,y1,z1), (x2,y2,z2), (x3,y3,z3) is within
a three-dimensional view cube. If the polygon is within the cube, the A (accept) bit of the CCR will be set.
If the polygon is entirely outside of the cube, then the R bit will be cleared. If the polygon can not be ac-
cepted or rejected, then further processing is required to clip the polygon.
Registers:
d0 = dimension d4 = unused
d1 = limit d5 = unused
d2 = unused d6 = unused
d3 = unused d7 = unused
Memory Map:
X Memory Y Memory
(n0=3) r0
→
x0 Xmin
←
r4
y0 Xmax
z0 Ymin
x1 Ymax
y1 Zmin
z1 Zmax
x2
y2
z2
x3
y3
z3
Polygon Accept/Reject
Program ICycles
Words
ori #$e0,ccr ;set accept/reject/overflow bits 1 1
move x:(r0)+n0,d0.s y:(r4)+,d1.s ;get x0,Xmin 1 1
fcmp d1,d0 x:(r0)+n0,d0.s ;x0-Xmin, get x1 1 1
fcmp d1,d0 x:(r0)+n0,d0.s ;x1-Xmin, get x2 1 1
fcmp d1,d0 x:(r0)-n0,d0.s ;x2-Xmin, get x3 1 1
fcmpg d1,d0 y:(r4)+,d1.s ;x3-Xmin, Xmax 1 1
fcmp d0,d1 x:(r0)-n0,d0.s ;Xmax-x3, get x2 1 1
fcmp d0,d1 x:(r0)-n0,d0.s ;Xmax-x2, get x1 1 1
fcmp d0,d1 x:(r0)+,d0.s ;Xmax-x1, get x0 1 1
fcmpg d0,d1 x:(r0)+n0,d0.s y:(r4)+,d1.s ;Xmax-x0, y0,Ymin 1 1
fcmp d1,d0 x:(r0)+n0,d0.s ;y0-Ymin, get y1 1 1
fcmp d1,d0 x:(r0)+n0,d0.s ;y1-Ymin, get y2 1 1
fcmp d1,d0 x:(r0)-n0,d0.s ;y2-Ymin, get y3 1 1
fcmpg d1,d0 y:(r4)+,d1.s ;y3-Ymin, ymax 1 1
fcmp d0,d1 x:(r0)-n0,d0.s ;Ymax-y3, get y2 1 1
fcmp d0,d1 x:(r0)-n0,d0.s ;Ymax-y2, get y1 1 1