Motorola DSP96002 - Manual (Page 642)

MOTOROLA DSP96002 USER’S MANUAL B-123
move #90.0,d7.s ;get pi/2
fcmp d7,d6 #180.0,d7.s ;see if greater than 90
fsub.x d6,d7 ffge ;reduce to less than 90
ftfr.x d6,d7 fflt ;copy if no change
;
; First quadrant CORDIC trig computation
; Input angle in d7 in degrees
; Output d1=sine, d0=cosine
;
move #tantab,r0 ;point to tangent table
fclr d1 #scale,d0.s ;y=0, x=scale
fclr d5 #45.0,d6.s ;z=0,alp=45
do #tabsize,_cordic
fcmp d5,d7 x:(r0)+,d4.s ;angle < z? get tangent
fneg.x d4 fflt ;yes, rotate cw
fsub.x d6,d5 fflt ;yes, subtract angle
fadd.x d6,d5 ffge ;no, add angle for ccw
fmpy.x d1,d4,d2 ;y*tan
fmpy d0,d4,d2 fsub.x d2,d0 ;x*tan, x’=x-y*tan
fadd.x d2,d1 ;y’=y+x*tan
fscale.x #-1,d6 ;alp=alp/2
_cordic
fcopys.s d3,d1 ;fix sign of sine
end
Program ICycles
Words
Argument Reduction 10 10
Quadrantizing 7 7
CORDIC Algorithm 16 8N+9
---- -------
Totals: 33 8N+26
B.1.52 Four Quadrant Trigonometric COSINE (CORDIC Algorithm)
page 132,60,1,1
opt mex,cex
tabsize equ 16