Motorola DSP96002 User Manual page 643

org x:0
scale set
tantab
tanarg set
dup
scale set
dc
tanarg set
endm
org p:$100
;
; Do argument reduction, input in d6 in degrees
;
move
fadd.x d7,d6
fmpy.x d5,d6,d6
floor d6,d5
fsub.x d5,d6
fmpy.x d5,d6,d6
fadd.x d7,d6
;
; Input angle in d6 in degrees, -180 < d6 < 180
;
fabs.x d6
move
fcmp d7,d6
fsub.x d6,d7
ftfr.x d6,d7
fneg.x d3
;
; First quadrant CORDIC trig computation
; Input angle in d7 in degrees
; Output d1=sine, d0=cosine
;
move
fclr d1
fclr d5
do #tabsize,_cordic
fcmp d5,d7
fneg.x d4
fsub.x d6,d5
fadd.x d6,d5
fmpy.x d1,d4,d2
fmpy d0,d4,d2
B-124
1.0
45.0*3.14159/180.0
tabsize
scale*@cos(tanarg)
@tan(tanarg)
tanarg/2.0
#-180.0,d7.s
#1.0/360.0,d5.s
#360.0,d5.s
#90.0,d7.s
d6.s,d3.s
#180.0,d7.s
ffge
fflt
ffge
#tantab,r0
#scale,d0.s
#45.0,d6.s
x:(r0)+,d4.s
fflt
fflt
ffge
fsub.x d2,d0
DSP96002 USER'S MANUAL
;get range min
;adjust to min, get range
;reduce range
;get int part
;get frac part, spread
;spread fraction part to range
;adjust to min
;make positive, get pi/2
;save new sign
;see if greater than 90
;reduce to less than 90
;transfer if no change
;flip if other quadrant
;point to tangent table
;y=0, x=scale
;z=0,alp=45
;angle < z? get tangent
;yes, rotate cw
;yes, subtract angle
;no, add angle for ccw
;y*tan
;x*tan, x'=x-y*tan
MOTOROLA