Motorola DSP96002 - Manual (Page 711)

B-192 DSP96002 USER’S MANUAL MOTOROLA
dp_move move x:(r1),d0.l ;move exponent
move d0.l,x:(r0)
move x:(r1+sign),d0.l ;move sign
move d0.l,x:(r0+sign)
move x:(r1+ms),d0.l ;move ms
move d0.l,x:(r0+ms)
move x:(r1+ls),d0.l ;move ls
move d0.l,x:(r0+ls)
rts
;
; MOTOROLA DSP96002 DPLIB - VERSION 1.0
;
; DP_MPY - Multiply two double precision numbers.
;
; Entry point: dp_mpy: c(r0)
←
c(r1) * c(r2)
;
; c d
; * a b
; d b
; c b
; d a
; c a
; x y
;
; Inputs: r0 contains the lowest address of a 4-word internal
; extended precision number
; r1 contains the lowest address of a 4-word internal
; extended precision number
;
; Outputs: r0 contains the lowest address of a 4-word internal
; extended precision number
;
; Alters: D0.L,D1.L,D2.L,D3.L,D4.L,D5.L,D6.L,D7.L,D0.M
;
dp_mpy clr d4 x:(r1+ms),d2.l ;get c
move x:(r2+ms),d3.l ;get a
mpyu d2,d3,d0 x:(r2+ls),d5.l ;c*a, get b
mpyu d5,d2,d2 d0.m,d1.l ;c*b, move high
move d2.m,d2.l
add d2,d0 x:(r1+ls),d2.l ;add to low, get d
addc d4,d1 x:(r2),d5.l ;get exponent
mpyu d2,d3,d2 x:(r2+sign),d7.l ;d*a
move d2.m,d2.l
add d2,d0 x:(r1),d6.l ;add to low
addc d4,d1 #bias,d4.l ;get bias
jeq uflow ;if *0, set 0 result
inc d5 ifmi ;if normed
jmi _nonorm
lsl d0 ;if not normed
rol d1 ;if not normed
_nonorm add d5,d6 d1.l,x:(r0+ms) ;do exponents
sub d4,d6 d0.l,x:(r0+ls) ;1 bias
move x:(r1+sign),d1.l