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QRZ! Ham Radio 8
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b130.asm
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Assembly Source File
|
1992-04-28
|
2KB
|
27 lines
; This program was originally published in the Motorola DSP96002 Users Manual
; and is provided under a DISCLAIMER OF WARRANTY available from Motorola DSP
; Operation, 6501 William Cannon Drive West, Austin, Texas 78735-8598. For
; more information, refer to the DSP96002 Users Manual, Appendix B, DSP
; Benchmarks.
;
; B.1.30 Newton-Raphson Approximation for SQRT(x)
;The approximation of sqrt(x) may be performed by using the Newton-Raphson iteration to first find
;1.0/sqrt(x). The sqrt(x) then can be approximated by x*(1.0/sqrt(x)).
;
;
; Newton-Raphson Approximation Program ICycles
; of SQRT(x) Words
seedr d5,d4 ;y approx 1/sqrt(x) 1 1
fmpy.s d4,d4,d2 #.5,d7.s ;y*y, get .5 2 2
fmpy.s d5,d2,d2 #3.0,d3.s ;x*y*y, get 3.0 2 2
fmpy d4,d7,d2 fsub.s d2,d3 d3.s,d6.s ;y/2, 3-x*y*y 1 1
fmpy.s d2,d3,d4 d6.s,d3.s ;y/2*(3-x*y*y) 1 1
fmpy.s d4,d4,d2 ;y*y 1 1
fmpy.s d5,d2,d2 ;x*y*y 1 1
fmpy d4,d7,d2 fsub.s d2,d3 d3.s,d6.s ;y/2, 3-x*y*y 1 1
fmpy.s d2,d3,d4 ;y/2*(3-x*y*y) 1 1
fmpy.s d5,d4,d4 ;x*(1/sqrt(x)) 1 1
; --- ---
; Totals: 12 12