{
    Subroutine to compute the square root of x
    using the 1/sqrt(x) approximation.

            X = sqrt(Y) = Y/sqrt(Y)

        Calling Registers
    F0 = Y Input Value
    F8 = 3.0
    F1 = 0.5

        Result Registers
    F0 = sqrt(Y)

        Altered Registers
    F0, F4, F12

        Computation Time
    14 Cycles

    Version 0.02    7/6/90      Gordon A. Sterling
}

#include "asm_glob.h"

.SEGMENT/PM     Assembly_Library_Code_Space;

.PRECISION=MACHINE_PRECISION;

.GLOBAL sqrt;

sqrt:           F4=RSQRTS F0;                   {Fetch seed}
                F12=F4*F4;                      {F12=X0^2}
                F12=F12*F0;                     {F12=C*X0^2}
                F4=F1*F4, F12=F8-F12;           {F4=.5*X0, F10=3-C*X0^2}
                F4=F4*F12;                      {F4=X1=.5*X0(3-C*X0^2)}
                F12=F4*F4;                      {F12=X1^2}
                F12=F12*F0;                     {F12=C*X1^2}
                F4=F1*F4, F12=F8-F12;           {F4=.5*X1, F10=3-C*X1^2}
                F4=F4*F12;                      {F4=X2=.5*X1(3-C*X1^2)}
                F12=F4*F4;                      {F12=X2^2}
                F12=F12*F0;                     {F12=C*X2^2}
                RTS (DB), F4=F1*F4, F12=F8-F12; {F4=.5*X2, F10=3-C*X2^2}
                F4=F4*F12;                      {F4=X3=.5*X2(3-C*X2^2)}
                F0=F4*F0;                       {X=sqrt(Y)=Y/sqrt(Y)}
.ENDSEG;