.MODULE rsg_sub;

{

        Real SG Coefficient Adaptation Subroutine

        Calling Parameters
                MX0 = Error
                MY1 = Beta
                I2 --> Oldest input data value in delay line
                L2 = Filter length
                I6 --> Beginning of filter coefficient table
                L6 = Filter length
                M1,M5 = 1
                M6 = 2
                M3,M7 = -1
                CNTR = Filter length

        Return Values
                Coefficients updated
                I2 --> Oldest input data value in delay line
                I6 --> Beginning of filter coefficient table

        Altered Registers
                AY0,AR,MX0,MF,MR

        Computation Time
                (2 * Filter length) + 6 + 3 cycles

        All coefficients and data are assumed to be in 1.15 format.
}

.ENTRY  rsg;

rsg:    MF=MX0*MY1(RND), MX0=DM(I2,M1);         {MF=Error*Beta}
        MR=MX0*MF(RND), AY0=PM(I6,M5);
        DO adapt UNTIL CE;
          AR=MR1+AY0, MX0=DM(I2,M1), AY0=PM(I6,M7);
adapt:    PM(I6,M6)=AR, MR=MX0*MF(RND);
        MODIFY (I2,M3);                         {Point to oldest data}
        MODIFY (I6,M7);                         {Point to start of table}
        RTS;
.ENDMOD;