MASH 1-1 sigma delta modulator

hi all,

can somebody share the pseudo-code of MASH 1-1 sigma delta modulator for
fractional-N pll.


Thanks
adani

"adani" <adnan.shah@gmail.com> wrote in message 
news:i5WdnStaTNqjoX3bnZ2dnUVZ_oCvnZ2d@giganews.com...
> hi all,
>
> can somebody share the pseudo-code of MASH 1-1 sigma delta modulator for
> fractional-N pll.
>
>
> Thanks
> adani
>
>

struct MASH {
    unsigned a[4];      // Accumulators
    unsigned c[4][4];   // Carry flip flops

    MASH() {
        // Initial values
        memset(c, 0, sizeof c);
        a[0] = 1;
        a[1] = 0;
        a[2] = 0;
        a[3] = 0;
    }

    int Clock(unsigned F);
};


int MASH::Clock(unsigned F) {
    register union {
        __int64  i64;
        unsigned i32[2];
    };

    // Carry flip-flops
    c[3][3] = c[3][2]; c[3][2] = c[3][1]; c[3][1] = c[3][0];
                       c[2][2] = c[2][1]; c[2][1] = c[2][0];
                                          c[1][1] = c[1][0];
    // Accumulators
    i64=a[0]; i64+=F;    a[0] = i32[0]; c[0][0] = i32[1];
    i64=a[1]; i64+=a[0]; a[1] = i32[0]; c[1][0] = i32[1];
    i64=a[2]; i64+=a[1]; a[2] = i32[0]; c[2][0] = i32[1];
    i64=a[3]; i64+=a[2]; a[3] = i32[0]; c[3][0] = i32[1];

    // Comment-out lines below to lower MASH order
    return  c[0][0]
        +   c[1][0] -   c[1][1]
        +   c[2][0] - 2*c[2][1] +   c[2][2]
        +   c[3][0] - 3*c[3][1] + 3*c[3][2] - c[3][3]
        ;
}

Thanks!

it really helped.

Regards,
Adani
>"adani" <adnan.shah@gmail.com> wrote in message 
>news:i5WdnStaTNqjoX3bnZ2dnUVZ_oCvnZ2d@giganews.com...
>> hi all,
>>
>> can somebody share the pseudo-code of MASH 1-1 sigma delta modulator
for
>> fractional-N pll.
>>
>>
>> Thanks
>> adani
>>
>>
>
>struct MASH {
>    unsigned a[4];      // Accumulators
>    unsigned c[4][4];   // Carry flip flops
>
>    MASH() {
>        // Initial values
>        memset(c, 0, sizeof c);
>        a[0] = 1;
>        a[1] = 0;
>        a[2] = 0;
>        a[3] = 0;
>    }
>
>    int Clock(unsigned F);
>};
>
>
>int MASH::Clock(unsigned F) {
>    register union {
>        __int64  i64;
>        unsigned i32[2];
>    };
>
>    // Carry flip-flops
>    c[3][3] = c[3][2]; c[3][2] = c[3][1]; c[3][1] = c[3][0];
>                       c[2][2] = c[2][1]; c[2][1] = c[2][0];
>                                          c[1][1] = c[1][0];
>    // Accumulators
>    i64=a[0]; i64+=F;    a[0] = i32[0]; c[0][0] = i32[1];
>    i64=a[1]; i64+=a[0]; a[1] = i32[0]; c[1][0] = i32[1];
>    i64=a[2]; i64+=a[1]; a[2] = i32[0]; c[2][0] = i32[1];
>    i64=a[3]; i64+=a[2]; a[3] = i32[0]; c[3][0] = i32[1];
>
>    // Comment-out lines below to lower MASH order
>    return  c[0][0]
>        +   c[1][0] -   c[1][1]
>        +   c[2][0] - 2*c[2][1] +   c[2][2]
>        +   c[3][0] - 3*c[3][1] + 3*c[3][2] - c[3][3]
>        ;
>}
>
>
>