Storage efficient sliding window sum

1. A delay buffer comprising:

a first shift register receiving input data and having a shift signal input port, the first shift register operable to shift the input data responsive to a shift signal on the shift signal input port;

means for determining an effective bit width of the input data, said determining means providing a shift signal to the first shift register shift signal input port;

a first delay line receiving the shifted data from the first shift register;

a second delay line of equal length to the first delay line receiving the shift signal; and

a second shift register receiving the output from the first delay line and having a shift signal input port receiving the output of the second delay line, the second shift register shifting the data contained therein according to the shift signal.

2. A delay buffer as defined in claim 1 wherein the input data is 29 bits and the first delay line is 12 bits in width and the shift signal is two bits.

3. A delay as defined in claim 1 further comprising a summer receiving the input data and connected to the second shift register to receive the data contained therein after shifting.

4. A delay buffer as defined in claim 1 wherein the means for determining effective bit width comprises:

means for converting the input data to 2s complement format;

means for defining an initial shift value;

means for defining an index value of the number of bits of the input data minus 1;

means for comparing the value of an input data bit corresponding to the index value to an input data bit corresponding the index value minus 1;

means for incrementing the index and shift values upon a positive compare from the comparing means and

means for outputting the shift value upon a negative compare from the comparing means.