A Mass Formula for Linear Codes With Prescribed Hull Dimension and Related Classification

The hull of a linear code over a finite field is the intersection of the code and its dual, which was introduced by Assmus and Key to classify finite projective planes. The main objective of this paper is to obtain a closed mass formula for linear codes with prescribed hull dimension. We simplify the mass formula obtained by Sendrier and provide an alternative proof for the mass formula for self-orthogonal codes obtained by Pless. Finally, we obtain a classification of (optimal) ternary linear codes with small parameters.