Circuit for performing pooling operation in neural processor

Embodiments relate to a denominator circuit that determines the number of valid elements of a data surface covered by a kernel depending on various locations of the kernel relative to the data surface. The denominator circuit includes a first circuit and a second circuit that have the same structure. The first circuit receives numbers representing different horizontal locations of a reference point in the kernel and generates a first matrix with first output elements corresponding to the different horizontal locations. The second circuit receives numbers representing different vertical locations of a reference point in the kernel and generates a second matrix with second output elements corresponding to the different vertical locations. A matrix multiplication of the first matrix and the second matrix is performed to obtain an array of valid elements covered by the kernel.