How is the circular convolution implemented? about snake HOT 2 CLOSED

class CircConv(nn.Module):
    def __init__(self, state_dim, out_state_dim=None, n_adj=4):
        super(CircConv, self).__init__()

        self.n_adj = n_adj
        out_state_dim = state_dim if out_state_dim is None else out_state_dim
        self.fc = nn.Conv1d(state_dim, out_state_dim, kernel_size=self.n_adj*2+1)

    def forward(self, input, adj):
        input = torch.cat([input[..., -self.n_adj:], input, input[..., :self.n_adj]], dim=2)
        return self.fc(input)