I would like help with 2 things:
1. How can I replace the X-style multipliers with triangle-style multipliers? More like this:
I was told people here would show how to customize the tikz-dsp library?
2. The state variable labels
d_0[n], d_1[n], ...were added afterward in an image editing program. How could I make them in the document itself? Actually the lines are ugly, it would be best to fit the labels right next to the arrows they go with, like: