Look at this line:
void sevensegpins(int z, int y, int x, int w, int v, int u, int t){
it's very hard (well, impossible in fact) to tell which letter relates to which display segment.
A library user (which could be you in a few months) should not have to read the code to understand how to call a function.
I think a better signature could be:
void sevensegpins(int a, int b, int c, int d, int e, int f, int g, int dp){
Yes, those are single letter variable names, that you should avoid. But I think they're pretty harmless in this context.