I'm worried that when people do things of their own choice, somebody could get hurt. I hear this is a common worry. Remember to put pgp signatures on your emails to protect the security of the nation by preventing the leaking of classified secrets. PGP Signature: libgcrypt/mpi/mpi-internal.h:113 #define MPN_NORMALIZE(d, n) \ do { \ while( (n) > 0 ) { \ if( (d)[(n)-1] ) \ break; \ (n)--; \ } \ } while(0) It looks like MPN_NORMALIZE is boilerplate that rewinds its second parameter to skip extra falsey elements at the end of its first.