Now that I think about it, for the uint126_t encoding case, you actually need to inspect up to the first 3 bytes. I've only implemented this for encoding/decod

Now that I think about it, for the uint126_t encoding case, you actually need to inspect up to the first 3 bytes. I've only implemented this for encoding/decoding uint64_ts, in which case there's a little trick that saves one byte, but the trick only works because 64 % 7 == 1. Maybe it's most clear if I spell out the 19 cases necessary to encode any uint128_t (system using BSR (leading 1s) insteod of LZCNT (leading 0s)). 0 xxxxxxx -> 0 to 127 10 xxxxxx yyyyyyyy -> 128 to 2**14 - 1 110 xxxxx yyyyyyyy zzzzzzzz -> 2**14 to 2**21-1 1110 xxxx yyyyyyyy zzzzzzzz aaaaaaaa -> 2**21 to 2**28-1 11110 xxx yyyyyyyy zzzzzzzz ... 2 more bytes -> 2**28 to 2**35-1 111110 xx yyyyyyyy zzzzzzzz ... 3 more bytes -> 2**35 to 2**42-1 1111110 x yyyyyyyy zzzzzzzz ... 4 more bytes -> 2**42 to 2**49-1 11111110 yyyyyyyy zzzzzzzz ... 5 more bytes -> 2**49 to 2**56-1 11111111 0 yyyyyyy zzzzzzzz ... 6 more bytes -> 2**56 to 2**63-1 11111111 10 yyyyyy zzzzzzzz ... 7 more bytes -> 2**63 to 2**70-1 11111111 110 yyyyy zzzzzzzz ... 8 more bytes -> 2**70 to 2**77-1 11111111 1110 yyyy zzzzzzzz ... 9 more bytes -> 2**77 to 2**84-1 11111111 11110 yyy zzzzzzzz ... 10 more bytes -> 2**84 to 2**91-1 11111111 111110 yy zzzzzzzz ... 11 more bytes -> 2**91 to 2**98-1 11111111 1111110 y zzzzzzzz ... 12 more bytes -> 2**98 to 2**105-1 11111111 1111111 0 zzzzzzzz ... 13 more bytes -> 2**105 to 2**112-1 11111111 11111111 0zzzzzzz ... 14 more bytes -> 2**112 to 2**119-1 11111111 11111111 10zzzzzz ... 15 more bytes -> 2**119 to 2**126-1 11111111 11111111 110zzzzz ... 16 more bytes -> 2**126 to 2**133-1