The precompile at 0x09 wraps the BLAKE2b F compression function:
https://tools.ietf.org/html/rfc7693#section-3.2
The precompile requires 6 inputs tightly encoded, taking exactly 213
bytes, as explained below.
- `rounds` - the number of rounds - 32-bit unsigned big-endian word
- `h` - the state vector - 8 unsigned 64-bit little-endian words
- `m` - the message block vector - 16 unsigned 64-bit little-endian words
- `t_0, t_1` - offset counters - 2 unsigned 64-bit little-endian words
- `f` - the final block indicator flag - 8-bit word
[4 bytes for rounds][64 bytes for h][128 bytes for m][8 bytes for t_0]
[8 bytes for t_1][1 byte for f]
The boolean `f` parameter is considered as `true` if set to `1`.
The boolean `f` parameter is considered as `false` if set to `0`.
All other values yield an invalid encoding of `f` error.
The precompile should compute the F function as specified in the RFC
(https://tools.ietf.org/html/rfc7693#section-3.2) and return the updated
state vector `h` with unchanged encoding (little-endian).
See EIP-152 for details.
Péter Szilágyi
Piotr Dyraga