in include/hash/xxhash.h [2001:2012]
XXH_PUBLIC_API XXH_errorcode XXH64_reset(XXH64_state_t* statePtr, XXH64_hash_t seed)
{
XXH64_state_t state; /* use a local state to memcpy() in order to avoid strict-aliasing warnings */
memset(&state, 0, sizeof(state));
state.v1 = seed + XXH_PRIME64_1 + XXH_PRIME64_2;
state.v2 = seed + XXH_PRIME64_2;
state.v3 = seed + 0;
state.v4 = seed - XXH_PRIME64_1;
/* do not write into reserved64, might be removed in a future version */
memcpy(statePtr, &state, sizeof(state) - sizeof(state.reserved64));
return XXH_OK;
}