gcc -Wall -march=native -mtune=native -fprofile-generate -O3 sha256test.c -o sha256test -lcrypto
./sha256test 25 "00000000c7e6e62a5d21dcb25bb2a937b19b2d32c8bd2339a22f18a4d3926862 robin"
gcc -Wall -march=native -mtune=native -fprofile-use -O3 sha256test.c -o sha256test -lcrypto