Measure time during AES run

aes-32bit/aes.cpp

@@ -1,3 +1,4 @@
+#include <chrono>
 #include <cstdio>
 #include <iostream>
 #include <stdint.h>
@@ -195,9 +196,17 @@ int main(int argc, char* argv[])
         cycles = std::atoi(argv[1]);
     }
 
+    const auto start{std::chrono::steady_clock::now()};
+    {
         for (int i = 0; i < cycles; i++) {
             uint8_t key[16] = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff };
             uint8_t in[16] =  { 0xab, 0xcd, 0xef, 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef, 0x01, 0x23, 0x45, 0x67, 0x89};
             aes(in, in, key);
         }
     }
+    const auto end{std::chrono::steady_clock::now()};
+    const std::chrono::duration<double> elapsed_seconds{end - start};
+ 
+    std::cout << "AES (" << cycles  << " runs)\nElapsed time: ";
+    std::cout << elapsed_seconds.count() << "s\n"; // Before C++20
+}