step 1 done

helper.c

@@ -1,5 +1,6 @@
 #include <stdint.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 void print_uint128(unsigned __int128 n) {
     if (n == 0) {
@@ -23,3 +24,36 @@ void print_uint128(unsigned __int128 n) {
     }
     putchar('\n');
 }
+
+uint64_t rand64() {
+    uint64_t r = 0;
+    for (int i = 0; i < 4; i++) {
+        r = (r << 16) | (rand() & 0xFFFF);
+    }
+    return r;
+}
+
+// Stitch two 64-bit random numbers into a 128-bit number
+unsigned __int128 generate_stitched_128() {
+    // Make sure to seed rand() in your main function with srand(time(NULL))
+    uint64_t top_half = rand64();
+    uint64_t bottom_half = rand64();
+
+    // Cast the top half to 128-bit, shift it over by 64 bits, and attach the bottom
+    unsigned __int128 full_number = ((unsigned __int128)top_half << 64) | bottom_half;
+
+    return full_number;
+}
+
+unsigned __int128 generate_prime_candidate() {
+    // 1. Get the raw random bytes
+    unsigned __int128 candidate = generate_stitched_128();
+
+    // 2. Force the bottom bit to 1 (Ensures it is odd)
+    candidate = candidate | 1;
+
+    // 3. Force the top bit to 1 (Ensures it is a full 128-bit number)
+    candidate = candidate | ((unsigned __int128)1 << 127);
+
+    return candidate;
+}