Initial commit.

foo.c

@@ -0,0 +1,83 @@
+#define _GNU_SOURCE
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <linux/random.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+
+#include <gmp.h>
+
+
+#define START_TIMEIT()                                          \
+  struct timeval __start, __end; gettimeofday(&__start, NULL)
+
+#define END_TIMEIT()                                                    \
+  gettimeofday(&__end, NULL);                                           \
+  double __sdiff = (__end.tv_sec - __start.tv_sec), __udiff = (__end.tv_usec - __start.tv_usec)
+
+
+#define GET_TIMEIT()                            \
+  __sdiff + __udiff * 1e-6
+
+#define TIMEIT_FORMAT "%lf"
+
+const static char *p_str =
+  "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+  "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+  "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+  "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+  "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+  "505CAF";
+
+static inline ssize_t
+getrandom(void *buffer, size_t length, unsigned int flags)
+{
+  return syscall(SYS_getrandom, buffer, length, flags);
+}
+
+
+mpz_t p, t;
+
+uint32_t convert(mpz_t n)
+{
+  uint32_t i;
+
+  for (i = 0; mpz_cmp(n, t) > -1; i++) {
+    mpz_mul_2exp(n, n, 1);
+    mpz_mod(n, n, p);
+  }
+  return i;
+}
+
+int main()
+{
+  // mpz_t p;
+  mpz_init_set_str(p, p_str, 0);
+
+  gmp_randstate_t _rstate;
+  unsigned long int _rseed;
+
+  gmp_randinit_default(_rstate);
+  getrandom(&_rseed, sizeof(unsigned long int), GRND_RANDOM);
+  gmp_randseed_ui(_rstate, _rseed);
+
+  // mpz_t t;
+  mpz_init_set_str(t, "1", 0);
+  mpz_mul_2exp(t, t, 1536-8);
+
+  mpz_t n;
+  mpz_init(n);
+
+  START_TIMEIT();
+  for (int i=0; i < 5e3; i++) {
+    mpz_urandomm(n, _rstate, p);
+    convert(n);
+  }
+  END_TIMEIT();
+  printf(TIMEIT_FORMAT "\n", GET_TIMEIT());
+
+  return 0;
+
+}