Add support to xorshift PRNG

Author: acassen

lib/utils.c

@@ -614,6 +614,18 @@ poor_prng(unsigned int *seed)
 	return shuffle;
 }
 
+/*
+ *	XorShift*
+ */
+uint32_t
+xorshift_prng(uint64_t *state)
+{
+	*state ^= *state >> 12;
+	*state ^= *state << 25;
+	*state ^= *state >> 27;
+	return (*state * 0x2545F4914F6CDD1DULL) >> 32;
+}
+
 /*
  * Copy string src to buffer dst of size dsize.  At most dsize-1
  * chars will be copied.  Always NUL terminates (unless dsize == 0).

lib/utils.h

@@ -155,6 +155,7 @@ extern uint32_t adler_crc32(uint8_t *, size_t);
 extern uint32_t fletcher_crc32(uint8_t *, size_t);
 extern int integer_to_string(const int, char *, size_t);
 extern uint32_t poor_prng(unsigned int *);
+extern uint32_t xorshift_prng(uint64_t *);
 extern size_t strlcpy(char *, const char *, size_t);
 
 #endif