initial implementation of xorshift128 and xorshift128plus

benchmark.c

@@ -0,0 +1,46 @@
+#include <stdio.h>
+#include <time.h>
+
+#include "xorshift.h"
+
+struct timespec clock_diff(struct timespec start, struct timespec stop)
+{
+	struct timespec diff;
+	if ((stop.tv_nsec-start.tv_nsec) < 0) {
+
+		diff.tv_sec  = stop.tv_sec - start.tv_sec - 1;
+		diff.tv_nsec = 1e9 + stop.tv_nsec - start.tv_nsec;
+
+	} else {
+
+		diff.tv_sec  = stop.tv_sec  - start.tv_sec;
+		diff.tv_nsec = stop.tv_nsec - start.tv_nsec;
+	}
+
+	return diff;
+}
+
+
+#define BENCHMARK(func)												\
+{																	\
+	struct timespec start, stop, diff;								\
+																	\
+	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start);				\
+																	\
+	for (size_t i = 0; i < 1e9; ++i)								\
+		(void)func();												\
+																	\
+	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &stop);					\
+	diff = clock_diff(start, stop);									\
+																	\
+	printf("%ld:%ld\n", (long)diff.tv_sec, (long)diff.tv_nsec);		\
+}																	\
+
+
+int main()
+{
+	BENCHMARK(xorshift128);
+	BENCHMARK(xorshift128plus);
+
+	return 0;
+}