Add timing to benchmarks

Makefile

@@ -16,6 +16,7 @@
 
 CFLAGS += -std=c11 -pedantic -Wall -Wextra
 CFLAGS += -O2 -flto
+CFLAGS += -D_XOPEN_SOURCE=700
 
 SRC = main.c sud.c solve.c
 OBJ = $(SRC:.c=.o)

main.c

@@ -22,6 +22,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <time.h>
 
 #define PROG_UPDATEPRD 20
 #define NPUZZLES 1024U
@@ -65,11 +66,24 @@ int main(void)
 	puts("100%");
 
 	bool res[NPUZZLES];
+	struct timespec start, end;
 	fputs("Solving... ", stdout);
+	fflush(stdout);
+	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start);
 	for (i = 0; i < NPUZZLES; ++i)
 		res[i] = solve(&puzzles[i]);
+	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end);
 	puts("done");
 
+	long secs = end.tv_sec - start.tv_sec;
+	long nanos = end.tv_nsec - start.tv_nsec;
+	if (nanos < 0) {
+		--secs;
+		nanos += 1000000000;
+	}
+	const double tot_micros = 1e6 * (double)secs + (double)nanos / 1e3;
+	const double avg_micros = tot_micros / NPUZZLES;
+
 	unsigned error = 0, incomplete = 0, incorrect = 0, solved = 0;
 	for (i = 0; i < NPUZZLES; ++i) {
 		if (!res[i]) {
@@ -90,6 +104,7 @@ int main(void)
 	}
 
 	puts("\n       SUMMARY\n       =======");
+	printf("Average time: %.3lf µs\n", avg_micros);
 	printf("Solved:       %4u/%u\n", solved, NPUZZLES);
 	printf("Incomplete:   %4u/%u\n", incomplete, NPUZZLES);
 	printf("Incorrect:    %4u/%u\n", incorrect, NPUZZLES);