Add a simple test for LFSR generator
Adds a simple test suite to check the speed of the LFSR
generator and verify its results. Just run:
make t/lfsr-test
./t/lfsr-test
to compile the test suite and print its usage
Signed-off-by: Alex Pyrgiotis <apyrgio@grnet.gr>
create mode 100644 t/lfsr-test.c
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/t/lfsr-test.c b/t/lfsr-test.c
new file mode 100644
index 0000000..193a7f9
--- /dev/null
+++ b/t/lfsr-test.c
@@ -0,0 +1,127 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <math.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "../lib/lfsr.h"
+
+void usage()
+{
+ printf("Usage: lfsr-test 0x<numbers> [seed] [spin] [verify]\n");
+ printf("-------------------------------------------------------------\n");
+ printf("*numbers: how many random numbers to produce (in hex)\n"
+ "seed: initial value\n"
+ "spin: how many iterations before we produce a number\n"
+ "verify: check if LFSR has iterated correctly\n\n"
+ "Only <numbers> is required. The rest are evaluated to 0 or false\n"
+ "Elapsed/mean time and verification results are printed at the"
+ "end of the test\n");
+}
+
+int main(int argc, char *argv[])
+{
+ int r;
+ struct timespec start, end;
+ struct fio_lfsr *fl;
+ int verify = 0;
+ unsigned int spin = 0;
+ uint64_t seed = 0;
+ uint64_t numbers;
+ uint64_t v_size;
+ uint64_t i;
+ void *v = NULL, *v_start;
+ double total, mean;
+
+ /* Read arguments */
+ switch (argc) {
+ case 5: if (strncmp(argv[4], "verify", 7) == 0)
+ verify = 1;
+ case 4: spin = atoi(argv[3]);
+ case 3: seed = atol(argv[2]);
+ case 2: numbers = strtol(argv[1], NULL, 16);
+ break;
+ default: usage();
+ return 1;
+ }
+
+ /* Initialize LFSR */
+ fl = malloc(sizeof(struct fio_lfsr));
+ if (!fl) {
+ perror("malloc");
+ return 1;
+ }
+
+ r = lfsr_init(fl, numbers, seed, spin);
+ if (r) {
+ printf("Initialization failed.\n");
+ return r;
+ }
+
+ /* Print specs */
+ printf("LFSR specs\n");
+ printf("==========================\n");
+ printf("Size is %u\n", 64 - __builtin_clzl(fl->cached_bit));
+ printf("Max val is %lu\n", fl->max_val);
+ printf("XOR-mask is 0x%lX\n", fl->xormask);
+ printf("Seed is %lu\n", fl->last_val);
+ printf("Spin is %u\n", fl->spin);
+ printf("Cycle length is %lu\n", fl->cycle_length);
+
+ /* Create verification table */
+ if (verify) {
+ v_size = numbers * sizeof(uint8_t);
+ v = malloc(v_size);
+ memset(v, 0, v_size);
+ printf("\nVerification table is %lf KBs\n", (double)(v_size) / 1024);
+ }
+ v_start = v;
+
+ /*
+ * Iterate over a tight loop until we have produced all the requested
+ * numbers. Verifying the results should introduce some small yet not
+ * negligible overhead.
+ */
+ fprintf(stderr, "\nTest initiated... ");
+ clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start);
+ while (!lfsr_next(fl, &i, fl->max_val)) {
+ if (verify)
+ *(uint8_t *)(v + i) += 1;
+ }
+ clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end);
+ fprintf(stderr, "finished.\n");
+
+ /* Check if all expected numbers within range have been calculated */
+ r = 0;
+ if (verify) {
+ fprintf(stderr, "Verifying results... ");
+ for (i = 0; i < numbers; i++) {
+ if (*(uint8_t *)(v + 1) != 1) {
+ fprintf(stderr, "failed.\n");
+ r = 1;
+ break;
+ }
+ }
+ if (!r)
+ fprintf(stderr, "OK!\n");
+ }
+
+ /* Calculate elapsed time and mean time per number */
+ total = (end.tv_sec - start.tv_sec) * pow(10,9) +
+ end.tv_nsec - start.tv_nsec;
+ mean = total / fl->num_vals;
+
+ printf("\nTime results ");
+ if (verify)
+ printf("(slower due to verification)");
+ printf("\n==============================\n");
+ printf("Elapsed: %lf s\n", total / pow(10,9));
+ printf("Mean: %lf ns\n", mean);
+
+ free(v_start);
+ free(fl);
+ return r;
+}