Add a simple test for LFSR generator

[fio.git] / t / lfsr-test.c

diff --git a/t/lfsr-test.c b/t/lfsr-test.c
new file mode 100644 (file)
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;
+}