"Fossies" - the Fresh Open Source Software Archive

Member "xdelta3-3.0.11/examples/compare_test.c" (24 Mar 2015, 2430 Bytes) of package /linux/misc/xdelta3-3.0.11.tar.gz:

    1 #include <stdio.h>
    2 #include <stdlib.h>
    3 #include <time.h>
    4 #include <string.h>
    5 #include <assert.h>
    6 
    7 #include "xdelta3.h"
    8 
    9 #define NUM (1<<20)
   10 #define ITERS 100
   11 
   12 /* From wikipedia on RDTSC */
   13 inline uint64_t rdtsc() {
   14   uint32_t lo, hi;
   15   asm volatile ("rdtsc" : "=a" (lo), "=d" (hi));
   16   return (uint64_t)hi << 32 | lo;
   17 }
   18 
   19 typedef int (*test_func)(const char *s1, const char *s2, int n);
   20 
   21 void run_test(const char *buf1, const char *buf2,
   22           const char *name, test_func func) {
   23   uint64_t start, end;
   24   uint64_t accum = 0;
   25   int i, x;
   26 
   27   for (i = 0; i < ITERS; i++) {
   28     start = rdtsc();
   29     x = func(buf1, buf2, NUM);
   30     end = rdtsc();
   31     accum += end - start;
   32     assert(x == NUM - 1);
   33   }
   34 
   35   accum /= ITERS;
   36 
   37   printf("%s : %qu cycles\n", name, accum);
   38 }
   39 
   40 /* Build w/ -fno-builtin for this to be fast, this assumes that there
   41  * is a difference at s1[n-1] */
   42 int memcmp_fake(const char *s1, const char *s2, int n) {
   43   int x = memcmp(s1, s2, n);
   44   return x < 0 ? n - 1 : n + 1;
   45 }
   46 
   47 #define UNALIGNED_OK 1
   48 static inline int
   49 test2(const char *s1c, const char *s2c, int n)
   50 {
   51   int i = 0;
   52 #if UNALIGNED_OK
   53   int nint = n / sizeof(int);
   54 
   55   if (nint >> 3)
   56     {
   57       int j = 0;
   58       const int *s1 = (const int*)s1c;
   59       const int *s2 = (const int*)s2c;
   60       int nint_8 = nint - 8;
   61 
   62       while (i <= nint_8 &&
   63          s1[i++] == s2[j++] &&
   64          s1[i++] == s2[j++] &&
   65          s1[i++] == s2[j++] &&
   66          s1[i++] == s2[j++] &&
   67          s1[i++] == s2[j++] &&
   68          s1[i++] == s2[j++] &&
   69          s1[i++] == s2[j++] &&   
   70          s1[i++] == s2[j++]) { }
   71 
   72       i = (i - 1) * sizeof(int);
   73     }
   74 #endif
   75 
   76   while (i < n && s1c[i] == s2c[i])
   77     {
   78       i++;
   79     }
   80   return i;
   81 }
   82 
   83 static inline int
   84 test1(const char *s1c, const char *s2c, int n) {
   85   int i = 0;
   86   while (i < n && s1c[i] == s2c[i])
   87     {
   88       i++;
   89     }
   90   return i;
   91 }
   92 
   93 int main(/*int argc, char **argv*/) {
   94   char *buf1 = malloc(NUM+1);
   95   char *buf2 = malloc(NUM+1);
   96   int i;
   97 
   98   for (i = 0; i < NUM; i++) {
   99     buf1[i] = buf2[i] = rand();
  100   }
  101 
  102   buf2[NUM-1]++;
  103 
  104   printf ("ALIGNED\n");
  105 
  106   run_test(buf1, buf2, "memcmp", &memcmp_fake);
  107   run_test(buf1, buf2, "test1", &test1);
  108   run_test(buf1, buf2, "test2", &test2);
  109 
  110   for (i = 0; i < NUM; i++) {
  111     buf1[i] = buf2[i+1] = rand();
  112   }
  113 
  114   buf2[NUM]++;
  115 
  116   printf ("UNALIGNED\n");
  117 
  118   run_test(buf1, buf2+1, "memcmp", &memcmp_fake);
  119   run_test(buf1, buf2+1, "test1", &test1);
  120   run_test(buf1, buf2+1, "test2", &test2);
  121 
  122   return 0;
  123 }