ass3/mart/sws1-assignment3-s4109503-s4202015/exercise2.c

   1 #include <stdlib.h>
   2
   3 typedef unsigned char uc;
   4 typedef unsigned __int128 uint128;
   5
   6 void addvector(int *r, const int *a, const int *b, size_t len)
   7 {
   8         for(int *r2 = r; r2 < r + len;r2++, a++, b++)
   9                 *r2 = *a + *b;
  10 }
  11
  12 int memcmp(const void *s1, const void *s2, size_t n)
  13 {
  14         for(uc *s3 = (uc*)s1, *s4 = (uc*)s2; s3 < (uc*)s1 + n; s3++, s4++)
  15                 if(*s3 != *s4)
  16                         return *s3-*s4;
  17         return 0;
  18 }
  19
  20 int memcmp_backwards(const void *s1, const void *s2, size_t n)
  21 {
  22         for(uc *s3 = (uc*)s1+n, *s4 = (uc*)s2+n; s3 >= (uc*)s1; s3--, s4--)
  23                 if(*s3 != *s4)
  24                         return *s3-*s4;
  25         return 0;
  26 }
  27
  28 int memcmp_fast(const void *s1, const void *s2, size_t n)
  29 {
  30         uint128 *s3 = (uint128 *)s1;
  31         uint128 *s4 = (uint128 *)s2;
  32         unsigned int blocks = n/sizeof(uint128);
  33         for(; s3<((uint128*)s1)+blocks; s3++, s4++)
  34                 if(*s3 != *s4)
  35                         return memcmp(s3, s4, sizeof(uint128));
  36         return memcmp(s3, s4, n % sizeof(uint128));
  37 }