Adding a few count functions.

lemire · Mar 24, 2017 · 40d74c4 · 40d74c4
1 parent ca889a4
commit 40d74c4
Show file tree

Hide file tree

Showing 2 changed files with 38 additions and 0 deletions.
diff --git a/include/bitset.h b/include/bitset.h
@@ -114,9 +114,14 @@ size_t bitset_intersection_count(const bitset_t * restrict b1, const bitset_t *
 /* compute the difference in-place (to b1), to generate a new bitset first call bitset_copy */
 void bitset_inplace_difference(bitset_t * restrict b1, const bitset_t * restrict b2);
 
+/* compute the size of the difference */
+size_t  bitset_difference_count(const bitset_t *restrict b1, const bitset_t * restrict b2) ;
+
 /* compute the symmetric difference in-place (to b1), return true if successful, to generate a new bitset first call bitset_copy */
 bool bitset_inplace_symmetric_difference(bitset_t * restrict b1, const bitset_t * restrict b2);
 
+/* compute the size of the symmetric difference  */
+size_t  bitset_symmetric_difference_count(const bitset_t *restrict b1, const bitset_t * restrict b2);
 
 /* iterate over the set bits
  like so :

diff --git a/src/bitset.c b/src/bitset.c
@@ -209,6 +209,20 @@ void bitset_inplace_difference(bitset_t *restrict b1, const bitset_t * restrict
   }
 }
 
+
+size_t  bitset_difference_count(const bitset_t *restrict b1, const bitset_t * restrict b2) {
+  size_t minlength = b1->arraysize < b2->arraysize ? b1->arraysize : b2->arraysize;
+  size_t k = 0;
+  size_t answer = 0;
+  for( ; k < minlength; ++k) {
+    answer += __builtin_popcountll (b1->array[k] & ~ (b2->array[k]));
+  }
+  for( ; k < b1->arraysize ; ++k) {
+    answer += __builtin_popcountll (b1->array[k]);
+  }
+  return answer;
+}
+
 bool bitset_inplace_symmetric_difference(bitset_t *restrict b1, const bitset_t * restrict b2) {
   size_t minlength = b1->arraysize < b2->arraysize ? b1->arraysize : b2->arraysize;
   size_t k = 0;
@@ -222,3 +236,22 @@ bool bitset_inplace_symmetric_difference(bitset_t *restrict b1, const bitset_t *
   }
   return true;
 }
+
+size_t  bitset_symmetric_difference_count(const bitset_t *restrict b1, const bitset_t * restrict b2) {
+  size_t minlength = b1->arraysize < b2->arraysize ? b1->arraysize : b2->arraysize;
+  size_t k = 0;
+  size_t answer = 0;
+  for( ; k < minlength; ++k) {
+    answer += __builtin_popcountll(b1->array[k] ^ b2->array[k]);
+  }
+  if(b2->arraysize > b1->arraysize) {
+    for( ; k < b2->arraysize; ++k) {
+      answer += __builtin_popcountll(b2->array[k]);
+    }
+  } else {
+    for( ; k < b1->arraysize; ++k) {
+      answer += __builtin_popcountll(b1->array[k]);
+    }
+  }
+  return true;
+}