cutils: bitops: Add Hamming weight to bitmask

Change-Id: I5c6b7adf711007edfffcb4fdf8e05b04bcffef54
2013-01-19 22:53:46 -08:00 · 2013-01-19 22:53:46 -08:00 · f90fd9eeb3
parent 2448146982
commit f90fd9eeb3
1 changed files with 10 additions and 0 deletions
--- a/include/cutils/bitops.h
+++ b/include/cutils/bitops.h
@ -75,6 +75,16 @@ static inline int bitmask_ffz(unsigned int *bitmask, int num_bits)
    return -1;
 }

+static inline int bitmask_weight(unsigned int *bitmask, int num_bits)
+{
+    int i;
+    int weight = 0;
+
+    for (i = 0; i < BITS_TO_WORDS(num_bits); i++)
+        weight += __builtin_popcount(bitmask[i]);
+    return weight;
+}
+
 static inline void bitmask_set(unsigned int *bitmask, int bit)
 {
    bitmask[BIT_WORD(bit)] |= BIT_MASK(bit);