From: David Given <dg@cowlark.com>
Date: Sat, 4 Feb 2017 22:08:52 +0000 (+0100)
Subject: Add a routine to count the number of set bits in a bitset.
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=bd24a0b7782960c0ad9e41ea9e35ace21e2d0f6c;p=ack.git

Add a routine to count the number of set bits in a bitset.
---

diff --git a/modules/src/data/bitmap.c b/modules/src/data/bitmap.c
index d47684d9d..dff7db163 100644
--- a/modules/src/data/bitmap.c
+++ b/modules/src/data/bitmap.c
@@ -85,3 +85,30 @@ int bitmap_find_unset_bit(unsigned int* bitmap, int size)
 
 	return -1;
 }
+
+static int count_bits_in_word(unsigned int word)
+{
+	int i = 0;
+	while (word)
+	{
+		if (word & 1)
+			i++;
+		word >>= 1;
+	}
+	return i;
+}
+
+int bitmap_count_set_bits(unsigned int* bitmap, int size)
+{
+	int word;
+	int words = ((size-1) / BITS_PER_WORD) + 1;
+	int count = 0;
+
+	for (word=0; word<words; word++)
+	{
+		unsigned int w = bitmap[word];
+		count += count_bits_in_word(w);
+	}
+
+	return count;
+}
diff --git a/modules/src/data/bitmap.h b/modules/src/data/bitmap.h
index 999bb7ecb..65ead3f23 100644
--- a/modules/src/data/bitmap.h
+++ b/modules/src/data/bitmap.h
@@ -9,6 +9,7 @@ extern int bitmap_findfirst(unsigned int* bitmap, int size);
 extern void bitmap_and(unsigned int* dest, int size, unsigned int* src);
 extern void bitmap_or(unsigned int* dest, int size, unsigned int* src);
 extern int bitmap_find_unset_bit(unsigned int* bitmap, int size);
+extern int bitmap_count_set_bits(unsigned int* bitmap, int size);
 
 #define BITS_PER_WORD (sizeof(unsigned int)*8)
 #define WORDS_FOR_BITMAP_SIZE(n) (((n-1) / BITS_PER_WORD) + 1)