[PATCH 01/11] lib/igt_aux: add hweight helper for bitmaps

[Andrzej Hajda <andrzej.hajda@intel.com>]

There are multiple places where such helper can be useful.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 lib/igt_aux.c | 28 ++++++++++++++++++++++++++++
 lib/igt_aux.h |  2 ++
 2 files changed, 30 insertions(+)

diff --git a/lib/igt_aux.c b/lib/igt_aux.c
index 5c26798129fc..d3280c3514a0 100644
--- a/lib/igt_aux.c
+++ b/lib/igt_aux.c
@@ -2124,3 +2124,31 @@ void igt_wait_and_close(int fence_fd)
 	poll(&(struct pollfd){fence_fd, POLLIN}, 1, -1);
 	close(fence_fd);
 }
+
+static uint64_t bitmap_get_nbits(void *bitmap, int nbits)
+{
+	uint64_t val = 0;
+
+	igt_assert(nbits < BITS_PER_TYPE(val));
+
+	memcpy(&val, bitmap, DIV_ROUND_UP(nbits, BITS_PER_BYTE));
+	return val & ((1ULL << nbits) - 1);
+}
+
+/**
+ * igt_bitmap_hweight: count enabled bits in bitmap
+ *
+ * @bitmap: pointer to bitmap
+ * @nbits: number of bits to examine
+ */
+int igt_bitmap_hweight(void *bitmap, int nbits)
+{
+	uint64_t *p = bitmap;
+	int ret = 0;
+
+	for (; nbits >= BITS_PER_TYPE(*p); nbits -= BITS_PER_TYPE(*p))
+		ret += igt_hweight(*p++);
+	if (nbits)
+		ret += igt_hweight(bitmap_get_nbits(p, nbits));
+	return ret;
+}
diff --git a/lib/igt_aux.h b/lib/igt_aux.h
index e8a1788b28df..885c6b096e49 100644
--- a/lib/igt_aux.h
+++ b/lib/igt_aux.h
@@ -352,4 +352,6 @@ void *igt_memdup(const void *ptr, size_t len);
 
 void igt_wait_and_close(int fence_fd);
 
+int igt_bitmap_hweight(void *bitmap, int nbits);
+
 #endif /* IGT_AUX_H */

-- 
2.43.0