From 553930424dec0cb1a83d2c928c260de6626b0d11 Mon Sep 17 00:00:00 2001
From: Keith Whitwell <keithw@vmware.com>
Date: Wed, 21 Sep 2011 11:22:43 -0600
Subject: util: add u_bit_scan helper

---
 src/gallium/auxiliary/util/u_math.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

(limited to 'src/gallium/auxiliary')

diff --git a/src/gallium/auxiliary/util/u_math.h b/src/gallium/auxiliary/util/u_math.h
index 46d9322932a..c74c1da7675 100644
--- a/src/gallium/auxiliary/util/u_math.h
+++ b/src/gallium/auxiliary/util/u_math.h
@@ -424,6 +424,22 @@ unsigned ffs( unsigned u )
 #endif
 
 
+/* Destructively loop over all of the bits in a mask as in:
+ *
+ * while (mymask) {
+ *   int i = u_bit_scan(&mymask);
+ *   ... process element i
+ * }
+ * 
+ */
+static INLINE int u_bit_scan(unsigned *mask)
+{
+   int i = ffs(*mask) - 1;
+   *mask &= ~(1 << i);
+   return i;
+}
+
+
 /**
  * Return float bits.
  */
-- 
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