From 96fdf1efbd1b048f4df468c07c5e5134a061265c Mon Sep 17 00:00:00 2001
From: Paul Khuong <pkhuong@appnexus.com>
Date: Thu, 17 Apr 2014 16:25:10 -0400
Subject: [PATCH] ck_cc: new bitwise ops

GCC and compatible compilers support ffs/ctz/clz/popcount. Expose that
in ck_cc and default to slow but portable software emulation.
---
 include/ck_cc.h     | 68 ++++++++++++++++++++++++++++++++++++++++++++-
 include/gcc/ck_cc.h | 39 +++++++++++++++++++++++++-
 2 files changed, 105 insertions(+), 2 deletions(-)

diff --git a/include/ck_cc.h b/include/ck_cc.h
index c85176d..a4baaa5 100644
--- a/include/ck_cc.h
+++ b/include/ck_cc.h
@@ -1,5 +1,6 @@
 /*
  * Copyright 2009-2014 Samy Al Bahra.
+ * Copyright 2014 Paul Khuong.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -85,5 +86,70 @@
 #define CK_CC_UNLIKELY(x) x
 #endif
 
-#endif /* _CK_CC_H */
+#ifndef CK_F_CC_FFS
+#define CK_F_CC_FFS
+CK_CC_INLINE static int
+ck_cc_ffs(unsigned int x)
+{
+	unsigned int i;
+
+	if (x == 0)
+		return 0;
+
+	for (i = 1; (x & 1) == 0; i++, x >>= 1);
+
+	return i;
+}
+#endif
+
+#ifndef CK_F_CC_CLZ
+#define CK_F_CC_CLZ
+#include <ck_limits.h>
+
+CK_CC_INLINE static int
+ck_cc_clz(unsigned int x)
+{
+	unsigned int count, i;
+
+	for (count = 0, i = sizeof(unsigned int) * CHAR_BIT; i > 0; count++) {
+		unsigned int bit = 1U << --i;
+
+		if (x & bit)
+			break;
+	}
+
+	return count;
+}
+#endif
+
+#ifndef CK_F_CC_CTZ
+#define CK_F_CC_CTZ
+CK_CC_INLINE static int
+ck_cc_ctz(unsigned int x)
+{
+	unsigned int i;
+
+	if (x == 0)
+		return 0;
+
+	for (i = 0; (x & 1) == 0; i++, x >>= 1);
+
+	return i;
+}
+#endif
 
+#ifndef CK_F_CC_POPCOUNT
+#define CK_F_CC_POPCOUNT
+CK_CC_INLINE static int
+ck_cc_popcount(unsigned int x)
+{
+	unsigned int acc;
+
+	for (acc = 0; x != 0; x >>= 1)
+		acc += x & 1;
+
+	return acc;
+}
+#endif
+
+#endif /* _CK_CC_H */
diff --git a/include/gcc/ck_cc.h b/include/gcc/ck_cc.h
index 7a98c94..084e7bf 100644
--- a/include/gcc/ck_cc.h
+++ b/include/gcc/ck_cc.h
@@ -1,5 +1,6 @@
 /*
  * Copyright 2009-2014 Samy Al Bahra.
+ * Copyright 2014 Paul Khuong.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -96,5 +97,41 @@
  */
 #define CK_CC_ALIASED __attribute__((__may_alias__))
 
-#endif /* _CK_GCC_CC_H */
+/*
+ * Portability wrappers for bitwise ops.
+ */
+
+#define CK_F_CC_FFS
+#define CK_F_CC_CLZ
+#define CK_F_CC_CTZ
+#define CK_F_CC_POPCOUNT
+
+CK_CC_INLINE static int
+ck_cc_ffs(unsigned int x)
+{
+
+	return __builtin_ffs(x);
+}
+
+CK_CC_INLINE static int
+ck_cc_clz(unsigned int x)
+{
 
+	return __builtin_clz(x);
+}
+
+CK_CC_INLINE static int
+ck_cc_ctz(unsigned int x)
+{
+
+	return __builtin_ctz(x);
+}
+
+CK_CC_INLINE static int
+ck_cc_popcount(unsigned int x)
+{
+
+	return __builtin_popcount(x);
+}
+
+#endif /* _CK_GCC_CC_H */