Merge 2610c05b5b95cc7036b3d6dfb894c6cfbdb68483 as Samba-4.0alpha16

1 files changed, 150 insertions, 0 deletions

diff --git a/lib/ccan/ilog/ilog.h b/lib/ccan/ilog/ilog.h
new file mode 100644
index 0000000000..55dd009885
--- /dev/null
+++ b/lib/ccan/ilog/ilog.h
@@ -0,0 +1,150 @@
+#if !defined(_ilog_H)
+# define _ilog_H (1)
+# include "config.h"
+# include <stdint.h>
+# include <limits.h>
+# include <ccan/compiler/compiler.h>
+
+/**
+ * ilog32 - Integer binary logarithm of a 32-bit value.
+ * @_v: A 32-bit value.
+ * Returns floor(log2(_v))+1, or 0 if _v==0.
+ * This is the number of bits that would be required to represent _v in two's
+ *  complement notation with all of the leading zeros stripped.
+ * Note that many uses will resolve to the fast macro version instead.
+ *
+ * See Also:
+ *	ilog32_nz(), ilog64()
+ *
+ * Example:
+ *	// Rounds up to next power of 2 (if not a power of 2).
+ *	static uint32_t round_up32(uint32_t i)
+ *	{
+ *		assert(i != 0);
+ *		return 1U << ilog32(i-1);
+ *	}
+ */
+int ilog32(uint32_t _v) IDEMPOTENT;
+
+/**
+ * ilog32_nz - Integer binary logarithm of a non-zero 32-bit value.
+ * @_v: A 32-bit value.
+ * Returns floor(log2(_v))+1, or undefined if _v==0.
+ * This is the number of bits that would be required to represent _v in two's
+ *  complement notation with all of the leading zeros stripped.
+ * Note that many uses will resolve to the fast macro version instead.
+ * See Also:
+ *	ilog32(), ilog64_nz()
+ * Example:
+ *	// Find Last Set (ie. highest bit set, 0 to 31).
+ *	static uint32_t fls32(uint32_t i)
+ *	{
+ *		assert(i != 0);
+ *		return ilog32_nz(i) - 1;
+ *	}
+ */
+int ilog32_nz(uint32_t _v) IDEMPOTENT;
+
+/**
+ * ilog64 - Integer binary logarithm of a 64-bit value.
+ * @_v: A 64-bit value.
+ * Returns floor(log2(_v))+1, or 0 if _v==0.
+ * This is the number of bits that would be required to represent _v in two's
+ *  complement notation with all of the leading zeros stripped.
+ * Note that many uses will resolve to the fast macro version instead.
+ * See Also:
+ *	ilog64_nz(), ilog32()
+ */
+int ilog64(uint64_t _v) IDEMPOTENT;
+
+/**
+ * ilog64_nz - Integer binary logarithm of a non-zero 64-bit value.
+ * @_v: A 64-bit value.
+ * Returns floor(log2(_v))+1, or undefined if _v==0.
+ * This is the number of bits that would be required to represent _v in two's
+ *  complement notation with all of the leading zeros stripped.
+ * Note that many uses will resolve to the fast macro version instead.
+ * See Also:
+ *	ilog64(), ilog32_nz()
+ */
+int ilog64_nz(uint64_t _v) IDEMPOTENT;
+
+/**
+ * STATIC_ILOG_32 - The integer logarithm of an (unsigned, 32-bit) constant.
+ * @_v: A non-negative 32-bit constant.
+ * Returns floor(log2(_v))+1, or 0 if _v==0.
+ * This is the number of bits that would be required to represent _v in two's
+ *  complement notation with all of the leading zeros stripped.
+ * This macro should only be used when you need a compile-time constant,
+ * otherwise ilog32 or ilog32_nz are just as fast and more flexible.
+ *
+ * Example:
+ *	#define MY_PAGE_SIZE	4096
+ *	#define MY_PAGE_BITS	(STATIC_ILOG_32(PAGE_SIZE) - 1)
+ */
+#define STATIC_ILOG_32(_v) (STATIC_ILOG5((uint32_t)(_v)))
+
+/**
+ * STATIC_ILOG_64 - The integer logarithm of an (unsigned, 64-bit) constant.
+ * @_v: A non-negative 64-bit constant.
+ * Returns floor(log2(_v))+1, or 0 if _v==0.
+ * This is the number of bits that would be required to represent _v in two's
+ *  complement notation with all of the leading zeros stripped.
+ * This macro should only be used when you need a compile-time constant,
+ * otherwise ilog64 or ilog64_nz are just as fast and more flexible.
+ */
+#define STATIC_ILOG_64(_v) (STATIC_ILOG6((uint64_t)(_v)))
+
+/* Private implementation details */
+
+/*Note the casts to (int) below: this prevents "upgrading"
+   the type of an entire expression to an (unsigned) size_t.*/
+#if INT_MAX>=2147483647 && HAVE_BUILTIN_CLZ
+#define builtin_ilog32_nz(v) \
+	(((int)sizeof(unsigned)*CHAR_BIT) - __builtin_clz(v))
+#elif LONG_MAX>=2147483647L && HAVE_BUILTIN_CLZL
+#define builtin_ilog32_nz(v) \
+	(((int)sizeof(unsigned)*CHAR_BIT) - __builtin_clzl(v))
+#endif
+
+#if INT_MAX>=9223372036854775807LL && HAVE_BUILTIN_CLZ
+#define builtin_ilog64_nz(v) \
+	(((int)sizeof(unsigned)*CHAR_BIT) - __builtin_clz(v))
+#elif LONG_MAX>=9223372036854775807LL && HAVE_BUILTIN_CLZL
+#define builtin_ilog64_nz(v) \
+	(((int)sizeof(unsigned long)*CHAR_BIT) - __builtin_clzl(v))
+#elif HAVE_BUILTIN_CLZLL
+#define builtin_ilog64_nz(v) \
+	(((int)sizeof(unsigned long long)*CHAR_BIT) - __builtin_clzll(v))
+#endif
+
+#ifdef builtin_ilog32_nz
+#define ilog32(_v) (builtin_ilog32_nz(_v)&-!!(_v))
+#define ilog32_nz(_v) builtin_ilog32_nz(_v)
+#else
+#define ilog32_nz(_v) ilog32(_v)
+#define ilog32(_v) (IS_COMPILE_CONSTANT(_v) ? STATIC_ILOG_32(_v) : ilog32(_v))
+#endif /* builtin_ilog32_nz */
+
+#ifdef builtin_ilog64_nz
+#define ilog64(_v) (builtin_ilog64_nz(_v)&-!!(_v))
+#define ilog64_nz(_v) builtin_ilog64_nz(_v)
+#else
+#define ilog64_nz(_v) ilog64(_v)
+#define ilog64(_v) (IS_COMPILE_CONSTANT(_v) ? STATIC_ILOG_64(_v) : ilog64(_v))
+#endif /* builtin_ilog64_nz */
+
+/* Macros for evaluating compile-time constant ilog. */
+# define STATIC_ILOG0(_v) (!!(_v))
+# define STATIC_ILOG1(_v) (((_v)&0x2)?2:STATIC_ILOG0(_v))
+# define STATIC_ILOG2(_v) (((_v)&0xC)?2+STATIC_ILOG1((_v)>>2):STATIC_ILOG1(_v))
+# define STATIC_ILOG3(_v) \
+ (((_v)&0xF0)?4+STATIC_ILOG2((_v)>>4):STATIC_ILOG2(_v))
+# define STATIC_ILOG4(_v) \
+ (((_v)&0xFF00)?8+STATIC_ILOG3((_v)>>8):STATIC_ILOG3(_v))
+# define STATIC_ILOG5(_v) \
+ (((_v)&0xFFFF0000)?16+STATIC_ILOG4((_v)>>16):STATIC_ILOG4(_v))
+# define STATIC_ILOG6(_v) \
+ (((_v)&0xFFFFFFFF00000000ULL)?32+STATIC_ILOG5((_v)>>32):STATIC_ILOG5(_v))
+
+#endif /* _ilog_H */