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l---------ccan/ccan/ilog/LICENSE1
-rw-r--r--ccan/ccan/ilog/ilog.c141
-rw-r--r--ccan/ccan/ilog/ilog.h154
3 files changed, 296 insertions, 0 deletions
diff --git a/ccan/ccan/ilog/LICENSE b/ccan/ccan/ilog/LICENSE
new file mode 120000
index 0000000..b7951da
--- /dev/null
+++ b/ccan/ccan/ilog/LICENSE
@@ -0,0 +1 @@
+../../licenses/CC0 \ No newline at end of file
diff --git a/ccan/ccan/ilog/ilog.c b/ccan/ccan/ilog/ilog.c
new file mode 100644
index 0000000..5f5122d
--- /dev/null
+++ b/ccan/ccan/ilog/ilog.c
@@ -0,0 +1,141 @@
+/*(C) Timothy B. Terriberry (tterribe@xiph.org) 2001-2009 CC0 (Public domain).
+ * See LICENSE file for details. */
+#include "ilog.h"
+#include <limits.h>
+
+/*The fastest fallback strategy for platforms with fast multiplication appears
+ to be based on de Bruijn sequences~\cite{LP98}.
+ Tests confirmed this to be true even on an ARM11, where it is actually faster
+ than using the native clz instruction.
+ Define ILOG_NODEBRUIJN to use a simpler fallback on platforms where
+ multiplication or table lookups are too expensive.
+
+ @UNPUBLISHED{LP98,
+ author="Charles E. Leiserson and Harald Prokop",
+ title="Using de {Bruijn} Sequences to Index a 1 in a Computer Word",
+ month=Jun,
+ year=1998,
+ note="\url{http://supertech.csail.mit.edu/papers/debruijn.pdf}"
+ }*/
+static UNNEEDED const unsigned char DEBRUIJN_IDX32[32]={
+ 0, 1,28, 2,29,14,24, 3,30,22,20,15,25,17, 4, 8,
+ 31,27,13,23,21,19,16, 7,26,12,18, 6,11, 5,10, 9
+};
+
+/* We always compile these in, in case someone takes address of function. */
+#undef ilog32_nz
+#undef ilog32
+#undef ilog64_nz
+#undef ilog64
+
+int ilog32(uint32_t _v){
+/*On a Pentium M, this branchless version tested as the fastest version without
+ multiplications on 1,000,000,000 random 32-bit integers, edging out a
+ similar version with branches, and a 256-entry LUT version.*/
+# if defined(ILOG_NODEBRUIJN)
+ int ret;
+ int m;
+ ret=_v>0;
+ m=(_v>0xFFFFU)<<4;
+ _v>>=m;
+ ret|=m;
+ m=(_v>0xFFU)<<3;
+ _v>>=m;
+ ret|=m;
+ m=(_v>0xFU)<<2;
+ _v>>=m;
+ ret|=m;
+ m=(_v>3)<<1;
+ _v>>=m;
+ ret|=m;
+ ret+=_v>1;
+ return ret;
+/*This de Bruijn sequence version is faster if you have a fast multiplier.*/
+# else
+ int ret;
+ ret=_v>0;
+ _v|=_v>>1;
+ _v|=_v>>2;
+ _v|=_v>>4;
+ _v|=_v>>8;
+ _v|=_v>>16;
+ _v=(_v>>1)+1;
+ ret+=DEBRUIJN_IDX32[_v*0x77CB531U>>27&0x1F];
+ return ret;
+# endif
+}
+
+int ilog32_nz(uint32_t _v)
+{
+ return ilog32(_v);
+}
+
+int ilog64(uint64_t _v){
+# if defined(ILOG_NODEBRUIJN)
+ uint32_t v;
+ int ret;
+ int m;
+ ret=_v>0;
+ m=(_v>0xFFFFFFFFU)<<5;
+ v=(uint32_t)(_v>>m);
+ ret|=m;
+ m=(v>0xFFFFU)<<4;
+ v>>=m;
+ ret|=m;
+ m=(v>0xFFU)<<3;
+ v>>=m;
+ ret|=m;
+ m=(v>0xFU)<<2;
+ v>>=m;
+ ret|=m;
+ m=(v>3)<<1;
+ v>>=m;
+ ret|=m;
+ ret+=v>1;
+ return ret;
+# else
+/*If we don't have a 64-bit word, split it into two 32-bit halves.*/
+# if LONG_MAX<9223372036854775807LL
+ uint32_t v;
+ int ret;
+ int m;
+ ret=_v>0;
+ m=(_v>0xFFFFFFFFU)<<5;
+ v=(uint32_t)(_v>>m);
+ ret|=m;
+ v|=v>>1;
+ v|=v>>2;
+ v|=v>>4;
+ v|=v>>8;
+ v|=v>>16;
+ v=(v>>1)+1;
+ ret+=DEBRUIJN_IDX32[v*0x77CB531U>>27&0x1F];
+ return ret;
+/*Otherwise do it in one 64-bit operation.*/
+# else
+ static const unsigned char DEBRUIJN_IDX64[64]={
+ 0, 1, 2, 7, 3,13, 8,19, 4,25,14,28, 9,34,20,40,
+ 5,17,26,38,15,46,29,48,10,31,35,54,21,50,41,57,
+ 63, 6,12,18,24,27,33,39,16,37,45,47,30,53,49,56,
+ 62,11,23,32,36,44,52,55,61,22,43,51,60,42,59,58
+ };
+ int ret;
+ ret=_v>0;
+ _v|=_v>>1;
+ _v|=_v>>2;
+ _v|=_v>>4;
+ _v|=_v>>8;
+ _v|=_v>>16;
+ _v|=_v>>32;
+ _v=(_v>>1)+1;
+ ret+=DEBRUIJN_IDX64[_v*0x218A392CD3D5DBF>>58&0x3F];
+ return ret;
+# endif
+# endif
+}
+
+int ilog64_nz(uint64_t _v)
+{
+ return ilog64(_v);
+}
+
diff --git a/ccan/ccan/ilog/ilog.h b/ccan/ccan/ilog/ilog.h
new file mode 100644
index 0000000..32702b1
--- /dev/null
+++ b/ccan/ccan/ilog/ilog.h
@@ -0,0 +1,154 @@
+/* CC0 (Public domain) - see LICENSE file for details */
+#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) CONST_FUNCTION;
+
+/**
+ * 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) CONST_FUNCTION;
+
+/**
+ * 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) CONST_FUNCTION;
+
+/**
+ * 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) CONST_FUNCTION;
+
+/**
+ * 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
+/* This used to be builtin_ilog32_nz(_v)&-!!(_v), which means it zeroes out
+ * the undefined builtin_ilog32_nz(0) return. But clang UndefinedBehaviorSantizer
+ * complains, so do the branch: */
+#define ilog32(_v) ((_v) ? builtin_ilog32_nz(_v) : 0)
+#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 ilog32(_v) ((_v) ? builtin_ilog32_nz(_v) : 0)
+#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 */
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