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Gets in sync with tommy library.

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This commit is contained in:
Andrea Mazzoleni 2013-06-22 23:56:19 +02:00
parent 1b0a38f924
commit 80e3cc4d4f
1 changed files with 10 additions and 15 deletions
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25
tommytypes.h
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@ -84,26 +84,13 @@ typedef int tommy_bool_t; /**< Generic boolean type. */
* Definition of the inline keyword if available.
*/
#if !defined(tommy_inline)
#if __STDC_VERSION__ >= 199901L || defined(__cplusplus)
#define tommy_inline inline
#elif defined(_MSC_VER) || defined(__GNUC__)
#if defined(_MSC_VER) || defined(__GNUC__)
#define tommy_inline static __inline
#else
#define tommy_inline static
#endif
#endif
/** \internal
* Definition of the always_inline keyword if available.
*/
#if !defined(tommy_always_inline)
#if defined(__GNUC__)
#define tommy_always_inline static __attribute__((always_inline)) __inline
#else
#define tommy_always_inline tommy_inline
#endif
#endif
/** \internal
* Definition of the restrict keyword if available.
*/
@ -253,7 +240,15 @@ tommy_inline unsigned tommy_ilog2_u32(tommy_uint32_t value)
_BitScanReverse(&count, value);
return count;
#elif defined(__GNUC__)
return 31 - __builtin_clz(value);
/*
* GCC implements __builtin_clz(x) as "__builtin_clz(x) = bsr(x) ^ 31"
*
* Where "x ^ 31 = 31 - x", but gcc does not optimize "31 - __builtin_clz(x)" to bsr(x),
* but generates 31 - (bsr(x) xor 31).
*
* So we write "__builtin_clz(x) ^ 31" instead of "31 - __builtin_clz(x)".
*/
return __builtin_clz(value) ^ 31;
#else
/* Find the log base 2 of an N-bit integer in O(lg(N)) operations with multiply and lookup */
/* from http://graphics.stanford.edu/~seander/bithacks.html */