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Use _BitScanReverse for EC_ILOG with MSVC.

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Also updates the TI dsplib macros to use the same EC_CLZ mechanism
 as everything else.
This commit is contained in:
Timothy B. Terriberry 2010-12-23 08:06:48 -08:00 • committed by Jean-Marc Valin
parent 1aaa50d1c1
commit df2c71ea5a
1 changed files with 22 additions and 12 deletions
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34
libcelt/ecintrin.h
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@ -83,17 +83,30 @@
/*Count leading zeros.
This macro should only be used for implementing ec_ilog(), if it is defined.
All other code should use EC_ILOG() instead.*/
#ifdef __GNUC_PREREQ
#if __GNUC_PREREQ(3,4)
# if INT_MAX>=2147483647
# define EC_CLZ0 sizeof(unsigned)*CHAR_BIT
# define EC_CLZ(_x) (__builtin_clz(_x))
# elif LONG_MAX>=2147483647L
# define EC_CLZ0 sizeof(unsigned long)*CHAR_BIT
# define EC_CLZ(_x) (__builtin_clzl(_x))
#if defined(_MSC_VER)
# include <intrin.h>
static __inline int ec_bsr(unsigned long _x){
unsigned long ret;
_BitScanReverse(&ret,_x);
return (int)ret;
}
# define EC_CLZ0 (1)
# define EC_CLZ(_x) (-ec_bsr(_x))
#elif defined(ENABLE_TI_DSPLIB)
# include "dsplib.h"
# define EC_CLZ0 (31)
# define EC_CLZ(_x) (_lnorm(x))
#elif defined(__GNUC_PREREQ)
# if __GNUC_PREREQ(3,4)
# if INT_MAX>=2147483647
# define EC_CLZ0 ((int)sizeof(unsigned)*CHAR_BIT)
# define EC_CLZ(_x) (__builtin_clz(_x))
# elif LONG_MAX>=2147483647L
# define EC_CLZ0 ((int)sizeof(unsigned long)*CHAR_BIT)
# define EC_CLZ(_x) (__builtin_clzl(_x))
# endif
# endif
#endif
#endif
#if defined(EC_CLZ)
/*Note that __builtin_clz is not defined when _x==0, according to the gcc
@ -101,9 +114,6 @@
The majority of the time we can never pass it zero.
When we need to, it can be special cased.*/
# define EC_ILOG(_x) (EC_CLZ0-EC_CLZ(_x))
#elif defined(ENABLE_TI_DSPLIB)
#include "dsplib.h"
#define EC_ILOG(x) (31 - _lnorm(x))
#else
# define EC_ILOG(_x) (ec_ilog(_x))
#endif