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avutil/x86/intmath: Use tzcnt in place of bsf.

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Signed-off-by: Matt Oliver <protogonoi@gmail.com>
This commit is contained in:
Matt Oliver 2015-10-28 18:47:16 +11:00
parent e82883aa88
commit 6c6ac9cb17
1 changed files with 15 additions and 39 deletions
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42
libavutil/x86/intmath.h
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@ -25,55 +25,31 @@
#include "config.h"
#if HAVE_FAST_CLZ
#if defined(__INTEL_COMPILER) || defined(_MSC_VER)
# if defined(__INTEL_COMPILER)
# define ff_log2(x) (_bit_scan_reverse((x)|1))
# define ff_log2_16bit av_log2
# define ff_ctz(v) _bit_scan_forward(v)
# define ff_ctzll ff_ctzll_x86
static av_always_inline av_const int ff_ctzll_x86(long long v)
{
# if ARCH_X86_64
uint64_t c;
__asm__("bsfq %1,%0" : "=r" (c) : "r" (v));
return c;
# else
return ((uint32_t)v == 0) ? _bit_scan_forward((uint32_t)(v >> 32)) + 32 : _bit_scan_forward((uint32_t)v);
# endif
}
#elif defined(_MSC_VER)
# define ff_log2 ff_log2_x86
static av_always_inline av_const int ff_log2_x86(unsigned int v) {
static av_always_inline av_const int ff_log2_x86(unsigned int v)
{
unsigned long n;
_BitScanReverse(&n, v|1);
return n;
}
# endif
# define ff_log2_16bit av_log2
# define ff_ctz ff_ctz_x86
static av_always_inline av_const int ff_ctz_x86(int v) {
unsigned long c;
_BitScanForward(&c, v);
return c;
}
# define ff_ctz(v) _tzcnt_u32(v)
# if ARCH_X86_64
# define ff_ctzll(v) _tzcnt_u64(v)
# else
# define ff_ctzll ff_ctzll_x86
static av_always_inline av_const int ff_ctzll_x86(long long v)
{
unsigned long c;
# if ARCH_X86_64
_BitScanForward64(&c, v);
# else
if ((uint32_t)v == 0) {
_BitScanForward(&c, (uint32_t)(v >> 32));
c += 32;
} else {
_BitScanForward(&c, (uint32_t)v);
return ((uint32_t)v == 0) ? _tzcnt_u32((uint32_t)(v >> 32)) + 32 : _tzcnt_u32((uint32_t)v);
}
# endif
return c;
}
#endif /* __INTEL_COMPILER */