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Emulate _BitScanReverse64 for 32 bits builds

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This commit is contained in:
Gael Guennebaud 2016-07-11 11:38:04 +02:00
parent ef05463fcf
commit 18c35747ce
1 changed files with 14 additions and 2 deletions
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16
unsupported/Eigen/CXX11/src/Tensor/TensorIntDiv.h
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@ -53,10 +53,20 @@ namespace {
{
#ifdef __CUDA_ARCH__
return __clzll(val);
#elif EIGEN_COMP_MSVC
#elif EIGEN_COMP_MSVC && EIGEN_ARCH_x86_64
unsigned long index;
_BitScanReverse64(&index, val);
return 63 - index;
#elif EIGEN_COMP_MSVC
// MSVC's _BitScanReverse64 is not available for 32bits builds.
unsigned int lo = (unsigned int)(val&0xffffffff);
unsigned int hi = (unsigned int)((val>>32)&0xffffffff);
int n;
if(hi==0)
n = 32 + count_leading_zeros<unsigned int>(lo);
else
n = count_leading_zeros<unsigned int>(hi);
return n;
#else
EIGEN_STATIC_ASSERT(sizeof(unsigned long long) == 8, YOU_MADE_A_PROGRAMMING_MISTAKE);
return __builtin_clzll(static_cast<uint64_t>(val));
@ -110,7 +120,9 @@ namespace {
return static_cast<uint64_t>((static_cast<__uint128_t>(1) << (64+log_div)) / static_cast<__uint128_t>(divider) - (static_cast<__uint128_t>(1) << 64) + 1);
#else
const uint64_t shift = 1ULL << log_div;
TensorUInt128<uint64_t, uint64_t> result = (TensorUInt128<uint64_t, static_val<0> >(shift, 0) / TensorUInt128<static_val<0>, uint64_t>(divider) - TensorUInt128<static_val<1>, static_val<0> >(1, 0) + TensorUInt128<static_val<0>, static_val<1> >(1));
TensorUInt128<uint64_t, uint64_t> result = TensorUInt128<uint64_t, static_val<0> >(shift, 0) / TensorUInt128<static_val<0>, uint64_t>(divider)
- TensorUInt128<static_val<1>, static_val<0> >(1, 0)
+ TensorUInt128<static_val<0>, static_val<1> >(1);
return static_cast<uint64_t>(result);
#endif
}