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revert the hamming distance to use unsigned long, on 64bit machines, using size_t

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with __build_popcountl doesn't return correct number of bits. the ll version should work, but for simplicity,
locking it down to long for now.  TODO add a unit test for the Hamming distance.
This commit is contained in:
Ethan Rublee 2011-01-24 16:59:14 +00:00
parent 581018354f
commit a47b6c23f5
1 changed files with 7 additions and 4 deletions
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11
modules/features2d/src/brief.cpp
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@ -138,13 +138,16 @@ Hamming::ResultType Hamming::operator()(const unsigned char* a, const unsigned c
}
else
#endif
//for portability just use unsigned long -- and use the __builtin_popcountl (see docs for __builtin_popcountl)
//as opposed to size_t -- TODO smart switching, if the size_t is a 64bits, use __builtin_popcountll
typedef unsigned long pop_t;
size_t i;
const size_t modulo = size % sizeof(size_t);
const size_t modulo = size % sizeof(pop_t);
const size_t end = size - modulo;
for (i = 0; i < end; i += sizeof(size_t))
for (i = 0; i < end; i += sizeof(pop_t))
{
size_t a2 = *reinterpret_cast<const size_t*> (a + i);
size_t b2 = *reinterpret_cast<const size_t*> (b + i);
size_t a2 = *reinterpret_cast<const pop_t*> (a + i);
size_t b2 = *reinterpret_cast<const pop_t*> (b + i);
result += __builtin_popcountl(a2 ^ b2);
}
if (modulo)