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fixing bug related to using the hamming distance on descriptors whose length is not divisible by sizeof(size_t).

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This commit is contained in:
Ethan Rublee 2011-01-20 02:36:46 +00:00
parent c987b9f180
commit 1e1a139270
1 changed files with 21 additions and 5 deletions
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26
modules/features2d/src/brief.cpp
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@ -49,6 +49,9 @@
#include <arm_neon.h>
#endif
#include <iostream>
#include <iomanip>
using namespace cv;
inline int smoothedSum(const Mat& sum, const KeyPoint& pt, int y, int x)
@ -116,7 +119,7 @@ Hamming::ResultType Hamming::operator()(const unsigned char* a, const unsigned c
static uint64_t features = android_getCpuFeatures();
if ((features & ANDROID_CPU_ARM_FEATURE_NEON))
{
for (int i = 0; i < size; i += 16)
for (size_t i = 0; i < size; i += 16)
{
uint8x16_t A_vec = vld1q_u8 (a + i);
uint8x16_t B_vec = vld1q_u8 (b + i);
@ -134,13 +137,26 @@ Hamming::ResultType Hamming::operator()(const unsigned char* a, const unsigned c
}
}
else
#endif
for (int i = 0; i < size; i += sizeof(unsigned long))
#endif
size_t i;
const size_t modulo = size % sizeof(size_t);
const size_t end = size - modulo;
for (i = 0; i < end; i += sizeof(size_t))
{
unsigned long a2 = *reinterpret_cast<const unsigned long*> (a + i);
unsigned long b2 = *reinterpret_cast<const unsigned long*> (b + i);
size_t a2 = *reinterpret_cast<const size_t*> (a + i);
size_t b2 = *reinterpret_cast<const size_t*> (b + i);
result += __builtin_popcountl(a2 ^ b2);
}
if (modulo)
{
//in the case where size is not divisible by sizeof(size_t)
//need to mask of the bits at the end
size_t a2=0,b2=0;
memcpy(&a2,a+end,modulo);
memcpy(&b2,b+end,modulo);
//std::cout << std::hex << (a2^b2) << std::endl;
result += __builtin_popcountl(a2 ^ b2);
}
return result;
#else
return HammingLUT()(a,b,size);