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#include <vector>
#include <algorithm>
#include <stdint.h>
/* fingerprint matcher settings */
#define ACOUSTID_MAX_BIT_ERROR 2
#define ACOUSTID_MAX_ALIGN_OFFSET 120
#define BITCOUNT(x) __builtin_popcount(x)
inline float
match_fingerprints(const std::vector<int32_t> &a, const std::vector<int32_t> &b)
{
int i, j, topcount;
int maxsize = std::max(a.size(), b.size());
int numcounts = maxsize * 2 + 1;
int *counts = (int*)malloc(sizeof(int) * numcounts);
memset(counts, 0, sizeof(int) * numcounts);
for (i = 0; i < a.size(); i++) {
int jbegin = std::max(0, i - ACOUSTID_MAX_ALIGN_OFFSET);
int jend = std::min(b.size(), size_t(i + ACOUSTID_MAX_ALIGN_OFFSET));
for (j = jbegin; j < jend; j++) {
int biterror = BITCOUNT(a[i] ^ b[j]);
if (biterror <= ACOUSTID_MAX_BIT_ERROR) {
int offset = i - j + maxsize;
counts[offset]++;
}
}
}
topcount = 0;
for (i = 0; i < numcounts; i++) {
if (counts[i] > topcount) {
topcount = counts[i];
}
}
free(counts);
return (float)topcount / std::min(a.size(), b.size());
}
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