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#include "tensorflow/core/lib/hash/hash.h"
#include "tensorflow/core/platform/port.h"
#include "tensorflow/core/lib/core/raw_coding.h"
#include <string.h>
namespace tensorflow {
// 0xff is in case char is signed.
static inline uint32 ByteAs32(char c) { return static_cast<uint32>(c) & 0xff; }
static inline uint64 ByteAs64(char c) { return static_cast<uint64>(c) & 0xff; }
uint32 Hash32(const char* data, size_t n, uint32 seed) {
// 'm' and 'r' are mixing constants generated offline.
// They're not really 'magic', they just happen to work well.
const uint32 m = 0x5bd1e995;
const int r = 24;
// Initialize the hash to a 'random' value
uint32 h = seed ^ n;
// Mix 4 bytes at a time into the hash
while (n >= 4) {
uint32 k = core::DecodeFixed32(data);
k *= m;
k ^= k >> r;
k *= m;
h *= m;
h ^= k;
data += 4;
n -= 4;
}
// Handle the last few bytes of the input array
switch (n) {
case 3:
h ^= ByteAs32(data[2]) << 16;
TF_FALLTHROUGH_INTENDED;
case 2:
h ^= ByteAs32(data[1]) << 8;
TF_FALLTHROUGH_INTENDED;
case 1:
h ^= ByteAs32(data[0]);
h *= m;
}
// Do a few final mixes of the hash to ensure the last few
// bytes are well-incorporated.
h ^= h >> 13;
h *= m;
h ^= h >> 15;
return h;
}
uint64 Hash64(const char* data, size_t n, uint64 seed) {
const uint64 m = 0xc6a4a7935bd1e995;
const int r = 47;
uint64 h = seed ^ (n * m);
while (n >= 8) {
uint64 k = core::DecodeFixed64(data);
data += 8;
n -= 8;
k *= m;
k ^= k >> r;
k *= m;
h ^= k;
h *= m;
}
switch (n) {
case 7:
h ^= ByteAs64(data[6]) << 48;
TF_FALLTHROUGH_INTENDED;
case 6:
h ^= ByteAs64(data[5]) << 40;
TF_FALLTHROUGH_INTENDED;
case 5:
h ^= ByteAs64(data[4]) << 32;
TF_FALLTHROUGH_INTENDED;
case 4:
h ^= ByteAs64(data[3]) << 24;
TF_FALLTHROUGH_INTENDED;
case 3:
h ^= ByteAs64(data[2]) << 16;
TF_FALLTHROUGH_INTENDED;
case 2:
h ^= ByteAs64(data[1]) << 8;
TF_FALLTHROUGH_INTENDED;
case 1:
h ^= ByteAs64(data[0]);
h *= m;
}
h ^= h >> r;
h *= m;
h ^= h >> r;
return h;
}
} // namespace tensorflow
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