1 files changed, 113 insertions, 0 deletions
diff --git a/tensorflow/core/lib/hash/hash.cc b/tensorflow/core/lib/hash/hash.cc
new file mode 100644
index 0000000000..075d252412
--- /dev/null
+++ b/tensorflow/core/lib/hash/hash.cc
@@ -0,0 +1,113 @@
+#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