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diff --git a/src/core/lib/gpr/useful.h b/src/core/lib/gpr/useful.h
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+++ b/src/core/lib/gpr/useful.h
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+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_GPR_USEFUL_H
+#define GRPC_CORE_LIB_GPR_USEFUL_H
+
+/** useful macros that don't belong anywhere else */
+
+#define GPR_MIN(a, b) ((a) < (b) ? (a) : (b))
+#define GPR_MAX(a, b) ((a) > (b) ? (a) : (b))
+#define GPR_CLAMP(a, min, max) ((a) < (min) ? (min) : (a) > (max) ? (max) : (a))
+/** rotl, rotr assume x is unsigned */
+#define GPR_ROTL(x, n) (((x) << (n)) | ((x) >> (sizeof(x) * 8 - (n))))
+#define GPR_ROTR(x, n) (((x) >> (n)) | ((x) << (sizeof(x) * 8 - (n))))
+
+#define GPR_ARRAY_SIZE(array) (sizeof(array) / sizeof(*(array)))
+
+#define GPR_SWAP(type, a, b) \
+  do {                       \
+    type x = a;              \
+    a = b;                   \
+    b = x;                   \
+  } while (0)
+
+/** Set the \a n-th bit of \a i (a mutable pointer). */
+#define GPR_BITSET(i, n) ((*(i)) |= (1u << (n)))
+
+/** Clear the \a n-th bit of \a i (a mutable pointer). */
+#define GPR_BITCLEAR(i, n) ((*(i)) &= ~(1u << (n)))
+
+/** Get the \a n-th bit of \a i */
+#define GPR_BITGET(i, n) (((i) & (1u << (n))) != 0)
+
+#define GPR_INTERNAL_HEXDIGIT_BITCOUNT(x)                        \
+  ((x) - (((x) >> 1) & 0x77777777) - (((x) >> 2) & 0x33333333) - \
+   (((x) >> 3) & 0x11111111))
+
+/** Returns number of bits set in bitset \a i */
+#define GPR_BITCOUNT(i)                          \
+  (((GPR_INTERNAL_HEXDIGIT_BITCOUNT(i) +         \
+     (GPR_INTERNAL_HEXDIGIT_BITCOUNT(i) >> 4)) & \
+    0x0f0f0f0f) %                                \
+   255)
+
+#define GPR_ICMP(a, b) ((a) < (b) ? -1 : ((a) > (b) ? 1 : 0))
+
+#define GPR_HASH_POINTER(x, range) \
+  ((((size_t)x) >> 4) ^ (((size_t)x) >> 9) ^ (((size_t)x) >> 14)) % (range)
+
+#endif /* GRPC_CORE_LIB_GPR_USEFUL_H */