Initial checkin of gRPC to third_party/

third_party/grpc/include/grpc/support/useful.h

Index: third_party/grpc/include/grpc/support/useful.h
diff --git a/third_party/grpc/include/grpc/support/useful.h b/third_party/grpc/include/grpc/support/useful.h
new file mode 100644
index 0000000000000000000000000000000000000000..a0e76da29efa1ea35c53754f8cc8fb357a487575
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+++ b/third_party/grpc/include/grpc/support/useful.h
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+/*
+ *
+ * Copyright 2015-2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_SUPPORT_USEFUL_H
+#define GRPC_SUPPORT_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))
+
+#endif /* GRPC_SUPPORT_USEFUL_H */