grpc/include/grpc/support/useful.h

/*
 *
 * Copyright 2015, 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:
 *
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 * 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.
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 * 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
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 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 */

#ifndef GRPC_SUPPORT_USEFUL_H
#define GRPC_SUPPORT_USEFUL_H

#include <grpc/support/port_platform.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)

/** Returns number of bits set in bitset \a i */
int gpr_bitcount(gpr_uint32 i) {
  i = i - ((i >> 1) & 0x55555555);
  i = (i & 0x33333333) + ((i >> 2) & 0x33333333);
  return (((i + (i >> 4)) & 0xF0F0F0F) * 0x1010101) >> 24;
}

#endif  /* GRPC_SUPPORT_USEFUL_H */