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/* go-type-identity.c -- hash and equality identity functions.

   Copyright 2009 The Go Authors. All rights reserved.

   Use of this source code is governed by a BSD-style

   license that can be found in the LICENSE file.  */

#include <stddef.h>

#include "go-type.h"

/* The 64-bit type.  */

typedef unsigned int DItype __attribute__ ((mode (DI)));

/* An identity hash function for a type.  This is used for types where

   we can simply use the type value itself as a hash code.  This is

   true of, e.g., integers and pointers.  */

uintptr_t

__go_type_hash_identity (const void *key, uintptr_t key_size)

{

  uintptr_t ret;

  uintptr_t i;

  const unsigned char *p;

  if (key_size <= 8)

    {

      union

      {

        DItype v;

        unsigned char a[8];

      } u;

      u.v = 0;

      __builtin_memcpy (&u.a, key, key_size);

      if (sizeof (uintptr_t) >= 8)

        return (uintptr_t) u.v;

      else

        return (uintptr_t) ((u.v >> 32) ^ (u.v & 0xffffffff));

    }

  ret = 5381;

  for (i = 0, p = (const unsigned char *) key; i < key_size; i++, p++)

    ret = ret * 33 + *p;

  return ret;

}

/* An identity equality function for a type.  This is used for types

   where we can check for equality by checking that the values have

   the same bits.  */

_Bool

__go_type_equal_identity (const void *k1, const void *k2, uintptr_t key_size)

{

  return __builtin_memcmp (k1, k2, key_size) == 0;

}