vpx_ports/mem.h

   1 /*
   2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11
  12 #ifndef VPX_PORTS_MEM_H
  13 #define VPX_PORTS_MEM_H
  14 #include "vpx_config.h"
  15 #include "vpx/vpx_integer.h"
  16
  17 #if defined(__GNUC__) && __GNUC__
  18 #define DECLARE_ALIGNED(n,typ,val)  typ val __attribute__ ((aligned (n)))
  19 #elif defined(_MSC_VER)
  20 #define DECLARE_ALIGNED(n,typ,val)  __declspec(align(n)) typ val
  21 #else
  22 #warning No alignment directives known for this compiler.
  23 #define DECLARE_ALIGNED(n,typ,val)  typ val
  24 #endif
  25 #endif
  26
  27
  28 /* Declare an aligned array on the stack, for situations where the stack
  29  * pointer may not have the alignment we expect. Creates an array with a
  30  * modified name, then defines val to be a pointer, and aligns that pointer
  31  * within the array.
  32  */
  33 #define DECLARE_ALIGNED_ARRAY(a,typ,val,n)\
  34 typ val##_[(n)+(a)/sizeof(typ)+1];\
  35 typ *val = (typ*)((((intptr_t)val##_)+(a)-1)&((intptr_t)-(a)))
  36
  37
  38 /* Indicates that the usage of the specified variable has been audited to assure
  39  * that it's safe to use uninitialized. Silences 'may be used uninitialized'
  40  * warnings on gcc.
  41  */
  42 #if defined(__GNUC__) && __GNUC__
  43 #define UNINITIALIZED_IS_SAFE(x) x=x
  44 #else
  45 #define UNINITIALIZED_IS_SAFE(x) x
  46 #endif