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  1. /**************************************************************************
  2.  *
  3.  * Copyright 2008-2010 VMware, Inc.
  4.  * All Rights Reserved.
  5.  *
  6.  * Permission is hereby granted, free of charge, to any person obtaining a
  7.  * copy of this software and associated documentation files (the
  8.  * "Software"), to deal in the Software without restriction, including
  9.  * without limitation the rights to use, copy, modify, merge, publish,
  10.  * distribute, sub license, and/or sell copies of the Software, and to
  11.  * permit persons to whom the Software is furnished to do so, subject to
  12.  * the following conditions:
  13.  *
  14.  * The above copyright notice and this permission notice (including the
  15.  * next paragraph) shall be included in all copies or substantial portions
  16.  * of the Software.
  17.  *
  18.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19.  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20.  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  21.  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
  22.  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  23.  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  24.  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25.  *
  26.  **************************************************************************/
  27.  
  28.  
  29. /*
  30.  * Memory alignment wrappers.
  31.  */
  32.  
  33.  
  34. #ifndef _OS_MEMORY_H_
  35. #error "Must not be included directly. Include os_memory.h instead"
  36. #endif
  37.  
  38.  
  39. #include "pipe/p_compiler.h"
  40.  
  41.  
  42.  
  43. /**
  44.  * Add two size_t values with integer overflow check.
  45.  * TODO: leverage __builtin_add_overflow where available
  46.  */
  47. static inline bool
  48. add_overflow_size_t(size_t a, size_t b, size_t *res)
  49. {
  50.    *res = a + b;
  51.    return *res < a || *res < b;
  52. }
  53.  
  54.  
  55. /**
  56.  * Return memory on given byte alignment
  57.  */
  58. static INLINE void *
  59. os_malloc_aligned(size_t size, size_t alignment)
  60. {
  61.    char *ptr, *buf;
  62.    size_t alloc_size;
  63.  
  64.    /*
  65.     * Calculate
  66.     *
  67.     *   alloc_size = size + alignment + sizeof(void *)
  68.     *
  69.     * while checking for overflow.
  70.     */
  71.    if (add_overflow_size_t(size, alignment, &alloc_size) ||
  72.        add_overflow_size_t(alloc_size, sizeof(void *), &alloc_size)) {
  73.       return NULL;
  74.    }
  75.  
  76.    ptr = (char *) os_malloc(alloc_size);
  77.    if (!ptr)
  78.       return NULL;
  79.  
  80.    buf = (char *)(((uintptr_t)ptr + sizeof(void *) + alignment - 1) & ~((uintptr_t)(alignment - 1)));
  81.    *(char **)(buf - sizeof(void *)) = ptr;
  82.  
  83.    return buf;
  84. }
  85.  
  86.  
  87. /**
  88.  * Free memory returned by align_malloc().
  89.  */
  90. static INLINE void
  91. os_free_aligned(void *ptr)
  92. {
  93.    if (ptr) {
  94.       void **cubbyHole = (void **) ((char *) ptr - sizeof(void *));
  95.       void *realAddr = *cubbyHole;
  96.       os_free(realAddr);
  97.    }
  98. }
  99.