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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