source/lib/alignment.h

   1 /* Copyright (C) 2021 Wildfire Games.
   2  *
   3  * Permission is hereby granted, free of charge, to any person obtaining
   4  * a copy of this software and associated documentation files (the
   5  * "Software"), to deal in the Software without restriction, including
   6  * without limitation the rights to use, copy, modify, merge, publish,
   7  * distribute, sublicense, and/or sell copies of the Software, and to
   8  * permit persons to whom the Software is furnished to do so, subject to
   9  * the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included
  12  * in all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  15  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  16  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  17  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  18  * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  19  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  20  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  21  */
  22
  23 #ifndef INCLUDED_ALIGNMENT
  24 #define INCLUDED_ALIGNMENT
  25
  26 #include "lib/sysdep/compiler.h"        // MSC_VERSION
  27 #include "lib/sysdep/arch.h"    // ARCH_AMD64
  28
  29 template<typename T>
  30 inline bool IsAligned(T t, uintptr_t multiple)
  31 {
  32         return (uintptr_t(t) % multiple) == 0;
  33 }
  34
  35 template<size_t multiple>
  36 inline size_t Align(size_t n)
  37 {
  38         cassert(multiple != 0 && ((multiple & (multiple-1)) == 0));     // is power of 2
  39         return (n + multiple-1) & ~(multiple-1);
  40 }
  41
  42
  43 // bridge the differences between MSC and GCC alignment definitions.
  44 // example: ALIGNED(int, 8) myAlignedVariable = 0;
  45 #if MSC_VERSION
  46 # define ALIGNED(type, multiple) __declspec(align(multiple)) type
  47 #elif GCC_VERSION
  48 # define ALIGNED(type, multiple) type __attribute__((aligned(multiple)))
  49 #else
  50 # define ALIGNED(type, multiple) type
  51 #endif
  52
  53
  54 //
  55 // SIMD vector
  56 //
  57
  58 static const size_t vectorSize = 16;
  59 #define VECTOR_ALIGNED(type) ALIGNED(type, 16)  // ALIGNED() requires a literal; keep in sync with vectorSize
  60
  61 #define ASSERT_VECTOR_MULTIPLE(size)\
  62         ASSERT(IsAligned(size, vectorSize))
  63
  64 #define ASSERT_VECTOR_ALIGNED(pointer)\
  65         ASSERT_VECTOR_MULTIPLE(pointer);\
  66         ASSUME_ALIGNED(pointer, vectorSize)
  67
  68
  69 //
  70 // CPU cache
  71 //
  72
  73 static const size_t cacheLineSize = 64; // (L2)
  74 #define CACHE_ALIGNED(type) ALIGNED(type, 64)   // ALIGNED() requires a literal; keep in sync with cacheLineSize
  75
  76
  77
  78
  79 //
  80 // MMU pages
  81 //
  82
  83 #ifdef ARCH_PPC64
  84 // NOTE: ppc64 can operate in either 4k or 64k page size mode
  85 // If the define page size is larger than the active page size,
  86 // the allocator functions normally.  If the defined page size
  87 // is less than the active page size, the allocator fails tests.
  88 //
  89 // Define the page size to the maximum known architectural page
  90 // size on ppc64 systems.
  91 static const size_t g_PageSize = 64 * 1024;     // 64 KB
  92 #else
  93 static const size_t g_PageSize = 4 * 1024;      // 4 KB
  94 #endif
  95 static const size_t g_LargePageSize = 2 * 1024 * 1024;  // 2 MB
  96
  97
  98 //
  99 // misc
 100 //
 101
 102 static const size_t allocationAlignment = 16;
 103
 104 static const size_t KiB = size_t(1) << 10;
 105 static const size_t MiB = size_t(1) << 20;
 106 static const size_t GiB = size_t(1) << 30;
 107
 108 // waio opens files with FILE_FLAG_NO_BUFFERING, so Windows requires
 109 // file offsets / buffers and sizes to be sector-aligned. querying the
 110 // actual sector size via GetDiskFreeSpace is inconvenient and slow.
 111 // we always request large blocks anyway, so just check whether inputs
 112 // are aligned to a `maximum' sector size. this catches common mistakes
 113 // before they cause scary "IO failed" errors. if the value turns out
 114 // to be too low, the Windows APIs will still complain.
 115 static const uintptr_t maxSectorSize = 0x1000;
 116
 117 #endif  // #ifndef INCLUDED_ALIGNMENT