mfbt/tests/TestCeilingFloor.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/MathAlgorithms.h"
   8
   9 using mozilla::CeilingLog2;
  10 using mozilla::FloorLog2;
  11 using mozilla::RoundUpPow2;
  12
  13 static void
  14 TestCeiling()
  15 {
  16   for (uint32_t i = 0; i <= 1; i++) {
  17     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 0);
  18   }
  19   for (uint32_t i = 2; i <= 2; i++) {
  20     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 1);
  21   }
  22   for (uint32_t i = 3; i <= 4; i++) {
  23     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 2);
  24   }
  25   for (uint32_t i = 5; i <= 8; i++) {
  26     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 3);
  27   }
  28   for (uint32_t i = 9; i <= 16; i++) {
  29     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 4);
  30   }
  31 }
  32
  33 static void
  34 TestFloor()
  35 {
  36   for (uint32_t i = 0; i <= 1; i++) {
  37     MOZ_RELEASE_ASSERT(FloorLog2(i) == 0);
  38   }
  39   for (uint32_t i = 2; i <= 3; i++) {
  40     MOZ_RELEASE_ASSERT(FloorLog2(i) == 1);
  41   }
  42   for (uint32_t i = 4; i <= 7; i++) {
  43     MOZ_RELEASE_ASSERT(FloorLog2(i) == 2);
  44   }
  45   for (uint32_t i = 8; i <= 15; i++) {
  46     MOZ_RELEASE_ASSERT(FloorLog2(i) == 3);
  47   }
  48   for (uint32_t i = 16; i <= 31; i++) {
  49     MOZ_RELEASE_ASSERT(FloorLog2(i) == 4);
  50   }
  51 }
  52
  53 static void
  54 TestRoundUpPow2()
  55 {
  56   MOZ_RELEASE_ASSERT(RoundUpPow2(0) == 1);
  57   MOZ_RELEASE_ASSERT(RoundUpPow2(1) == 1);
  58   MOZ_RELEASE_ASSERT(RoundUpPow2(2) == 2);
  59   MOZ_RELEASE_ASSERT(RoundUpPow2(3) == 4);
  60   MOZ_RELEASE_ASSERT(RoundUpPow2(4) == 4);
  61   MOZ_RELEASE_ASSERT(RoundUpPow2(5) == 8);
  62   MOZ_RELEASE_ASSERT(RoundUpPow2(6) == 8);
  63   MOZ_RELEASE_ASSERT(RoundUpPow2(7) == 8);
  64   MOZ_RELEASE_ASSERT(RoundUpPow2(8) == 8);
  65   MOZ_RELEASE_ASSERT(RoundUpPow2(9) == 16);
  66
  67   MOZ_RELEASE_ASSERT(RoundUpPow2(15) == 16);
  68   MOZ_RELEASE_ASSERT(RoundUpPow2(16) == 16);
  69   MOZ_RELEASE_ASSERT(RoundUpPow2(17) == 32);
  70
  71   MOZ_RELEASE_ASSERT(RoundUpPow2(31) == 32);
  72   MOZ_RELEASE_ASSERT(RoundUpPow2(32) == 32);
  73   MOZ_RELEASE_ASSERT(RoundUpPow2(33) == 64);
  74
  75   size_t MaxPow2 = size_t(1) << (sizeof(size_t) * CHAR_BIT - 1);
  76   MOZ_RELEASE_ASSERT(RoundUpPow2(MaxPow2 - 1) == MaxPow2);
  77   MOZ_RELEASE_ASSERT(RoundUpPow2(MaxPow2) == MaxPow2);
  78   // not valid to round up when past the max power of two
  79 }
  80
  81 int
  82 main()
  83 {
  84   TestCeiling();
  85   TestFloor();
  86
  87   TestRoundUpPow2();
  88   return 0;
  89 }