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 TestCeiling() {
  14   for (uint32_t i = 0; i <= 1; i++) {
  15     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 0);
  16   }
  17   for (uint32_t i = 2; i <= 2; i++) {
  18     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 1);
  19   }
  20   for (uint32_t i = 3; i <= 4; i++) {
  21     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 2);
  22   }
  23   for (uint32_t i = 5; i <= 8; i++) {
  24     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 3);
  25   }
  26   for (uint32_t i = 9; i <= 16; i++) {
  27     MOZ_RELEASE_ASSERT(CeilingLog2(i) == 4);
  28   }
  29 }
  30
  31 static void TestFloor() {
  32   for (uint32_t i = 0; i <= 1; i++) {
  33     MOZ_RELEASE_ASSERT(FloorLog2(i) == 0);
  34   }
  35   for (uint32_t i = 2; i <= 3; i++) {
  36     MOZ_RELEASE_ASSERT(FloorLog2(i) == 1);
  37   }
  38   for (uint32_t i = 4; i <= 7; i++) {
  39     MOZ_RELEASE_ASSERT(FloorLog2(i) == 2);
  40   }
  41   for (uint32_t i = 8; i <= 15; i++) {
  42     MOZ_RELEASE_ASSERT(FloorLog2(i) == 3);
  43   }
  44   for (uint32_t i = 16; i <= 31; i++) {
  45     MOZ_RELEASE_ASSERT(FloorLog2(i) == 4);
  46   }
  47 }
  48
  49 static void TestRoundUpPow2() {
  50   MOZ_RELEASE_ASSERT(RoundUpPow2(0) == 1);
  51   MOZ_RELEASE_ASSERT(RoundUpPow2(1) == 1);
  52   MOZ_RELEASE_ASSERT(RoundUpPow2(2) == 2);
  53   MOZ_RELEASE_ASSERT(RoundUpPow2(3) == 4);
  54   MOZ_RELEASE_ASSERT(RoundUpPow2(4) == 4);
  55   MOZ_RELEASE_ASSERT(RoundUpPow2(5) == 8);
  56   MOZ_RELEASE_ASSERT(RoundUpPow2(6) == 8);
  57   MOZ_RELEASE_ASSERT(RoundUpPow2(7) == 8);
  58   MOZ_RELEASE_ASSERT(RoundUpPow2(8) == 8);
  59   MOZ_RELEASE_ASSERT(RoundUpPow2(9) == 16);
  60
  61   MOZ_RELEASE_ASSERT(RoundUpPow2(15) == 16);
  62   MOZ_RELEASE_ASSERT(RoundUpPow2(16) == 16);
  63   MOZ_RELEASE_ASSERT(RoundUpPow2(17) == 32);
  64
  65   MOZ_RELEASE_ASSERT(RoundUpPow2(31) == 32);
  66   MOZ_RELEASE_ASSERT(RoundUpPow2(32) == 32);
  67   MOZ_RELEASE_ASSERT(RoundUpPow2(33) == 64);
  68
  69   size_t MaxPow2 = size_t(1) << (sizeof(size_t) * CHAR_BIT - 1);
  70   MOZ_RELEASE_ASSERT(RoundUpPow2(MaxPow2 - 1) == MaxPow2);
  71   MOZ_RELEASE_ASSERT(RoundUpPow2(MaxPow2) == MaxPow2);
  72   // not valid to round up when past the max power of two
  73 }
  74
  75 int main() {
  76   TestCeiling();
  77   TestFloor();
  78
  79   TestRoundUpPow2();
  80   return 0;
  81 }