src/tests/math_func.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file math_func.cpp Test functionality from core/math_func. */
   9
  10 #include "../stdafx.h"
  11
  12 #include "../3rdparty/catch2/catch.hpp"
  13
  14 #include "../core/math_func.hpp"
  15
  16 TEST_CASE("DivideApproxTest - Negative")
  17 {
  18         CHECK(-2 == DivideApprox(-5, 2));
  19         CHECK(2 == DivideApprox(-5, -2));
  20         CHECK(-1 == DivideApprox(-66, 80));
  21 }
  22
  23 TEST_CASE("DivideApproxTest, Divide")
  24 {
  25         CHECK(2 == DivideApprox(5, 2));
  26         CHECK(3 == DivideApprox(80, 30));
  27         CHECK(3 == DivideApprox(8, 3));
  28         CHECK(0 == DivideApprox(3, 8));
  29 }
  30
  31 TEST_CASE("IntSqrtTest - Zero")
  32 {
  33         CHECK(0 == IntSqrt(0));
  34 }
  35
  36 TEST_CASE("IntSqrtTest - FindSqRt")
  37 {
  38         CHECK(5 == IntSqrt(25));
  39         CHECK(10 == IntSqrt(100));
  40         CHECK(9 == IntSqrt(88));
  41         CHECK(1696 == IntSqrt(2876278));
  42 }
  43
  44
  45 TEST_CASE("ClampTo")
  46 {
  47         CHECK(0 == ClampTo<uint8_t>(std::numeric_limits<int64_t>::lowest()));
  48         CHECK(0 == ClampTo<uint8_t>(-1));
  49         CHECK(0 == ClampTo<uint8_t>(0));
  50         CHECK(1 == ClampTo<uint8_t>(1));
  51
  52         CHECK(255 == ClampTo<uint8_t>(std::numeric_limits<uint64_t>::max()));
  53         CHECK(255 == ClampTo<uint8_t>(256));
  54         CHECK(255 == ClampTo<uint8_t>(255));
  55         CHECK(254 == ClampTo<uint8_t>(254));
  56
  57         CHECK(-128 == ClampTo<int8_t>(std::numeric_limits<int64_t>::lowest()));
  58         CHECK(-128 == ClampTo<int8_t>(-129));
  59         CHECK(-128 == ClampTo<int8_t>(-128));
  60         CHECK(-127 == ClampTo<int8_t>(-127));
  61
  62         CHECK(127 == ClampTo<int8_t>(std::numeric_limits<uint64_t>::max()));
  63         CHECK(127 == ClampTo<int8_t>(128));
  64         CHECK(127 == ClampTo<int8_t>(127));
  65         CHECK(126 == ClampTo<int8_t>(126));
  66
  67         CHECK(126 == ClampTo<int64_t>(static_cast<uint8_t>(126)));
  68         CHECK(126 == ClampTo<uint64_t>(static_cast<int8_t>(126)));
  69         CHECK(0 == ClampTo<uint64_t>(static_cast<int8_t>(-126)));
  70         CHECK(0 == ClampTo<uint8_t>(static_cast<int8_t>(-126)));
  71
  72         /* The realm around 64 bits types is tricky as there is not one type/method that works for all. */
  73
  74         /* lowest/max uint64_t does not get clamped when clamping to uint64_t. */
  75         CHECK(std::numeric_limits<uint64_t>::lowest() == ClampTo<uint64_t>(std::numeric_limits<uint64_t>::lowest()));
  76         CHECK(std::numeric_limits<uint64_t>::max() == ClampTo<uint64_t>(std::numeric_limits<uint64_t>::max()));
  77
  78         /* negative int64_t get clamped to 0. */
  79         CHECK(0 == ClampTo<uint64_t>(std::numeric_limits<int64_t>::lowest()));
  80         CHECK(0 == ClampTo<uint64_t>(int64_t(-1)));
  81         /* positive int64_t remain the same. */
  82         CHECK(1 == ClampTo<uint64_t>(int64_t(1)));
  83         CHECK(static_cast<uint64_t>(std::numeric_limits<int64_t>::max()) == ClampTo<uint64_t>(std::numeric_limits<int64_t>::max()));
  84
  85         /* max uint64_t gets clamped to max int64_t. */
  86         CHECK(std::numeric_limits<int64_t>::max() == ClampTo<int64_t>(std::numeric_limits<uint64_t>::max()));
  87 }
  88
  89
  90 TEST_CASE("SoftClamp")
  91 {
  92         /* Special behaviour of soft clamp returning the average of min/max when min is higher than max. */
  93         CHECK(1250 == SoftClamp(0, 1500, 1000));
  94         int million = 1000 * 1000;
  95         CHECK(1250 * million == SoftClamp(0, 1500 * million, 1000 * million));
  96         CHECK(0 == SoftClamp(0, 1500 * million, -1500 * million));
  97 }