third_party/WebKit/Source/wtf/SaturatedArithmeticTest.cpp

   1 /*
   2  * Copyright (c) 2012, Google Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  *     * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *     * Redistributions in binary form must reproduce the above
  11  * copyright notice, this list of conditions and the following disclaimer
  12  * in the documentation and/or other materials provided with the
  13  * distribution.
  14  *     * Neither the name of Google Inc. nor the names of its
  15  * contributors may be used to endorse or promote products derived from
  16  * this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 #include "config.h"
  32
  33 #include "wtf/SaturatedArithmetic.h"
  34 #include <gtest/gtest.h>
  35 #include <limits.h>
  36
  37 namespace WTF {
  38
  39 TEST(SaturatedArithmeticTest, Addition)
  40 {
  41     EXPECT_EQ(0, saturatedAddition(0, 0));
  42     EXPECT_EQ(1, saturatedAddition(0, 1));
  43     EXPECT_EQ(100, saturatedAddition(0, 100));
  44     EXPECT_EQ(150, saturatedAddition(100, 50));
  45
  46     EXPECT_EQ(-1, saturatedAddition(0, -1));
  47     EXPECT_EQ(0, saturatedAddition(1, -1));
  48     EXPECT_EQ(50, saturatedAddition(100, -50));
  49     EXPECT_EQ(-50, saturatedAddition(50, -100));
  50
  51     EXPECT_EQ(INT_MAX - 1, saturatedAddition(INT_MAX - 1, 0));
  52     EXPECT_EQ(INT_MAX, saturatedAddition(INT_MAX - 1, 1));
  53     EXPECT_EQ(INT_MAX, saturatedAddition(INT_MAX - 1, 2));
  54     EXPECT_EQ(INT_MAX - 1, saturatedAddition(0, INT_MAX - 1));
  55     EXPECT_EQ(INT_MAX, saturatedAddition(1, INT_MAX - 1));
  56     EXPECT_EQ(INT_MAX, saturatedAddition(2, INT_MAX - 1));
  57     EXPECT_EQ(INT_MAX, saturatedAddition(INT_MAX - 1, INT_MAX - 1));
  58     EXPECT_EQ(INT_MAX, saturatedAddition(INT_MAX, INT_MAX));
  59
  60     EXPECT_EQ(INT_MIN, saturatedAddition(INT_MIN, 0));
  61     EXPECT_EQ(INT_MIN + 1, saturatedAddition(INT_MIN + 1, 0));
  62     EXPECT_EQ(INT_MIN + 2, saturatedAddition(INT_MIN + 1, 1));
  63     EXPECT_EQ(INT_MIN + 3, saturatedAddition(INT_MIN + 1, 2));
  64     EXPECT_EQ(INT_MIN, saturatedAddition(INT_MIN + 1, -1));
  65     EXPECT_EQ(INT_MIN, saturatedAddition(INT_MIN + 1, -2));
  66     EXPECT_EQ(INT_MIN + 1, saturatedAddition(0, INT_MIN + 1));
  67     EXPECT_EQ(INT_MIN, saturatedAddition(-1, INT_MIN + 1));
  68     EXPECT_EQ(INT_MIN, saturatedAddition(-2, INT_MIN + 1));
  69
  70     EXPECT_EQ(INT_MAX / 2 + 10000, saturatedAddition(INT_MAX / 2, 10000));
  71     EXPECT_EQ(INT_MAX, saturatedAddition(INT_MAX / 2 + 1, INT_MAX / 2 + 1));
  72     EXPECT_EQ(-1, saturatedAddition(INT_MIN, INT_MAX));
  73 }
  74
  75 TEST(SaturatedArithmeticTest, Subtraction)
  76 {
  77     EXPECT_EQ(0, saturatedSubtraction(0, 0));
  78     EXPECT_EQ(-1, saturatedSubtraction(0, 1));
  79     EXPECT_EQ(-100, saturatedSubtraction(0, 100));
  80     EXPECT_EQ(50, saturatedSubtraction(100, 50));
  81
  82     EXPECT_EQ(1, saturatedSubtraction(0, -1));
  83     EXPECT_EQ(2, saturatedSubtraction(1, -1));
  84     EXPECT_EQ(150, saturatedSubtraction(100, -50));
  85     EXPECT_EQ(150, saturatedSubtraction(50, -100));
  86
  87     EXPECT_EQ(INT_MAX, saturatedSubtraction(INT_MAX, 0));
  88     EXPECT_EQ(INT_MAX - 1, saturatedSubtraction(INT_MAX, 1));
  89     EXPECT_EQ(INT_MAX - 1, saturatedSubtraction(INT_MAX - 1, 0));
  90     EXPECT_EQ(INT_MAX, saturatedSubtraction(INT_MAX - 1, -1));
  91     EXPECT_EQ(INT_MAX, saturatedSubtraction(INT_MAX - 1, -2));
  92     EXPECT_EQ(-INT_MAX + 1, saturatedSubtraction(0, INT_MAX - 1));
  93     EXPECT_EQ(-INT_MAX, saturatedSubtraction(-1, INT_MAX - 1));
  94     EXPECT_EQ(-INT_MAX - 1, saturatedSubtraction(-2, INT_MAX - 1));
  95     EXPECT_EQ(-INT_MAX - 1, saturatedSubtraction(-3, INT_MAX - 1));
  96
  97     EXPECT_EQ(INT_MIN, saturatedSubtraction(INT_MIN, 0));
  98     EXPECT_EQ(INT_MIN + 1, saturatedSubtraction(INT_MIN + 1, 0));
  99     EXPECT_EQ(INT_MIN, saturatedSubtraction(INT_MIN + 1, 1));
 100     EXPECT_EQ(INT_MIN, saturatedSubtraction(INT_MIN + 1, 2));
 101
 102     EXPECT_EQ(0, saturatedSubtraction(INT_MIN, INT_MIN));
 103     EXPECT_EQ(0, saturatedSubtraction(INT_MAX, INT_MAX));
 104     EXPECT_EQ(INT_MAX, saturatedSubtraction(INT_MAX, INT_MIN));
 105 }
 106
 107 TEST(SaturatedArithmeticTest, SetSigned)
 108 {
 109     const int kFractionBits = 6;
 110     const int intMaxForLayoutUnit = INT_MAX >> kFractionBits;
 111     const int intMinForLayoutUnit = INT_MIN >> kFractionBits;
 112
 113     EXPECT_EQ(0, saturatedSet(0, kFractionBits));
 114
 115     // Internally the max number we can represent (without saturating)
 116     // is all the (non-sign) bits set except for the bottom n fraction bits
 117     const int maxInternalRepresentation = INT_MAX ^ ((1 << kFractionBits)-1);
 118     EXPECT_EQ(maxInternalRepresentation,
 119         saturatedSet(intMaxForLayoutUnit, kFractionBits));
 120
 121     EXPECT_EQ(getMaxSaturatedSetResultForTesting(kFractionBits),
 122         saturatedSet(intMaxForLayoutUnit + 100, kFractionBits));
 123
 124     EXPECT_EQ((intMaxForLayoutUnit - 100) << kFractionBits,
 125         saturatedSet(intMaxForLayoutUnit - 100, kFractionBits));
 126
 127     EXPECT_EQ(getMinSaturatedSetResultForTesting(kFractionBits),
 128         saturatedSet(intMinForLayoutUnit, kFractionBits));
 129
 130     EXPECT_EQ(getMinSaturatedSetResultForTesting(kFractionBits),
 131         saturatedSet(intMinForLayoutUnit - 100, kFractionBits));
 132
 133     EXPECT_EQ((intMinForLayoutUnit + 100) << kFractionBits,
 134         saturatedSet(intMinForLayoutUnit + 100, kFractionBits));
 135 }
 136
 137 TEST(SaturatedArithmeticTest, SetUnsigned)
 138 {
 139     const int kFractionBits = 6;
 140     const int intMaxForLayoutUnit = INT_MAX >> kFractionBits;
 141
 142     EXPECT_EQ(0, saturatedSet((unsigned)0, kFractionBits));
 143
 144     EXPECT_EQ(getMaxSaturatedSetResultForTesting(kFractionBits),
 145         saturatedSet((unsigned)intMaxForLayoutUnit, kFractionBits));
 146
 147     const unsigned kOverflowed = intMaxForLayoutUnit + 100;
 148     EXPECT_EQ(getMaxSaturatedSetResultForTesting(kFractionBits),
 149         saturatedSet(kOverflowed, kFractionBits));
 150
 151     const unsigned kNotOverflowed = intMaxForLayoutUnit - 100;
 152     EXPECT_EQ((intMaxForLayoutUnit - 100) << kFractionBits,
 153         saturatedSet(kNotOverflowed, kFractionBits));
 154 }
 155
 156 } // namespace WTF