1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// REQUIRES: std-at-least-c++26
10
11// The test uses "Placeholder variables with no name"
12// UNSUPPORTED: apple-clang-15, apple-clang-16
13
14// <numeric>
15
16// template<class T>
17// constexpr T sub_sat(T x, T y) noexcept; // freestanding
18
19#include <cassert>
20#include <concepts>
21#include <limits>
22#include <numeric>
23
24#include "test_macros.h"
25
26template <typename IntegerT>
27constexpr bool test_signed() {
28 constexpr auto minVal = std::numeric_limits<IntegerT>::min();
29 constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
30
31 std::same_as<IntegerT> decltype(auto) _ = std::sub_sat(minVal, maxVal);
32
33 static_assert(noexcept(std::sub_sat(minVal, maxVal)));
34
35 // clang-format off
36
37 // Limit values (-1, 0, 1, min, max)
38
39 assert(std::sub_sat(IntegerT{-1}, IntegerT{-1}) == IntegerT{ 0});
40 assert(std::sub_sat(IntegerT{-1}, IntegerT{ 0}) == IntegerT{-1});
41 assert(std::sub_sat(IntegerT{-1}, IntegerT{ 1}) == IntegerT{-2});
42 assert(std::sub_sat(IntegerT{-1}, minVal) == IntegerT{-1} - minVal);
43 assert(std::sub_sat(IntegerT{-1}, maxVal) == IntegerT{-1} - maxVal);
44
45 assert(std::sub_sat(IntegerT{ 0}, IntegerT{-1}) == IntegerT{ 1});
46 assert(std::sub_sat(IntegerT{ 0}, IntegerT{ 0}) == IntegerT{ 0});
47 assert(std::sub_sat(IntegerT{ 0}, IntegerT{ 1}) == IntegerT{-1});
48 assert(std::sub_sat(IntegerT{ 0}, minVal) == maxVal); // saturated
49 assert(std::sub_sat(IntegerT{ 0}, maxVal) == -maxVal);
50
51 assert(std::sub_sat( minVal, IntegerT{-1}) == minVal - IntegerT{-1});
52 assert(std::sub_sat( minVal, IntegerT{ 0}) == minVal);
53 assert(std::sub_sat( minVal, IntegerT{ 1}) == minVal); // saturated
54 assert(std::sub_sat( minVal, minVal) == IntegerT{0});
55 assert(std::sub_sat( minVal, maxVal) == minVal); // saturated
56
57 assert(std::sub_sat( maxVal, IntegerT{-1}) == maxVal); // saturated
58 assert(std::sub_sat( maxVal, IntegerT{ 0}) == maxVal);
59 assert(std::sub_sat( maxVal, IntegerT{ 1}) == maxVal - IntegerT{ 1});
60 assert(std::sub_sat( maxVal, minVal) == maxVal); // saturated
61 assert(std::sub_sat( maxVal, maxVal) == IntegerT{0});
62
63 // No saturation (no limit values)
64
65 assert(std::sub_sat(IntegerT{ 27}, IntegerT{-28}) == 55);
66 assert(std::sub_sat(IntegerT{ 27}, IntegerT{ 28}) == -1);
67 assert(std::sub_sat(IntegerT{-27}, IntegerT{ 28}) == -55);
68 assert(std::sub_sat(IntegerT{-27}, IntegerT{-28}) == 1);
69
70 // Saturation (no limit values)
71
72 {
73 constexpr IntegerT lesserVal = minVal / IntegerT{2} + IntegerT{27};
74 constexpr IntegerT biggerVal = maxVal / IntegerT{2} + IntegerT{28};
75 assert(std::sub_sat(lesserVal, biggerVal) == minVal); // saturated
76 }
77 {
78 constexpr IntegerT biggerVal = maxVal / IntegerT{2} + IntegerT{28};
79 constexpr IntegerT lesserVal = minVal / IntegerT{2} + IntegerT{27};
80 assert(std::sub_sat(biggerVal, lesserVal) == maxVal); // saturated
81 }
82
83 // clang-format on
84
85 return true;
86}
87
88template <typename IntegerT>
89constexpr bool test_unsigned() {
90 constexpr auto minVal = std::numeric_limits<IntegerT>::min();
91 constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
92
93 std::same_as<IntegerT> decltype(auto) _ = std::sub_sat(minVal, maxVal);
94
95 static_assert(noexcept(std::sub_sat(minVal, maxVal)));
96
97 // clang-format off
98
99 // Limit values (0, 1, min, max)
100
101 assert(std::sub_sat(IntegerT{0}, IntegerT{0}) == IntegerT{0});
102 assert(std::sub_sat(IntegerT{0}, IntegerT{1}) == minVal); // saturated
103 assert(std::sub_sat(IntegerT{0}, minVal) == minVal);
104 assert(std::sub_sat(IntegerT{0}, maxVal) == minVal); // saturated
105
106 assert(std::sub_sat(IntegerT{1}, IntegerT{0}) == IntegerT{1});
107 assert(std::sub_sat(IntegerT{1}, IntegerT{1}) == IntegerT{0});
108 assert(std::sub_sat(IntegerT{1}, minVal) == IntegerT{1});
109 assert(std::sub_sat(IntegerT{1}, maxVal) == minVal); // saturated
110
111 assert(std::sub_sat( minVal, IntegerT{0}) == IntegerT{0});
112 assert(std::sub_sat( minVal, IntegerT{1}) == minVal);
113 assert(std::sub_sat( minVal, maxVal) == minVal);
114 assert(std::sub_sat( minVal, maxVal) == minVal);
115
116 assert(std::sub_sat( maxVal, IntegerT{0}) == maxVal);
117 assert(std::sub_sat( maxVal, IntegerT{1}) == maxVal - IntegerT{1});
118 assert(std::sub_sat( maxVal, minVal) == maxVal);
119 assert(std::sub_sat( maxVal, maxVal) == IntegerT{0});
120
121 // Saturation (no limit values)
122
123 {
124 constexpr IntegerT lesserVal = minVal / IntegerT{2} + IntegerT{27};
125 constexpr IntegerT biggerVal = maxVal / IntegerT{2} + IntegerT{28};
126 assert(std::sub_sat(lesserVal, biggerVal) == minVal); // saturated
127 }
128
129 // clang-format on
130
131 return true;
132}
133
134constexpr bool test() {
135 // Signed
136 test_signed<signed char>();
137 test_signed<short int>();
138 test_signed<int>();
139 test_signed<long int>();
140 test_signed<long long int>();
141#ifndef TEST_HAS_NO_INT128
142 test_signed<__int128_t>();
143#endif
144 // Unsigned
145 test_unsigned<unsigned char>();
146 test_unsigned<unsigned short int>();
147 test_unsigned<unsigned int>();
148 test_unsigned<unsigned long int>();
149 test_unsigned<unsigned long long int>();
150#ifndef TEST_HAS_NO_INT128
151 test_unsigned<__uint128_t>();
152#endif
153
154 return true;
155}
156
157int main(int, char**) {
158 test();
159 static_assert(test());
160
161 return 0;
162}
163

source code of libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/sub_sat.pass.cpp