2 * Copyright (C) 2016 The Android Open Source Project
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
22 #include <type_traits>
25 # define LIKELY( exp ) (__builtin_expect( !!(exp), true ))
26 # define UNLIKELY( exp ) (__builtin_expect( !!(exp), false ))
28 # define LIKELY( exp ) (__builtin_expect( !!(exp), 1 ))
29 # define UNLIKELY( exp ) (__builtin_expect( !!(exp), 0 ))
32 #if __cplusplus >= 201402L
33 #define CONSTEXPR constexpr
44 * +-+------+------------+
45 * |s|eee.ee|mm.mmmm.mmmm|
46 * +-+------+------------+
48 * minimum (denormal) value: 2^-24 = 5.96e-8
49 * minimum (normal) value: 2^-14 = 6.10e-5
50 * maximum value: 2-2^-10 = 65504
52 * Integers between 0 and 2048 can be represented exactly
57 fp16() noexcept = default;
58 explicit constexpr fp16(uint16_t b) noexcept : bits(b) { }
59 void setS(unsigned int s) noexcept { bits = uint16_t((bits & 0x7FFF) | (s<<15)); }
60 void setE(unsigned int s) noexcept { bits = uint16_t((bits & 0xE3FF) | (s<<10)); }
61 void setM(unsigned int s) noexcept { bits = uint16_t((bits & 0xFC00) | (s<< 0)); }
62 constexpr unsigned int getS() const noexcept { return bits >> 15u; }
63 constexpr unsigned int getE() const noexcept { return (bits >> 10u) & 0x1Fu; }
64 constexpr unsigned int getM() const noexcept { return bits & 0x3FFu; }
71 fp32() noexcept = default;
72 explicit constexpr fp32(float f) : fp(f) { }
73 void setS(unsigned int s) noexcept { bits = uint32_t((bits & 0x7FFFFFFF) | (s<<31)); }
74 void setE(unsigned int s) noexcept { bits = uint32_t((bits & 0x807FFFFF) | (s<<23)); }
75 void setM(unsigned int s) noexcept { bits = uint32_t((bits & 0xFF800000) | (s<< 0)); }
76 constexpr unsigned int getS() const noexcept { return bits >> 31u; }
77 constexpr unsigned int getE() const noexcept { return (bits >> 23u) & 0xFFu; }
78 constexpr unsigned int getM() const noexcept { return bits & 0x7FFFFFu; }
82 CONSTEXPR half(float v) noexcept : mBits(ftoh(v)) { }
83 CONSTEXPR operator float() const noexcept { return htof(mBits); }
85 uint16_t getBits() const noexcept { return mBits.bits; }
86 unsigned int getExponent() const noexcept { return mBits.getE(); }
87 unsigned int getMantissa() const noexcept { return mBits.getM(); }
90 friend class std::numeric_limits<half>;
91 friend CONSTEXPR half operator"" _hf(long double v);
93 enum Binary { binary };
94 explicit constexpr half(Binary, uint16_t bits) noexcept : mBits(bits) { }
95 static CONSTEXPR fp16 ftoh(float v) noexcept;
96 static CONSTEXPR float htof(fp16 v) noexcept;
100 inline CONSTEXPR half::fp16 half::ftoh(float v) noexcept {
103 if (UNLIKELY(in.getE() == 0xFF)) { // inf or nan
105 out.setM(in.getM() ? 0x200 : 0);
107 int e = static_cast<int>(in.getE()) - 127 + 15;
110 out.setE(0x31); // +/- inf
115 unsigned int m = in.getM();
116 out.setE(uint16_t(e));
128 inline CONSTEXPR float half::htof(half::fp16 in) noexcept {
130 if (UNLIKELY(in.getE() == 0x1F)) { // inf or nan
132 out.setM(in.getM() ? 0x400000 : 0);
134 if (in.getE() == 0) {
136 // TODO: denormal half float, treat as zero for now
137 // (it's stupid because they can be represented as regular float)
140 int e = static_cast<int>(in.getE()) - 15 + 127;
141 unsigned int m = in.getM();
142 out.setE(uint32_t(e));
150 inline CONSTEXPR android::half operator"" _hf(long double v) {
151 return android::half(android::half::binary, android::half::ftoh(static_cast<float>(v)).bits);
154 } // namespace android
158 template<> struct is_floating_point<android::half> : public std::true_type {};
161 class numeric_limits<android::half> {
163 typedef android::half type;
165 static constexpr const bool is_specialized = true;
166 static constexpr const bool is_signed = true;
167 static constexpr const bool is_integer = false;
168 static constexpr const bool is_exact = false;
169 static constexpr const bool has_infinity = true;
170 static constexpr const bool has_quiet_NaN = true;
171 static constexpr const bool has_signaling_NaN = false;
172 static constexpr const float_denorm_style has_denorm = denorm_absent;
173 static constexpr const bool has_denorm_loss = true;
174 static constexpr const bool is_iec559 = false;
175 static constexpr const bool is_bounded = true;
176 static constexpr const bool is_modulo = false;
177 static constexpr const bool traps = false;
178 static constexpr const bool tinyness_before = false;
179 static constexpr const float_round_style round_style = round_indeterminate;
181 static constexpr const int digits = 11;
182 static constexpr const int digits10 = 3;
183 static constexpr const int max_digits10 = 5;
184 static constexpr const int radix = 2;
185 static constexpr const int min_exponent = -13;
186 static constexpr const int min_exponent10 = -4;
187 static constexpr const int max_exponent = 16;
188 static constexpr const int max_exponent10 = 4;
190 inline static constexpr type round_error() noexcept { return android::half(android::half::binary, 0x3800); }
191 inline static constexpr type min() noexcept { return android::half(android::half::binary, 0x0400); }
192 inline static constexpr type max() noexcept { return android::half(android::half::binary, 0x7bff); }
193 inline static constexpr type lowest() noexcept { return android::half(android::half::binary, 0xfbff); }
194 inline static constexpr type epsilon() noexcept { return android::half(android::half::binary, 0x1400); }
195 inline static constexpr type infinity() noexcept { return android::half(android::half::binary, 0x7c00); }
196 inline static constexpr type quiet_NaN() noexcept { return android::half(android::half::binary, 0x7fff); }
197 inline static constexpr type denorm_min() noexcept { return android::half(android::half::binary, 0x0001); }
198 inline static constexpr type signaling_NaN() noexcept { return android::half(android::half::binary, 0x7dff); }