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authorGravatar Abseil Team <absl-team@google.com>2021-11-22 08:22:28 -0800
committerGravatar Derek Mauro <dmauro@google.com>2021-11-22 14:44:20 -0500
commitec0d76f1d012cc1a4b3b08dfafcfc5237f5ba2c9 (patch)
tree3ed0065b80edc2f3c10b06e0cc9314118f9caa63 /absl/random/internal/traits.h
parent72c765111173a61de6e4184bb837f855b7869952 (diff)
Export of internal Abseil changes
-- a0847bf19789c97689f1a8b0133a53b8af5e5caa by Samuel Benzaquen <sbenza@google.com>: Add support for absl::(u)int128 to random distributions and generators. PiperOrigin-RevId: 411565479 GitOrigin-RevId: a0847bf19789c97689f1a8b0133a53b8af5e5caa Change-Id: Ide434bdd93fcab8e90f791796498de14833b667c
Diffstat (limited to 'absl/random/internal/traits.h')
-rw-r--r--absl/random/internal/traits.h58
1 files changed, 53 insertions, 5 deletions
diff --git a/absl/random/internal/traits.h b/absl/random/internal/traits.h
index 75772bd9..f874a0f7 100644
--- a/absl/random/internal/traits.h
+++ b/absl/random/internal/traits.h
@@ -20,6 +20,8 @@
#include <type_traits>
#include "absl/base/config.h"
+#include "absl/numeric/bits.h"
+#include "absl/numeric/int128.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
@@ -59,6 +61,31 @@ class is_widening_convertible {
rank<A>() <= rank<B>();
};
+template <typename T>
+struct IsIntegral : std::is_integral<T> {};
+template <>
+struct IsIntegral<absl::int128> : std::true_type {};
+template <>
+struct IsIntegral<absl::uint128> : std::true_type {};
+
+template <typename T>
+struct MakeUnsigned : std::make_unsigned<T> {};
+template <>
+struct MakeUnsigned<absl::int128> {
+ using type = absl::uint128;
+};
+template <>
+struct MakeUnsigned<absl::uint128> {
+ using type = absl::uint128;
+};
+
+template <typename T>
+struct IsUnsigned : std::is_unsigned<T> {};
+template <>
+struct IsUnsigned<absl::int128> : std::false_type {};
+template <>
+struct IsUnsigned<absl::uint128> : std::true_type {};
+
// unsigned_bits<N>::type returns the unsigned int type with the indicated
// number of bits.
template <size_t N>
@@ -81,19 +108,40 @@ struct unsigned_bits<64> {
using type = uint64_t;
};
-#ifdef ABSL_HAVE_INTRINSIC_INT128
template <>
struct unsigned_bits<128> {
- using type = __uint128_t;
+ using type = absl::uint128;
+};
+
+// 256-bit wrapper for wide multiplications.
+struct U256 {
+ uint128 hi;
+ uint128 lo;
+};
+template <>
+struct unsigned_bits<256> {
+ using type = U256;
};
-#endif
template <typename IntType>
struct make_unsigned_bits {
- using type = typename unsigned_bits<std::numeric_limits<
- typename std::make_unsigned<IntType>::type>::digits>::type;
+ using type = typename unsigned_bits<
+ std::numeric_limits<typename MakeUnsigned<IntType>::type>::digits>::type;
};
+template <typename T>
+int BitWidth(T v) {
+ // Workaround for bit_width not supporting int128.
+ // Don't hardcode `64` to make sure this code does not trigger compiler
+ // warnings in smaller types.
+ constexpr int half_bits = sizeof(T) * 8 / 2;
+ if (sizeof(T) == 16 && (v >> half_bits) != 0) {
+ return bit_width(static_cast<uint64_t>(v >> half_bits)) + half_bits;
+ } else {
+ return bit_width(static_cast<uint64_t>(v));
+ }
+}
+
} // namespace random_internal
ABSL_NAMESPACE_END
} // namespace absl