Export of internal Abseil changes
--
e54b9c7bbb0c58475676c268e2e19c69f4bce48a by Jorg Brown <jorg@google.com>:
Tweak ABSL_PREDICT_TRUE slightly, for better code on some platforms and/or
optimization levels. "false || (x)" is more verbose than "!!(x)", but
ultimately more efficient.
For example, given this code:
void InitIfNecessary() {
if (ABSL_PREDICT_TRUE(NeedsInit())) {
SlowInitIfNecessary();
}
}
Clang with default optimization level will produce:
Before this CL After this CL
InitIfNecessary: InitIfNecessary:
push rbp push rbp
mov rbp, rsp mov rbp, rsp
call NeedsInit call NeedsInit
xor al, -1
xor al, -1
test al, 1 test al, 1
jne .LBB2_1 jne .LBB3_1
jmp .LBB2_2 jmp .LBB3_2
.LBB2_1: .LBB3_1:
call SlowInitIfNecessary call SlowInitIfNecessary
.LBB2_2: .LBB3_2:
pop rbp pop rbp
ret ret
PiperOrigin-RevId: 276401386
--
0a3c4dfd8342bf2b1b11a87f1c662c883f73cab7 by Abseil Team <absl-team@google.com>:
Fix comment nit: sem_open => sem_init.
The code calls sem_init, not sem_open, to initialize an unnamed semaphore.
(sem_open creates or opens a named semaphore.)
PiperOrigin-RevId: 276344072
--
b36a664e9459057509a90e83d3482e1d3a4c44c7 by Abseil Team <absl-team@google.com>:
Fix typo in flat_hash_map.h: exchaged -> exchanged
PiperOrigin-RevId: 276295792
--
7bbd8d18276eb110c8335743e35fceb662ddf3d6 by Samuel Benzaquen <sbenza@google.com>:
Add assertions to verify use of iterators.
PiperOrigin-RevId: 276283300
--
677398a8ffcb1f59182cffe57a4fe7ff147a0404 by Laramie Leavitt <lar@google.com>:
Migrate distribution_impl.h/cc to generate_real.h/cc.
Combine the methods RandU64To<Float,Double> into a single method:
GenerateRealFromBits().
Remove rejection sampling from absl::uniform_real_distribution.
PiperOrigin-RevId: 276158675
--
c60c9d11d24b0c546329d998e78e15a84b3153f5 by Abseil Team <absl-team@google.com>:
Internal change
PiperOrigin-RevId: 276126962
--
4c840cab6a8d86efa29b397cafaf7520eece68cc by Andy Soffer <asoffer@google.com>:
Update CMakeLists.txt to address https://github.com/abseil/abseil-cpp/issues/365.
This does not cover every platform, but it does at least address the
first-order issue of assuming gcc implies x86.
PiperOrigin-RevId: 276116253
--
98da366e6b5d51afe5d7ac6722126aca23d85ee6 by Abseil Team <absl-team@google.com>:
Internal change
PiperOrigin-RevId: 276097452
GitOrigin-RevId: e54b9c7bbb0c58475676c268e2e19c69f4bce48a
Change-Id: I02d84454bb71ab21ad3d39650acf6cc6e36f58d7
This commit is contained in:
Abseil Team
Derek Mauro
parent
19b021cb3f
commit
078b89b3c0
28 changed files with 739 additions and 370 deletions
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@ -69,10 +69,10 @@ cc_library(
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"//absl/base:base_internal",
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"//absl/base:core_headers",
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"//absl/meta:type_traits",
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"//absl/random/internal:distribution_impl",
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"//absl/random/internal:distributions",
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"//absl/random/internal:fast_uniform_bits",
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"//absl/random/internal:fastmath",
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"//absl/random/internal:generate_real",
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"//absl/random/internal:iostream_state_saver",
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"//absl/random/internal:traits",
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"//absl/random/internal:uniform_helper",
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@ -58,7 +58,7 @@ absl_cc_library(
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DEPS
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absl::base_internal
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absl::core_headers
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absl::random_internal_distribution_impl
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absl::random_internal_generate_real
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absl::random_internal_distributions
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absl::random_internal_fast_uniform_bits
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absl::random_internal_fastmath
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@ -543,19 +543,18 @@ absl_cc_library(
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# Internal-only target, do not depend on directly.
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absl_cc_library(
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NAME
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random_internal_distribution_impl
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random_internal_generate_real
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HDRS
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"internal/distribution_impl.h"
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"internal/generate_real.h"
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COPTS
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${ABSL_DEFAULT_COPTS}
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LINKOPTS
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${ABSL_DEFAULT_LINKOPTS}
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DEPS
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absl::bits
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absl::config
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absl::int128
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absl::random_internal_fastmath
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absl::random_internal_traits
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absl::type_traits
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)
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# Internal-only target, do not depend on directly.
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@ -767,9 +766,9 @@ absl_cc_test(
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# Internal-only target, do not depend on directly.
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absl_cc_test(
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NAME
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random_internal_distribution_impl_test
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random_internal_generate_real_test
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SRCS
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"internal/distribution_impl_test.cc"
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"internal/generate_real_test.cc"
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COPTS
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${ABSL_TEST_COPTS}
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LINKOPTS
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@ -777,8 +776,7 @@ absl_cc_test(
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DEPS
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absl::bits
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absl::flags
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absl::int128
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absl::random_internal_distribution_impl
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absl::random_internal_generate_real
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gtest_main
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)
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@ -1029,7 +1027,6 @@ absl_cc_library(
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${ABSL_DEFAULT_LINKOPTS}
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DEPS
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absl::core_headers
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absl::random_internal_distribution_impl
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absl::random_internal_fast_uniform_bits
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absl::random_internal_iostream_state_saver
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absl::random_internal_traits
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@ -22,9 +22,10 @@
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#include <ostream>
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#include <type_traits>
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#include "absl/random/internal/distribution_impl.h"
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#include "absl/meta/type_traits.h"
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#include "absl/random/internal/fast_uniform_bits.h"
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#include "absl/random/internal/fastmath.h"
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#include "absl/random/internal/generate_real.h"
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#include "absl/random/internal/iostream_state_saver.h"
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namespace absl {
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@ -275,15 +276,21 @@ typename beta_distribution<RealType>::result_type
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beta_distribution<RealType>::AlgorithmJoehnk(
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URBG& g, // NOLINT(runtime/references)
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const param_type& p) {
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using random_internal::GeneratePositiveTag;
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using random_internal::GenerateRealFromBits;
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using real_type =
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absl::conditional_t<std::is_same<RealType, float>::value, float, double>;
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// Based on Joehnk, M. D. Erzeugung von betaverteilten und gammaverteilten
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// Zufallszahlen. Metrika 8.1 (1964): 5-15.
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// This method is described in Knuth, Vol 2 (Third Edition), pp 134.
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using RandU64ToReal = typename random_internal::RandU64ToReal<result_type>;
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using random_internal::PositiveValueT;
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result_type u, v, x, y, z;
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for (;;) {
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u = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g));
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v = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g));
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u = GenerateRealFromBits<real_type, GeneratePositiveTag, false>(
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fast_u64_(g));
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v = GenerateRealFromBits<real_type, GeneratePositiveTag, false>(
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fast_u64_(g));
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// Direct method. std::pow is slow for float, so rely on the optimizer to
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// remove the std::pow() path for that case.
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@ -327,12 +334,14 @@ typename beta_distribution<RealType>::result_type
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beta_distribution<RealType>::AlgorithmCheng(
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URBG& g, // NOLINT(runtime/references)
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const param_type& p) {
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using random_internal::GeneratePositiveTag;
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using random_internal::GenerateRealFromBits;
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using real_type =
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absl::conditional_t<std::is_same<RealType, float>::value, float, double>;
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// Based on Cheng, Russell CH. Generating beta variates with nonintegral
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// shape parameters. Communications of the ACM 21.4 (1978): 317-322.
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// (https://dl.acm.org/citation.cfm?id=359482).
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using RandU64ToReal = typename random_internal::RandU64ToReal<result_type>;
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using random_internal::PositiveValueT;
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static constexpr result_type kLogFour =
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result_type(1.3862943611198906188344642429163531361); // log(4)
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static constexpr result_type kS =
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@ -341,8 +350,10 @@ beta_distribution<RealType>::AlgorithmCheng(
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const bool use_algorithm_ba = (p.method_ == param_type::CHENG_BA);
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result_type u1, u2, v, w, z, r, s, t, bw_inv, lhs;
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for (;;) {
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u1 = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g));
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u2 = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g));
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u1 = GenerateRealFromBits<real_type, GeneratePositiveTag, false>(
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fast_u64_(g));
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u2 = GenerateRealFromBits<real_type, GeneratePositiveTag, false>(
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fast_u64_(g));
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v = p.y_ * std::log(u1 / (1 - u1));
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w = p.a_ * std::exp(v);
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bw_inv = result_type(1) / (p.b_ + w);
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@ -92,7 +92,7 @@ TYPED_TEST(BetaDistributionInterfaceTest, SerializeTest) {
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for (TypeParam alpha : kValues) {
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for (TypeParam beta : kValues) {
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ABSL_INTERNAL_LOG(
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INFO, absl::StrFormat("Smoke test for Beta(%f, %f)", alpha, beta));
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INFO, absl::StrFormat("Smoke test for Beta(%a, %a)", alpha, beta));
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param_type param(alpha, beta);
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absl::beta_distribution<TypeParam> before(alpha, beta);
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@ -21,8 +21,9 @@
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#include <limits>
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#include <type_traits>
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#include "absl/random/internal/distribution_impl.h"
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#include "absl/meta/type_traits.h"
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#include "absl/random/internal/fast_uniform_bits.h"
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#include "absl/random/internal/generate_real.h"
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#include "absl/random/internal/iostream_state_saver.h"
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namespace absl {
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@ -118,9 +119,14 @@ typename exponential_distribution<RealType>::result_type
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exponential_distribution<RealType>::operator()(
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URBG& g, // NOLINT(runtime/references)
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const param_type& p) {
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using random_internal::NegativeValueT;
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const result_type u = random_internal::RandU64ToReal<
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result_type>::template Value<NegativeValueT, false>(fast_u64_(g));
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using random_internal::GenerateNegativeTag;
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using random_internal::GenerateRealFromBits;
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using real_type =
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absl::conditional_t<std::is_same<RealType, float>::value, float, double>;
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const result_type u = GenerateRealFromBits<real_type, GenerateNegativeTag,
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false>(fast_u64_(g)); // U(-1, 0)
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// log1p(-x) is mathematically equivalent to log(1 - x) but has more
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// accuracy for x near zero.
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return p.neg_inv_lambda_ * std::log1p(u);
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@ -28,8 +28,8 @@
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#include <limits>
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#include <type_traits>
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#include "absl/random/internal/distribution_impl.h"
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#include "absl/random/internal/fast_uniform_bits.h"
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#include "absl/random/internal/generate_real.h"
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#include "absl/random/internal/iostream_state_saver.h"
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namespace absl {
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@ -207,12 +207,18 @@ namespace random_internal {
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template <typename URBG>
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inline double gaussian_distribution_base::zignor_fallback(URBG& g, bool neg) {
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using random_internal::GeneratePositiveTag;
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using random_internal::GenerateRealFromBits;
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// This fallback path happens approximately 0.05% of the time.
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double x, y;
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do {
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// kRInv = 1/r, U(0, 1)
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x = kRInv * std::log(RandU64ToDouble<PositiveValueT, false>(fast_u64_(g)));
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y = -std::log(RandU64ToDouble<PositiveValueT, false>(fast_u64_(g)));
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x = kRInv *
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std::log(GenerateRealFromBits<double, GeneratePositiveTag, false>(
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fast_u64_(g)));
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y = -std::log(
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GenerateRealFromBits<double, GeneratePositiveTag, false>(fast_u64_(g)));
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} while ((y + y) < (x * x));
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return neg ? (x - kR) : (kR - x);
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}
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@ -220,6 +226,10 @@ inline double gaussian_distribution_base::zignor_fallback(URBG& g, bool neg) {
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template <typename URBG>
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inline double gaussian_distribution_base::zignor(
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URBG& g) { // NOLINT(runtime/references)
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using random_internal::GeneratePositiveTag;
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using random_internal::GenerateRealFromBits;
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using random_internal::GenerateSignedTag;
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while (true) {
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// We use a single uint64_t to generate both a double and a strip.
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// These bits are unused when the generated double is > 1/2^5.
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@ -227,7 +237,8 @@ inline double gaussian_distribution_base::zignor(
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// values (those smaller than 1/2^5, which all end up on the left tail).
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uint64_t bits = fast_u64_(g);
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int i = static_cast<int>(bits & kMask); // pick a random strip
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double j = RandU64ToDouble<SignedValueT, false>(bits); // U(-1, 1)
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double j = GenerateRealFromBits<double, GenerateSignedTag, false>(
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bits); // U(-1, 1)
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const double x = j * zg_.x[i];
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// Retangular box. Handles >97% of all cases.
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@ -244,7 +255,8 @@ inline double gaussian_distribution_base::zignor(
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}
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// i > 0: Wedge samples using precomputed values.
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double v = RandU64ToDouble<PositiveValueT, false>(fast_u64_(g)); // U(0, 1)
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double v = GenerateRealFromBits<double, GeneratePositiveTag, false>(
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fast_u64_(g)); // U(0, 1)
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if ((zg_.f[i + 1] + v * (zg_.f[i] - zg_.f[i + 1])) <
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std::exp(-0.5 * x * x)) {
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return x;
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@ -175,9 +175,9 @@ cc_library(
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)
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cc_library(
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name = "distribution_impl",
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name = "generate_real",
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hdrs = [
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"distribution_impl.h",
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"generate_real.h",
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],
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copts = ABSL_DEFAULT_COPTS,
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linkopts = ABSL_DEFAULT_LINKOPTS,
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@ -185,8 +185,7 @@ cc_library(
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":fastmath",
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":traits",
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"//absl/base:bits",
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"//absl/base:config",
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"//absl/numeric:int128",
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"//absl/meta:type_traits",
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],
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)
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@ -398,16 +397,17 @@ cc_test(
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)
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cc_test(
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name = "distribution_impl_test",
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name = "generate_real_test",
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size = "small",
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srcs = ["distribution_impl_test.cc"],
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srcs = [
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"generate_real_test.cc",
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],
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copts = ABSL_TEST_COPTS,
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linkopts = ABSL_DEFAULT_LINKOPTS,
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deps = [
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":distribution_impl",
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":generate_real",
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"//absl/base:bits",
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"//absl/flags:flag",
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"//absl/numeric:int128",
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"@com_google_googletest//:gtest_main",
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],
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)
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@ -1,194 +0,0 @@
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef ABSL_RANDOM_INTERNAL_DISTRIBUTION_IMPL_H_
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#define ABSL_RANDOM_INTERNAL_DISTRIBUTION_IMPL_H_
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// This file contains some implementation details which are used by one or more
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// of the absl random number distributions.
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#include <cfloat>
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#include <cstddef>
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#include <cstdint>
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#include <cstring>
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#include <limits>
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#include <type_traits>
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#if (defined(_WIN32) || defined(_WIN64)) && defined(_M_IA64)
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#include <intrin.h> // NOLINT(build/include_order)
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#pragma intrinsic(_umul128)
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#define ABSL_INTERNAL_USE_UMUL128 1
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#endif
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#include "absl/base/config.h"
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#include "absl/base/internal/bits.h"
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#include "absl/numeric/int128.h"
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#include "absl/random/internal/fastmath.h"
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#include "absl/random/internal/traits.h"
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namespace absl {
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namespace random_internal {
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// Creates a double from `bits`, with the template fields controlling the
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// output.
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//
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// RandU64To is both more efficient and generates more unique values in the
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// result interval than known implementations of std::generate_canonical().
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//
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// The `Signed` parameter controls whether positive, negative, or both are
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// returned (thus affecting the output interval).
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// When Signed == SignedValueT, range is U(-1, 1)
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// When Signed == NegativeValueT, range is U(-1, 0)
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// When Signed == PositiveValueT, range is U(0, 1)
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//
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// When the `IncludeZero` parameter is true, the function may return 0 for some
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// inputs, otherwise it never returns 0.
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//
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// The `ExponentBias` parameter determines the scale of the output range by
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// adjusting the exponent.
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//
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// When a value in U(0,1) is required, use:
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// RandU64ToDouble<PositiveValueT, true, 0>();
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//
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// When a value in U(-1,1) is required, use:
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// RandU64ToDouble<SignedValueT, false, 0>() => U(-1, 1)
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// This generates more distinct values than the mathematically equivalent
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// expression `U(0, 1) * 2.0 - 1.0`, and is preferable.
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//
|
||||
// Scaling the result by powers of 2 (and avoiding a multiply) is also possible:
|
||||
// RandU64ToDouble<PositiveValueT, false, 1>(); => U(0, 2)
|
||||
// RandU64ToDouble<PositiveValueT, false, -1>(); => U(0, 0.5)
|
||||
//
|
||||
|
||||
// Tristate types controlling the output.
|
||||
struct PositiveValueT {};
|
||||
struct NegativeValueT {};
|
||||
struct SignedValueT {};
|
||||
|
||||
// RandU64ToDouble is the double-result variant of RandU64To, described above.
|
||||
template <typename Signed, bool IncludeZero, int ExponentBias = 0>
|
||||
inline double RandU64ToDouble(uint64_t bits) {
|
||||
static_assert(std::is_same<Signed, PositiveValueT>::value ||
|
||||
std::is_same<Signed, NegativeValueT>::value ||
|
||||
std::is_same<Signed, SignedValueT>::value,
|
||||
"");
|
||||
|
||||
// Maybe use the left-most bit for a sign bit.
|
||||
uint64_t sign = std::is_same<Signed, NegativeValueT>::value
|
||||
? 0x8000000000000000ull
|
||||
: 0; // Sign bits.
|
||||
|
||||
if (std::is_same<Signed, SignedValueT>::value) {
|
||||
sign = bits & 0x8000000000000000ull;
|
||||
bits = bits & 0x7FFFFFFFFFFFFFFFull;
|
||||
}
|
||||
if (IncludeZero) {
|
||||
if (bits == 0u) return 0;
|
||||
}
|
||||
|
||||
// Number of leading zeros is mapped to the exponent: 2^-clz
|
||||
int clz = base_internal::CountLeadingZeros64(bits);
|
||||
// Shift number left to erase leading zeros.
|
||||
bits <<= IncludeZero ? clz : (clz & 63);
|
||||
|
||||
// Shift number right to remove bits that overflow double mantissa. The
|
||||
// direction of the shift depends on `clz`.
|
||||
bits >>= (64 - DBL_MANT_DIG);
|
||||
|
||||
// Compute IEEE 754 double exponent.
|
||||
// In the Signed case, bits is a 63-bit number with a 0 msb. Adjust the
|
||||
// exponent to account for that.
|
||||
const uint64_t exp =
|
||||
(std::is_same<Signed, SignedValueT>::value ? 1023U : 1022U) +
|
||||
static_cast<uint64_t>(ExponentBias - clz);
|
||||
constexpr int kExp = DBL_MANT_DIG - 1;
|
||||
// Construct IEEE 754 double from exponent and mantissa.
|
||||
const uint64_t val = sign | (exp << kExp) | (bits & ((1ULL << kExp) - 1U));
|
||||
|
||||
double res;
|
||||
static_assert(sizeof(res) == sizeof(val), "double is not 64 bit");
|
||||
// Memcpy value from "val" to "res" to avoid aliasing problems. Assumes that
|
||||
// endian-ness is same for double and uint64_t.
|
||||
std::memcpy(&res, &val, sizeof(res));
|
||||
|
||||
return res;
|
||||
}
|
||||
|
||||
// RandU64ToFloat is the float-result variant of RandU64To, described above.
|
||||
template <typename Signed, bool IncludeZero, int ExponentBias = 0>
|
||||
inline float RandU64ToFloat(uint64_t bits) {
|
||||
static_assert(std::is_same<Signed, PositiveValueT>::value ||
|
||||
std::is_same<Signed, NegativeValueT>::value ||
|
||||
std::is_same<Signed, SignedValueT>::value,
|
||||
"");
|
||||
|
||||
// Maybe use the left-most bit for a sign bit.
|
||||
uint64_t sign = std::is_same<Signed, NegativeValueT>::value
|
||||
? 0x80000000ul
|
||||
: 0; // Sign bits.
|
||||
|
||||
if (std::is_same<Signed, SignedValueT>::value) {
|
||||
uint64_t a = bits & 0x8000000000000000ull;
|
||||
sign = static_cast<uint32_t>(a >> 32);
|
||||
bits = bits & 0x7FFFFFFFFFFFFFFFull;
|
||||
}
|
||||
if (IncludeZero) {
|
||||
if (bits == 0u) return 0;
|
||||
}
|
||||
|
||||
// Number of leading zeros is mapped to the exponent: 2^-clz
|
||||
int clz = base_internal::CountLeadingZeros64(bits);
|
||||
// Shift number left to erase leading zeros.
|
||||
bits <<= IncludeZero ? clz : (clz & 63);
|
||||
// Shift number right to remove bits that overflow double mantissa. The
|
||||
// direction of the shift depends on `clz`.
|
||||
bits >>= (64 - FLT_MANT_DIG);
|
||||
|
||||
// Construct IEEE 754 float exponent.
|
||||
// In the Signed case, bits is a 63-bit number with a 0 msb. Adjust the
|
||||
// exponent to account for that.
|
||||
const uint32_t exp =
|
||||
(std::is_same<Signed, SignedValueT>::value ? 127U : 126U) +
|
||||
static_cast<uint32_t>(ExponentBias - clz);
|
||||
constexpr int kExp = FLT_MANT_DIG - 1;
|
||||
const uint32_t val = sign | (exp << kExp) | (bits & ((1U << kExp) - 1U));
|
||||
|
||||
float res;
|
||||
static_assert(sizeof(res) == sizeof(val), "float is not 32 bit");
|
||||
// Assumes that endian-ness is same for float and uint32_t.
|
||||
std::memcpy(&res, &val, sizeof(res));
|
||||
|
||||
return res;
|
||||
}
|
||||
|
||||
template <typename Result>
|
||||
struct RandU64ToReal {
|
||||
template <typename Signed, bool IncludeZero, int ExponentBias = 0>
|
||||
static inline Result Value(uint64_t bits) {
|
||||
return RandU64ToDouble<Signed, IncludeZero, ExponentBias>(bits);
|
||||
}
|
||||
};
|
||||
|
||||
template <>
|
||||
struct RandU64ToReal<float> {
|
||||
template <typename Signed, bool IncludeZero, int ExponentBias = 0>
|
||||
static inline float Value(uint64_t bits) {
|
||||
return RandU64ToFloat<Signed, IncludeZero, ExponentBias>(bits);
|
||||
}
|
||||
};
|
||||
|
||||
} // namespace random_internal
|
||||
} // namespace absl
|
||||
|
||||
#endif // ABSL_RANDOM_INTERNAL_DISTRIBUTION_IMPL_H_
|
||||
144
absl/random/internal/generate_real.h
Normal file
144
absl/random/internal/generate_real.h
Normal file
|
|
@ -0,0 +1,144 @@
|
|||
// Copyright 2017 The Abseil Authors.
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||||
// you may not use this file except in compliance with the License.
|
||||
// You may obtain a copy of the License at
|
||||
//
|
||||
// https://www.apache.org/licenses/LICENSE-2.0
|
||||
//
|
||||
// Unless required by applicable law or agreed to in writing, software
|
||||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
#ifndef ABSL_RANDOM_INTERNAL_GENERATE_REAL_H_
|
||||
#define ABSL_RANDOM_INTERNAL_GENERATE_REAL_H_
|
||||
|
||||
// This file contains some implementation details which are used by one or more
|
||||
// of the absl random number distributions.
|
||||
|
||||
#include <cstdint>
|
||||
#include <cstring>
|
||||
#include <limits>
|
||||
#include <type_traits>
|
||||
|
||||
#include "absl/base/internal/bits.h"
|
||||
#include "absl/meta/type_traits.h"
|
||||
#include "absl/random/internal/fastmath.h"
|
||||
#include "absl/random/internal/traits.h"
|
||||
|
||||
namespace absl {
|
||||
namespace random_internal {
|
||||
|
||||
// Tristate tag types controlling the output of GenerateRealFromBits.
|
||||
struct GeneratePositiveTag {};
|
||||
struct GenerateNegativeTag {};
|
||||
struct GenerateSignedTag {};
|
||||
|
||||
// GenerateRealFromBits generates a single real value from a single 64-bit
|
||||
// `bits` with template fields controlling the output.
|
||||
//
|
||||
// The `SignedTag` parameter controls whether positive, negative,
|
||||
// or either signed/unsigned may be returned.
|
||||
// When SignedTag == GeneratePositiveTag, range is U(0, 1)
|
||||
// When SignedTag == GenerateNegativeTag, range is U(-1, 0)
|
||||
// When SignedTag == GenerateSignedTag, range is U(-1, 1)
|
||||
//
|
||||
// When the `IncludeZero` parameter is true, the function may return 0 for some
|
||||
// inputs, otherwise it never returns 0.
|
||||
//
|
||||
// When a value in U(0,1) is required, use:
|
||||
// Uniform64ToReal<double, PositiveValueT, true>;
|
||||
//
|
||||
// When a value in U(-1,1) is required, use:
|
||||
// Uniform64ToReal<double, SignedValueT, false>;
|
||||
//
|
||||
// This generates more distinct values than the mathematical equivalent
|
||||
// `U(0, 1) * 2.0 - 1.0`.
|
||||
//
|
||||
// Scaling the result by powers of 2 (and avoiding a multiply) is also possible:
|
||||
// GenerateRealFromBits<double>(..., -1); => U(0, 0.5)
|
||||
// GenerateRealFromBits<double>(..., 1); => U(0, 2)
|
||||
//
|
||||
template <typename RealType, // Real type, either float or double.
|
||||
typename SignedTag = GeneratePositiveTag, // Whether a positive,
|
||||
// negative, or signed
|
||||
// value is generated.
|
||||
bool IncludeZero = true>
|
||||
inline RealType GenerateRealFromBits(uint64_t bits, int exp_bias = 0) {
|
||||
using real_type = RealType;
|
||||
using uint_type = absl::conditional_t<std::is_same<real_type, float>::value,
|
||||
uint32_t, uint64_t>;
|
||||
|
||||
static_assert(
|
||||
(std::is_same<double, real_type>::value ||
|
||||
std::is_same<float, real_type>::value),
|
||||
"GenerateRealFromBits must be parameterized by either float or double.");
|
||||
|
||||
static_assert(sizeof(uint_type) == sizeof(real_type),
|
||||
"Mismatched unsinged and real types.");
|
||||
|
||||
static_assert((std::numeric_limits<real_type>::is_iec559 &&
|
||||
std::numeric_limits<real_type>::radix == 2),
|
||||
"RealType representation is not IEEE 754 binary.");
|
||||
|
||||
static_assert((std::is_same<SignedTag, GeneratePositiveTag>::value ||
|
||||
std::is_same<SignedTag, GenerateNegativeTag>::value ||
|
||||
std::is_same<SignedTag, GenerateSignedTag>::value),
|
||||
"");
|
||||
|
||||
static constexpr int kExp = std::numeric_limits<real_type>::digits - 1;
|
||||
static constexpr uint_type kMask = (static_cast<uint_type>(1) << kExp) - 1u;
|
||||
static constexpr int kUintBits = sizeof(uint_type) * 8;
|
||||
|
||||
int exp = exp_bias + int{std::numeric_limits<real_type>::max_exponent - 2};
|
||||
|
||||
// Determine the sign bit.
|
||||
// Depending on the SignedTag, this may use the left-most bit
|
||||
// or it may be a constant value.
|
||||
uint_type sign = std::is_same<SignedTag, GenerateNegativeTag>::value
|
||||
? (static_cast<uint_type>(1) << (kUintBits - 1))
|
||||
: 0;
|
||||
if (std::is_same<SignedTag, GenerateSignedTag>::value) {
|
||||
if (std::is_same<uint_type, uint64_t>::value) {
|
||||
sign = bits & uint64_t{0x8000000000000000};
|
||||
}
|
||||
if (std::is_same<uint_type, uint32_t>::value) {
|
||||
const uint64_t tmp = bits & uint64_t{0x8000000000000000};
|
||||
sign = static_cast<uint32_t>(tmp >> 32);
|
||||
}
|
||||
// adjust the bits and the exponent to account for removing
|
||||
// the leading bit.
|
||||
bits = bits & uint64_t{0x7FFFFFFFFFFFFFFF};
|
||||
exp++;
|
||||
}
|
||||
if (IncludeZero) {
|
||||
if (bits == 0u) return 0;
|
||||
}
|
||||
|
||||
// Number of leading zeros is mapped to the exponent: 2^-clz
|
||||
// bits is 0..01xxxxxx. After shifting, we're left with 1xxx...0..0
|
||||
int clz = base_internal::CountLeadingZeros64(bits);
|
||||
bits <<= (IncludeZero ? clz : (clz & 63)); // remove 0-bits.
|
||||
exp -= clz; // set the exponent.
|
||||
bits >>= (63 - kExp);
|
||||
|
||||
// Construct the 32-bit or 64-bit IEEE 754 floating-point value from
|
||||
// the individual fields: sign, exp, mantissa(bits).
|
||||
uint_type val =
|
||||
(std::is_same<SignedTag, GeneratePositiveTag>::value ? 0u : sign) |
|
||||
(static_cast<uint_type>(exp) << kExp) |
|
||||
(static_cast<uint_type>(bits) & kMask);
|
||||
|
||||
// bit_cast to the output-type
|
||||
real_type result;
|
||||
memcpy(static_cast<void*>(&result), static_cast<const void*>(&val),
|
||||
sizeof(result));
|
||||
return result;
|
||||
}
|
||||
|
||||
} // namespace random_internal
|
||||
} // namespace absl
|
||||
|
||||
#endif // ABSL_RANDOM_INTERNAL_GENERATE_REAL_H_
|
||||
|
|
@ -12,57 +12,74 @@
|
|||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
#include "absl/random/internal/distribution_impl.h"
|
||||
#include "absl/random/internal/generate_real.h"
|
||||
|
||||
#include <cfloat>
|
||||
#include <cstddef>
|
||||
#include <cstdint>
|
||||
#include <string>
|
||||
|
||||
#include "gtest/gtest.h"
|
||||
#include "absl/base/internal/bits.h"
|
||||
#include "absl/flags/flag.h"
|
||||
#include "absl/numeric/int128.h"
|
||||
|
||||
ABSL_FLAG(int64_t, absl_random_test_trials, 50000,
|
||||
"Number of trials for the probability tests.");
|
||||
|
||||
using absl::random_internal::NegativeValueT;
|
||||
using absl::random_internal::PositiveValueT;
|
||||
using absl::random_internal::RandU64ToDouble;
|
||||
using absl::random_internal::RandU64ToFloat;
|
||||
using absl::random_internal::SignedValueT;
|
||||
using absl::random_internal::GenerateNegativeTag;
|
||||
using absl::random_internal::GeneratePositiveTag;
|
||||
using absl::random_internal::GenerateRealFromBits;
|
||||
using absl::random_internal::GenerateSignedTag;
|
||||
|
||||
namespace {
|
||||
|
||||
TEST(DistributionImplTest, U64ToFloat_Positive_NoZero_Test) {
|
||||
TEST(GenerateRealTest, U64ToFloat_Positive_NoZero_Test) {
|
||||
auto ToFloat = [](uint64_t a) {
|
||||
return RandU64ToFloat<PositiveValueT, false>(a);
|
||||
return GenerateRealFromBits<float, GeneratePositiveTag, false>(a);
|
||||
};
|
||||
EXPECT_EQ(ToFloat(0x0000000000000000), 2.710505431e-20f);
|
||||
EXPECT_EQ(ToFloat(0x0000000000000001), 5.421010862e-20f);
|
||||
EXPECT_EQ(ToFloat(0x8000000000000000), 0.5);
|
||||
EXPECT_EQ(ToFloat(0x8000000000000001), 0.5);
|
||||
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), 0.9999999404f);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToFloat_Positive_Zero_Test) {
|
||||
TEST(GenerateRealTest, U64ToFloat_Positive_Zero_Test) {
|
||||
auto ToFloat = [](uint64_t a) {
|
||||
return RandU64ToFloat<PositiveValueT, true>(a);
|
||||
return GenerateRealFromBits<float, GeneratePositiveTag, true>(a);
|
||||
};
|
||||
EXPECT_EQ(ToFloat(0x0000000000000000), 0.0);
|
||||
EXPECT_EQ(ToFloat(0x0000000000000001), 5.421010862e-20f);
|
||||
EXPECT_EQ(ToFloat(0x8000000000000000), 0.5);
|
||||
EXPECT_EQ(ToFloat(0x8000000000000001), 0.5);
|
||||
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), 0.9999999404f);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToFloat_Negative_NoZero_Test) {
|
||||
TEST(GenerateRealTest, U64ToFloat_Negative_NoZero_Test) {
|
||||
auto ToFloat = [](uint64_t a) {
|
||||
return RandU64ToFloat<NegativeValueT, false>(a);
|
||||
return GenerateRealFromBits<float, GenerateNegativeTag, false>(a);
|
||||
};
|
||||
EXPECT_EQ(ToFloat(0x0000000000000000), -2.710505431e-20f);
|
||||
EXPECT_EQ(ToFloat(0x0000000000000001), -5.421010862e-20f);
|
||||
EXPECT_EQ(ToFloat(0x8000000000000000), -0.5);
|
||||
EXPECT_EQ(ToFloat(0x8000000000000001), -0.5);
|
||||
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), -0.9999999404f);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToFloat_Signed_NoZero_Test) {
|
||||
TEST(GenerateRealTest, U64ToFloat_Negative_Zero_Test) {
|
||||
auto ToFloat = [](uint64_t a) {
|
||||
return RandU64ToFloat<SignedValueT, false>(a);
|
||||
return GenerateRealFromBits<float, GenerateNegativeTag, true>(a);
|
||||
};
|
||||
EXPECT_EQ(ToFloat(0x0000000000000000), 0.0);
|
||||
EXPECT_EQ(ToFloat(0x0000000000000001), -5.421010862e-20f);
|
||||
EXPECT_EQ(ToFloat(0x8000000000000000), -0.5);
|
||||
EXPECT_EQ(ToFloat(0x8000000000000001), -0.5);
|
||||
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), -0.9999999404f);
|
||||
}
|
||||
|
||||
TEST(GenerateRealTest, U64ToFloat_Signed_NoZero_Test) {
|
||||
auto ToFloat = [](uint64_t a) {
|
||||
return GenerateRealFromBits<float, GenerateSignedTag, false>(a);
|
||||
};
|
||||
EXPECT_EQ(ToFloat(0x0000000000000000), 5.421010862e-20f);
|
||||
EXPECT_EQ(ToFloat(0x0000000000000001), 1.084202172e-19f);
|
||||
|
|
@ -72,9 +89,9 @@ TEST(DistributionImplTest, U64ToFloat_Signed_NoZero_Test) {
|
|||
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), -0.9999999404f);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToFloat_Signed_Zero_Test) {
|
||||
TEST(GenerateRealTest, U64ToFloat_Signed_Zero_Test) {
|
||||
auto ToFloat = [](uint64_t a) {
|
||||
return RandU64ToFloat<SignedValueT, true>(a);
|
||||
return GenerateRealFromBits<float, GenerateSignedTag, true>(a);
|
||||
};
|
||||
EXPECT_EQ(ToFloat(0x0000000000000000), 0);
|
||||
EXPECT_EQ(ToFloat(0x0000000000000001), 1.084202172e-19f);
|
||||
|
|
@ -84,9 +101,9 @@ TEST(DistributionImplTest, U64ToFloat_Signed_Zero_Test) {
|
|||
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), -0.9999999404f);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToFloat_Signed_Bias_Test) {
|
||||
TEST(GenerateRealTest, U64ToFloat_Signed_Bias_Test) {
|
||||
auto ToFloat = [](uint64_t a) {
|
||||
return RandU64ToFloat<SignedValueT, true, 1>(a);
|
||||
return GenerateRealFromBits<float, GenerateSignedTag, true>(a, 1);
|
||||
};
|
||||
EXPECT_EQ(ToFloat(0x0000000000000000), 0);
|
||||
EXPECT_EQ(ToFloat(0x0000000000000001), 2 * 1.084202172e-19f);
|
||||
|
|
@ -96,9 +113,9 @@ TEST(DistributionImplTest, U64ToFloat_Signed_Bias_Test) {
|
|||
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), 2 * -0.9999999404f);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToFloatTest) {
|
||||
TEST(GenerateRealTest, U64ToFloatTest) {
|
||||
auto ToFloat = [](uint64_t a) -> float {
|
||||
return RandU64ToFloat<PositiveValueT, true>(a);
|
||||
return GenerateRealFromBits<float, GeneratePositiveTag, true>(a);
|
||||
};
|
||||
|
||||
EXPECT_EQ(ToFloat(0x0000000000000000), 0.0f);
|
||||
|
|
@ -150,44 +167,60 @@ TEST(DistributionImplTest, U64ToFloatTest) {
|
|||
}
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToDouble_Positive_NoZero_Test) {
|
||||
TEST(GenerateRealTest, U64ToDouble_Positive_NoZero_Test) {
|
||||
auto ToDouble = [](uint64_t a) {
|
||||
return RandU64ToDouble<PositiveValueT, false>(a);
|
||||
return GenerateRealFromBits<double, GeneratePositiveTag, false>(a);
|
||||
};
|
||||
|
||||
EXPECT_EQ(ToDouble(0x0000000000000000), 2.710505431213761085e-20);
|
||||
EXPECT_EQ(ToDouble(0x0000000000000001), 5.42101086242752217004e-20);
|
||||
EXPECT_EQ(ToDouble(0x0000000000000002), 1.084202172485504434e-19);
|
||||
EXPECT_EQ(ToDouble(0x8000000000000000), 0.5);
|
||||
EXPECT_EQ(ToDouble(0x8000000000000001), 0.5);
|
||||
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), 0.999999999999999888978);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToDouble_Positive_Zero_Test) {
|
||||
TEST(GenerateRealTest, U64ToDouble_Positive_Zero_Test) {
|
||||
auto ToDouble = [](uint64_t a) {
|
||||
return RandU64ToDouble<PositiveValueT, true>(a);
|
||||
return GenerateRealFromBits<double, GeneratePositiveTag, true>(a);
|
||||
};
|
||||
|
||||
EXPECT_EQ(ToDouble(0x0000000000000000), 0.0);
|
||||
EXPECT_EQ(ToDouble(0x0000000000000001), 5.42101086242752217004e-20);
|
||||
EXPECT_EQ(ToDouble(0x8000000000000000), 0.5);
|
||||
EXPECT_EQ(ToDouble(0x8000000000000001), 0.5);
|
||||
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), 0.999999999999999888978);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToDouble_Negative_NoZero_Test) {
|
||||
TEST(GenerateRealTest, U64ToDouble_Negative_NoZero_Test) {
|
||||
auto ToDouble = [](uint64_t a) {
|
||||
return RandU64ToDouble<NegativeValueT, false>(a);
|
||||
return GenerateRealFromBits<double, GenerateNegativeTag, false>(a);
|
||||
};
|
||||
|
||||
EXPECT_EQ(ToDouble(0x0000000000000000), -2.710505431213761085e-20);
|
||||
EXPECT_EQ(ToDouble(0x0000000000000001), -5.42101086242752217004e-20);
|
||||
EXPECT_EQ(ToDouble(0x0000000000000002), -1.084202172485504434e-19);
|
||||
EXPECT_EQ(ToDouble(0x8000000000000000), -0.5);
|
||||
EXPECT_EQ(ToDouble(0x8000000000000001), -0.5);
|
||||
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToDouble_Signed_NoZero_Test) {
|
||||
TEST(GenerateRealTest, U64ToDouble_Negative_Zero_Test) {
|
||||
auto ToDouble = [](uint64_t a) {
|
||||
return RandU64ToDouble<SignedValueT, false>(a);
|
||||
return GenerateRealFromBits<double, GenerateNegativeTag, true>(a);
|
||||
};
|
||||
|
||||
EXPECT_EQ(ToDouble(0x0000000000000000), 0.0);
|
||||
EXPECT_EQ(ToDouble(0x0000000000000001), -5.42101086242752217004e-20);
|
||||
EXPECT_EQ(ToDouble(0x0000000000000002), -1.084202172485504434e-19);
|
||||
EXPECT_EQ(ToDouble(0x8000000000000000), -0.5);
|
||||
EXPECT_EQ(ToDouble(0x8000000000000001), -0.5);
|
||||
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978);
|
||||
}
|
||||
|
||||
TEST(GenerateRealTest, U64ToDouble_Signed_NoZero_Test) {
|
||||
auto ToDouble = [](uint64_t a) {
|
||||
return GenerateRealFromBits<double, GenerateSignedTag, false>(a);
|
||||
};
|
||||
|
||||
EXPECT_EQ(ToDouble(0x0000000000000000), 5.42101086242752217004e-20);
|
||||
|
|
@ -198,9 +231,9 @@ TEST(DistributionImplTest, U64ToDouble_Signed_NoZero_Test) {
|
|||
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToDouble_Signed_Zero_Test) {
|
||||
TEST(GenerateRealTest, U64ToDouble_Signed_Zero_Test) {
|
||||
auto ToDouble = [](uint64_t a) {
|
||||
return RandU64ToDouble<SignedValueT, true>(a);
|
||||
return GenerateRealFromBits<double, GenerateSignedTag, true>(a);
|
||||
};
|
||||
EXPECT_EQ(ToDouble(0x0000000000000000), 0);
|
||||
EXPECT_EQ(ToDouble(0x0000000000000001), 1.084202172485504434e-19);
|
||||
|
|
@ -210,9 +243,9 @@ TEST(DistributionImplTest, U64ToDouble_Signed_Zero_Test) {
|
|||
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToDouble_Signed_Bias_Test) {
|
||||
TEST(GenerateRealTest, U64ToDouble_GenerateSignedTag_Bias_Test) {
|
||||
auto ToDouble = [](uint64_t a) {
|
||||
return RandU64ToDouble<SignedValueT, true, -1>(a);
|
||||
return GenerateRealFromBits<double, GenerateSignedTag, true>(a, -1);
|
||||
};
|
||||
EXPECT_EQ(ToDouble(0x0000000000000000), 0);
|
||||
EXPECT_EQ(ToDouble(0x0000000000000001), 1.084202172485504434e-19 / 2);
|
||||
|
|
@ -222,9 +255,9 @@ TEST(DistributionImplTest, U64ToDouble_Signed_Bias_Test) {
|
|||
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978 / 2);
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToDoubleTest) {
|
||||
TEST(GenerateRealTest, U64ToDoubleTest) {
|
||||
auto ToDouble = [](uint64_t a) {
|
||||
return RandU64ToDouble<PositiveValueT, true>(a);
|
||||
return GenerateRealFromBits<double, GeneratePositiveTag, true>(a);
|
||||
};
|
||||
|
||||
EXPECT_EQ(ToDouble(0x0000000000000000), 0.0);
|
||||
|
|
@ -296,9 +329,9 @@ TEST(DistributionImplTest, U64ToDoubleTest) {
|
|||
}
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, U64ToDoubleSignedTest) {
|
||||
TEST(GenerateRealTest, U64ToDoubleSignedTest) {
|
||||
auto ToDouble = [](uint64_t a) {
|
||||
return RandU64ToDouble<SignedValueT, false>(a);
|
||||
return GenerateRealFromBits<double, GenerateSignedTag, false>(a);
|
||||
};
|
||||
|
||||
EXPECT_EQ(ToDouble(0x0000000000000000), 5.42101086242752217004e-20);
|
||||
|
|
@ -379,10 +412,10 @@ TEST(DistributionImplTest, U64ToDoubleSignedTest) {
|
|||
}
|
||||
}
|
||||
|
||||
TEST(DistributionImplTest, ExhaustiveFloat) {
|
||||
TEST(GenerateRealTest, ExhaustiveFloat) {
|
||||
using absl::base_internal::CountLeadingZeros64;
|
||||
auto ToFloat = [](uint64_t a) {
|
||||
return RandU64ToFloat<PositiveValueT, true>(a);
|
||||
return GenerateRealFromBits<float, GeneratePositiveTag, true>(a);
|
||||
};
|
||||
|
||||
// Rely on RandU64ToFloat generating values from greatest to least when
|
||||
|
|
@ -23,8 +23,8 @@
|
|||
#include <ostream>
|
||||
#include <type_traits>
|
||||
|
||||
#include "absl/random/internal/distribution_impl.h"
|
||||
#include "absl/random/internal/fastmath.h"
|
||||
#include "absl/random/internal/generate_real.h"
|
||||
#include "absl/random/internal/iostream_state_saver.h"
|
||||
#include "absl/random/internal/traits.h"
|
||||
#include "absl/random/uniform_int_distribution.h"
|
||||
|
|
|
|||
|
|
@ -22,9 +22,9 @@
|
|||
#include <ostream>
|
||||
#include <type_traits>
|
||||
|
||||
#include "absl/random/internal/distribution_impl.h"
|
||||
#include "absl/random/internal/fast_uniform_bits.h"
|
||||
#include "absl/random/internal/fastmath.h"
|
||||
#include "absl/random/internal/generate_real.h"
|
||||
#include "absl/random/internal/iostream_state_saver.h"
|
||||
|
||||
namespace absl {
|
||||
|
|
@ -164,9 +164,9 @@ typename poisson_distribution<IntType>::result_type
|
|||
poisson_distribution<IntType>::operator()(
|
||||
URBG& g, // NOLINT(runtime/references)
|
||||
const param_type& p) {
|
||||
using random_internal::PositiveValueT;
|
||||
using random_internal::RandU64ToDouble;
|
||||
using random_internal::SignedValueT;
|
||||
using random_internal::GeneratePositiveTag;
|
||||
using random_internal::GenerateRealFromBits;
|
||||
using random_internal::GenerateSignedTag;
|
||||
|
||||
if (p.split_ != 0) {
|
||||
// Use Knuth's algorithm with range splitting to avoid floating-point
|
||||
|
|
@ -186,7 +186,8 @@ poisson_distribution<IntType>::operator()(
|
|||
for (int split = p.split_; split > 0; --split) {
|
||||
double r = 1.0;
|
||||
do {
|
||||
r *= RandU64ToDouble<PositiveValueT, true>(fast_u64_(g));
|
||||
r *= GenerateRealFromBits<double, GeneratePositiveTag, true>(
|
||||
fast_u64_(g)); // U(-1, 0)
|
||||
++n;
|
||||
} while (r > p.emu_);
|
||||
--n;
|
||||
|
|
@ -205,10 +206,11 @@ poisson_distribution<IntType>::operator()(
|
|||
// and k = max(f).
|
||||
const double a = p.mean_ + 0.5;
|
||||
for (;;) {
|
||||
const double u =
|
||||
RandU64ToDouble<PositiveValueT, false>(fast_u64_(g)); // (0, 1)
|
||||
const double v =
|
||||
RandU64ToDouble<SignedValueT, false>(fast_u64_(g)); // (-1, 1)
|
||||
const double u = GenerateRealFromBits<double, GeneratePositiveTag, false>(
|
||||
fast_u64_(g)); // U(0, 1)
|
||||
const double v = GenerateRealFromBits<double, GenerateSignedTag, false>(
|
||||
fast_u64_(g)); // U(-1, 1)
|
||||
|
||||
const double x = std::floor(p.s_ * v / u + a);
|
||||
if (x < 0) continue; // f(negative) = 0
|
||||
const double rhs = x * p.lmu_;
|
||||
|
|
|
|||
|
|
@ -34,7 +34,6 @@
|
|||
#include <type_traits>
|
||||
|
||||
#include "absl/base/optimization.h"
|
||||
#include "absl/random/internal/distribution_impl.h"
|
||||
#include "absl/random/internal/fast_uniform_bits.h"
|
||||
#include "absl/random/internal/iostream_state_saver.h"
|
||||
#include "absl/random/internal/traits.h"
|
||||
|
|
|
|||
|
|
@ -39,8 +39,9 @@
|
|||
#include <limits>
|
||||
#include <type_traits>
|
||||
|
||||
#include "absl/random/internal/distribution_impl.h"
|
||||
#include "absl/meta/type_traits.h"
|
||||
#include "absl/random/internal/fast_uniform_bits.h"
|
||||
#include "absl/random/internal/generate_real.h"
|
||||
#include "absl/random/internal/iostream_state_saver.h"
|
||||
|
||||
namespace absl {
|
||||
|
|
@ -76,6 +77,7 @@ class uniform_real_distribution {
|
|||
// is not possible, so value generation cannot use the full range of the
|
||||
// real type.
|
||||
assert(range_ <= (std::numeric_limits<result_type>::max)());
|
||||
assert(std::isfinite(range_));
|
||||
}
|
||||
|
||||
result_type a() const { return lo_; }
|
||||
|
|
@ -151,10 +153,15 @@ template <typename URBG>
|
|||
typename uniform_real_distribution<RealType>::result_type
|
||||
uniform_real_distribution<RealType>::operator()(
|
||||
URBG& gen, const param_type& p) { // NOLINT(runtime/references)
|
||||
using random_internal::PositiveValueT;
|
||||
using random_internal::GeneratePositiveTag;
|
||||
using random_internal::GenerateRealFromBits;
|
||||
using real_type =
|
||||
absl::conditional_t<std::is_same<RealType, float>::value, float, double>;
|
||||
|
||||
while (true) {
|
||||
const result_type sample = random_internal::RandU64ToReal<
|
||||
result_type>::template Value<PositiveValueT, true>(fast_u64_(gen));
|
||||
const result_type sample =
|
||||
GenerateRealFromBits<real_type, GeneratePositiveTag, true>(
|
||||
fast_u64_(gen));
|
||||
const result_type res = p.a() + (sample * p.range_);
|
||||
if (res < p.b() || p.range_ <= 0 || !std::isfinite(p.range_)) {
|
||||
return res;
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue