summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--.gitignore16
-rw-r--r--LICENSE202
-rw-r--r--build.ninja26
-rw-r--r--dewpoint.cc163
4 files changed, 407 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..0082cc7
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,16 @@
+# Copyright 2021 Benjamin Barenblat
+#
+# 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.
+
+.ninja_*
+dewpoint \ No newline at end of file
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..d645695
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,202 @@
+
+ Apache License
+ Version 2.0, January 2004
+ http://www.apache.org/licenses/
+
+ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+ 1. Definitions.
+
+ "License" shall mean the terms and conditions for use, reproduction,
+ and distribution as defined by Sections 1 through 9 of this document.
+
+ "Licensor" shall mean the copyright owner or entity authorized by
+ the copyright owner that is granting the License.
+
+ "Legal Entity" shall mean the union of the acting entity and all
+ other entities that control, are controlled by, or are under common
+ control with that entity. For the purposes of this definition,
+ "control" means (i) the power, direct or indirect, to cause the
+ direction or management of such entity, whether by contract or
+ otherwise, or (ii) ownership of fifty percent (50%) or more of the
+ outstanding shares, or (iii) beneficial ownership of such entity.
+
+ "You" (or "Your") shall mean an individual or Legal Entity
+ exercising permissions granted by this License.
+
+ "Source" form shall mean the preferred form for making modifications,
+ including but not limited to software source code, documentation
+ source, and configuration files.
+
+ "Object" form shall mean any form resulting from mechanical
+ transformation or translation of a Source form, including but
+ not limited to compiled object code, generated documentation,
+ and conversions to other media types.
+
+ "Work" shall mean the work of authorship, whether in Source or
+ Object form, made available under the License, as indicated by a
+ copyright notice that is included in or attached to the work
+ (an example is provided in the Appendix below).
+
+ "Derivative Works" shall mean any work, whether in Source or Object
+ form, that is based on (or derived from) the Work and for which the
+ editorial revisions, annotations, elaborations, or other modifications
+ represent, as a whole, an original work of authorship. For the purposes
+ of this License, Derivative Works shall not include works that remain
+ separable from, or merely link (or bind by name) to the interfaces of,
+ the Work and Derivative Works thereof.
+
+ "Contribution" shall mean any work of authorship, including
+ the original version of the Work and any modifications or additions
+ to that Work or Derivative Works thereof, that is intentionally
+ submitted to Licensor for inclusion in the Work by the copyright owner
+ or by an individual or Legal Entity authorized to submit on behalf of
+ the copyright owner. For the purposes of this definition, "submitted"
+ means any form of electronic, verbal, or written communication sent
+ to the Licensor or its representatives, including but not limited to
+ communication on electronic mailing lists, source code control systems,
+ and issue tracking systems that are managed by, or on behalf of, the
+ Licensor for the purpose of discussing and improving the Work, but
+ excluding communication that is conspicuously marked or otherwise
+ designated in writing by the copyright owner as "Not a Contribution."
+
+ "Contributor" shall mean Licensor and any individual or Legal Entity
+ on behalf of whom a Contribution has been received by Licensor and
+ subsequently incorporated within the Work.
+
+ 2. Grant of Copyright License. Subject to the terms and conditions of
+ this License, each Contributor hereby grants to You a perpetual,
+ worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+ copyright license to reproduce, prepare Derivative Works of,
+ publicly display, publicly perform, sublicense, and distribute the
+ Work and such Derivative Works in Source or Object form.
+
+ 3. Grant of Patent License. Subject to the terms and conditions of
+ this License, each Contributor hereby grants to You a perpetual,
+ worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+ (except as stated in this section) patent license to make, have made,
+ use, offer to sell, sell, import, and otherwise transfer the Work,
+ where such license applies only to those patent claims licensable
+ by such Contributor that are necessarily infringed by their
+ Contribution(s) alone or by combination of their Contribution(s)
+ with the Work to which such Contribution(s) was submitted. If You
+ institute patent litigation against any entity (including a
+ cross-claim or counterclaim in a lawsuit) alleging that the Work
+ or a Contribution incorporated within the Work constitutes direct
+ or contributory patent infringement, then any patent licenses
+ granted to You under this License for that Work shall terminate
+ as of the date such litigation is filed.
+
+ 4. Redistribution. You may reproduce and distribute copies of the
+ Work or Derivative Works thereof in any medium, with or without
+ modifications, and in Source or Object form, provided that You
+ meet the following conditions:
+
+ (a) You must give any other recipients of the Work or
+ Derivative Works a copy of this License; and
+
+ (b) You must cause any modified files to carry prominent notices
+ stating that You changed the files; and
+
+ (c) You must retain, in the Source form of any Derivative Works
+ that You distribute, all copyright, patent, trademark, and
+ attribution notices from the Source form of the Work,
+ excluding those notices that do not pertain to any part of
+ the Derivative Works; and
+
+ (d) If the Work includes a "NOTICE" text file as part of its
+ distribution, then any Derivative Works that You distribute must
+ include a readable copy of the attribution notices contained
+ within such NOTICE file, excluding those notices that do not
+ pertain to any part of the Derivative Works, in at least one
+ of the following places: within a NOTICE text file distributed
+ as part of the Derivative Works; within the Source form or
+ documentation, if provided along with the Derivative Works; or,
+ within a display generated by the Derivative Works, if and
+ wherever such third-party notices normally appear. The contents
+ of the NOTICE file are for informational purposes only and
+ do not modify the License. You may add Your own attribution
+ notices within Derivative Works that You distribute, alongside
+ or as an addendum to the NOTICE text from the Work, provided
+ that such additional attribution notices cannot be construed
+ as modifying the License.
+
+ You may add Your own copyright statement to Your modifications and
+ may provide additional or different license terms and conditions
+ for use, reproduction, or distribution of Your modifications, or
+ for any such Derivative Works as a whole, provided Your use,
+ reproduction, and distribution of the Work otherwise complies with
+ the conditions stated in this License.
+
+ 5. Submission of Contributions. Unless You explicitly state otherwise,
+ any Contribution intentionally submitted for inclusion in the Work
+ by You to the Licensor shall be under the terms and conditions of
+ this License, without any additional terms or conditions.
+ Notwithstanding the above, nothing herein shall supersede or modify
+ the terms of any separate license agreement you may have executed
+ with Licensor regarding such Contributions.
+
+ 6. Trademarks. This License does not grant permission to use the trade
+ names, trademarks, service marks, or product names of the Licensor,
+ except as required for reasonable and customary use in describing the
+ origin of the Work and reproducing the content of the NOTICE file.
+
+ 7. Disclaimer of Warranty. Unless required by applicable law or
+ agreed to in writing, Licensor provides the Work (and each
+ Contributor provides its Contributions) on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ implied, including, without limitation, any warranties or conditions
+ of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+ PARTICULAR PURPOSE. You are solely responsible for determining the
+ appropriateness of using or redistributing the Work and assume any
+ risks associated with Your exercise of permissions under this License.
+
+ 8. Limitation of Liability. In no event and under no legal theory,
+ whether in tort (including negligence), contract, or otherwise,
+ unless required by applicable law (such as deliberate and grossly
+ negligent acts) or agreed to in writing, shall any Contributor be
+ liable to You for damages, including any direct, indirect, special,
+ incidental, or consequential damages of any character arising as a
+ result of this License or out of the use or inability to use the
+ Work (including but not limited to damages for loss of goodwill,
+ work stoppage, computer failure or malfunction, or any and all
+ other commercial damages or losses), even if such Contributor
+ has been advised of the possibility of such damages.
+
+ 9. Accepting Warranty or Additional Liability. While redistributing
+ the Work or Derivative Works thereof, You may choose to offer,
+ and charge a fee for, acceptance of support, warranty, indemnity,
+ or other liability obligations and/or rights consistent with this
+ License. However, in accepting such obligations, You may act only
+ on Your own behalf and on Your sole responsibility, not on behalf
+ of any other Contributor, and only if You agree to indemnify,
+ defend, and hold each Contributor harmless for any liability
+ incurred by, or claims asserted against, such Contributor by reason
+ of your accepting any such warranty or additional liability.
+
+ END OF TERMS AND CONDITIONS
+
+ APPENDIX: How to apply the Apache License to your work.
+
+ To apply the Apache License to your work, attach the following
+ boilerplate notice, with the fields enclosed by brackets "[]"
+ replaced with your own identifying information. (Don't include
+ the brackets!) The text should be enclosed in the appropriate
+ comment syntax for the file format. We also recommend that a
+ file or class name and description of purpose be included on the
+ same "printed page" as the copyright notice for easier
+ identification within third-party archives.
+
+ Copyright [yyyy] [name of copyright owner]
+
+ 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
+
+ http://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.
diff --git a/build.ninja b/build.ninja
new file mode 100644
index 0000000..57fd2d4
--- /dev/null
+++ b/build.ninja
@@ -0,0 +1,26 @@
+# Copyright 2021 Benjamin Barenblat
+#
+# 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.
+
+cxx = g++
+
+cxxflags = -std=c++17 -Wall -Wextra -Wno-sign-compare -fdiagnostics-show-template-tree -pipe -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -O3 -DNDEBUG -fstack-protector-strong -ffunction-sections -fdata-sections -flto
+
+ldflags = -flto -Wl,-O2 -Wl,-z,relro -Wl,--gc-sections -Wl,--as-needed
+
+rule cxxld
+ command = $cxx $cxxflags $ldflags $in -o $out $libs
+ description = Compiling and linking $out
+
+build dewpoint: cxxld dewpoint.cc
+ libs = -lm
diff --git a/dewpoint.cc b/dewpoint.cc
new file mode 100644
index 0000000..4acb9e9
--- /dev/null
+++ b/dewpoint.cc
@@ -0,0 +1,163 @@
+// Copyright 2021 Benjamin Barenblat
+//
+// 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.
+
+#include <getopt.h>
+#include <locale.h>
+#include <math.h>
+#include <stdlib.h>
+
+#include <iostream>
+#include <optional>
+#include <string_view>
+
+namespace {
+
+constexpr std::string_view kShortUsage =
+ "Usage: dewpoint TEMPERATURE HUMIDITY\n";
+
+constexpr std::string_view kHelp =
+ R"(Compute the dew point from a given temperature and humidity. Temperatures are
+interpreted by default according to the current locale; humidity is interpreted
+as a percentage.
+
+Options:
+ -c, --celsius, --centigrade
+ use the Celsius temperature scale
+ -f, --fahrenheit use the Fahrenheit temperature scale
+ --help display this help and exit
+)";
+
+constexpr std::string_view kAskForHelp =
+ "Try 'dewpoint --help' for more information\n";
+
+enum {
+ kHelpLongOption = 128,
+};
+
+bool LocaleUsesFahrenheit(std::string_view locale) {
+ int underscore = locale.find('_');
+ int dot = locale.find('.');
+ if (underscore == std::string_view::npos || dot == std::string_view::npos ||
+ dot <= underscore) {
+ return false;
+ }
+ std::string_view territory =
+ locale.substr(underscore + 1, dot - underscore - 1);
+ return territory == "US" /* United States */ ||
+ territory == "LR" /* Liberia */ ||
+ territory == "FM" /* Micronesia */ ||
+ territory == "KY" /* Cayman Islands */ ||
+ territory == "MH" /* Marshall Islands */ ||
+ territory == "PW" /* Palau */;
+}
+
+std::optional<float> ReadFloat(const char* s) {
+ char* end;
+ float f = strtof(s, &end);
+ if (*end != '\0') {
+ return std::nullopt;
+ }
+ return f;
+}
+
+// Approximates the dew point of air at the specified temperature and relative
+// humidity using the Magnus formula. For a complete derivation, see equation 8
+// of Mark G. Lawrence, "The Relationship Between Relative Humidity and the
+// Dewpoint Temperature in Moist Air," Bulletin of the American Meteorological
+// Society 86(2) (February 2005), 225-234,
+// https://doi.org/10.1175/BAMS-86-2-225.
+float DewPoint(float celsius, float humidity) {
+ constexpr float kA = 17.625;
+ constexpr float kB = 243.04;
+
+ float x = log(humidity * 0.01f) + kA * celsius / (kB + celsius);
+ return kB * x / (kA - x);
+}
+
+float DewPointFahrenheit(float fahrenheit, float humidity) {
+ return 9.0f / 5.0f * DewPoint(5.0f / 9.0f * (fahrenheit - 32.0f), humidity) +
+ 32.0f;
+}
+
+} // namespace
+
+int main(int argc, char* argv[]) {
+ setlocale(LC_ALL, "");
+
+ std::string measurement_locale = "C";
+ if (const char* s = setlocale(LC_MEASUREMENT, ""); s != nullptr) {
+ measurement_locale = s;
+ }
+
+ const bool locale_uses_fahrenheit = LocaleUsesFahrenheit(measurement_locale);
+ bool use_fahrenheit = locale_uses_fahrenheit;
+
+ static option long_options[] = {
+ {"celsius", no_argument, nullptr, 'c'},
+ {"centigrade", no_argument, nullptr, 'c'},
+ {"fahrenheit", no_argument, nullptr, 'f'},
+ {"help", no_argument, nullptr, kHelpLongOption},
+ {nullptr, 0, nullptr, 0},
+ };
+ while (true) {
+ int c = getopt_long(argc, argv, "cf", long_options, nullptr);
+ if (c == -1) {
+ break;
+ }
+ switch (c) {
+ case 'c':
+ use_fahrenheit = false;
+ break;
+ case 'f':
+ use_fahrenheit = true;
+ break;
+ case kHelpLongOption:
+ std::cout << kShortUsage << kHelp
+ << "\nYour current measurement locale is "
+ << measurement_locale << ", which uses "
+ << (locale_uses_fahrenheit ? "Fahrenheit" : "Celsius")
+ << " by\ndefault.\n";
+ return 0;
+ case '?':
+ std::cerr << kAskForHelp;
+ return 1;
+ default:
+ std::cerr << "Internal error; please report.\n";
+ return 1;
+ }
+ }
+
+ if (optind != argc - 2) {
+ std::cerr << kShortUsage << kAskForHelp;
+ return 1;
+ }
+
+ std::optional<float> temperature = ReadFloat(argv[1]);
+ if (!temperature.has_value()) {
+ std::cerr << "dewpoint: invalid temperature \"" << argv[1] << "\"\n"
+ << kAskForHelp;
+ return 1;
+ }
+
+ std::optional<float> humidity = ReadFloat(argv[2]);
+ if (!humidity.has_value() || *humidity <= 0.0f) {
+ std::cerr << "dewpoint: invalid humidity \"" << argv[1] << "\"\n"
+ << kAskForHelp;
+ return 1;
+ }
+
+ float dew_point = use_fahrenheit ? DewPointFahrenheit(*temperature, *humidity)
+ : DewPoint(*temperature, *humidity);
+ std::cout << static_cast<int>(rintf(dew_point)) << '\n';
+}