diff options
| -rw-r--r-- | .gitignore | 16 | ||||
| -rw-r--r-- | LICENSE | 202 | ||||
| -rw-r--r-- | build.ninja | 26 | ||||
| -rw-r--r-- | dewpoint.cc | 163 |
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 @@ -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'; +} |