Fill in gpio-util functionality

Process the command line arguments to know which GPIO
to set and what to set it to. Then create the GPIO
object and call the appropriate functions on it.

Change-Id: Ib8da78e5ae92e5ae0716901aa71243226668be10
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/gpio-util/argument.cpp b/gpio-util/argument.cpp
new file mode 100644
index 0000000..222b7d3
--- /dev/null
+++ b/gpio-util/argument.cpp
@@ -0,0 +1,95 @@
+/**
+ * Copyright © 2017 IBM Corporation
+ *
+ * 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.
+ */
+#include <iostream>
+#include <iterator>
+#include <algorithm>
+#include "argument.hpp"
+
+namespace phosphor
+{
+namespace gpio
+{
+
+ArgumentParser::ArgumentParser(int argc, char** argv)
+{
+    int option = 0;
+    while (-1 != (option = getopt_long(argc, argv, optionStr, options, NULL)))
+    {
+        if ((option == '?') || (option == 'h'))
+        {
+            usage(argv);
+            exit(-1);
+        }
+
+        auto i = &options[0];
+        while ((i->val != option) && (i->val != 0))
+        {
+            ++i;
+        }
+
+        if (i->val)
+        {
+            arguments[i->name] = (i->has_arg ? optarg : trueString);
+        }
+    }
+}
+
+const std::string& ArgumentParser::operator[](const std::string& opt)
+{
+    auto i = arguments.find(opt);
+    if (i == arguments.end())
+    {
+        return emptyString;
+    }
+    else
+    {
+        return i->second;
+    }
+}
+
+void ArgumentParser::usage(char** argv)
+{
+    std::cerr << "Usage: " << argv[0] << " [options]\n";
+    std::cerr << "Options:\n";
+    std::cerr << "    --help            Print this menu.\n";
+    std::cerr << "    --gpio=<gpio>     The GPIO number.  Example: 1\n";
+    std::cerr << "    --path=<path>     The path to the GPIO device."
+                                        "  Example: /dev/gpiochip0\n";
+    std::cerr << "    --delay=<delay>   The delay in ms in between a toggle."
+                                        "  Example: 5\n";
+    std::cerr << "    --action=<action> The action to do.\n";
+    std::cerr << "                      Valid actions: low, high, low_high, "
+                                        "high_low\n";
+    std::cerr << std::flush;
+}
+
+const option ArgumentParser::options[] =
+{
+    { "action", required_argument, NULL, 'a' },
+    { "gpio",   required_argument, NULL, 'g' },
+    { "delay",  required_argument, NULL, 'd' },
+    { "path",   required_argument, NULL, 'p' },
+    { "help",   no_argument,       NULL, 'h' },
+    { 0, 0, 0, 0},
+};
+
+const char* ArgumentParser::optionStr = "a:g:d:p:h?";
+
+const std::string ArgumentParser::trueString = "true";
+const std::string ArgumentParser::emptyString = "";
+
+}
+}