add gitignore for vscode.

add cmake build.
add main function in ulog_example.c.

Author: whwu

.gitignore

@@ -50,3 +50,5 @@ modules.order
 Module.symvers
 Mkfile.old
 dkms.conf
+build/
+.vscode

CMakeLists.txt

@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.5)
+
+project(ulog)
+
+add_subdirectory(tests)
+add_subdirectory(src)

src/CMakeLists.txt

@@ -0,0 +1,5 @@
+# Set the project name
+project(ulog)
+
+# Add a library with the above sources
+add_library(${PROJECT_NAME} ulog.c)

tests/CMakeLists.txt

@@ -0,0 +1,7 @@
+project(ulog_example)
+
+include_directories(${PROJECT_SOURCE_DIR}/../src)
+
+add_executable(ulog_example ulog_example.c)
+
+target_link_libraries(ulog_example ulog)

tests/ulog_example.c

@@ -0,0 +1,57 @@
+#include <stdio.h>
+#include "ulog.h"
+
+// To use uLog, you must define a function to process logging messages. It can
+// write the messages to a console, to a file, to an in-memory buffer: the
+// choice is yours.  And you get to choose the format of the message.
+//
+// The following example prints to the console.
+//
+// One caveat: msg is a static string and will be over-written at the next call
+// to ULOG.  This means you may print it or copy it, but saving a pointer to it
+// will lead to confusion and astonishment.
+//
+void my_console_logger(ulog_level_t severity, char *msg)
+{
+  printf("console: %s [%s]: %s\n",
+         "time", // user defined function
+         ulog_level_name(severity),
+         msg);
+}
+
+void my_file_logger(ulog_level_t severity, char *msg)
+{
+  printf("file: %s [%s]: %s\n",
+         "time", // user defined function
+         ulog_level_name(severity),
+         msg);
+}
+
+int main()
+{
+  int arg = 42;
+
+  ULOG_INIT();
+
+  // log messages with a severity of WARNING or higher to the console.  The
+  // user must supply a method for my_console_logger, e.g. along the lines
+  // of what is shown above.
+  ULOG_SUBSCRIBE(my_console_logger, ULOG_DEBUG_LEVEL);
+
+  // log messages with a severity of DEBUG or higher to a file.  The user must
+  // provide a method for my_file_logger (not shown here).
+  ULOG_SUBSCRIBE(my_file_logger, ULOG_WARNING_LEVEL);
+
+  ULOG_INFO("Info, arg=%d", arg);         // logs to file but not console
+  ULOG_CRITICAL("Critical, arg=%d", arg); // logs to file and console
+
+  // dynamically change the threshold for a specific logger
+  ULOG_SUBSCRIBE(my_console_logger, ULOG_INFO_LEVEL);
+
+  ULOG_INFO("Info, arg=%d", arg); // logs to file and console
+
+  // remove a logger
+  ULOG_UNSUBSCRIBE(my_file_logger);
+
+  ULOG_INFO("Info, arg=%d", arg); // logs to console only
+}