add Windows support

README.md

@@ -4,7 +4,7 @@ Streamed C++ [ULog](https://docs.px4.io/main/en/dev_log/ulog_file_format.html) r
 
 ## Properties
 - Options for keeping log data in memory or processing immediately.
-- Pure C++17 without additional dependencies (`SimpleWriter` requires POSIX for file IO).
+- Pure C++17 without additional dependencies (`SimpleWriter` requires platform-specific `fsync`/`FlushFileBuffers`).
 - The reader is ~10 times as fast compared to the [python implementation](https://github.com/PX4/pyulog).
   However, the API is more low-level, and if you're just looking for an easy-to-use parsing library, use pyulog.
 - Unsupported ULog features:

ulog_cpp/messages.cpp

@@ -278,7 +278,7 @@ Value::NativeTypeVariant Value::asNativeTypeVariant() const
         if (_backing_ref_end - string_start_iterator < _field_ref.arrayLength()) {
           throw AccessException("Decoding fault, memory too short");
         }
-        int string_length = strnlen(string_start_iterator.base(), _field_ref.arrayLength());
+        const int string_length = strnlen(&(*string_start_iterator), _field_ref.arrayLength());
         return std::string(string_start_iterator, string_start_iterator + string_length);
       }
 

ulog_cpp/messages.hpp

@@ -586,7 +586,7 @@ class MessageFormat {
   /**
    * @return the list of fields, in-order
    */
-  std::vector<std::shared_ptr<Field>> fields() const { return _fields_ordered; }
+  const std::vector<std::shared_ptr<Field>>& fields() const { return _fields_ordered; }
 
   /**
    * @return the list of field names, in-order

ulog_cpp/simple_writer.cpp

@@ -5,7 +5,12 @@
 
 #include "simple_writer.hpp"
 
+#ifdef _WIN32
+#include <fileapi.h>
+#include <windows.h>  // NOLINT
+#else
 #include <unistd.h>
+#endif
 
 namespace ulog_cpp {
 
@@ -108,7 +113,11 @@ void SimpleWriter::fsync()
 {
   if (_file) {
     fflush(_file);
+#ifdef _WIN32
+    FlushFileBuffers(reinterpret_cast<HANDLE>(static_cast<uintptr_t>(_fileno(_file))));
+#else
     ::fsync(fileno(_file));
+#endif
   }
 }
 uint16_t SimpleWriter::writeAddLoggedMessage(const std::string& message_format_name,