diff --git a/CalculatorCInterface.dll b/CalculatorCInterface.dll
index 4f2e819..baa9af2 100644
Binary files a/CalculatorCInterface.dll and b/CalculatorCInterface.dll differ
diff --git a/deploy/CalculatorCInterface.dll b/deploy/CalculatorCInterface.dll
index 4f2e819..baa9af2 100644
Binary files a/deploy/CalculatorCInterface.dll and b/deploy/CalculatorCInterface.dll differ
diff --git a/deploy/helloworld.exe b/deploy/helloworld.exe
index 7b6c969..5114fc5 100644
Binary files a/deploy/helloworld.exe and b/deploy/helloworld.exe differ
diff --git a/helloworld.exe b/helloworld.exe
index 7b6c969..5114fc5 100644
Binary files a/helloworld.exe and b/helloworld.exe differ
diff --git a/helloworld.lpi b/helloworld.lpi
new file mode 100644
index 0000000..ef82eec
--- /dev/null
+++ b/helloworld.lpi
@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<CONFIG>
+  <ProjectOptions>
+    <Version Value="12"/>
+    <PathDelim Value="\"/>
+    <General>
+      <Flags>
+        <MainUnitHasCreateFormStatements Value="False"/>
+        <MainUnitHasTitleStatement Value="False"/>
+        <MainUnitHasScaledStatement Value="False"/>
+      </Flags>
+      <SessionStorage Value="InProjectDir"/>
+      <Title Value="helloworld"/>
+      <UseAppBundle Value="False"/>
+      <ResourceType Value="res"/>
+    </General>
+    <BuildModes>
+      <Item Name="Default" Default="True"/>
+    </BuildModes>
+    <PublishOptions>
+      <Version Value="2"/>
+      <UseFileFilters Value="True"/>
+    </PublishOptions>
+    <RunParams>
+      <FormatVersion Value="2"/>
+    </RunParams>
+    <RequiredPackages>
+      <Item>
+        <PackageName Value="LazUtils"/>
+      </Item>
+    </RequiredPackages>
+    <Units>
+      <Unit>
+        <Filename Value="helloworld.lpr"/>
+        <IsPartOfProject Value="True"/>
+      </Unit>
+      <Unit>
+        <Filename Value="unit1.pas"/>
+        <IsPartOfProject Value="True"/>
+        <UnitName Value="Unit1"/>
+      </Unit>
+      <Unit>
+        <Filename Value="tariffcalculator.pas"/>
+        <IsPartOfProject Value="True"/>
+        <UnitName Value="TariffCalculator"/>
+      </Unit>
+    </Units>
+  </ProjectOptions>
+  <CompilerOptions>
+    <Version Value="11"/>
+    <PathDelim Value="\"/>
+    <Target>
+      <Filename Value="helloworld"/>
+    </Target>
+    <SearchPaths>
+      <IncludeFiles Value="$(ProjOutDir)"/>
+      <UnitOutputDirectory Value="lib\$(TargetCPU)-$(TargetOS)"/>
+    </SearchPaths>
+    <Linking>
+      <Debugging>
+        <DebugInfoType Value="dsDwarf3"/>
+      </Debugging>
+    </Linking>
+  </CompilerOptions>
+  <Debugging>
+    <Exceptions>
+      <Item>
+        <Name Value="EAbort"/>
+      </Item>
+      <Item>
+        <Name Value="ECodetoolError"/>
+      </Item>
+      <Item>
+        <Name Value="EFOpenError"/>
+      </Item>
+    </Exceptions>
+  </Debugging>
+</CONFIG>
diff --git a/helloworld.lpr b/helloworld.lpr
index bc7752b..6129a0e 100644
--- a/helloworld.lpr
+++ b/helloworld.lpr
@@ -6,29 +6,44 @@ program helloworld(output);
 
 
 uses
-    TariffCalculator, CTypes;
+    TariffCalculator, CTypes, LazUtils, LazFileUtils, LazUtf8;
 
 var
-   TariffCalc:  TariffCalculatorHandle;
+   //TariffCalc:  TariffCalculatorHandle;
    CustomerRepo: array[0..100] of char;
    LocalCustomerRepo: array[0..100] of char;
+   LocalBranchName: array[0..32] of char;
+   FileToCommit: array[0..128] of char;
+   CommitMessage: array[0..256] of char;
 
 begin
-writeLn('Hello, World!') ;
 // TariffCalc := NewTariffCalculator;
 // DeleteTariffCalculator(TariffCalc);
-   if InitGitLibrary() > 0 then
-        begin
-        writeLn('init OK!') ;
-        CustomerRepo := 'https://git.mimbach49.de/GerhardHoffmann/customer_999.git';
-        LocalCustomerRepo := 'C:\\tmp\\customer_999';
-        CloneRepository(CustomerRepo, LocalCustomerRepo);
 
-        ShutdownGitLibrary();
+   CustomerRepo := 'https://git.mimbach49.de/GerhardHoffmann/customer_999.git';
+   LocalCustomerRepo := 'C:\\tmp\\customer_999';
+   LocalBranchName := 'zg1/zone1';
+   FileToCommit := 'etc/psa_tariff/tariff01.json';
+   CommitMessage := 'TEST TEST';
+   if not DirectoryExistsUTF8(ExpandFilenameUtf8(LocalCustomerRepo)) then
+       CreateDirUTF8(ExpandFilenameUtf8(LocalCustomerRepo));
+
+   if InitGitLibrary() > 0 then
+        Try
+           writeLn('initialized git library') ;
+           if not DirectoryExistsUTF8(ExpandFilenameUtf8(LocalCustomerRepo+'\\.git')) then
+              CloneRepository(CustomerRepo, LocalCustomerRepo);
+           if not CheckoutLocalBranch(LocalCustomerRepo, LocalBranchName) = 0 then
+             writeLn('cannot check out') ;
+           if not CommitFile(LocalCustomerRepo, LocalBranchName, FileToCommit, CommitMessage) = 0 then
+             writeLn('cannot check out') ;
+        Finally
+           if ShutdownGitLibrary() >= 0 then
+              writeLn('shutdown git library') ;
         end
    else
        begin
-       writeLn('init NOT OK!') ;
+       writeLn('initializing git library FAILED') ;
        Readln;
        end;
 end.
diff --git a/tariffcalculator.pas b/tariffcalculator.pas
index 0464ade..9e1658a 100644
--- a/tariffcalculator.pas
+++ b/tariffcalculator.pas
@@ -1,6 +1,6 @@
 unit TariffCalculator;
 
-{$mode ObjFPC}{$H-}
+{$mode ObjFPC}{$H+}
 
 interface
 
@@ -18,6 +18,9 @@ procedure DeleteTariffCalculator(handle: TariffCalculatorHandle); stdcall;
 function InitGitLibrary: cint32; stdcall;
 function ShutdownGitLibrary: cint32; stdcall;
 function CloneRepository(var url; var local_path) : cint32; stdcall;
+function CheckoutLocalBranch(var local_path; var branch_name) : cint32; stdcall;
+function CommitFile(var local_path; var branch_name;
+                    var file_name; var comment) : cint32; stdcall;
 
 implementation
 
@@ -30,6 +33,9 @@ procedure DeleteTariffCalculator(handle: TariffCalculatorHandle); stdcall; exter
 function InitGitLibrary: cint32; stdcall; external DLLName;
 function ShutdownGitLibrary: cint32; stdcall; external DLLName;
 function CloneRepository(var url; var local_path) : cint32; stdcall; external DLLName;
+function CheckoutLocalBranch(var local_path; var branch_name) : cint32; stdcall; external DLLName;
+function CommitFile(var local_path; var branch_name;
+                    var file_name; var comment) : cint32; stdcall; external DLLName;
 
 end.