Merge pull request #2454 from tastywheattasteslikechicken/FixVtableAbort

[mono.git] / docs / unmanaged-calls

diff --git a/docs/unmanaged-calls b/docs/unmanaged-calls
index 944abd7d19e4542b88a6ef8f467871921d1a9e66..7542623166bb74c22d1dd7e14bafcf13b229dafe 100644 (file)
--- a/docs/unmanaged-calls
+++ b/docs/unmanaged-calls
@@ -1,3 +1,6 @@
+Author: Dietmar Maurer (dietmar@ximian.com)
+(C) 2001 Ximian, Inc.
+
 More about PInvoke and Internal calls
 =====================================
 
@@ -6,11 +9,16 @@ More about PInvoke and Internal calls
 PInvoke stands for Platform Invoke. It is possible to call functions contained
 in native shared libraries, for example you can declare:
 
-       [DllImport("cygwin1.dll", EntryPoint="puts", CharSet=CharSet.Ansi)]
+       [DllImport("cygwin1.dll", EntryPoint="puts"]
        public static extern int puts (string name);
 
 If you then call "puts(...)" it invokes the native "puts" functions in
-"cygwin1.dll"
+"cygwin1.dll". It is also possible to specify several marshalling attributes
+for the arguments, for example you can specify that they puts() function expect
+ts the string in Ansi encoding by setting the CharSet attribute field:
+
+       [DllImport("cygwin1.dll", EntryPoint="puts", CharSet=CharSet.Ansi)]
+       public static extern int puts (string name);
 
 2.) What are internal calls
 
@@ -25,6 +33,10 @@ our array implementation:
 If you call this GetRank() function it invokes
 ves_icall_System_Array_GetRank() inside the mono runtime.
 
+If you write your own runtime environment you can add internal calls with
+mono_add_internal_call(). 
+
+
 2.) Runtime considerations
 
 Invoking native (unmanaged) code has several implications:
@@ -60,9 +72,9 @@ Invoking native (unmanaged) code has several implications:
 The easiest way to implement this is to always create a wrapper function for
 PInvoke calls, which takes care of argument marshalling and LMF save/restore.
 
-3.) When/how does the runtime call unmanaged internal calls
+4.) When/how does the runtime call unmanaged internal calls
 
-We don't need to convert and arguments, so we need only take care of the LMF
+We don't need to convert any arguments, so we need only take care of the LMF
 structure. 
 
 - LDFTN, CALLI, Delegate::Invoke, Delegate::BeginInvoke: We must generate
@@ -110,13 +122,14 @@ ves_icall_puts (MonoLMF lmf, MonoString *string);
 But this depends somehow on the calling conventions, and I don't know if that
 works on all plattforms? 
 
-4.) What is stored in the LMF
+
+5.) What is stored in the LMF
 
 - all caller saved registers (since we can trust unmanaged code)
 - the instruction pointer of the last managed instruction
 - a MonoMethod pointer for the unmanaged function
 - the address of the thread local lfm_addr pointer (to avoid another call to
-  arch_get_lmf_addr when restoring LMF
+  arch_get_lmf_addr when restoring LMF)
 
 The LMF is allocated on the stack, so we also know the stack position for
 stack unwinding.