From 3fdfd51466782c8f229aba096e620dd3ddd292c8 Mon Sep 17 00:00:00 2001
From: Joel Sherrill <joel.sherrill@OARcorp.com>
Date: Mon, 19 Oct 1998 12:52:31 +0000
Subject: Added.

---
 doc/supplements/template/Makefile      |  7 ++-
 doc/supplements/template/callconv.t    | 92 ++++++++++++++++++++++++++++++++++
 doc/supplements/template/template.texi |  4 +-
 3 files changed, 100 insertions(+), 3 deletions(-)
 create mode 100644 doc/supplements/template/callconv.t

(limited to 'doc/supplements/template')

diff --git a/doc/supplements/template/Makefile b/doc/supplements/template/Makefile
index 048aef9958..2eae2792c3 100644
--- a/doc/supplements/template/Makefile
+++ b/doc/supplements/template/Makefile
@@ -24,7 +24,7 @@ COMMON_FILES=../../common/cpright.texi ../../common/setup.texi \
 FILES= $(PROJECT).texi preface.texi \
   $(COMMON_FILES) $(GENERATED_FILES)
 GENERATED_FILES=\
-  cpumodel.texi
+  cpumodel.texi callconv.texi
 
 #  bsp.texi callconv.texi cpumodel.texi cputable.texi fatalerr.texi \
 #  intr.texi memmodel.texi preface.texi timetbl.texi timedata.texi wksheets.texi 
@@ -52,6 +52,11 @@ cpumodel.texi: cpumodel.t Makefile
 	    -u "Top" \
 	    -n "" ${*}.t
 
+callconv.texi: callconv.t Makefile
+	$(BMENU) -p "" \
+	    -u "Top" \
+	    -n "" ${*}.t
+
 replace: timedata.texi
 
 intr.texi: intr.t MVME136_TIMES
diff --git a/doc/supplements/template/callconv.t b/doc/supplements/template/callconv.t
new file mode 100644
index 0000000000..abdcce0304
--- /dev/null
+++ b/doc/supplements/template/callconv.t
@@ -0,0 +1,92 @@
+@c
+@c  COPYRIGHT (c) 1988-1998.
+@c  On-Line Applications Research Corporation (OAR).
+@c  All rights reserved.
+@c
+@c  $Id$
+@c
+
+@chapter Calling Conventions
+
+@section Introduction
+
+Each high-level language compiler generates
+subroutine entry and exit code based upon a set of rules known
+as the compiler's calling convention.   These rules address the
+following issues:
+
+@itemize @bullet
+@item register preservation and usage
+@item parameter passing
+@item call and return mechanism
+@end itemize
+
+A compiler's calling convention is of importance when
+interfacing to subroutines written in another language either
+assembly or high-level.  Even when the high-level language and
+target processor are the same, different compilers may use
+different calling conventions.  As a result, calling conventions
+are both processor and compiler dependent.
+
+@section Processor Background
+
+The MC68xxx architecture supports a simple yet
+effective call and return mechanism.  A subroutine is invoked
+via the branch to subroutine (@code{XXX}) or the jump to subroutine
+(@code{XXX}) instructions.  These instructions push the return address
+on the current stack.  The return from subroutine (@code{XXX})
+instruction pops the return address off the current stack and
+transfers control to that instruction.  It is is important to
+note that the XXX call and return mechanism does not
+automatically save or restore any registers.  It is the
+responsibility of the high-level language compiler to define the
+register preservation and usage convention.
+
+@section Calling Mechanism
+
+All RTEMS directives are invoked using either a @code{XXX}
+or @code{XXX} instruction and return to the user application via the
+@code{XXX} instruction.
+
+@section Register Usage
+
+As discussed above, the @code{XXX} and @code{XXX} instructions do
+not automatically save any registers.  RTEMS uses the registers
+@b{D0}, @b{D1}, @b{A0}, and @b{A1} as scratch registers.  These registers are
+not preserved by RTEMS directives therefore, the contents of
+these registers should not be assumed upon return from any RTEMS
+directive.
+
+@section Parameter Passing
+
+RTEMS assumes that arguments are placed on the
+current stack before the directive is invoked via the @code{XXX} or @code{XXX}
+instruction.  The first argument is assumed to be closest to the
+return address on the stack.  This means that the first argument
+of the C calling sequence is pushed last.  The following
+pseudo-code illustrates the typical sequence used to call a
+RTEMS directive with three (3) arguments:
+
+@example
+@group
+push third argument
+push second argument
+push first argument
+invoke directive
+remove arguments from the stack
+@end group
+@end example
+
+The arguments to RTEMS are typically pushed onto the
+stack using a move instruction with a pre-decremented stack
+pointer as the destination.  These arguments must be removed
+from the stack after control is returned to the caller.  This
+removal is typically accomplished by adding the size of the
+argument list in bytes to the current stack pointer.
+
+@section User-Provided Routines
+
+All user-provided routines invoked by RTEMS, such as
+user extensions, device drivers, and MPCI routines, must also
+adhere to these calling conventions.
+
diff --git a/doc/supplements/template/template.texi b/doc/supplements/template/template.texi
index fe36128d60..0f8e57bd25 100644
--- a/doc/supplements/template/template.texi
+++ b/doc/supplements/template/template.texi
@@ -65,7 +65,7 @@ END-INFO-DIR-ENTRY
 
 @include preface.texi
 @include cpumodel.texi
-@c @include callconv.texi
+@include callconv.texi
 @c @include memmodel.texi
 @c @include intr.texi
 @c @include fatalerr.texi
@@ -84,7 +84,7 @@ Applications Supplement.
 @menu
 * Preface::
 * CPU Model Dependent Features::
-** Calling Conventions::
+* Calling Conventions::
 ** Memory Model::
 ** Interrupt Processing::
 ** Default Fatal Error Processing::
-- 
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