path: root/doc/supplements/i960/callconv.t
diff options
Diffstat (limited to 'doc/supplements/i960/callconv.t')
1 files changed, 0 insertions, 97 deletions
diff --git a/doc/supplements/i960/callconv.t b/doc/supplements/i960/callconv.t
deleted file mode 100644
index d112e67123..0000000000
--- a/doc/supplements/i960/callconv.t
+++ /dev/null
@@ -1,97 +0,0 @@
-@c COPYRIGHT (c) 1988-2002.
-@c On-Line Applications Research Corporation (OAR).
-@c All rights reserved.
-@c $Id$
-@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
-All members of the i960 architecture family support
-two methods for performing procedure calls: a RISC-style
-branch-and-link and an integrated call and return mechanism.
-On a branch-and-link, the processor branches to the
-invoked procedure and saves the return address in a register,
-@code{G14}. Typically, the invoked procedure will not invoke another
-procedure and is referred to as a leaf procedure. Many
-high-level language compilers for the i960 family recognize leaf
-procedures and automatically optimize them to utilize the
-branch-and-link mechanism. Branch-and-link procedures are
-invoked using the @code{bal} and @code{balx} instructions and return control
-via the @code{bx} instruction. By convention, @code{G14} is zero when not in
-a leaf procedure. It is the responsibility of the leaf
-procedure to clear @code{G14} before returning.
-The integrated call and return mechanism also
-branches to the invoked procedure and saves the return address
-as did the branch and link mechanism. However, the important
-difference is that the @code{call}, @code{callx}, and @code{calls} instructions save
-the local register set (@code{R0} through @code{R15}) before transferring
-control to the invoked procedure. The @code{ret} instruction
-automatically restores the previous local register set. The
-i960CA provides a register cache which can be configured to
-retain the last five to sixteen recent register caches. When
-the register cache is full, the oldest cached register set is
-written to the stack.
-@section Calling Mechanism
-All RTEMS directives are invoked using either a @code{call}
-or @code{callx} instruction and return to the user via the @code{ret}
-@section Register Usage
-As discussed above, the @code{call} and @code{callx} instructions
-automatically save the current contents of the local register
-set (@code{R0} through @code{R15}). The contents of the local registers will
-be restored as part of returning to the application. The
-contents of global registers @code{G0} through @code{G7} are not preserved by
-RTEMS directives.
-@section Parameter Passing
-RTEMS uses the standard i960 family C parameter
-passing mechanism in which @code{G0} contains the first parameter, @code{G1}
-the second, and so on for the remaining parameters. No RTEMS
-directive requires more than six parameters.
-@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.
-@section Leaf Procedures
-RTEMS utilizes leaf procedures internally to improve
-performance. This improves execution speed as well as reducing
-stack usage and the number of register sets which must be cached.