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2002-07-30 Joel Sherrill <joel@OARcorp.com>

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* callconf.t: Added some markups for fonts and clarified
	some places.
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Joel Sherrill
2002-07-31 00:14:11 +00:00
parent 2d35d1124f
commit 4b4d4fde1f
2 changed files with 17 additions and 13 deletions
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4
doc/supplements/i960/ChangeLog
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@@ -1,3 +1,7 @@
2002-07-30 Joel Sherrill <joel@OARcorp.com>
* callconf.t: Added some markups for fonts and clarified
some places.
2002-03-27 Ralf Corsepius <corsepiu@faw.uni-ulm.de>
* Makefile.am: Remove AUTOMAKE_OPTIONS.

26
doc/supplements/i960/callconv.t
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@@ -38,22 +38,22 @@ 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,
G14. Typically, the invoked procedure will not invoke another
@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 bal and balx instructions and return control
via the bx instruction. By convention, G14 is zero when not in
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 G14 before returning.
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 call, callx, and calls instructions save
the local register set (R0 through R15) before transferring
control to the invoked procedure. The ret instruction
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
@@ -62,23 +62,23 @@ written to the stack.
@section Calling Mechanism
All RTEMS directives are invoked using either a call
or callx instruction and return to the user via the ret
All RTEMS directives are invoked using either a @code{call}
or @code{callx} instruction and return to the user via the @code{ret}
instruction.
@section Register Usage
As discussed above, the call and callx instructions
As discussed above, the @code{call} and @code{callx} instructions
automatically save the current contents of the local register
set (R0 through R15). The contents of the local registers will
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 G0 through G7 are not preserved by
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 G0 contains the first parameter, G1
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.