RTEMS TI C3x/C4x Applications Supplement
When passing parameters on the stack, the calling convention assumes
that arguments are placed on the current stack before the subroutine
is invoked via the 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
subroutine with three (3) arguments:
push third argument push second argument push first argument invoke subroutine remove arguments from the stack
The arguments to RTEMS are typically pushed onto the
stack using a sti instruction with a pre-incremented 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 subtracting the size of the
argument list in words from the current stack pointer.
With the GNU Compiler Suite, parameter passing via the
stack is selected by invoking the compiler with the
-mmemparm XXX argument. This argument must be
included when linking the application in order to
ensure that support libraries also compiled assuming
parameter passing via the stack are used. The default
parameter passing mechanism is XXX.
When this parameter passing mecahanism is selected, the XXX
symbol is predefined by the C and C++ compilers
and the XXX symbol is predefined by the assembler.
This behavior is the same for the GNU and Texas Instruments
toolsets. RTEMS uses these predefines to determine how
parameters are passed in to those C3x/C4x specific routines
that were written in assembly language.
RTEMS TI C3x/C4x Applications Supplement
Copyright © 1988-2004 OAR Corporation