RTEMS CPU Architecture Supplement
RTEMS assumes that arguments are placed on the current stack before the directive is invoked via the bsr or jsr 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:
push third argument push second argument push first argument invoke directive remove arguments from the stack
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.
RTEMS CPU Architecture Supplement
Copyright © 1988-2007OAR Corporation