rhapsody のもの
xptcinvoke_asm_ppc_rhapsody.s
には少なくとも説明がある

.data
        .align 2
#
#   XPTC_InvokeByIndex(nsISupports* that, PRUint32 methodIndex,
#                   PRUint32 paramCount, nsXPTCVariant* params)
#

.globl __XPTC_InvokeByIndex     
__XPTC_InvokeByIndex:

#
# save off the incoming values in the callers parameter area
#               
............
# set up for and call 'invoke_count_words' to get new stack size
#       
............
# prepare args for 'invoke_copy_to_stack' call
#               
............
# create "temporary" stack frame for _invoke_copy_to_stack to operate in.
............
# remove temporary stack frame.
............