MSG_INBOUND_POST_STACK
if( (headptr < MSG_INBOUND_POST_STACK) || (headptr >= (MSG_INBOUND_POST_STACK+MSG_BOUND_STACK_SIZE))) {
if( headptr >= (MSG_INBOUND_POST_STACK+MSG_BOUND_STACK_SIZE) )
headptr = MSG_INBOUND_POST_STACK;