stackframe

C++ 编写的EROS RTOS

-*- text -*-

OLD LOGIC:

On entry to the stub procedure, the stack has a message structure
pointer and a return PC.  We immediately do a PUSHA, reserve 4 words
on the stack to hold the new IPC block, and then start diddling
register values.  Once the PUSHA and the space reservation has been
done, the stack looks like:

	offset	item		size
	52	Msg struct ptr
	48	return PC
	44	EAX
	40	ECX
	36	EDX
	32	EBX
	28	<unused>
	24	EBP
	20	ESI
	16	EDI
	12	rcv ptr		(32)
	8	snd len		(32)
	4	snd ptr		(32)
	0	IPC type	(32)

The Msg structure offsets are:

	offset	item		        size

	62	FILL			(16)
	60	key info		(16)
	58	FILL			(16)
	56	rcv keys		(16)
	52	rcv len			(32)
	48	rcv data		(32)
	44	rcv w[3]		(32)
	40	rcv w[2]		(32)
	36	rcv w[1]		(32)
	32	rcv w[0] (return code)	(32)
	28	invoked key		(32)
	26	FILL			(16)
	24	snd keys		(16)
	20	snd len			(32, <= 64k)
	16	snd data		(32)
	12	snd w[3]		(32)
	8	snd w[2]		(32)
	4	snd w[1]		(32)
	0	snd w[0] (order code)	(32)

I debated the merits of having the kernel interface PLAN for the
PUSHA, but it seems a bit wasteful.


NEW LOGIC

On entry to the stub procedure, the stack has a message structure
pointer and a return PC.  We immediately do a PUSHA and load %EBP to
point to the message structure, and then start diddling register
values.  Once the PUSHA and the stack pointer adjustment has been
done, the stack looks like:

	offset	item
	36	Msg struct ptr
	32	return PC
	28	EAX
	24	ECX
	20	EDX
	16	EBX
	12	<unused>
	8	EBP
	4	ESI
	0	EDI

The Msg structure offsets are:

	offset	item		        size

        64      rcv keyInfo             (16)
        60      rcv w3                  (32)
        56      rcv w2                  (32)
        52      rcv w1                  (32)
        48      rcv code                (32)
        44      snd w3                  (32)
        40      snd w2                  (32)
        36      snd w1                  (32)
        32      snd code                (32)
        31      rcv key 3               (8)
        30      rcv key 2               (8)
        29      rcv key 1               (8)
        28      rcv key 0               (8)
        24      rcv data                (32)
        20      rcv len                 (32)
        19      snd key 3               (8)
        18      snd key 2               (8)
        17      snd key 1               (8)
        16      snd key 0               (8)
        12      snd data                (32)
        8       snd len                 (32)
        4       invoked key             (32)
        0       invocation type         (32)