[wdmaudiodev] Re: RevokeMapping
- From: "Frank Berreth" <fberreth@xxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Wed, 2 Jul 2003 10:22:50 -0700
Since you talk about RevokeMappings, after rearranging the buffer descriptor
list the current mapping which gets revoked is taken out. The ICH would start
playing at the next mapping (if the ICH was in a run state before, which it
normally is not when RevokeMappings is called).
There might be a "jump" backwards in the position since the position reported
at GetPosition includes also partially played buffers. Since this buffer is now
taken out, the next position reported includes all released mappings + current
play position in the current (next) buffer which might be lower than a
previously reported position. That means the bytes played in the revoked buffer
are basically considered not being played (I don't know if that is correct or
not and frankly speaking - if you ask me - RevokeMappings shouldn't be there to
start with).
-Frank.
This posting is provided "AS IS" with no warranties, and confers no rights.
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Marc Sillinger
Sent: Wednesday, July 02, 2003 7:33 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] RevokeMapping
Hi,
this should be an easy question for most of you :
I wonder what happens on AC'97, when RevokeMappings is
called with a tag that matches the current buffer
(CIV). From what I've seen, after the ICH is reset,
CIV = LVI = 0. Hence, the Buffer Descriptor list is
rearranged so that the current buffer data is located
at index 0. Now, I believe the PICB is reset too, so
what happens when DMA is resumed ? does the ICH replay
a part of the current mapping, or how did the current
position get saved ?
Or does portcls prevent the cancellation of the
current mapping ?
thanks
Marc.
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