Browse Prior Art Database

Multiple Link Source Access of Queues and Stacks

IP.com Disclosure Number: IPCOM000117869D
Original Publication Date: 1996-Jun-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Ouchi, NK: AUTHOR

Abstract

Disclosed is a mechanism that permits multiple source - sink pairs to share a common memory buffer. Each pair uses a specific memory address to store or fetch data. The mechanism manages the memory pointers and checks for over/under runs. Thus, each source and sink does not need additional mechanisms to implement queues and stacks. This permits ease of construction of complex multiple device control units such as those for DASD.

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Multiple Link Source Access of Queues and Stacks

      Disclosed is a mechanism that permits multiple source - sink
pairs to share a common memory buffer.  Each pair uses a specific
memory address to store or fetch data.  The mechanism manages the
memory pointers and checks for over/under runs.  Thus, each source
and sink does not need additional mechanisms to implement queues and
stacks.  This permits ease of construction of complex multiple device
control units such as those for DASD.

      The serial link uses a 32-byte packet and requires an
acknowledge frame before another packet is sent.  This permits the
link to pace the transfer and interleave the transfer of several
messages on the physical link.  The term "virtual channel" is used to
the addressing and transfer mechanism for messages.  Disclosed is a
mechanism that permits two virtual channels to share a portion of a
common buffer as a Queue or a Stack.  These are illustrated in Figs.
1 and 2.  Fig. 1 illustrates two links that share a portion of the
buffer.  The mechanism uses a common address that the source o store
data into the First In First Out (FIFO) Queue and from which the sink
link fetches data.  The mechanism manages the memory pointers and
PREVENTS over/under runs by withholding the acknowledge frames when
the condition is about to occur.  Fig. 2 illustrates a Last In First
Out (LIFO) Stack.  The Stack is similar to a Queue except the sink
link takes the most recent, the last, ele...