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Signal Processor Operating System Task Schedule and Dispatch Operation

IP.com Disclosure Number: IPCOM000116730D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 8 page(s) / 267K

Publishing Venue

IBM

Related People

Davis, GT: AUTHOR [+6]

Abstract

Disclosed is a very light Real Time Digital Signal Processing (DSP) Kernel is needed for a Multiprocessing DSP system that supports tasks running Asynchronously and Synchronously without a Hard Real-Time MIP's per task allocation. Another DSP kernel that has similar features is ISPOS, the 'IBM* Signal Processor Operating System'.

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Signal Processor Operating System Task Schedule and Dispatch Operation

      Disclosed is a very light Real Time Digital Signal Processing
(DSP) Kernel is needed for a Multiprocessing DSP system that supports
tasks running Asynchronously and Synchronously without a Hard
Real-Time MIP's per task allocation.  Another DSP kernel that has
similar features is ISPOS, the 'IBM* Signal Processor Operating
System'.

      In the Communications Adapter, there are basically two types of
tasks:  Foreground or Real Time Tasks and Background or Non Real-Time
Tasks.  The "Foreground Task" is really a "Priority Real Time Task"
and the term Real-Time Task  will be used.  Non Real-Time Tasks  will
perform polling based tasks that have no real time data processing
requirements.

Features of this invention include:
  1.  Non Real-Time Tasks  serviced round robin.
  2.  Real-Time Tasks  invoked periodically by an INT1 with Task
       Control Blocks.
  3.  Other XSPOS internal tasks invoked by an INT2 at 8000Hz.
  4.  Non Hard Real Time approach.  In allocating tasks, the
Worst-case
       MIPs used are not assumed for all cases.  This allows for a
       higher MIP utilization ratio.  The tasks are run on a
statistical
       basis.
  5.  Error condition if Real-Time Task  not serviced by next call.
  6.  This lighter Kernel uses less MIPs than other Kernels.
  7.  This lighter Kernel saves in code and data space.
  8.  This Kernel will allow Real-Time Tasks  and Non Real-Time Tasks
       to run in protected mode for up to 60% of the highest
frequency
       interrupt period.
  9.  This allows Real-Time Tasks  and Non Real-Time Tasks  to
       communicate with shared variables.

       Real-Time Task  Scheduling, INT1 at 9600 Hz
  XSPOS Foreground (Real-Time Task Scheduler): The XSPOS Foreground
Manager will reside in the INT1 handler which will be called at
9.6KHz.
This is analogous to the ISPOS 9.6KHz Frame Manager.

Potential Real-Time Task  Scheduled Tasks
  1.  ISDN By-Pass Task
  2.  Protocol Transmit
  3.  Protocol Receive
  4.  Modem Transmit dispatch for low speed modems
  5.  Modem Receive dispatch for low speed modems
  6.  V.22bis Tx
  7.  V.22bis Rx
  8.  V.32bis Tx/Rx Modem task dispatch

       Potential Non Real-Time Task  Scheduled Tasks
  1.  XSPOS Host Command Handlers
  2.  Protocol Queue I/F Handler
  3.  Handshake/Autospeed Detection
  4.  Modem Retrain

       Real-Time Task  chain structure

      This chain is entered only by the acceptance of Interrupt 1
(9.6 Khz) and is serviced in the foreground.  Each chain entry is the
address of a Task Control Block and is one word (2 bytes).

      A 9600Hz interrupt will be used to call a foreground task
scheduler.  A current count will be incremented at this 9600Hz rate
in order to manage task execution.  Note that tasks that expect to
run every 20 8KHz sampl...