The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 14, 2010
Filed:
May. 11, 2006
Richard Roy Grisenthwaite, Nr Royston, GB;
Paul Kimelman, Alamo, CA (US);
David James Seal, Cambridge, GB;
David Aaron Rusling, Wokingham, GB;
Richard Roy Grisenthwaite, Nr Royston, GB;
Paul Kimelman, Alamo, CA (US);
David James Seal, Cambridge, GB;
David Aaron Rusling, Wokingham, GB;
ARM Limited, Cambridge, GB;
Abstract
A data processorhas privilege levels associated with it including a user level and a privileged level. The processoralso has multiple stack memories which can be used including one or more process stacks, a main stack and a deep stack. The stack memory to be used is de-coupled from the privilege level. An activation level state variable tracking the number of pending exceptions is held by the processor and used to modify which stack memory stores pending state values when an exception occurs. If the system is at a base level of activation, corresponding to currently no pending exceptions, then when an exception occurs the current state data is saved on the process stack with the main stack being available for the exception handling code. Particular exceptions can be flagged as requiring use of a deep stack rather than either the process stack or the main stack. If the system is not at the base level of activation, then the main stack is used to save state variables when an exception occurs rather than the process stack.