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:
Oct. 08, 1996
Filed:
Feb. 08, 1994
Graham B Whitted, III, Irvine, CA (US);
Hsiao-Shih Chang, Orange, CA (US);
James A Kane, Newport Beach, CA (US);
Meridian Semiconductor, Inc., Irvine, CA (US);
Abstract
A segment limit check circuit performs limit checks on fetch addresses generated by a CPU. The circuit and method for performing the fetch limit check are simplified over the prior art by effectively moving the fetch limit check to linear address space. For a microprocessor that uses physical addresses of 32-bits and performs fetches as 16-byte aligned accesses, the circuit of the present invention generates a 33-bit linear address and a 33-bit upper limit value. A comparator compares the upper 29 bits of the linear address with the upper 29-bits of the upper limit value. If a match occurs, the circuit decodes the 4 low-order bits of the upper limit value to determine which of the 16 instruction bytes (if any) fall outside the segment limit.