发明名称 |
CIRCUIT AND METHOD FOR DETECTING SEGMENT LIMIT ERRORS FOR CODE FETCHES |
摘要 |
A segment limit check circuit (126) performs limit checks on fetch addresses generated by a CPU (110). 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 (100) 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 (122) and a 33-bit upper limit value (230). A comparator (300) 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. |
申请公布号 |
WO9522803(A2) |
申请公布日期 |
1995.08.24 |
申请号 |
WO1995US01651 |
申请日期 |
1995.02.08 |
申请人 |
MERIDIAN SEMICONDUCTOR, INC. |
发明人 |
WHITTED, GRAHAM, B., III;CHANG, HSIAO-SHIH;KANE, JAMES, A. |
分类号 |
G06F9/30;G06F9/355;G06F9/38;G06F12/02;G06F12/14 |
主分类号 |
G06F9/30 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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