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Software Implementation of an Architecture's Virtual Translation Mechanism

IP.com Disclosure Number: IPCOM000038043D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brase, BA: AUTHOR [+2]

Abstract

The virtual address translation mechanism as defined by the Architecture document is cumbersome to compute. The software implementation of this process provides a check on the hardware model and on any test case in question. It is an efficient and exact method that can be used consistently by individuals with widely varying degrees of experience.

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Software Implementation of an Architecture's Virtual Translation Mechanism

The virtual address translation mechanism as defined by the Architecture document is cumbersome to compute. The software implementation of this process provides a check on the hardware model and on any test case in question. It is an efficient and exact method that can be used consistently by individuals with widely varying degrees of experience.

The processor architecture allows for address translation. The simulation group must verify the hardware implementation of this process. Many of the translation testcases are coded by hand; thus, a method to determine the expected results is needed.

The user enters the HATORG, the effective address, and the segment register as input, and the HAT real address is the result. The following series of equations come from the processor Architecture Document and are used as the basis of this implementation. op = b'0' ºº HATORG ºº 15 x b'0'

opb1 = (x00' ºº VPI) xor SID

opb2 = b'000 º HAT mask ºº 13 x b'1'

opb = 6 x b'0' ºº opb3 ºº b'00'

real address = opa or opb

ThePFT real address may be calculated in like fashion. In addition, a valuable procedure is to perform the reverse of this process. That is, starting with the real address, calculate the virtual address. This is a function not performed by the hardware, but it is a valuable aid in simulation.

Disclosed anonymously.

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