EP0470570A2
Expired / Lapsed
EP
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Method and apparatus for byte order switching in a computer
Assignee: Graphics Properties Holdings Inc
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Filing: 1991-08-06
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Granted: —
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Expires: 2011-08-06
Abstract
Abstract A method and apparatus which enables a given computer to run programs using either a big endian or little endian architecture is disclosed. The method uses the fact that exclusive-ORing the lower two bits of a byte address in one architecture with binary 3 converts that byte address to the equivalent byte address in the other architecture. The method is implemented in software in a preferred embodiment, but a hardware implementation is also disclosed.
Inventors
- 👤 Larry B. Weber
- 👤 Earl A. Killian
- 👤 Mark I. Himmelstein
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 08:19
CPC Classifications
G; G06; G06F; G06F7/00; G06F7/76; G06F7/768; G06F9/00; G06F9/06; G06F9/30; G06F9/34
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
68 words
A method for converting a program which uses a first predefined byte order addressing method to a second predefined byte order addressing method comprising the steps of: finding all instructions in the program which operate on bytes of data; exclusive-ORing the lower two bits of the byte address with binary three; and replacing the lower two bits of the byte address with the result of the exclusive-ORing operation.
Claim 2
Independent Claim
68 words
A method for converting a program which uses a first predefined byte order addressing method to a second predefined byte order addressing method comprising the steps of: finding all instructions in the program which operate on bytes of data; exclusive-ORing the lower two bits of the byte address with binary three; and replacing the lower two bits of the byte address with the result of the exclusive-ORing operation.
Claim 3
Independent Claim
71 words
An apparatus for converting a program which uses a first predefined byte order addressing method to a second predefined byte order addressing method comprising: means for finding all instructions in the program which operate on bytes of data; means for exclusive-ORing the lower two bits of the byte address with binary three; and means for replacing the lower two bits of the byte address with the result of the exclusive-ORing operation.
Claim 4
Independent Claim
71 words
An apparatus for converting a program which uses a first predefined byte order addressing method to a second predefined byte order addressing method comprising: means for finding all instructions in the program which operate on bytes of data; means for exclusive-ORing the lower two bits of the byte address with binary three; and means for replacing the lower two bits of the byte address with the result of the exclusive-ORing operation.
Claim 5
Dependent Claim
69 words
In a digital computer having a predefined byte order addressing method, a compiler capable of compiling programs of the same or different byte order addressing method, the compiler comprising: means for detecting if a new program has a different byte order addressing method than the program previously compiled; and means for converting instructions which access parts of computer words into the predefined byte order addressing method of the computer.
Claim 6
Dependent Claim
69 words
In a digital computer having a predefined byte order addressing method, a compiler capable of compiling programs of the same or different byte order addressing method, the compiler comprising: means for detecting if a new program has a different byte order addressing method than the program previously compiled; and means for converting instructions which access parts of computer words into the predefined byte order addressing method of the computer.
Claim 7
Dependent Claim
39 words
The compiler of claim 3 wherein the means for converting instructions further comprises: means for detecting the lower two bits of the byte address; and means for exclusive-ORing the lower two bits of the byte address with binary 3.
References Cited (Backward Citations)
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