Symbol encoding for tolerance to single byte errors

• US 7,788,567 B1
• Filed: 12/11/2003
• Issued: 08/31/2010
• Est. Priority Date: 11/18/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Whitby-Strevens, Colin, Hauck, Jerrold Von
• Primary Examiner(s): Abraham; Esaw T
• Application Number:
  US10/735,260
• Time in Patent Office: 2,455 Days
• Field of Search: 714/714, 714/752, 714/786, 714/799
• US Class Current: 714/752
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: H03M 13/31 combining coding for error detection or correction and efficient use of the spectrum without error detection or correction H03M5/14 , H03M5/145
• CPC Class Codes: H03M 5/145 Conversion to or from block codes or representations thereof

Abstract

The present invention provides a method that protects symbol types by characterizing symbols as one of two types—DATA or NON_DATA, generating a symbol characterization bit, placing the symbol characterization bit at both ends of the symbol, and transmitting the symbol with the symbol characterization bits at both ends. Thus, a single byte error may affect a type bit in two consecutive symbols, and will affect one or the other of the type bits in a single symbol, but cannot affect both type bits in a single symbol.

Claims

1. A method of protecting symbol types transmitted across a communication medium comprising:

encoding a symbol comprising a plurality of bits, wherein a most significant bit and a least significant bit of said symbol indicate at least a type of said symbol; and

transmitting the symbol across the communication medium;

wherein said encoding protects symbol types, as a single byte error cannot affect both said most significant bit and said least significant bit of said symbol.

2. The method of claim 1, wherein the symbol is encoded with said most significant bit identical to said least significant bit.

3. The method of claim 2, wherein the symbol consists of eight bits.

4. The method of claim 2, wherein the symbol type corresponds to either a first type or a second type.

5. The method of claim 4, wherein if said most significant bit and said least significant bit both comprise a high bit, the symbol type corresponds to one of the first and second type, and if the most significant bit and the least significant bit of the symbol both comprise a low bit, the symbol type corresponds to the other of the first and second types.

6. The method of claim 5, wherein said first type comprises a data symbol, and said second type comprises a non-data symbol.

7. The method of claim 5, wherein a bit adjacent to the most significant bit of said symbol and a bit adjacent to the least significant bit of said symbol are adapted to indicate a symbol subtype.

8. The method of claim 7, wherein said symbol subtype comprises one of (i) a control symbol, or (ii) an arbitration request symbol.

9. The method of claim 5, wherein at least five bits of said symbol are adapted to indicate a symbol subtype, said at least five bits not including said most significant bit and said least significant bit.

10. The method of claim 2, wherein said communication medium comprises a bus compliant with a high-speed serialized bus protocol.

11. The method of claim 10, wherein said high-speed serialized bus protocol comprises at least one of the IEEE Std. 1394b and 1394c standards.

12. A computerized apparatus for transmitting data across a communication medium, said apparatus comprising:

a first module to encode a symbol comprising a plurality of bits, wherein the first module indicates a type of said symbol by setting or resetting both a most significant bit and a least significant bit of said symbol; and

a second module to transmit the encoded symbol across the communication medium.

13. The apparatus of claim 12, wherein the symbol type corresponds to either a first type or a second type;

wherein if the most significant bit and the least significant bit of the symbol are both set, the symbol type corresponds to the first type, and if the most significant bit and the least significant bit of the symbol are both reset, the symbol type corresponds to the second type.

14. The apparatus of claim 12, wherein a bit adjacent to the most significant bit of said symbol and a bit adjacent to the least significant bit of said symbol indicate a symbol subtype.

15. The apparatus of claim 12, wherein a plurality of bits of said symbol are adapted to indicate a symbol subtype, said plurality of bits not including the most significant bit and the least significant bit of said symbol.

16. The apparatus of claim 15, wherein said communication medium comprises a bus compliant with a high-speed serialized bus protocol.

17. The apparatus of claim 16, wherein said high-speed serialized bus protocol comprises at least one of the IEEE Std. 1394b and 1394c standards.