Systems and methods for error correction and decoding on multi-level physical media
First Claim
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1. A method for operating a flash device, said method comprising:
- reading, from flash memory cells the flash device, data symbols and redundancy symbols;
calculating syndrome symbols based on the redundancy symbols;
calculating estimated syndrome symbols based on at least the data symbols;
calculating differences between the syndrome symbols and corresponding estimated syndrome symbols to provide error syndromes; and
calculating corrected data symbols in response to the data symbols, the error syndromes;
wherein the calculating of the corrected data symbols involves calculating Lee distances.
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Abstract
Apparatus and methods for operating a flash device characterized by use of Lee distance based codes in a flash device so as to increase the number of errors that can be corrected for a given number of redundancy cells, compared with Hamming distance based codes.
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Citations
23 Claims
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1. A method for operating a flash device, said method comprising:
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reading, from flash memory cells the flash device, data symbols and redundancy symbols; calculating syndrome symbols based on the redundancy symbols; calculating estimated syndrome symbols based on at least the data symbols; calculating differences between the syndrome symbols and corresponding estimated syndrome symbols to provide error syndromes; and
calculating corrected data symbols in response to the data symbols, the error syndromes;wherein the calculating of the corrected data symbols involves calculating Lee distances. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps of:
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reading, from flash memory cells the flash device, data symbols and redundancy symbols; calculating syndrome symbols based on the redundancy symbols; calculating estimated syndrome symbols based on at least the data symbols; calculating differences between the syndrome symbols and corresponding estimated syndrome symbols provide error syndromes; and
calculating corrected data symbols in response to the data symbols, the error syndromes;wherein the calculating of the corrected data symbols involves calculating Lee distances.
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13. A decoder comprising:
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a first circuit for calculating syndrome symbols based on redundancy symbols read from a flash memory array; a second circuit for calculating estimated syndrome symbols based on at least data symbols read from the flash memory array; a subtraction unit arranged to calculate differences between the syndrome symbols and corresponding estimated syndrome symbols to provide error syndromes; and a recovery block that is arranged to calculate corrected data symbols in response to the data symbols, the error syndromes by calculating Lee distances. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification