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Access control apparatus, access control system, processor, access control method, memory access control apparatus, memory access control system, and memory access control method

  • US 20070136647A1
  • Filed: 09/13/2006
  • Published: 06/14/2007
  • Est. Priority Date: 11/30/2005
  • Status: Active Grant
First Claim
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1. An access control apparatus to control an access among a writer, a reader, and a memory, comprising:

  • a parity generator that generates a parity for original data to be written into the memory;

    a parity adder that generates parity-added data by adding the parity generated by the parity generator to the original data;

    a first syndrome generator that generates a first syndrome which is a value associated with a first access code used by the writer to request writing of the original data into the memory;

    a first mask generator that generates the first mask data, based on the first syndrome, the first access code, and a first memory address at which the original data is to be written by the writer;

    a first XOR unit that obtains first post-operation data by calculating an XOR between the parity-added data and the first mask data;

    a writing unit that writes the first post-operation data into the memory;

    a second syndrome generator that generates a second syndrome which is a value associated with a second access code used by the reader to request reading of data from the memory;

    a second mask generator that generates the second mask data, based on the second syndrome, the second access code, and a second memory address from which the data is to be read by the reader;

    a reading unit that reads the first post-operation data from the memory;

    a second XOR unit that obtains second post-operation data by calculating an XOR between the second mask data and the first post-operation data;

    a data syndrome calculator that calculates a real data syndrome based on the second post-operation data; and

    an output determining unit that determines whether the second post-operation data is to be output as the original data, based on the real data syndrome.

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