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Problem 861. Memory Map File: Access and Update

Created by Richard Zapor

Challenge is to read data from a memory map file and also update the file.

Memory Mapping allows placing large static arrays in virtual memory with good point access times. Minimal consumption of valuable RAM occurs. Medium size TB files can be Mapped on a 64 bit machine. Who has TBs of Hard drive?

With Write Access the Actual file gets data permanently overwritten.

(Note: 8GB logical vector took 60 sec on first large access. Subsequent large accesses returned in msec domain)

Applications include Genome Mapping .

Input: Memory Mapped Variable

Output: Value of location 1

Update location 2 to value of 2

Example:

x is variable

x.data(1:4) is [1234  1111  54543  32465]
Change x.data(2) to 2 
x.data(1:4) becomes  [1234  2  54543  32465]
Output location 1 value: 1234

Follow Up Challenge: Busting the Cody 3GB Memory Limit using multiple mapped files.

Problem Group

Solution Statistics

8 correct solutions 3 incorrect solutions
Last solution submitted on Nov 26, 2014

Problem Comments