ESD (SHARED DATA)

 WHAT IS SHARED DATA?

some data is common to different threads or process eg:

  • Time, which is continuously updated by the process, is also used by display process in a system.
  • Port input data , which is received by one process and further processed by the another process.
  • Memory buffer data which is inserted by one process and further processed, analyzed and calculated by other process.
A big problem in embedded systems occurs in embedded software when an interrupt service routine and the main program share the same data. What happens if the main program is in the middle of doing some important calculations using some piece of data…an interrupt occurs that alters that piece of data…and then the main program finishes its calculation? Oops! The calculation performed by the main program might be corrupted because it is based off the wrong/different data value. This is known as the shared data problem

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