SDL-News: What does this mean?


Subject: SDL-News: What does this mean?
From: Zhang Yongqian (zhangyq#mail.ustc.edu.cn)
Date: Fri Mar 08 2002 - 03:17:17 GMT


Hello, all,

     I am reading a paper about the timing limit of SDL. There is a section as below. I am not sure
the meaning of it. Would you like to give me a hand? (The paragraph marked with "~~~" puzzle me )

    " A typical assumption on the progress of time in SDL, as has been adopted by most tool vendors [13,14] is to assume that time only progresses when the system is in a stable inactive state, i.e. where no signals can be sent or consumed. With regard to real-time systems development, this is of limited use since with this approach when no timers are currently set then time, in effect, does not
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
progress. Further, since timer expiry results in an input signal being placed in the (possibly non-
~~~~~~~~~
empty) input queue of the associated agent, these signals can be in the queue any arbitrary time

before they are consumed. If the expired timer was to stop delivering plutonium, then such a delayed
                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
treatment is unlikely to be satisfactory. "
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


                      
                      BR,
                      Zhang Yongqian
                      University of Science&Technology of China
                      E-mail: zhangyq@mail.ustc.edu.cn

Hello, all,
 
     I am reading a paper about the timing limit of SDL. There is a section as below. I am not sure
the meaning of it. Would you like to give me a hand? (The paragraph marked with "~~~" puzzle me )
 
    " A typical assumption on the progress of time in SDL, as has been adopted by most tool vendors [13,14] is to assume that time only progresses when the system is in a stable inactive state, i.e. where no signals can be sent or consumed. With regard to real-time systems development, this is of limited use since with this approach when no timers are currently set then time, in effect, does not
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
progress. Further, since timer expiry results in an input signal being placed in the (possibly non-
~~~~~~~~~
empty) input queue of the associated agent, these signals can be in the queue any arbitrary time
 
before they are consumed. If the expired timer was to stop delivering plutonium, then such a delayed
                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
treatment is unlikely to be satisfactory. "
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 
                     
                      BR,
                      Zhang Yongqian  
                      University of Science&Technology of China
                      E-mail: zhangyq@mail.ustc.edu.cn
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