75 lines
1.8 KiB
Rexx
75 lines
1.8 KiB
Rexx
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integrater = .integrater~new(.routines~sine) -- start the integrater function
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call syssleep 2
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integrater~input = .routines~zero -- update the integrater function
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call syssleep .5
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say integrater~output
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integrater~stop -- terminate the updater thread
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::class integrater
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::method init
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expose stopped start v last_v last_t k
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use strict arg k
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stopped = .false
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start = .datetime~new -- initial time stamp
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v = 0
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last_v = 0
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last_t = 0
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self~input = k
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self~start
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-- spin off a new thread and start updating. Note, this method is unguarded
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-- to allow other threads to make calls
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::method start unguarded
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expose stopped
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reply -- this spins this method invocation off onto a new thread
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do while \stopped
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call sysSleep .1
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self~update -- perform the update operation
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end
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-- turn off the thread. Since this is unguarded,
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-- it can be called any time, any where
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::method stop unguarded
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expose stopped
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stopped = .true
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-- perform the update. Since this is a guarded method, the object
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-- start is protected.
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::method update
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expose start v last_v t last_t k
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numeric digits 20 -- give a lot of precision
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current = .datetime~new
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t = (current - start)~microseconds
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new_v = k~call(t) -- call the input function
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v += (last_v + new_v) * (t - last_t) / 2
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last_t = t
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last_v = new_v
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say new value is v
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-- a write-only attribute setter (this is GUARDED)
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::attribute input SET
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expose k last_t last_v
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self~update -- update current values
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use strict arg k -- update the call function to the provided value
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last_t = 0
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last_v = k~call(0) -- and update to the zero value
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-- the output function...returns current calculated value
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::attribute output GET
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expose v
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return v
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::routine zero
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return 0
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::routine sine
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use arg t
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return rxcalcsin(rxcalcpi() * t)
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::requires rxmath library
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