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(*
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File: DBuffer.thy
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Author: Stephan Merz
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Copyright: 1997 University of Munich
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Theory Name: DBuffer
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Logic Image: TLA
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Two FIFO buffers in a row, with interleaving assumption.
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*)
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DBuffer = Buffer +
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consts
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(* implementation variables *)
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inp, mid, out :: nat stfun
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q1, q2, qc :: nat list stfun
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DBInit :: stpred
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DBEnq, DBDeq, DBPass, DBNext :: action
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DBuffer :: temporal
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rules
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DB_base "basevars (inp,mid,out,q1,q2)"
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(* the concatenation of the two buffers *)
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qc_def "PRED qc == PRED (q2 @ q1)"
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DBInit_def "DBInit == PRED (BInit inp q1 mid & BInit mid q2 out)"
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DBEnq_def "DBEnq == ACT Enq inp q1 mid & unchanged (q2,out)"
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DBDeq_def "DBDeq == ACT Deq mid q2 out & unchanged (inp,q1)"
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DBPass_def "DBPass == ACT Deq inp q1 mid
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& (q2$ = $q2 @ [ mid$ ])
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& (out$ = $out)"
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DBNext_def "DBNext == ACT (DBEnq | DBDeq | DBPass)"
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DBuffer_def "DBuffer == TEMP Init DBInit
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& [][DBNext]_(inp,mid,out,q1,q2)
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& WF(DBDeq)_(inp,mid,out,q1,q2)
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& WF(DBPass)_(inp,mid,out,q1,q2)"
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end |