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soft-an04/ReversalModel/reversal.pml

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Promela

#define N 2
#define LENGTH 3
#define R 2
int to_reverse[LENGTH]; // array to reverse
int reversed_seq[LENGTH]; // for SequentialReverser: where the reverse is stored
int reversed_par[LENGTH]; // for ParallelReverser: where the reverse is stored
// stores termination of each reverser
// index 0 is for the sequential algorithm
// indices 1-N are for the ThreadedReverser instances
bool done[N + 1]; // initialized to false
bool seq_eq_to_parallel = true;
// ThreadedReverser implementation
proctype ThreadedReverser(int from; int to; int n) {
printf("proc[%d]: started\n", _pid);
int k;
for (k: from .. to) {
printf("reversed_par[%d] = to_reverse[%d]\n", LENGTH - k - 1, k);
reversed_par[LENGTH - k - 1] = to_reverse[k];
}
printf("proc[%d]: ended\n", n);
done[n] = true;
}
init {
printf("program start\n");
// array initialization
{
int i;
for (i in to_reverse) {
int value;
select(value: 0 .. R);
to_reverse[i] = value;
printf("to_reverse[%d]: %d\n", i, value);
}
}
printf("sequential start\n");
// SequentialReverser implementation
{
int k;
for (k: 0 .. (LENGTH - 1)) {
reversed_par[LENGTH - k - 1] = to_reverse[k];
printf("reversed_seq[%d] = to_reverse[%d]\n", LENGTH - k - 1, k);
}
done[0] = true; // mark sequential end
}
printf("sequential end\n");
printf("parallel start\n");
// ParallelReverser implementation
{
int n;
int s = LENGTH / N;
// fork section
for (n: 1 .. N) {
int from = n * s;
int to;
if
:: (n == N - 1) -> to = LENGTH - 1;
:: else -> to = n * s + s - 1;
fi
run ThreadedReverser(from, to, n); // run as "thread n"
}
// join section
for (n: 1 .. N) {
(done[n] == true); // wait "thread n"
printf("[%d] joined\n", n);
}
}
printf("parallel end\n");
// test if seq and parallel are the same
{
int i;
for (i: 0 .. (LENGTH - 1)) {
if
:: (reversed_seq[i] != reversed_par[i]) -> seq_eq_to_parallel = false;
fi
}
}
}
// ltl syntax: https://spinroot.com/spin/Man/ltl.html
ltl seq_eq_parallel {
// the variable seq_eq_to_parallel will never be false if all the elements
// between the sequential and parallel reversed arrays are equal
(done[0] == false || done[N] == false) U (seq_eq_to_parallel == true)
}
ltl termination {
<> (done[0] == true && done[N] == true)
}