Merge branch 'stclib:master' into modifiedHEADmodified

1 files changed, 105 insertions, 0 deletions

diff --git a/misc/examples/coroutines/dining_philosophers.c b/misc/examples/coroutines/dining_philosophers.c
new file mode 100644
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--- /dev/null
+++ b/misc/examples/coroutines/dining_philosophers.c
@@ -0,0 +1,105 @@
+// https://en.wikipedia.org/wiki/Dining_philosophers_problem
+#include <stdio.h>
+#include <time.h>
+#include <stc/crand.h>
+#include <stc/coroutine.h>
+ 
+// Define the number of philosophers and forks
+enum {
+    num_philosophers = 5,
+    num_forks = num_philosophers,
+};
+
+struct Philosopher {
+    int id;
+    cco_timer tm;
+    cco_sem* left_fork;
+    cco_sem* right_fork;
+    int cco_state; // required
+};
+
+struct Dining {
+    // Define semaphores for the forks
+    cco_sem forks[num_forks];
+    struct Philosopher ph[num_philosophers];
+    int cco_state; // required
+};
+
+ 
+// Philosopher coroutine
+int philosopher(struct Philosopher* p)
+{
+    double duration;
+    cco_routine(p) {
+        while (1) {
+            duration = 1.0 + crandf()*2.0;
+            printf("Philosopher %d is thinking for %.0f minutes...\n", p->id, duration*10);
+            cco_await_timer(&p->tm, duration);
+
+            printf("Philosopher %d is hungry...\n", p->id);
+            cco_await_sem(p->left_fork);
+            cco_await_sem(p->right_fork);
+
+            duration = 0.5 + crandf();
+            printf("Philosopher %d is eating for %.0f minutes...\n", p->id, duration*10);
+            cco_await_timer(&p->tm, duration);
+
+            cco_sem_release(p->left_fork);
+            cco_sem_release(p->right_fork);
+        }
+
+        cco_final:
+        printf("Philosopher %d finished\n", p->id);
+    }
+    return 0;
+}
+
+
+// Dining coroutine
+int dining(struct Dining* d)
+{
+    cco_routine(d) {
+        for (int i = 0; i < num_forks; ++i)
+            cco_sem_set(&d->forks[i], 1); // all forks available
+        for (int i = 0; i < num_philosophers; ++i) {
+            cco_reset(&d->ph[i]);
+            d->ph[i].id = i + 1;
+            d->ph[i].left_fork = &d->forks[i];
+            d->ph[i].right_fork = &d->forks[(i + 1) % num_forks];
+        }
+
+        while (1) {
+            // per-"frame" logic resume each philosopher
+            for (int i = 0; i < num_philosophers; ++i) {
+                philosopher(&d->ph[i]);
+            }
+            cco_yield(); // suspend, return control back to main
+        }
+
+        cco_final:
+        for (int i = 0; i < num_philosophers; ++i) {
+            cco_stop(&d->ph[i]);
+            philosopher(&d->ph[i]);
+        }
+        puts("Dining finished");
+    }
+    return 0;
+}
+
+int main(void)
+{
+    struct Dining dine;
+    cco_reset(&dine);
+    int n=0;
+    cco_timer tm = cco_timer_from(15.0); // seconds
+    csrand((uint64_t)time(NULL));
+
+    cco_blocking_call(dining(&dine))
+    {
+        if (cco_timer_expired(&tm))
+            cco_stop(&dine);
+        cco_sleep(0.001);
+        ++n;
+    }
+    printf("n=%d\n", n);
+}