Add a multicore_runner example that uses queues

Author: JamesH65

multicore/CMakeLists.txt

@@ -1,5 +1,6 @@
 if (NOT PICO_NO_HARDWARE)
     add_subdirectory(hello_multicore)
     add_subdirectory(multicore_runner)
+    add_subdirectory(multicore_runner_queue)
     add_subdirectory(multicore_fifo_irqs)
 endif ()

multicore/multicore_runner_queue/CMakeLists.txt

@@ -0,0 +1,13 @@
+add_executable(multicore_runner_queue
+        multicore_runner_queue.c
+        )
+
+target_link_libraries(multicore_runner_queue
+        pico_multicore
+        pico_stdlib)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(multicore_runner_queue)
+
+# add url via pico_set_program_url
+example_auto_set_url(multicore_runner_queue)

multicore/multicore_runner_queue/multicore_runner_queue.c

@@ -0,0 +1,97 @@
+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdio.h>
+#include "pico/stdlib.h"
+#include "pico/util/queue.h"
+#include "pico/multicore.h"
+
+#define FLAG_VALUE 123
+
+typedef struct
+{
+    void *func;
+    int32_t data;
+} queue_entry_t;
+
+queue_t call_queue;
+queue_t results_queue;
+
+void core1_entry() {
+    while (1) {
+        // Function pointer is passed to us via the queue_entry_t which also
+        // contains the function parameter.
+        // We provide an int32_t return value by simply pushing it back on the
+        // return queue which also indicates the result is ready.
+
+        queue_entry_t entry;
+
+        queue_remove_blocking(&call_queue, &entry);
+
+        int32_t (*func)() = (int32_t(*)())(entry.func);
+        int32_t result = (*func)(entry.data);
+
+        queue_add_blocking(&results_queue, &result);
+    }
+}
+
+int32_t factorial(int32_t n) {
+    int32_t f = 1;
+    for (int i = 2; i <= n; i++) {
+        f *= i;
+    }
+    return f;
+}
+
+int32_t fibonacci(int32_t n) {
+    if (n == 0) return 0;
+    if (n == 1) return 1;
+
+    int n1 = 0, n2 = 1, n3;
+
+    for (int i = 2; i <= n; i++) {
+        n3 = n1 + n2;
+        n1 = n2;
+        n2 = n3;
+    }
+    return n3;
+}
+
+#define TEST_NUM 10
+
+int main() {
+    int32_t res;
+
+    stdio_init_all();
+    printf("Hello, multicore_runner using queues!\n");
+
+    // This example dispatches arbitrary functions to run on the second core
+    // To do this we run a dispatcher on the second core that accepts a function
+    // pointer and runs it. The data is passed over using the queue library from
+    // pico_utils
+
+    queue_init(&call_queue, sizeof(queue_entry_t), 2);
+    queue_init(&results_queue, sizeof(int32_t), 2);
+
+    multicore_launch_core1(core1_entry);
+
+    queue_entry_t entry = {&factorial, TEST_NUM};
+    queue_add_blocking(&call_queue, &entry);
+
+    // We could now do a load of stuff on core 0 and get our result later
+
+    queue_remove_blocking(&results_queue, &res);
+
+    printf("Factorial %d is %d\n", TEST_NUM, res);
+
+    // Now try a different function
+    entry.func = &fibonacci;
+    queue_add_blocking(&call_queue, &entry);
+
+    queue_remove_blocking(&results_queue, &res);
+
+    printf("Fibonacci %d is %d\n", TEST_NUM, res);
+}