Add FreeRTOS heap4 intro card

src/tasks/task02_free_list.c

@@ -0,0 +1,64 @@
+#include "heap4_common.h"
+
+volatile size_t g_free_total;
+volatile size_t g_largest_free;
+volatile int g_node_count;
+
+static size_t list_total(HeapBlock *start)
+{
+    HeapBlock *block;
+    size_t total;
+
+    total = 0U;
+    for (block = start->next; block != 0; block = block->next)
+        total += block->size;
+    return total;
+}
+
+static size_t list_largest(HeapBlock *start)
+{
+    HeapBlock *block;
+    size_t largest;
+
+    largest = 0U;
+    for (block = start->next; block != 0; block = block->next)
+        if (block->size > largest)
+            largest = block->size;
+    return largest;
+}
+
+static int list_count(HeapBlock *start)
+{
+    HeapBlock *block;
+    int count;
+
+    count = 0;
+    for (block = start->next; block != 0; block = block->next)
+        count++;
+    return count;
+}
+
+int main(void)
+{
+    HeapBlock start;
+    HeapBlock a;
+    HeapBlock b;
+    HeapBlock c;
+
+    start.next = &a;
+    start.size = 0U;
+    a.next = &b;
+    a.size = 32U;
+    b.next = &c;
+    b.size = 80U;
+    c.next = 0;
+    c.size = 24U;
+
+    g_free_total = list_total(&start);
+    g_largest_free = list_largest(&start);
+    g_node_count = list_count(&start);
+
+    TRACE_PRINTF("free=%u largest=%u count=%d\n",
+                 (unsigned)g_free_total, (unsigned)g_largest_free, g_node_count);
+    return 0;
+}