Add FreeRTOS heap4 intro card

src/tasks/task03_heap_init.c

@@ -0,0 +1,49 @@
+#include "heap4_common.h"
+
+#define HEAP_BYTES 160U
+
+static uint8_t heap_area[HEAP_BYTES + HEAP4_ALIGNMENT];
+static HeapBlock start;
+static HeapBlock *end_marker;
+
+volatile size_t g_initial_free_size;
+volatile uintptr_t g_aligned_offset;
+volatile int g_end_is_last;
+
+static void heap_init(void)
+{
+    uintptr_t raw;
+    uintptr_t aligned;
+    size_t available;
+    HeapBlock *first;
+
+    raw = (uintptr_t)&heap_area[0];
+    aligned = heap4_align_address(raw);
+    available = HEAP_BYTES - (size_t)(aligned - raw);
+    available &= ~HEAP4_ALIGNMENT_MASK;
+
+    first = (HeapBlock *)aligned;
+    end_marker = (HeapBlock *)(aligned + available - sizeof(HeapBlock));
+    end_marker->next = 0;
+    end_marker->size = 0U;
+
+    first->next = end_marker;
+    first->size = (uint8_t *)end_marker - (uint8_t *)first;
+
+    start.next = first;
+    start.size = 0U;
+}
+
+int main(void)
+{
+    heap_init();
+
+    g_aligned_offset = (uintptr_t)start.next - (uintptr_t)&heap_area[0];
+    g_initial_free_size = start.next->size;
+    g_end_is_last = (start.next->next == end_marker) && (end_marker->next == 0);
+
+    TRACE_PRINTF("offset=%u free=%u end_last=%d\n",
+                 (unsigned)g_aligned_offset, (unsigned)g_initial_free_size,
+                 g_end_is_last);
+    return 0;
+}