Add FreeRTOS heap4 intro card

src/tasks/task08_coalescing.c

@@ -0,0 +1,76 @@
+#include "heap4_common.h"
+
+static uint8_t heap_area[192];
+static HeapBlock start;
+static HeapBlock *end_marker;
+
+volatile int g_free_count;
+volatile size_t g_merged_size;
+volatile int g_merged_with_right;
+
+static void insert_block_merge(HeapBlock *block)
+{
+    HeapBlock *iterator;
+    uint8_t *block_end;
+
+    for (iterator = &start; iterator->next < block; iterator = iterator->next)
+        ;
+
+    block_end = (uint8_t *)block + block->size;
+    if (block_end == (uint8_t *)iterator->next) {
+        block->size += iterator->next->size;
+        block->next = iterator->next->next;
+    } else {
+        block->next = iterator->next;
+    }
+
+    if (iterator != &start && heap4_blocks_touch(iterator, block)) {
+        iterator->size += block->size;
+        iterator->next = block->next;
+    } else {
+        iterator->next = block;
+    }
+}
+
+static int count_free(void)
+{
+    HeapBlock *block;
+    int count;
+
+    count = 0;
+    for (block = start.next; block != end_marker; block = block->next)
+        count++;
+    return count;
+}
+
+int main(void)
+{
+    HeapBlock *left;
+    HeapBlock *middle;
+    HeapBlock *right;
+
+    left = (HeapBlock *)&heap_area[0];
+    middle = (HeapBlock *)&heap_area[48];
+    right = (HeapBlock *)&heap_area[96];
+    end_marker = (HeapBlock *)&heap_area[160];
+
+    start.next = left;
+    left->next = right;
+    right->next = end_marker;
+    end_marker->next = 0;
+
+    left->size = 48U;
+    middle->size = 48U;
+    right->size = 64U;
+    end_marker->size = 0U;
+
+    insert_block_merge(middle);
+
+    g_free_count = count_free();
+    g_merged_size = start.next->size;
+    g_merged_with_right = start.next->next == end_marker;
+
+    TRACE_PRINTF("count=%d size=%u merged_right=%d\n",
+                 g_free_count, (unsigned)g_merged_size, g_merged_with_right);
+    return 0;
+}