feat: rebuild heap4 card around upstream FreeRTOS allocator

2026-07-14 23:24:56 +02:00
parent 032a06fdef
commit 2b17bb4ff9
41 changed files with 1462 additions and 2138 deletions
@@ -0,0 +1,136 @@
+#include "heap4_model.h"
+
+enum { BLOCK_BYTES = 48 };
+
+typedef struct {
+    ModelBlock first;
+    uint8_t first_payload[BLOCK_BYTES - sizeof(ModelBlock)];
+    ModelBlock middle;
+    uint8_t middle_payload[BLOCK_BYTES - sizeof(ModelBlock)];
+    ModelBlock last;
+    uint8_t last_payload[BLOCK_BYTES - sizeof(ModelBlock)];
+} CoalesceArena;
+
+typedef union {
+    uint64_t force_alignment;
+    CoalesceArena blocks;
+} AlignedCoalesceArena;
+
+AlignedCoalesceArena g_coalesce_arena;
+ModelBlock *g_free_head;
+volatile size_t g_before_nodes;
+volatile size_t g_before_total;
+volatile size_t g_before_largest;
+volatile size_t g_after_nodes;
+volatile size_t g_after_total;
+volatile size_t g_after_largest;
+volatile int g_task02_pass;
+
+static void insert_and_coalesce(ModelBlock *block)
+{
+    ModelBlock *previous = NULL;
+    ModelBlock *current = g_free_head;
+
+    while (current != NULL && (uintptr_t)current < (uintptr_t)block)
+    {
+        previous = current;
+        current = current->next;
+    }
+
+    block->next = current;
+    if (current != NULL &&
+        (uint8_t *)block + block->size == (uint8_t *)current)
+    {
+        block->size += current->size;
+        block->next = current->next;
+    }
+
+    if (previous != NULL &&
+        (uint8_t *)previous + previous->size == (uint8_t *)block)
+    {
+        previous->size += block->size;
+        previous->next = block->next;
+    }
+    else if (previous != NULL)
+    {
+        previous->next = block;
+    }
+    else
+    {
+        g_free_head = block;
+    }
+}
+
+static void measure(size_t *nodes, size_t *total, size_t *largest)
+{
+    ModelBlock *block;
+
+    *nodes = 0U;
+    *total = 0U;
+    *largest = 0U;
+    for (block = g_free_head; block != NULL; block = block->next)
+    {
+        (*nodes)++;
+        *total += block->size;
+        if (block->size > *largest)
+        {
+            *largest = block->size;
+        }
+    }
+}
+
+__attribute__((noinline)) void task02_fragmented_checkpoint(void)
+{
+#if defined(__GNUC__)
+    __asm__ volatile("" ::: "memory");
+#endif
+}
+
+__attribute__((noinline)) void task02_debug_checkpoint(void)
+{
+#if defined(__GNUC__)
+    __asm__ volatile("" ::: "memory");
+#endif
+}
+
+int main(void)
+{
+    CoalesceArena *arena = &g_coalesce_arena.blocks;
+    size_t nodes;
+    size_t total;
+    size_t largest;
+
+    arena->first.size = BLOCK_BYTES;
+    arena->middle.size = BLOCK_BYTES;
+    arena->last.size = BLOCK_BYTES;
+    g_free_head = NULL;
+
+    insert_and_coalesce(&arena->first);
+    insert_and_coalesce(&arena->last);
+    measure(&nodes, &total, &largest);
+    g_before_nodes = nodes;
+    g_before_total = total;
+    g_before_largest = largest;
+    task02_fragmented_checkpoint();
+
+    insert_and_coalesce(&arena->middle);
+    measure(&nodes, &total, &largest);
+    g_after_nodes = nodes;
+    g_after_total = total;
+    g_after_largest = largest;
+    g_task02_pass =
+        g_before_nodes == 2U && g_before_total == 96U &&
+        g_before_largest == 48U && g_after_nodes == 1U &&
+        g_after_total == 144U && g_after_largest == 144U &&
+        g_free_head == &arena->first && g_free_head->next == NULL;
+
+    task02_debug_checkpoint();
+
+#if defined(HOST_PRINTF)
+    printf("before_nodes=%zu before_total=%zu before_largest=%zu "
+           "after_nodes=%zu after_total=%zu after_largest=%zu pass=%d\n",
+           g_before_nodes, g_before_total, g_before_largest,
+           g_after_nodes, g_after_total, g_after_largest, g_task02_pass);
+#endif
+    return g_task02_pass ? 0 : 1;
+}