1 files changed, 88 insertions, 0 deletions
diff --git a/src/mem.c b/src/mem.c
index e69de29..2649db5 100644
--- a/src/mem.c
+++ b/src/mem.c
@@ -0,0 +1,88 @@
+#include <celeritas.h>
+
+void_pool void_pool_create(void* storage, const char* debug_label, u64 capacity, u64 entry_size) {
+  size_t _memory_requirements = capacity * entry_size;
+  // void* backing_buf = arena_alloc(a, memory_requirements);
+
+  assert(entry_size >= sizeof(void_pool_header));  // TODO: create my own assert with error message
+
+  void_pool pool = { .capacity = capacity,
+                     .entry_size = entry_size,
+                     .count = 0,
+                     .backing_buffer = storage,
+                     .free_list_head = NULL,
+                     .debug_label = debug_label };
+
+  void_pool_free_all(&pool);
+
+  return pool;
+}
+
+void void_pool_free_all(void_pool* pool) {
+  // set all entries to be free
+  for (u64 i = 0; i < pool->capacity; i++) {
+    void* ptr = &pool->backing_buffer[i * pool->entry_size];
+    void_pool_header* free_node = (void_pool_header*)ptr;  // we reuse the actual entry itself to hold the header
+    if (i == (pool->capacity - 1)) {
+      // if the last one we make its next pointer NULL indicating its full
+      free_node->next = NULL;
+    }
+    free_node->next = pool->free_list_head;
+    // now the head points to this entry
+    pool->free_list_head = free_node;
+  }
+}
+
+void* void_pool_get(void_pool* pool, u32 raw_handle) {
+  // An handle is an index into the array essentially
+  void* ptr = pool->backing_buffer + (raw_handle * pool->entry_size);
+  return ptr;
+}
+
+void* void_pool_alloc(void_pool* pool, u32* out_raw_handle) {
+  // get the next free node
+  if (pool->count == pool->capacity) {
+    // WARN("Pool is full!");
+    return NULL;
+  }
+  if (pool->free_list_head == NULL) {
+    // ERROR("%s Pool is full (head = null)", pool->debug_label);
+    return NULL;
+  }
+  void_pool_header* free_node = pool->free_list_head;
+
+  // What index does this become?
+  uintptr_t start = (uintptr_t)pool->backing_buffer;
+  uintptr_t cur = (uintptr_t)free_node;
+  // TRACE("%ld %ld ", start, cur);
+  assert(cur > start);
+  u32 index = (u32)((cur - start) / pool->entry_size);
+  /* printf("Index %d\n", index); */
+  if (out_raw_handle != NULL) {
+    *out_raw_handle = index;
+  }
+
+  pool->free_list_head = free_node->next;
+
+  memset(free_node, 0, pool->entry_size);
+  pool->count++;
+  return (void*)free_node;
+}
+
+void void_pool_dealloc(void_pool* pool, u32 raw_handle) {
+  // push free node back onto the free list
+  void* ptr = void_pool_get(pool, raw_handle);
+  void_pool_header* freed_node = (void_pool_header*)ptr;
+
+  freed_node->next = pool->free_list_head;
+  pool->free_list_head = freed_node;
+
+  pool->count--;
+}
+
+u32 void_pool_insert(void_pool* pool, void* item) {
+  u32 raw_handle;
+  void* item_dest = void_pool_alloc(pool, &raw_handle);
+  memcpy(item_dest, item, pool->entry_size);
+  return raw_handle;
+}