1 files changed, 135 insertions, 0 deletions
diff --git a/archive/src/std/mem.c b/archive/src/std/mem.c
new file mode 100644
index 0000000..1f9078b
--- /dev/null
+++ b/archive/src/std/mem.c
@@ -0,0 +1,135 @@
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "log.h"
+#include "mem.h"
+
+#ifndef DEFAULT_ALIGNMENT
+#define DEFAULT_ALIGNMENT (2 * sizeof(void*))
+#endif
+
+// --- Arena
+
+void* arena_alloc_align(arena* a, size_t size, size_t align) {
+  ptrdiff_t padding = -(uintptr_t)a->curr & (align - 1);
+  ptrdiff_t available = a->end - a->curr - padding;
+  // TRACE("Padding %td available %td", padding, available);
+  if (available < 0 || (ptrdiff_t)size > available) {
+    ERROR_EXIT("Arena ran out of memory\n");
+  }
+  void* p = a->curr + padding;
+  a->curr += padding + size;
+  return memset(p, 0, size);
+}
+void* arena_alloc(arena* a, size_t size) { return arena_alloc_align(a, size, DEFAULT_ALIGNMENT); }
+
+arena arena_create(void* backing_buffer, size_t capacity) {
+  return (arena){ .begin = backing_buffer,
+                  .curr = backing_buffer,
+                  .end = backing_buffer + (ptrdiff_t)capacity };
+}
+
+void arena_free_all(arena* a) {
+  a->curr = a->begin;  // pop everything at once and reset to the start.
+}
+
+void arena_free_storage(arena* a) { free(a->begin); }
+
+arena_save arena_savepoint(arena* a) {
+  arena_save savept = { .arena = a, .savepoint = a->curr };
+  return savept;
+}
+
+void arena_rewind(arena_save savepoint) { savepoint.arena->curr = savepoint.savepoint; }
+
+// --- Pool
+
+void_pool void_pool_create(arena* a, 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 = backing_buf,
+                     .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;
+}