From 633632105b7659ae5d9c53db9757d30768e99939 Mon Sep 17 00:00:00 2001
From: Abdelrahman <said.abdelrahman89@gmail.com>
Date: Sat, 24 Feb 2024 18:40:25 +0000
Subject: [PATCH] Implement base arena allocator

---
 mem/include/arena/mem_arena.h |  7 ++++
 mem/src/arena/mem_arena.c     | 73 +++++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100644 mem/include/arena/mem_arena.h
 create mode 100644 mem/src/arena/mem_arena.c

diff --git a/mem/include/arena/mem_arena.h b/mem/include/arena/mem_arena.h
new file mode 100644
index 0000000..2ab423c
--- /dev/null
+++ b/mem/include/arena/mem_arena.h
@@ -0,0 +1,7 @@
+#ifndef MEM_ARENA_H
+#define MEM_ARENA_H
+
+#include "aliases.h"
+#include <stdbool.h>
+
+#endif // !MEM_ARENA_H
diff --git a/mem/src/arena/mem_arena.c b/mem/src/arena/mem_arena.c
new file mode 100644
index 0000000..729b0aa
--- /dev/null
+++ b/mem/src/arena/mem_arena.c
@@ -0,0 +1,73 @@
+#include "mem_arena.h"
+#include "aliases.h"
+#include "mem_utils.h"
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifndef DEFAULT_ALIGNMENT
+#define DEFAULT_ALIGNMENT (2 * sizeof(void *))
+#endif /* ifndef DEFAULT_ALIGNMENT */
+
+typedef struct base_arena BaseArena;
+struct base_arena {
+  u8 *buf;
+  u8 *offset;
+  u64 capacity;
+  BaseArena *prev;
+  BaseArena *next;
+};
+
+internal bool base_arena_init(BaseArena *arena, u64 capacity);
+internal void *base_arena_alloc(BaseArena *arena, u64 size);
+internal void *base_arena_alloc_aligned(BaseArena *arena, u64 size,
+                                        u64 alignment);
+internal void base_arena_clear(BaseArena *arena);
+internal void base_arena_free(BaseArena *arena);
+
+internal bool base_arena_init(BaseArena *arena, u64 capacity) {
+  u64 alloc_size = sizeof(u8) * capacity;
+
+  arena->buf = (u8 *)malloc(alloc_size);
+  if (!(arena->buf)) {
+    return false;
+  }
+
+  memset(arena->buf, 0, alloc_size);
+  arena->capacity = capacity;
+  arena->offset = arena->buf;
+  arena->prev = arena->next = NULL;
+
+  return true;
+}
+
+internal void *base_arena_alloc(BaseArena *arena, u64 size) {
+  return base_arena_alloc_aligned(arena, size, DEFAULT_ALIGNMENT);
+}
+
+internal void *base_arena_alloc_aligned(BaseArena *arena, u64 size,
+                                        u64 alignment) {
+  u8 *output = mem_util_align_forward((void *)(arena->offset), alignment);
+  if (output + size >= arena->buf + arena->capacity) {
+    return NULL;
+  }
+
+  arena->offset += size;
+
+  return (void *)output;
+}
+
+internal void base_arena_clear(BaseArena *arena) {
+  memset(arena->buf, 0, arena->offset - arena->buf);
+  arena->offset = arena->buf;
+}
+
+internal void base_arena_free(BaseArena *arena) {
+  if (arena->buf) {
+    free(arena->buf);
+  }
+
+  arena->buf = arena->offset = NULL;
+  arena->capacity = 0;
+  arena->prev = arena->next = NULL;
+}