Set minimum capacity for arena

.gitignore

@@ -1,3 +1,4 @@
 .cache
+.vscode
 compile_commands.json
-libwizapp.so
+libwapp.so

compile

@@ -5,14 +5,14 @@ INCLUDE="\
 	-Ialiases \
 	-Icpath/include \
 	-Idstr/include \
-	$(find mem/include/ -type d | xargs -I{} printf "-I{} ") \
+	$(find mem/include -type d | xargs -I{} echo -n "-I{} ") \
 "
 SRC="\
 	cpath/src/*.c \
 	dstr/src/*.c \
 	mem/src/*/*.c \
 "
-CFLAGS="-shared -fPIC -Wall -Werror -pedantic"
-OUT="libwizapp.so"
+CFLAGS="-O3 -shared -fPIC -Wall -Werror -pedantic"
+OUT="libwapp.so"
 
 (set -x ; $CC $CFLAGS $INCLUDE $SRC -o $OUT)

cpath/include/cpath.h

@@ -3,15 +3,23 @@
 
 #include "aliases.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
 #define NUMPARTS(...)                                                          \
   (sizeof((const char *[]){"", __VA_ARGS__}) / sizeof(const char *) - 1)
 
-#define cpath_join_path(DST, ...)                                              \
+#define wapp_cpath_join_path(DST, ...)                                         \
   join_path(DST, NUMPARTS(__VA_ARGS__), __VA_ARGS__)
-#define cpath_dirname(DST, PATH) dirup(DST, 1, PATH)
-#define cpath_dirup(DST, COUNT, PATH) dirup(DST, COUNT, PATH)
+#define wapp_cpath_dirname(DST, PATH) dirup(DST, 1, PATH)
+#define wapp_cpath_dirup(DST, COUNT, PATH) dirup(DST, COUNT, PATH)
 
 void join_path(char *dst, u64 count, ...);
 void dirup(char *dst, u64 levels, const char *path);
 
+#ifdef __cplusplus
+}
+#endif // __cplusplus
+
 #endif // !PATH_UTILS_H

dstr/include/dstr.h

@@ -2,21 +2,30 @@
 #define DSTR_H
 
 #include "aliases.h"
+#include "mem_allocator.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
 
 typedef struct dstr String;
 
-String *dstr_with_capacity(u64 capacity);
-String *dstr_from_string(const char *str);
-void dstr_update(String **dst, const char *src);
-void dstr_free(String **str);
-void dstr_concat(String **dst, const char *src);
-void dstr_append(String **dst, char c);
-void dstr_resize(String **str);
-void dstr_clear(String *str);
-void dstr_print(const String *str);
-i64 dstr_find(const String *str, const char *substr);
-u64 dstr_length(const String *str);
-u64 dstr_capacity(const String *str);
-const char *dstr_to_cstr(const String *str);
+String *wapp_dstr_with_capacity(u64 capacity, const Allocator *allocator);
+String *wapp_dstr_from_string(const char *str, const Allocator *allocator);
+void wapp_dstr_update(String **dst, const char *src);
+void wapp_dstr_free(String **str);
+void wapp_dstr_concat(String **dst, const char *src);
+void wapp_dstr_append(String **dst, char c);
+void wapp_dstr_resize(String **str);
+void wapp_dstr_clear(String *str);
+void wapp_dstr_print(const String *str);
+i64 wapp_dstr_find(const String *str, const char *substr);
+u64 wapp_dstr_length(const String *str);
+u64 wapp_dstr_capacity(const String *str);
+const char *wapp_dstr_to_cstr(const String *str);
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus
 
 #endif // !DSTR_H

dstr/src/dstr.c

@@ -1,5 +1,7 @@
 #include "dstr.h"
 #include "aliases.h"
+#include "mem_allocator.h"
+#include "mem_libc.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -9,26 +11,34 @@
 #define CAPACITY_SCALAR 8
 
 struct dstr {
+  Allocator allocator;
   u64 capacity;
   u64 size;
   char buf[];
 };
 
-String *dstr_with_capacity(u64 capacity) {
-  String *out = (String *)malloc(sizeof(String) + capacity + 1);
+String *wapp_dstr_with_capacity(u64 capacity, const Allocator *allocator) {
+  Allocator alloc;
+  if (allocator) {
+    alloc = *allocator;
+  } else {
+    alloc = wapp_mem_libc_allocator();
+  }
 
+  String *out =
+      (String *)wapp_mem_allocator_alloc(&alloc, sizeof(String) + capacity + 1);
   if (!out) {
     return NULL;
   }
 
+  out->allocator = alloc;
   out->capacity = capacity;
   out->size = 0;
-  memset(out->buf, 0, capacity + 1);
 
   return out;
 }
 
-String *dstr_from_string(const char *str) {
+String *wapp_dstr_from_string(const char *str, const Allocator *allocator) {
   if (!str) {
     return NULL;
   }
@@ -37,19 +47,18 @@ String *dstr_from_string(const char *str) {
 
   u64 capacity = length * CAPACITY_SCALAR;
 
-  String *out = dstr_with_capacity(capacity);
-
+  String *out = wapp_dstr_with_capacity(capacity, allocator);
   if (!out) {
     return NULL;
   }
 
   out->size = length;
-  strncpy(out->buf, str, length);
+  strncpy(out->buf, str, length + 1);
 
   return out;
 }
 
-void dstr_update(String **dst, const char *src) {
+void wapp_dstr_update(String **dst, const char *src) {
   if (!dst || !(*dst)) {
     return;
   }
@@ -58,45 +67,44 @@ void dstr_update(String **dst, const char *src) {
 
   String *str = *dst;
 
-  if (length <= str->capacity) {
+  if (length < str->capacity) {
     memset(str->buf, 0, str->capacity);
 
     str->size = length;
 
-    strncpy(str->buf, src, length);
+    strncpy(str->buf, src, length + 1);
   } else {
     u64 capacity = length * CAPACITY_SCALAR;
 
-    String *tmp = (String *)realloc(*dst, sizeof(String) + capacity + 1);
-
+    String *tmp = (String *)wapp_mem_allocator_realloc(
+        &(str->allocator), *dst, sizeof(String) + capacity + 1);
     if (!tmp) {
       return;
     }
 
     tmp->capacity = capacity;
     tmp->size = length;
-    strncpy(tmp->buf, src, length);
+    strncpy(tmp->buf, src, length + 1);
 
     *dst = tmp;
   }
 }
 
-void dstr_free(String **str) {
+void wapp_dstr_free(String **str) {
   if (!str || !(*str)) {
     return;
   }
 
-  free(*str);
-  *str = NULL;
+  String *str_ptr = *str;
+  wapp_mem_allocator_free(&(str_ptr->allocator), (void **)str);
 }
 
-void dstr_concat(String **dst, const char *src) {
+void wapp_dstr_concat(String **dst, const char *src) {
   if (!dst || !(*dst)) {
     return;
   }
 
   u64 src_length = strlen(src);
-
   if (src_length == 0) {
     return;
   }
@@ -107,12 +115,12 @@ void dstr_concat(String **dst, const char *src) {
   memset(str, 0, new_length + 1);
 
   strncpy(str, (*dst)->buf, (*dst)->size);
-  strncat(str, src, src_length);
+  strncat(str, src, new_length + 1 - (*dst)->size);
 
-  dstr_update(dst, str);
+  wapp_dstr_update(dst, str);
 }
 
-void dstr_append(String **dst, char c) {
+void wapp_dstr_append(String **dst, char c) {
   if (!dst || !(*dst)) {
     return;
   }
@@ -125,18 +133,19 @@ void dstr_append(String **dst, char c) {
   strncpy(str, (*dst)->buf, (*dst)->size);
   str[(*dst)->size] = c;
 
-  dstr_update(dst, str);
+  wapp_dstr_update(dst, str);
 }
 
-void dstr_resize(String **str) {
+void wapp_dstr_resize(String **str) {
   if (!str || !(*str)) {
     return;
   }
 
+  String *str_ptr = *str;
   u64 capacity = (*str)->size;
 
-  String *tmp = (String *)realloc(*str, sizeof(String) + capacity + 1);
-
+  String *tmp = (String *)wapp_mem_allocator_realloc(
+      &(str_ptr->allocator), *str, sizeof(String) + capacity + 1);
   if (!tmp) {
     return;
   }
@@ -146,7 +155,7 @@ void dstr_resize(String **str) {
   *str = tmp;
 }
 
-void dstr_clear(String *str) {
+void wapp_dstr_clear(String *str) {
   if (!str || str->size == 0) {
     return;
   }
@@ -155,38 +164,33 @@ void dstr_clear(String *str) {
   str->size = 0;
 }
 
-void dstr_print(const String *str) {
+void wapp_dstr_print(const String *str) {
   if (!str) {
     return;
   }
 
-  printf("%s\n", str->buf);
+  printf("%.*s\n", (i32)str->size, str->buf);
 }
 
-i64 dstr_find(const String *str, const char *substr) {
+i64 wapp_dstr_find(const String *str, const char *substr) {
   if (!str || !substr) {
     return -1;
   }
 
   u64 substr_length = strlen(substr);
-
   if (substr_length == 0 || substr_length > str->size) {
     return -1;
   }
 
-  char buf[substr_length + 1];
-  memset(buf, 0, substr_length + 1);
-
+  const char *s1;
   for (u64 i = 0; i < str->size; ++i) {
-    if (i + substr_length >= str->size) {
+    if (i + substr_length > str->size) {
       break;
     }
 
-    for (u64 j = 0; j < substr_length; ++j) {
-      buf[j] = str->buf[i + j];
-    }
+    s1 = &(str->buf[i]);
 
-    if (strcmp(buf, substr) == 0) {
+    if (strncmp(s1, substr, substr_length) == 0) {
       return i;
     }
   }
@@ -194,7 +198,7 @@ i64 dstr_find(const String *str, const char *substr) {
   return -1;
 }
 
-u64 dstr_length(const String *str) {
+u64 wapp_dstr_length(const String *str) {
   if (!str) {
     return 0;
   }
@@ -202,7 +206,7 @@ u64 dstr_length(const String *str) {
   return str->size;
 }
 
-u64 dstr_capacity(const String *str) {
+u64 wapp_dstr_capacity(const String *str) {
   if (!str) {
     return 0;
   }
@@ -210,7 +214,7 @@ u64 dstr_capacity(const String *str) {
   return str->capacity;
 }
 
-const char *dstr_to_cstr(const String *str) {
+const char *wapp_dstr_to_cstr(const String *str) {
   if (!str) {
     return "";
   }

mem/include/allocator/mem_allocator.h

@@ -0,0 +1,40 @@
+#ifndef MEM_ALLOCATOR_H
+#define MEM_ALLOCATOR_H
+
+#include "aliases.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+typedef void *(MemAllocFunc)(u64 size, void *alloc_obj);
+typedef void *(MemAllocAlignedFunc)(u64 size, u64 alignment, void *alloc_obj);
+typedef void *(MemReallocFunc)(void *ptr, u64 size, void *alloc_obj);
+typedef void *(MemReallocAlignedFunc)(void *ptr, u64 size, u64 alignment,
+                                      void *alloc_obj);
+typedef void(MemFreeFunc)(void **ptr, void *alloc_obj);
+
+typedef struct allocator Allocator;
+struct allocator {
+  void *obj;
+  MemAllocFunc *alloc;
+  MemAllocAlignedFunc *alloc_aligned;
+  MemReallocFunc *realloc;
+  MemReallocAlignedFunc *realloc_aligned;
+  MemFreeFunc *free;
+};
+
+void *wapp_mem_allocator_alloc(const Allocator *allocator, u64 size);
+void *wapp_mem_allocator_alloc_aligned(const Allocator *allocator, u64 size,
+                                       u64 alignment);
+void *wapp_mem_allocator_realloc(const Allocator *allocator, void *ptr,
+                                 u64 size);
+void *wapp_mem_allocator_realloc_aligned(const Allocator *allocator, void *ptr,
+                                         u64 size, u64 alignment);
+void wapp_mem_allocator_free(const Allocator *allocator, void **ptr);
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus
+
+#endif // !MEM_ALLOCATOR_H

mem/include/arena/mem_arena.h

@@ -2,14 +2,27 @@
 #define MEM_ARENA_H
 
 #include "aliases.h"
+#include "mem_allocator.h"
 #include <stdbool.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
 typedef struct growing_arena Arena;
 
-bool mem_arena_init(Arena **arena, u64 base_capacity);
-void *mem_arena_alloc(Arena *arena, u64 size);
-void *mem_arena_alloc_aligned(Arena *arena, u64 size, u64 alignment);
-void mem_arena_clear(Arena *arena);
-void mem_arena_free(Arena **arena);
+Allocator wapp_mem_arena_allocator(const Arena *arena);
+bool wapp_mem_arena_init(Arena **arena, u64 base_capacity);
+void *wapp_mem_arena_alloc(Arena *arena, u64 size);
+void *wapp_mem_arena_alloc_aligned(Arena *arena, u64 size, u64 alignment);
+void *wapp_mem_arena_realloc(Arena *arena, void *ptr, u64 size);
+void *wapp_mem_arena_realloc_aligned(Arena *arena, void *ptr, u64 size,
+                                     u64 alignment);
+void wapp_mem_arena_clear(Arena *arena);
+void wapp_mem_arena_free(Arena **arena);
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus
 
 #endif // !MEM_ARENA_H

mem/include/ctx/mem_ctx.h

@@ -0,0 +1,32 @@
+#ifndef MEM_CTX_H
+#define MEM_CTX_H
+
+#include "mem_allocator.h"
+#include "mem_arena.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+typedef enum {
+  CTX_DEST_BUFFER_MAIN,
+  CTX_DEST_BUFFER_TEMP,
+
+  COUNT_CTX_DEST_BUFFER,
+} CTXDestBuffer;
+
+Allocator wapp_mem_ctx_allocator(CTXDestBuffer buffer);
+void wapp_mem_ctx_init(u64 main_buf_capacity, u64 temp_buf_capacity);
+void *wapp_mem_ctx_alloc(CTXDestBuffer buffer, u64 size);
+void *wapp_mem_ctx_alloc_aligned(CTXDestBuffer buffer, u64 size, u64 alignment);
+void *wapp_mem_ctx_realloc(CTXDestBuffer buffer, void *ptr, u64 size);
+void *wapp_mem_ctx_realloc_aligned(CTXDestBuffer buffer, void *ptr, u64 size,
+                                   u64 alignment);
+void wapp_mem_ctx_clear(CTXDestBuffer buffer);
+void wapp_mem_ctx_free(void);
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus
+
+#endif // !MEM_CTX_H

mem/include/libc/mem_libc.h

@@ -0,0 +1,15 @@
+#ifndef MEM_LIBC_H
+#define MEM_LIBC_H
+
+#include "mem_allocator.h"
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+Allocator wapp_mem_libc_allocator(void);
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus
+
+#endif // !MEM_LIBC_H

mem/include/util/mem_utils.h

@@ -3,6 +3,14 @@
 
 #include "aliases.h"
 
-void *mem_util_align_forward(void *ptr, u64 alignment);
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void *wapp_mem_util_align_forward(void *ptr, u64 alignment);
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus
 
 #endif // !MEM_UTILS_H

mem/src/allocator/mem_allocator.c

@@ -0,0 +1,45 @@
+#include "mem_allocator.h"
+#include <stdlib.h>
+
+void *wapp_mem_allocator_alloc(const Allocator *allocator, u64 size) {
+  if (!allocator || !(allocator->alloc)) {
+    return NULL;
+  }
+
+  return allocator->alloc(size, allocator->obj);
+}
+
+void *wapp_mem_allocator_alloc_aligned(const Allocator *allocator, u64 size,
+                                       u64 alignment) {
+  if (!allocator || !(allocator->alloc_aligned)) {
+    return NULL;
+  }
+
+  return allocator->alloc_aligned(size, alignment, allocator->obj);
+}
+
+void *wapp_mem_allocator_realloc(const Allocator *allocator, void *ptr,
+                                 u64 size) {
+  if (!allocator || !(allocator->realloc)) {
+    return NULL;
+  }
+
+  return allocator->realloc(ptr, size, allocator->obj);
+}
+
+void *wapp_mem_allocator_realloc_aligned(const Allocator *allocator, void *ptr,
+                                         u64 size, u64 alignment) {
+  if (!allocator || !(allocator->realloc_aligned)) {
+    return NULL;
+  }
+
+  return allocator->realloc_aligned(ptr, size, alignment, allocator->obj);
+}
+
+void wapp_mem_allocator_free(const Allocator *allocator, void **ptr) {
+  if (!allocator || !(allocator->free)) {
+    return;
+  }
+
+  allocator->free(ptr, allocator->obj);
+}

mem/src/arena/mem_arena.c

@@ -1,14 +1,33 @@
 #include "mem_arena.h"
 #include "aliases.h"
+#include "mem_allocator.h"
 #include "mem_utils.h"
+#include <math.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 
 #ifndef DEFAULT_ALIGNMENT
+// Why 2 * sizeof(void *) instead of sizeof(void *)
+// https://handmade.network/forums/t/6860-alignment_arena_allocator
 #define DEFAULT_ALIGNMENT (2 * sizeof(void *))
 #endif /* ifndef DEFAULT_ALIGNMENT */
 
+#define HDR_MAGIC_BYTE_COUNT 8
+#define HDR_MAGIC                                                              \
+  { 0x57, 0x41, 0x41, 0x52, 0x4e, 0x48, 0x44, 0x52 }
+#define MAX_HDR_SEARCH_LENGTH 256
+
+#define ARENA_MINIMUM_CAPACITY 1024
+
+typedef struct arena_alloc_hdr ArenaAllocHDR;
+struct arena_alloc_hdr {
+  u8 magic[HDR_MAGIC_BYTE_COUNT];
+  u64 alloc_size;
+  u64 alignment;
+  u8 *alloc_start;
+};
+
 typedef struct base_arena BaseArena;
 struct base_arena {
   u8 *buf;
@@ -24,35 +43,54 @@ struct growing_arena {
   u64 initial_capacity;
 };
 
+internal BaseArena *find_arena_from_pointer(const Arena *arena, void *ptr);
+
 internal bool base_arena_init(BaseArena *arena, u64 capacity);
 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 ArenaAllocHDR *find_alloc_header(BaseArena *arena, void *alloc_ptr);
+
+internal void *mem_arena_alloc(u64 size, void *alloc_obj);
+internal void *mem_arena_alloc_aligned(u64 size, u64 alignment,
+                                       void *alloc_obj);
+internal void *mem_arena_realloc(void *ptr, u64 size, void *alloc_obj);
+internal void *mem_arena_realloc_aligned(void *ptr, u64 size, u64 alignment,
+                                         void *alloc_obj);
 
 // PUBLIC API
 
-bool mem_arena_init(Arena **arena, u64 base_capacity) {
-  if (!arena || *arena) {
+Allocator wapp_mem_arena_allocator(const Arena *arena) {
+  return (Allocator){
+      .obj = (void *)arena,
+      .alloc = mem_arena_alloc,
+      .alloc_aligned = mem_arena_alloc_aligned,
+      .realloc = mem_arena_realloc,
+      .realloc_aligned = mem_arena_realloc_aligned,
+      .free = NULL,
+  };
+}
+
+bool wapp_mem_arena_init(Arena **arena, u64 base_capacity) {
+  if (!arena || *arena || base_capacity == 0) {
     return false;
   }
 
-  *arena = (Arena *)malloc(sizeof(Arena));
+  *arena = (Arena *)calloc(1, sizeof(Arena));
   Arena *arena_ptr = *arena;
   if (!arena_ptr) {
     return false;
   }
 
-  memset(arena_ptr, 0, sizeof(Arena));
-
-  arena_ptr->active_arena = (BaseArena *)malloc(sizeof(BaseArena));
+  arena_ptr->active_arena = (BaseArena *)calloc(1, sizeof(BaseArena));
   if (!(arena_ptr->active_arena)) {
+    wapp_mem_arena_free(arena);
     return false;
   }
 
-  memset(arena_ptr->active_arena, 0, sizeof(BaseArena));
-
   if (!base_arena_init(arena_ptr->active_arena, base_capacity)) {
+    wapp_mem_arena_free(arena);
     return false;
   }
 
@@ -62,11 +100,11 @@ bool mem_arena_init(Arena **arena, u64 base_capacity) {
   return true;
 }
 
-void *mem_arena_alloc(Arena *arena, u64 size) {
-  return mem_arena_alloc_aligned(arena, size, DEFAULT_ALIGNMENT);
+void *wapp_mem_arena_alloc(Arena *arena, u64 size) {
+  return wapp_mem_arena_alloc_aligned(arena, size, DEFAULT_ALIGNMENT);
 }
 
-void *mem_arena_alloc_aligned(Arena *arena, u64 size, u64 alignment) {
+void *wapp_mem_arena_alloc_aligned(Arena *arena, u64 size, u64 alignment) {
   if (!arena || !(arena->active_arena)) {
     return NULL;
   }
@@ -76,13 +114,11 @@ void *mem_arena_alloc_aligned(Arena *arena, u64 size, u64 alignment) {
     if (arena->active_arena->next) {
       arena->active_arena = arena->active_arena->next;
     } else {
-      arena->active_arena->next = (BaseArena *)malloc(sizeof(BaseArena));
+      arena->active_arena->next = (BaseArena *)calloc(1, sizeof(BaseArena));
       if (!(arena->active_arena->next)) {
         return NULL;
       }
 
-      memset(arena->active_arena->next, 0, sizeof(BaseArena));
-
       if (!base_arena_init(arena->active_arena->next,
                            arena->initial_capacity)) {
         free(arena->active_arena->next);
@@ -106,31 +142,80 @@ void *mem_arena_alloc_aligned(Arena *arena, u64 size, u64 alignment) {
   return output;
 }
 
-void mem_arena_clear(Arena *arena) {
+void *wapp_mem_arena_realloc(Arena *arena, void *ptr, u64 size) {
+  return wapp_mem_arena_realloc_aligned(arena, ptr, size, DEFAULT_ALIGNMENT);
+}
+
+void *wapp_mem_arena_realloc_aligned(Arena *arena, void *ptr, u64 size,
+                                     u64 alignment) {
+  if (!arena) {
+    return NULL;
+  }
+
+  BaseArena *base_arena = find_arena_from_pointer(arena, ptr);
+  if (!base_arena) {
+    return NULL;
+  }
+
+  ArenaAllocHDR *header = find_alloc_header(base_arena, ptr);
+  if (!header) {
+    return NULL;
+  }
+
+  if (header->alloc_start + header->alloc_size == base_arena->offset) {
+    // Avoid allocating new pointer and copying memory if pointer is at the end
+    // of the arena
+    i64 diff = size - header->alloc_size;
+
+    u8 *new_offset = base_arena->offset + diff;
+
+    u8 *clear_start = diff < 0 ? new_offset : base_arena->offset;
+    memset(clear_start, 0, llabs(diff));
+
+    header->alloc_size = size;
+    base_arena->offset = new_offset;
+
+    return header->alloc_start;
+  }
+
+  void *new_alloc = wapp_mem_arena_alloc_aligned(arena, size, alignment);
+  if (!new_alloc) {
+    return NULL;
+  }
+
+  u64 to_copy = size < header->alloc_size ? size : header->alloc_size;
+
+  memcpy(new_alloc, ptr, to_copy);
+
+  return new_alloc;
+}
+
+void wapp_mem_arena_clear(Arena *arena) {
   if (!arena) {
     return;
   }
 
-  BaseArena *new_active = NULL;
+  BaseArena *last_active = NULL;
   while (arena->active_arena) {
     base_arena_clear(arena->active_arena);
 
-    arena->active_arena = arena->active_arena->prev;
+    last_active = arena->active_arena;
 
-    if (arena->active_arena) {
-      new_active = arena->active_arena;
-    }
+    arena->active_arena = arena->active_arena->prev;
   }
 
-  arena->active_arena = new_active;
+  arena->active_arena = last_active;
 }
 
-void mem_arena_free(Arena **arena) {
+void wapp_mem_arena_free(Arena **arena) {
   if (!arena) {
     return;
   }
 
   Arena *arena_ptr = *arena;
+  if (!arena_ptr) {
+    return;
+  }
 
   BaseArena *current;
   BaseArena *next;
@@ -170,20 +255,44 @@ void mem_arena_free(Arena **arena) {
 
 // INTERNAL FUNCTIONS
 
+internal BaseArena *find_arena_from_pointer(const Arena *arena, void *ptr) {
+  if (!arena || !ptr) {
+    return NULL;
+  }
+
+  // Ensure pointer is not out of bounds
+  u8 *alloc = (u8 *)ptr;
+  BaseArena *active = arena->active_arena;
+
+  if (alloc > active->buf + arena->initial_capacity) {
+    return NULL;
+  }
+
+  for (u64 i = 0; i < arena->count; ++i) {
+    if (alloc >= active->buf && alloc < active->buf + arena->initial_capacity) {
+      return (BaseArena *)active;
+    }
+
+    active = active->prev;
+  }
+
+  return NULL;
+}
+
 internal bool base_arena_init(BaseArena *arena, u64 capacity) {
-  if (!arena || arena->buf) {
+  if (!arena || arena->buf || capacity == 0) {
     return false;
   }
 
-  u64 alloc_size = sizeof(u8) * capacity;
+  u64 arena_capacity =
+      capacity >= ARENA_MINIMUM_CAPACITY ? capacity : ARENA_MINIMUM_CAPACITY;
 
-  arena->buf = (u8 *)malloc(alloc_size);
+  arena->buf = (u8 *)calloc(arena_capacity, sizeof(u8));
   if (!(arena->buf)) {
     return false;
   }
 
-  memset(arena->buf, 0, alloc_size);
-  arena->capacity = capacity;
+  arena->capacity = arena_capacity;
   arena->offset = arena->buf;
   arena->prev = arena->next = NULL;
 
@@ -196,12 +305,23 @@ internal void *base_arena_alloc_aligned(BaseArena *arena, u64 size,
     return NULL;
   }
 
-  u8 *output = mem_util_align_forward((void *)(arena->offset), alignment);
+  u8 *start_offset = arena->offset;
+  u8 *alloc_start = arena->offset + sizeof(ArenaAllocHDR);
+
+  u8 *output = wapp_mem_util_align_forward((void *)alloc_start, alignment);
   if (output + size >= arena->buf + arena->capacity) {
     return NULL;
   }
 
-  arena->offset += size;
+  ArenaAllocHDR *header = (ArenaAllocHDR *)start_offset;
+  *header = (ArenaAllocHDR){
+      .magic = HDR_MAGIC,
+      .alloc_size = size,
+      .alignment = alignment,
+      .alloc_start = output,
+  };
+
+  arena->offset = output + size;
 
   return (void *)output;
 }
@@ -228,3 +348,59 @@ internal void base_arena_free(BaseArena *arena) {
   arena->capacity = 0;
   arena->prev = arena->next = NULL;
 }
+
+internal ArenaAllocHDR *find_alloc_header(BaseArena *arena, void *alloc_ptr) {
+  persistent const u8 magic[HDR_MAGIC_BYTE_COUNT] = HDR_MAGIC;
+
+  u8 *current = (u8 *)alloc_ptr;
+
+  u8 *max_search_end = current - MAX_HDR_SEARCH_LENGTH;
+  u8 *arena_buf_start = arena->buf;
+
+  u8 *search_end =
+      max_search_end > arena_buf_start ? max_search_end : arena_buf_start;
+
+  bool match;
+  for (; current >= search_end; --current) {
+    match = true;
+
+    for (u64 i = 0; i < HDR_MAGIC_BYTE_COUNT; ++i) {
+      if (current[i] != magic[i]) {
+        match = false;
+        break;
+      }
+    }
+
+    if (match) {
+      return (ArenaAllocHDR *)current;
+    }
+  }
+
+  return NULL;
+}
+
+internal void *mem_arena_alloc(u64 size, void *alloc_obj) {
+  Arena *arena = (Arena *)alloc_obj;
+
+  return wapp_mem_arena_alloc(arena, size);
+}
+
+internal void *mem_arena_alloc_aligned(u64 size, u64 alignment,
+                                       void *alloc_obj) {
+  Arena *arena = (Arena *)alloc_obj;
+
+  return wapp_mem_arena_alloc_aligned(arena, size, alignment);
+}
+
+internal void *mem_arena_realloc(void *ptr, u64 size, void *alloc_obj) {
+  Arena *arena = (Arena *)alloc_obj;
+
+  return wapp_mem_arena_realloc(arena, ptr, size);
+}
+
+internal void *mem_arena_realloc_aligned(void *ptr, u64 size, u64 alignment,
+                                         void *alloc_obj) {
+  Arena *arena = (Arena *)alloc_obj;
+
+  return wapp_mem_arena_realloc_aligned(arena, ptr, size, alignment);
+}

mem/src/ctx/mem_ctx.c

@@ -0,0 +1,106 @@
+#include "mem_ctx.h"
+#include "aliases.h"
+#include "mem_arena.h"
+#include <assert.h>
+#include <stdlib.h>
+
+typedef struct mem_ctx MemCTX;
+struct mem_ctx {
+  Arena *main;
+  Arena *temp;
+  bool main_initialised;
+  bool temp_initialised;
+};
+
+internal MemCTX g_context = {0};
+
+internal Arena *get_arena(CTXDestBuffer buffer);
+
+Allocator wapp_mem_ctx_allocator(CTXDestBuffer buffer) {
+  Arena *arena = get_arena(buffer);
+  return wapp_mem_arena_allocator(arena);
+}
+
+void wapp_mem_ctx_init(u64 main_buf_capacity, u64 temp_buf_capacity) {
+  g_context.main_initialised =
+      wapp_mem_arena_init(&g_context.main, main_buf_capacity);
+  g_context.temp_initialised =
+      wapp_mem_arena_init(&g_context.temp, temp_buf_capacity);
+}
+
+void *wapp_mem_ctx_alloc(CTXDestBuffer buffer, u64 size) {
+  Arena *arena = get_arena(buffer);
+  if (!arena) {
+    return NULL;
+  }
+
+  return wapp_mem_arena_alloc(arena, size);
+}
+
+void *wapp_mem_ctx_alloc_aligned(CTXDestBuffer buffer, u64 size,
+                                 u64 alignment) {
+  Arena *arena = get_arena(buffer);
+  if (!arena) {
+    return NULL;
+  }
+
+  return wapp_mem_arena_alloc_aligned(arena, size, alignment);
+}
+
+void *wapp_mem_ctx_realloc(CTXDestBuffer buffer, void *ptr, u64 size) {
+  Arena *arena = get_arena(buffer);
+  if (!arena) {
+    return NULL;
+  }
+
+  return wapp_mem_arena_realloc(arena, ptr, size);
+}
+
+void *wapp_mem_ctx_realloc_aligned(CTXDestBuffer buffer, void *ptr, u64 size,
+                                   u64 alignment) {
+  Arena *arena = get_arena(buffer);
+  if (!arena) {
+    return NULL;
+  }
+
+  return wapp_mem_arena_realloc_aligned(arena, ptr, size, alignment);
+}
+
+void wapp_mem_ctx_clear(CTXDestBuffer buffer) {
+  Arena *arena = get_arena(buffer);
+  if (!arena) {
+    return;
+  }
+
+  wapp_mem_arena_clear(arena);
+}
+
+void wapp_mem_ctx_free(void) {
+  wapp_mem_arena_free(&(g_context.main));
+  g_context.main_initialised = false;
+
+  wapp_mem_arena_free(&(g_context.temp));
+  g_context.temp_initialised = false;
+}
+
+internal Arena *get_arena(CTXDestBuffer buffer) {
+  Arena *output = NULL;
+
+  switch (buffer) {
+  case CTX_DEST_BUFFER_MAIN:
+    if (g_context.main_initialised) {
+      output = g_context.main;
+    }
+    break;
+  case CTX_DEST_BUFFER_TEMP:
+    if (g_context.temp_initialised) {
+      output = g_context.temp;
+    }
+    break;
+  default:
+    assert(false && "Not all context destination buffers are handled");
+    break;
+  }
+
+  return output;
+}

mem/src/libc/mem_libc.c

@@ -0,0 +1,48 @@
+#include "mem_libc.h"
+#include "aliases.h"
+#include "mem_allocator.h"
+#include <stdlib.h>
+#include <string.h>
+
+internal void *mem_libc_alloc(u64 size, void *alloc_obj);
+internal void *mem_libc_alloc_aligned(u64 size, u64 alignment, void *alloc_obj);
+internal void *mem_libc_realloc(void *ptr, u64 size, void *alloc_obj);
+internal void mem_libc_free(void **ptr, void *alloc_obj);
+
+Allocator wapp_mem_libc_allocator(void) {
+  return (Allocator){
+      .obj = NULL,
+      .alloc = mem_libc_alloc,
+      .alloc_aligned = mem_libc_alloc_aligned,
+      .realloc = mem_libc_realloc,
+      .realloc_aligned = NULL,
+      .free = mem_libc_free,
+  };
+}
+
+internal void *mem_libc_alloc(u64 size, void *alloc_obj) {
+  return calloc(1, size);
+}
+
+internal void *mem_libc_alloc_aligned(u64 size, u64 alignment,
+                                      void *alloc_obj) {
+  void *output = aligned_alloc(alignment, size);
+  if (output) {
+    memset(output, 0, size);
+  }
+
+  return output;
+}
+
+internal void *mem_libc_realloc(void *ptr, u64 size, void *alloc_obj) {
+  return realloc(ptr, size);
+}
+
+internal void mem_libc_free(void **ptr, void *alloc_obj) {
+  if (!ptr || !(*ptr)) {
+    return;
+  }
+
+  free(*ptr);
+  *ptr = NULL;
+}

mem/src/util/mem_utils.c

@@ -6,7 +6,7 @@
 
 internal bool is_power_of_two(u64 num) { return (num & (num - 1)) == 0; }
 
-void *mem_util_align_forward(void *ptr, u64 alignment) {
+void *wapp_mem_util_align_forward(void *ptr, u64 alignment) {
   if (!ptr) {
     return NULL;
   }