Add helper functions to handle the stack.

mentos/inc/kernel.h

@@ -11,9 +11,6 @@
 /// @brief The initial stack pointer.
 extern uintptr_t initial_esp;
 
-/// @brief Push the `item` of a given `type` on the `stack`.
-#define PUSH_ARG(stack, type, item) (*((type *)((stack) -= sizeof(type))) = (item))
-
 /// Kilobytes.
 #define K 1024
 /// Megabytes.

mentos/inc/klib/stack_helper.h

@@ -0,0 +1,18 @@
+///                MentOS, The Mentoring Operating system project
+/// @file stack_helper.h
+/// @brief Couple of macros that help accessing the stack.
+/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#pragma once
+
+/// @brief Access the value of the pointer.
+#define __ACCESS_PTR(type, ptr) (*(type *)(ptr))
+/// @brief Moves the pointer down.
+#define __MOVE_PTR_DOWN(type, ptr) ((ptr) -= sizeof(type))
+/// @brief Moves the pointer up.
+#define __MOVE_PTR_UP(type, ptr) ((ptr) += sizeof(type))
+/// @brief First, it moves the pointer down, and then it pushes the value at that memory location.
+#define PUSH_VALUE_ON_STACK(ptr, value) (__ACCESS_PTR(typeof(value), __MOVE_PTR_DOWN(typeof(value), ptr)) = (value))
+/// @brief First, it access the value at the given memory location, and then it moves the pointer up.
+#define POP_VALUE_FROM_STACK(value, ptr) ({value = __ACCESS_PTR(typeof(value), ptr); __MOVE_PTR_UP(typeof(value), ptr); })