From b500a8a7edb3e9a94191d83a1927f634fdc18ad8 Mon Sep 17 00:00:00 2001
From: Bananymous <bananymousosq@gmail.com>
Date: Wed, 16 Nov 2022 19:48:36 +0200
Subject: [PATCH] kmalloc

---
 kernel/Makefile                 |  1 +
 kernel/include/kernel/kmalloc.h | 12 ++++++
 kernel/kernel/kmalloc.cpp       | 67 +++++++++++++++++++++++++++++++++
 3 files changed, 80 insertions(+)
 create mode 100644 kernel/include/kernel/kmalloc.h
 create mode 100644 kernel/kernel/kmalloc.cpp

diff --git a/kernel/Makefile b/kernel/Makefile
index 1c28f559..e25ef61e 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -30,6 +30,7 @@ LIBS:=$(LIBS) $(KERNEL_ARCH_LIBS)
 KERNEL_OBJS=\
 $(KERNEL_ARCH_OBJS) \
 kernel/kernel.o \
+kernel/kmalloc.o \
 kernel/SSP.o \
  
 OBJS=\
diff --git a/kernel/include/kernel/kmalloc.h b/kernel/include/kernel/kmalloc.h
new file mode 100644
index 00000000..4ea1c0d5
--- /dev/null
+++ b/kernel/include/kernel/kmalloc.h
@@ -0,0 +1,12 @@
+#pragma once
+
+#include <stddef.h>
+
+void kmalloc_initialize();
+
+void* kmalloc(size_t);
+void kfree(void*);
+
+
+inline void* operator new(size_t size)   { return kmalloc(size); }
+inline void* operator new[](size_t size) { return kmalloc(size); }
diff --git a/kernel/kernel/kmalloc.cpp b/kernel/kernel/kmalloc.cpp
new file mode 100644
index 00000000..08d4c9ba
--- /dev/null
+++ b/kernel/kernel/kmalloc.cpp
@@ -0,0 +1,67 @@
+#include <kernel/multiboot.h>
+#include <kernel/kmalloc.h>
+#include <kernel/panic.h>
+#include <kernel/kprint.h>
+
+#include <stdint.h>
+#include <string.h>
+
+#define MB (1 << 20)
+
+struct kmalloc_info_t
+{
+	static constexpr size_t total_size	= 1 * MB;
+	void*	base_addr = (void*)0x00200000;
+	size_t	used;
+};
+static kmalloc_info_t s_kmalloc_info;
+
+void kmalloc_initialize()
+{
+	if (!(s_multiboot_info->flags & (1 << 6)))
+		Kernel::panic("Bootloader didn't give a memory map");
+
+	bool valid = false;
+	for (size_t i = 0; i < s_multiboot_info->mmap_length;)
+	{
+		multiboot_memory_map_t* mmmt = (multiboot_memory_map_t*)(s_multiboot_info->mmap_addr + i);
+
+		if (mmmt->type == 1)
+		{
+			char*	ptr1	= (char*)mmmt->base_addr;
+			char*	ptr2	= (char*)s_kmalloc_info.base_addr;
+			size_t	len1	= mmmt->length;
+			size_t	len2	= s_kmalloc_info.total_size;
+
+			if (ptr1 <= ptr2 && ptr1 + len1 >= ptr2 + len2)
+			{
+				valid = true;
+				break;
+			}
+		}
+
+		i += mmmt->size + sizeof(uint32_t);
+	}
+
+	if (!valid)
+		Kernel::panic("Could not find enough space for kmalloc");
+
+	memset(s_kmalloc_info.base_addr, 0, s_kmalloc_info.total_size);
+
+	s_kmalloc_info.used = 0;
+}
+
+void* kmalloc(size_t size)
+{
+	if (s_kmalloc_info.total_size - s_kmalloc_info.used < size)
+		Kernel::panic("Out of kernel memory");
+
+	char* result = (char*)s_kmalloc_info.base_addr + s_kmalloc_info.used;
+	s_kmalloc_info.used += size;
+	return (void*)result;
+}
+
+void kfree(void*)
+{
+
+}