Re-make: kernel heap (malloc, free) via free list alloc + add UEFI emulation doc

src/kernel/kheap.c

@@ -5,42 +5,60 @@
 
 #include "kheap.h"
 #include <stdint.h>
+#include "system.h"
 
-extern uint32_t end;
-uint32_t placement_address = (uint32_t)&end;
+// Free list allocator
 
-uint32_t kmalloc_int(uint32_t sz, int align, uint32_t *phys)
+static uint8_t heap[HEAP_SIZE];
+static block_t* free_list = NULL;
+
+void init_alloc()
 {
-	if (align == 1 && (placement_address & 0x00000FFF))
+	free_list = (block_t*)heap;
+	free_list->size = HEAP_SIZE-sizeof(block_t);
+	free_list->next = NULL;
+}
+
+void* malloc(size_t size)
+{
+	block_t* prev = NULL;
+	block_t* curr = free_list;
+
+	while (curr != NULL)
 	{
-		placement_address &= 0xFFFFF000;
-		placement_address += 0x1000;
+		if (curr->size >= size)
+		{
+			if (curr->size > (size_t)(size + sizeof(block_t)))
+			{
+				block_t* new_block = (block_t*)((uint8_t*)curr + sizeof(block_t) + size);
+				new_block->size = curr->size - size - sizeof(block_t);
+				new_block->next = curr->next;
+				curr->size = size;
+				curr->next = new_block;
+			}
+
+			if (prev == NULL)
+			{
+				free_list = curr->next;
+			} else {
+				prev->next = curr->next;
+			}
+
+			return (void*)((uint8_t*)curr + sizeof(block_t));
+		}
+
+		prev = curr;
+		curr = curr->next;
 	}
-	if (phys)
-	{
-		*phys = placement_address;
-	}
-	uint32_t tmp = placement_address;
-	placement_address += sz;
-	return tmp;
+
+	return NULL;
 }
 
-uint32_t kmalloc_a(uint32_t sz)
+void free(void* ptr)
 {
-	return kmalloc_int(sz, 1, 0);
-}
+	if (ptr == NULL) return;
 
-uint32_t kmalloc_p(uint32_t sz, uint32_t *phys)
-{
-	return kmalloc_int(sz, 0, phys);
-}
-
-uint32_t kmalloc_ap(uint32_t sz, uint32_t *phys)
-{
-	return kmalloc_int(sz, 1, phys);
-}
-
-uint32_t kmalloc(uint32_t sz)
-{
-	return kmalloc_int(sz, 0, 0);
+	block_t* block_to_free = (block_t*)((uint8_t*)ptr - sizeof(block_t));
+	block_to_free->next = free_list;
+	free_list = block_to_free;
 }

src/kernel/kheap.h

@@ -7,10 +7,19 @@
 #define KHEAP_H
 
 #include <stdint.h>
+#include "system.h"
 
-uint32_t kmalloc_a(uint32_t sz);
-uint32_t kmalloc_p(uint32_t sz, uint32_t *phys);
-uint32_t kmalloc_ap(uint32_t sz, uint32_t *phys);
-uint32_t kmalloc(uint32_t sz);
+typedef struct block
+{
+	size_t size;
+	struct block* next;
+} block_t;
+
+#define HEAP_SIZE 1024*1024	// 1MB malloc-able
+
+
+void init_alloc();
+void* malloc(size_t size);
+void free(void* ptr);
 
 #endif

src/kernel/kmain.c

@@ -13,6 +13,7 @@
 #include "../drivers/framebuffer.h"
 #include "kmain.h"
 #include "multiboot2.h"
+#include "kheap.h"
 
 void kmain(multiboot2_info *mb_info)
 {
@@ -66,14 +67,17 @@ void kmain(multiboot2_info *mb_info)
 
 	while ((uint8_t*) mmap < tags + mmap_tag->size)
 	{
+		
 		if (mmap->addr != 0)
 		{
+			/*
 			printf("[debug] base addr=0x%x%x, length=0x%x%x, type=%u\n",
 				(uint32_t) (mmap->addr >> 32),
 				(uint32_t) (mmap->addr & 0xFFFFFFFF),
 				(uint32_t) (mmap->len >> 32),
 				(uint32_t) (mmap->len & 0xFFFFFFFF),
 				mmap->type);
+			*/
 		}
 
 		mmap = (struct multiboot_mmap_entry*) ((uint8_t*)mmap + mmap_tag->entry_size);
@@ -86,8 +90,11 @@ void kmain(multiboot2_info *mb_info)
     isr_install();
     irq_install();
     __asm__ __volatile__("sti");
- 
-    //test_read_sector();
+
+    init_alloc();
+    void* ptr1 = malloc(256);
+    void* ptr2 = malloc(512);
+    free(ptr2); 
 
     timer_install();
     keyboard_install();