Cleaning up and commenting

src/kernel/boot/boot.S

@@ -54,17 +54,24 @@ _start:
   mov ds, eax
   mov es, eax
 
+  //; Jump to kernel address space
   movabs rax, offset upper_memory
   jmp rax
 
   upper_memory:
 
+  //; Move stack pointer to kernel space
   mov rax, KERNEL_OFFSET
   add rsp, rax
 
+  //; Remove identity mapping
   mov rax, 0
   movabs [BootP4], rax
 
+  //; Jump to kmain()
 .extern kmain
   movabs rax, offset kmain
-  jmp rax
+  call rax
+
+  hlt
+  jmp $

src/kernel/boot/kmain.c

@@ -2,14 +2,14 @@
 
 void clear_screen()
 {
-  unsigned char *vidmem = (void *)(0xB8000 + KERNEL_OFFSET);
+  unsigned char *vidmem = P2V(0xB8000);
   for(int i=0; i < 80*24*2; i++)
     *vidmem++ = 0;
 }
 
 void print_string(char *str)
 {
-  unsigned char *vidmem = (void *)(0xB8000 + KERNEL_OFFSET);
+  unsigned char *vidmem = P2V(0xB8000);
   while(*str)
   {
     *vidmem++ = *str++;

src/kernel/include/memory.h

@@ -1,6 +1,19 @@
 #pragma once
 #define KERNEL_OFFSET 0xFFFFFF8000000000
+
+#ifdef __ASSEMBLER__
 #define V2P(a) ((a) - KERNEL_OFFSET)
+#define P2V(a) ((a) + KERNEL_OFFSET)
+#else
+#include <stdint.h>
+#define V2P(a) ((uintptr_t)(a) - KERNEL_OFFSET)
+#define P2V(a) ((void *)((uintptr_t)(a) + KERNEL_OFFSET))
+#endif
+
+#define P1_OFFSET(a) (((a)>>12) & 0x1FF)
+#define P2_OFFSET(a) (((a)>>21) & 0x1FF)
+#define P3_OFFSET(a) (((a)>>30) & 0x1FF)
+#define P4_OFFSET(a) (((a)>>39) & 0x1FF)
 
 #define PAGE_PRESENT      0x001
 #define PAGE_WRITE        0x002