From 0ee22520f50b4f006a554c79dd0e5f1d5d780d4d Mon Sep 17 00:00:00 2001
From: "Anna (navi) Figueiredo Gomes" <navi@vlhl.dev>
Date: Sun, 7 Jan 2024 20:19:20 +0100
Subject: replace make with meson

Signed-off-by: Anna (navi) Figueiredo Gomes <navi@vlhl.dev>
---
 src/asm/boot.asm | 161 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 161 insertions(+)
 create mode 100644 src/asm/boot.asm

(limited to 'src/asm/boot.asm')

diff --git a/src/asm/boot.asm b/src/asm/boot.asm
new file mode 100644
index 0000000..ae68761
--- /dev/null
+++ b/src/asm/boot.asm
@@ -0,0 +1,161 @@
+[BITS 32]
+
+; Declare constants for the multiboot header.
+MBALIGN  equ  1 << 0            ; align loaded modules on page boundaries
+MEMINFO  equ  1 << 1            ; provide memory map
+MBFLAGS  equ  MBALIGN | MEMINFO ; this is the Multiboot 'flag' field
+MAGIC    equ  0x1BADB002        ; 'magic number' lets bootloader find the header
+CHECKSUM equ -(MAGIC + MBFLAGS)   ; checksum of above, to prove we are multiboot
+ 
+; Declare a multiboot header that marks the program as a kernel. These are magic
+; values that are documented in the multiboot standard. The bootloader will
+; search for this signature in the first 8 KiB of the kernel file, aligned at a
+; 32-bit boundary. The signature is in its own section so the header can be
+; forced to be within the first 8 KiB of the kernel file.
+section .multiboot
+align 4
+	dd MAGIC
+	dd MBFLAGS
+	dd CHECKSUM
+
+section .bootstrap
+
+present	equ 1 << 7
+not_sys	equ 1 << 4
+exec	equ 1 << 3
+cd		equ 1 << 2
+rw		equ 1 << 1
+access	equ 1 << 0
+
+gran_4k	equ 1 << 7
+sz_32	equ 1 << 6
+long_m	equ 1 << 5
+
+global gdt.ptr
+gdt:
+.null: equ $ - gdt
+	dq 0
+.code: equ $ - gdt
+	dd 0xffff
+	db 0
+	db present | not_sys | exec | rw
+	db gran_4k | long_m | 0xf
+	db 0
+.data: equ $ - gdt
+	dd 0xffff
+	db 0
+	db present | not_sys | rw
+	db gran_4k | sz_32 | 0xf
+	db 0
+.ptr:
+	dw $ - gdt - 1
+	dq gdt
+
+global bootstrap
+bootstrap:
+
+	mov dword [multiboot_magic], eax
+	mov dword [multiboot_header], ebx
+
+	mov eax, cr0
+	and eax, ~(1 << 31)
+	mov cr0, eax
+
+	mov edi, pml4 ;0x1000
+	mov cr3, edi
+	xor eax, eax
+	mov ecx, 1024
+	rep stosd
+
+	mov edi, 0x2000
+	mov ecx, 4096
+	rep stosd
+
+	mov edi, cr3
+
+	mov dword [edi], 0x2003
+	mov edi, 0x2000
+	mov dword [edi], 0x3003
+	add edi, 0x1000
+	mov dword [edi], 0x4003
+	mov dword [edi + 8], 0x5003
+	add edi, 0x1000
+
+	mov ebx, 0x00000003
+	mov ecx, 512
+
+.set_entry:
+	mov dword [edi], ebx
+	add ebx, 0x1000
+	add edi, 8
+	loop .set_entry
+
+	mov edi, 0x5000
+	mov ecx, 512
+
+.set_entry_2:
+	mov dword [edi], ebx
+	add ebx, 0x1000
+	add edi, 8
+	loop .set_entry_2
+
+	mov eax, cr4
+	or eax, 1 << 5
+	mov cr4, eax
+
+	mov ecx, 0xc0000080
+	rdmsr
+	or eax, 1 << 8 | 1 << 0
+	wrmsr
+
+	mov eax, cr0
+	or eax, 1 << 31
+	mov cr0, eax
+
+	lgdt [gdt.ptr]
+
+	mov ax, gdt.data
+	mov ds, ax
+	mov es, ax
+	mov fs, ax
+	mov gs, ax
+	mov ss, ax
+
+	extern start
+	jmp gdt.code:start
+
+global set_pml4
+set_pml4:
+	mov ecx, 0xC000080
+	rdmsr
+	and eax, ~(1 << 8)
+	wrmsr
+
+	mov eax, cr0
+	and eax, ~(1 << 31)
+	mov cr0, eax
+
+	mov cr3, edi
+
+	mov ecx, 0xC000080
+	rdmsr
+	or eax, 1 << 8
+	wrmsr
+
+	mov eax, cr0
+	or eax, 1 << 31
+	mov cr0, eax
+
+	retf
+
+section .data
+align 16
+global multiboot_header
+multiboot_header: dq 0
+global multiboot_magic
+multiboot_magic: dq 0
+
+section .bss
+global pml4
+align 4096
+pml4: resq 512
-- 
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