1 files changed, 176 insertions, 0 deletions
diff --git a/stage3/framebuffer.asm b/stage3/framebuffer.asm
new file mode 100644
index 0000000..e55ad04
--- /dev/null
+++ b/stage3/framebuffer.asm
@@ -0,0 +1,176 @@
+%include "stage3/colors.asm"
+global print_chr, print_str, print_dec, print_hex, clear_screen, newline
+extern memcpy
+
+section .data
+
+pos:
+.row: db 0
+.col: db 0
+
+cursor: dq 0xB8000
+color: db COLOR_WHITE | (COLOR_BLACK << 4)
+
+section .text
+
+set_color:
+	shl sil, 4
+	add dil, sil
+	mov [color], dil
+
+update_cursor:
+	mov rbx, [cursor]
+	sub rbx, 0xB8000
+	shr rbx, 1
+
+	mov dx, 0x3D4
+	mov al, 14
+	out dx, al
+
+	mov dx, 0x3D5
+	mov al, bh
+	out dx, al
+
+	mov dx, 0x3D4
+	mov al, 15
+	out dx, al
+
+	mov dx, 0x3D5
+	mov al, bl
+	out dx, al
+
+	ret
+
+set_chr:
+	mov rax, [cursor]
+	mov byte[rax], dil
+	inc rax
+	mov dil, [color]
+	mov [rax], dil
+	inc rax
+	mov [cursor], rax
+	jmp update_cursor
+
+vertical_tab:
+	mov al, [pos.row]
+	inc al
+	cmp al, 25
+	je .scroll
+	mov [pos.row], al
+	mov rax, [cursor]
+	add rax, 160
+	mov [cursor], rax
+	jmp update_cursor
+.scroll:
+	mov rdi, 0xB8000
+	mov rsi, 0xB80A0
+	mov rdx, 0xF00
+	jmp memcpy
+
+carriage_return:
+	mov rax, [cursor]
+	xor rbx, rbx
+	mov bl, [pos.col]
+	shl bl, 1
+	sub rax, rbx
+	mov [cursor], rax
+	mov byte[pos.col], 0
+	jmp update_cursor
+
+newline:
+	call vertical_tab
+	jmp carriage_return
+
+print_chr:
+	cmp dil, 10
+	je newline
+	cmp dil, 11
+	je vertical_tab
+	cmp dil, 13
+	je carriage_return
+	mov al, [pos.col]
+	inc al
+	cmp al, 80
+	je .newline
+	mov [pos.col], al
+	jmp set_chr
+.newline:
+	push rdi
+	call newline
+	pop rdi
+	jmp set_chr
+
+print_str:
+	mov rax, rdi
+.print:
+	mov dil, [rax]
+	cmp dil, 0
+	je .return
+	push rax
+	call print_chr
+	pop rax
+	inc rax
+	jmp .print
+.return:
+	ret
+
+print_hex:
+	mov rsi, 0x10
+	jmp print_num
+print_dec:
+	mov rsi, 10
+print_num:
+	mov rax, rdi
+	xor rcx, rcx
+.convert:
+	inc rcx
+	xor rdx, rdx
+	div rsi
+	cmp dl, 10
+	jb .digit
+	add dl, 'A'-10
+	jmp .next
+.digit:
+	add dl, '0'
+.next:
+	push rdx
+	cmp rax, 0
+	jne .convert
+.print:
+	cmp rcx, 0
+	je .return
+	dec rcx
+	pop rdi
+	push rcx
+	call print_chr
+	pop rcx
+	jmp .print
+.return:
+	ret
+
+clear_screen:
+	push rbx
+	push r12
+	push r13
+	push r14
+	push r15
+
+	mov qword[cursor], 0xB8000
+.clr:
+	cmp qword[cursor], 0xB8FA0
+	je .return
+	mov dil, ' '
+	call set_chr
+	jmp .clr
+.return:
+	mov qword[cursor], 0xB8000
+	mov byte[pos.row], 0
+	mov byte[pos.col], 0
+	call update_cursor
+
+	pop r15
+	pop r14
+	pop r13
+	pop r12
+	pop rbx
+	ret