; asmfuncs.asm
; Josh Holtrop
; Created: 10/23/03
; Modified: 12/25/03

[extern _putc]

%macro jzfar 1
	jnz	%%skip
	jmp	%1
%%skip:

%endmacro

;stores the parameter to the CR0 register
;extern dword write_cr0(dword cr0);
[global _write_cr0]
_write_cr0:
	push	ebp
	mov	ebp, esp
	mov	eax, [ebp+8]
	mov	cr0, eax
	pop	ebp
	ret

;returns the value in the CR0 register
;extern dword read_cr0();
[global _read_cr0]
_read_cr0:
	mov	eax, cr0;
	ret

;stores the parameter to the CR3 register
;extern dword write_cr3(dword cr3);
[global _write_cr3]
_write_cr3:
	push	ebp
	mov	ebp, esp
	mov	eax, [ebp+8]
	mov	cr3, eax
	pop	ebp
	ret

;returns the value in the CR3 register
;extern dword read_cr3();
[global _read_cr3]
_read_cr3:
	mov	eax, cr3;
	ret

;this function invalidates the page directory/table entry that
; would be used to access the memory address given in the parameter
;extern void invlpg(dword addr);
[global _invlpg]
_invlpg:
	mov	eax, [esp+4]
	invlpg	[eax]
	ret


;
;void writeCursorPosition(word pos)
;
[global _writeCursorPosition]
_writeCursorPosition:
	push	ebp
	mov	ebp, esp

	push	eax
	push	ebx
	push	edx

	mov	eax, [ebp+8]	;cursor position in ax

	mov	bl, al
	mov	dx, 0x03D4
	mov	al, 0x0E
	out	dx, al

	inc	dx
	mov	al, ah
	out	dx, al

	dec	dx
	mov	al, 0x0F
	out	dx, al

	inc	dx
	mov	al, bl
	out	dx, al

	pop	edx
	pop	ebx
	pop	eax
	pop	ebp

	ret


;
;word getCursorPosition()
;
[global _getCursorPosition]
_getCursorPosition:
	push	ebx
	push	edx

	xor	eax, eax
	mov	dx, 0x03D4
	mov	al, 0x0E
	out	dx, al

	inc	dx
	in	al, dx
	mov	bl, al

	dec	dx
	mov	al, 0x0F
	out	dx, al

	inc	dx
	in	al, dx
	mov	ah, bl

	pop	edx
	pop	ebx

	ret


;
;void console_scroll()
;
[global _console_scroll]
_console_scroll:
	pusha
	mov	esi, 0xc00b8000+160
	mov	edi, 0xc00b8000
	mov	ecx, 960			;(2000-80)/2
	rep	movsd
	mov	ax, 0x0720
	mov	ecx, 80
	rep	stosw
	popa
	ret



;
;void console_cls()
;
[global _console_cls]
_console_cls:
	pusha
	mov	edi, 0xc00b8000
	mov	ax, 0x0720
	mov	ecx, 2000
	rep	stosw
	push	dword 0
	call	_writeCursorPosition
	add	esp, 4
	popa
	ret




;
;int puts(char *str)
;
[global _puts]
_puts:
	push	ebp
	mov	ebp, esp
	push	esi
	push	eax
	mov	esi, [ebp+8]			;esi = to string
puts_loop:
	lodsb
	cmp	al, 0
	jz	puts_done
	push	eax
	call	_putc
	add	esp, 4
	jmp	puts_loop

puts_done:
	pop	eax
	pop	esi
	pop	ebp
	ret



        
[global _putDecu]
_putDecu:
	push	ebp
	mov	ebp, esp
	sub	esp, 24
	mov	DWORD [ebp-4], 1
	mov	BYTE [ebp-5], 0
L2:
	mov	edx, DWORD [ebp+8]
	mov	eax, -858993459
	mul	edx
	mov	eax, edx
	shr	eax, 3
	cmp	eax, DWORD [ebp-4]
	jae	L4
	jmp	L3
L4:
	mov	eax, DWORD [ebp-4]
	mov	edx, eax
	sal	edx, 2
	add	edx, eax
	lea	eax, [edx+edx]
	mov	DWORD [ebp-4], eax
	jmp	L2
L3:
	nop
L5:
	cmp	DWORD [ebp-4], 1
	ja	L7
	jmp	L6
L7:
	mov	edx, DWORD [ebp+8]
	mov	eax, edx
	mov	edx, 0
	div	DWORD [ebp-4]
	mov	DWORD [ebp-12], eax
	mov	al, BYTE [ebp-12]
	mov	BYTE [ebp-5], al
	mov	eax, 0
	mov	al, BYTE [ebp-5]
	imul	eax, DWORD [ebp-4]
	sub	DWORD [ebp+8], eax
	mov	edx, DWORD [ebp-4]
	mov	eax, -858993459
	mul	edx
	mov	eax, edx
	shr	eax, 3
	mov	DWORD [ebp-4], eax
	lea	eax, [ebp-5]
	add	BYTE [eax], 48
	sub	esp, 12
	mov	eax, 0
	mov	al, BYTE [ebp-5]
	push	eax
	call	_putc
	add	esp, 16
	jmp	L5
L6:
	sub	esp, 12
	mov	al, BYTE [ebp+8]
	add	eax, 48
	and	eax, 255
	push	eax
	call	_putc
	add	esp, 16
	leave
	ret




[global _putDec]
_putDec:
	push	ebp
	mov	ebp, esp
	sub	esp, 24
	cmp	DWORD [ebp+8], 0
	jns	L9
	sub	esp, 12
	push	45
	call	_putc
	add	esp, 16
	neg	DWORD [ebp+8]
L9:
	mov	DWORD [ebp-4], 1
	mov	BYTE [ebp-5], 0
L10:
	mov	eax, DWORD [ebp+8]
	cmp	eax, DWORD [ebp-4]
	jae	L12
	jmp	L11
L12:
	mov	eax, DWORD [ebp-4]
	mov	edx, eax
	sal	edx, 2
	add	edx, eax
	lea	eax, [edx+edx]
	mov	DWORD [ebp-4], eax
	jmp	L10
L11:
	mov	edx, DWORD [ebp-4]
	mov	eax, -858993459
	mul	edx
	mov	eax, edx
	shr	eax, 3
	mov	DWORD [ebp-4], eax
L13:
	cmp	DWORD [ebp-4], 1
	ja	L15
	jmp	L14
L15:
	mov	edx, DWORD [ebp+8]
	mov	eax, edx
	mov	edx, 0
	div	DWORD [ebp-4]
	mov	DWORD [ebp-12], eax
	mov	al, BYTE [ebp-12]
	mov	BYTE [ebp-5], al
	mov	eax, 0
	mov	al, BYTE [ebp-5]
	imul	eax, DWORD [ebp-4]
	sub	DWORD [ebp+8], eax
	mov	edx, DWORD [ebp-4]
	mov	eax, -858993459
	mul	edx
	mov	eax, edx
	shr	eax, 3
	mov	DWORD [ebp-4], eax
	lea	eax, [ebp-5]
	add	BYTE [eax], 48
	sub	esp, 12
	mov	eax, 0
	mov	al, BYTE [ebp-5]
	push	eax
	call	_putc
	add	esp, 16
	jmp	L13
L14:
	sub	esp, 12
	mov	al, BYTE [ebp+8]
	add	eax, 48
	and	eax, 255
	push	eax
	call	_putc
	add	esp, 16
	leave
	ret