Bootloader do some directory restructuring

bootloader/bios/utils.S

@@ -0,0 +1,280 @@
+.set SCREEN_WIDTH,	80
+.set SCREEN_HEIGHT,	25
+
+.code16
+
+.section .stage1
+
+# prints character to screen
+# al:		ascii character to print
+.global putc
+putc:
+	pushw %ax
+	pushw %bx
+	movb $0x0E, %ah
+	xorb %bh, %bh
+	int $0x10
+	popw %bx
+	popw %ax
+	ret
+
+# prints null terminated string to screen
+# ds:si:	string address
+.global puts
+puts:
+	pushw %si
+	pushw %bx
+	pushw %ax
+
+	movb $0x0E, %ah
+	xorb %bh, %bh
+
+ .puts_loop:
+	lodsb
+
+	test %al, %al
+	jz .puts_done
+
+	int $0x10
+	jmp .puts_loop
+
+ .puts_done:
+	popw %ax
+	popw %bx
+	popw %si
+	ret
+
+# compares memory between addresses
+# si:		ptr1
+# di:		ptr2
+# cx:		bytes count
+# return:
+#	al: 1 if equal, 0 otherwise
+.global memcmp
+memcmp:
+	# NOTE: using pusha + popa to save space
+	pusha
+	cld
+	repe cmpsb
+	popa
+	setzb %al
+	ret
+
+
+.section .stage2
+
+# read a character from keyboard
+# return:
+#	al: ascii
+#	ah: bios scan code
+.global getc
+getc:
+	movb $0x00, %ah
+	int $0x16
+	ret
+
+# prints newline to screen
+.global print_newline
+print_newline:
+	pushw %ax
+	movb $'\r', %al
+	call putc
+	movb $'\n', %al
+	call putc
+	pop %ax
+	ret
+
+# prints backspace to screen, can go back a line
+.global print_backspace
+print_backspace:
+	pushw %ax
+	pushw %bx
+	pushw %cx
+	pushw %dx
+
+	# get cursor position
+	movb $0x03, %ah
+	movb $0x00, %bh
+	int $0x10
+
+	# don't do anyting if on first row
+	testb %dh, %dh
+	jz .print_backspace_done
+
+	# go one line up if on first column
+	test %dl, %dl
+	jz .print_backspace_go_line_up
+
+	# otherwise decrease column
+	decb %dl
+	jmp .print_backspace_do_print
+
+ .print_backspace_go_line_up:
+	# decrease row and set column to the last one
+	decb %dh
+	movb $(SCREEN_WIDTH - 1), %dl
+
+ .print_backspace_do_print:
+	# set cursor position
+	movb $0x02, %ah
+	int $0x10
+
+	# print 'empty' character (space)
+	mov $' ', %al
+	call putc
+
+	# set cursor position
+	movb $0x02, %ah
+	int $0x10
+
+ .print_backspace_done:
+	popw %dx
+	popw %cx
+	popw %bx
+	popw %ax
+	ret
+
+# print number to screen
+# ax:	number to print
+# bx:	number base
+# cx:	min width (zero pads if shorter)
+.global print_number
+print_number:
+	pusha
+	pushl %ebp
+	movl %esp, %ebp
+
+	# save min width
+	subl $4, %esp
+	movw %cx, (%esp)
+
+	movw $print_number_buffer, %si
+	xorw %cx, %cx
+
+ .print_number_fill_loop:
+	# fill buffer with all remainders ax % bx
+	xorw %dx, %dx
+	divw %bx
+	movb %dl, (%si)
+	incw %si
+	incw %cx
+	testw %ax, %ax
+	jnz .print_number_fill_loop
+
+	# check if zero pad is required
+	cmpw (%esp), %cx
+	jae .print_number_print_loop
+
+	# dx: saved number count
+	# cx: zero pad count
+	movw %cx, %dx
+	movw (%esp), %cx
+	subw %dx, %cx
+	movb $'0', %al
+
+ .print_number_pad_zeroes:
+	call putc
+	loop .print_number_pad_zeroes
+
+	# restore number count
+	movw %dx, %cx
+
+ .print_number_print_loop:
+	decw %si
+	movb (%si), %al
+	cmpb $10, %al
+	jae .print_number_hex
+	addb $'0', %al
+	jmp .print_number_do_print
+ .print_number_hex:
+	addb $('a' - 10), %al
+ .print_number_do_print:
+	call putc
+	loop .print_number_print_loop
+
+	leavel
+	popa
+	ret
+
+# prints 8 bit hexadecimal number to screen
+#	al:		number to print
+.global print_hex8
+print_hex8:
+	pushw %ax
+	pushw %bx
+	pushw %cx
+
+	movw $16, %bx
+	movw $2,  %cx
+	andw $0xFF, %ax
+	call print_number
+
+	popw %cx
+	popw %bx
+	popw %ax
+	ret
+
+# prints 16 bit hexadecimal number to screen
+#	ax:		number to print
+.global print_hex16
+print_hex16:
+	pushw %bx
+	pushw %cx
+
+	movw $16, %bx
+	movw $4,  %cx
+	call print_number
+
+	popw %cx
+	popw %bx
+	ret
+
+# prints 32 bit hexadecimal number to screen
+#	eax:	number to print
+.global print_hex32
+print_hex32:
+	pushl %eax
+	pushw %dx
+
+	movw %ax, %dx
+
+	shrl $16, %eax;
+	call print_hex16
+
+	movw %dx, %ax
+	call print_hex16
+
+	popw %dx
+	popl %eax
+	ret
+
+# prints 64 bit hexadecimal number to screen
+#	edx:eax:	number to print
+.global print_hex64
+print_hex64:
+	xchgl %eax, %edx
+	call print_hex32
+	xchgl %eax, %edx
+	call print_hex32
+	ret
+
+# test if character is printable ascii
+#	al: character to test
+# return:
+#	al: 1 if is printable, 0 otherwise
+.global isprint
+isprint:
+	subb $0x20, %al
+	cmpb $(0x7E - 0x20), %al
+	ja .isprint_not_printable
+	movb $1, %al
+	ret
+ .isprint_not_printable:
+	movb $0, %al
+	ret
+
+.section .bss
+
+# enough for base 2 printing
+print_number_buffer:
+	.skip 16