加入尚未完成的保護模式切換功能

11 files changed, 1077 insertions, 24 deletions

diff --git a/Makefile b/Makefile
index c0f9b70..d34f629 100644
--- a/Makefile
+++ b/Makefile
@@ -2,16 +2,26 @@
 .PHONY: all clean run
 .SUFFIXES: .c.o .s.o
 
+FDIMAGE=floppy.img
+BINARY=bootsect 55aa kernel yotsh reader while1 pmboot pmkern
+YOT16_LIBC=yotlibc/yotlibc.a
+YOT32_KLIB=yotk32/yotk32.a
+
+QEMU=qemu-kvm
+RM=rm -f
+
 all: floppy.img
 
-floppy.img: 55aa bootsect kernel yotsh reader while1
+floppy.img: $(BINARY)
 	dd if=/dev/zero of=$@ bs=512 count=2880
 	dd if=55aa      of=$@ bs=1   count=2    seek=510 conv=notrunc
 	dd if=bootsect  of=$@ conv=notrunc
-	dd if=kernel    of=$@ bs=512 seek=1  conv=notrunc
-	dd if=yotsh     of=$@ bs=512 seek=32 conv=notrunc
-	dd if=while1    of=$@ bs=512 seek=72 conv=notrunc
-	dd if=reader    of=$@ bs=512 seek=73 conv=notrunc
+	dd if=kernel    of=$@ bs=512 seek=1   conv=notrunc
+	dd if=yotsh     of=$@ bs=512 seek=32  conv=notrunc
+	dd if=while1    of=$@ bs=512 seek=72  conv=notrunc
+	dd if=reader    of=$@ bs=512 seek=73  conv=notrunc
+	dd if=pmboot    of=$@ bs=512 seek=100 conv=notrunc
+	dd if=pmkern    of=$@ bs=512 seek=101 conv=notrunc
 
 .c.o: 
 	bcc -ansi -Mc -Iyotlibc -c $< -o $@
@@ -20,25 +30,40 @@ floppy.img: 55aa bootsect kernel yotsh reader while1
 
 bootsect: bootsect.s basic.s
 	nasm -f bin $< -o $@
+55aa:
+	echo "0000000: 55aa" | xxd -r > $@
 kernel: kernel.o
-	ld86 -T 0x0000 -d kernel.o -o kernel
+	ld86 -T 0x0000 -d $^ -o $@
 
-yotsh: yotsh.o yotlibc/yotlibc.a
-	ld86 -T 0x0000 -d yotsh.o yotlibc/yotlibc.a -o yotsh
-reader: reader.o yotlibc/yotlibc.a
-	ld86 -T 0x0000 -d reader.o yotlibc/yotlibc.a -o reader
-while1: while1.o yotlibc/yotlibc.a
-	ld86 -T 0x0000 -d while1.o yotlibc/yotlibc.a -o while1
+yotsh: yotsh.o $(YOT16_LIBC)
+	ld86 -T 0x0000 -d $^ -o $@
+reader: reader.o $(YOT16_LIBC)
+	ld86 -T 0x0000 -d $^ -o $@
+while1: while1.o $(YOT16_LIBC)
+	ld86 -T 0x0000 -d $^ -o $@
+
+pmboot: pmgdt.s
+	nasm -f bin -dload_offset=0x80500 -dpmkernel=0x80700 $< -o $@
+pmkern: pmkern.o pmint.o $(YOT32_KLIB)
+	ld -melf_i386 -Ttext 0x80700 $^ --oformat binary -o $@
+
+pmkern.o: pmkern.s
+	nasm -f elf32 $< -o $@
+pmint.o: pmint.c
+	gcc -m32 -masm=intel -ffreestanding -fleading-underscore \
+		-Iyotk32 -c $< -o $@
 
-55aa:
-	echo "0000000: 55aa" | xxd -r > $@
 
-yotlibc/yotlibc.a:
+$(YOT16_LIBC):
 	$(MAKE) -C yotlibc
+$(YOT32_KLIB):
+	$(MAKE) -C yotk32
 
 run: floppy.img
-	qemu-kvm -fda floppy.img $(QARG)
+	$(QEMU) -fda $(FDIMAGE) $(QARG)
 
 clean:
-	rm -f bootsect kernel kernel.o reader.o while1.o \
-		55aa yotsh yotsh.o floppy.img 
+	$(RM) $(FDIMAGE) $(BINARY) kernel.o reader.o while1.o yotsh.o \
+		pmkern.o pmint.o
+	$(MAKE) -C yotlibc clean
+	$(MAKE) -C yotk32 clean
diff --git a/pmgdt.s b/pmgdt.s
new file mode 100644
index 0000000..4978871
--- /dev/null
+++ b/pmgdt.s
@@ -0,0 +1,133 @@
+global _main
+global _pm_bootstrap
+global gdt_start
+global gdt_null
+global gdt_code
+global gdt_data
+global gdt_user_code
+global gdt_user_data
+global gdt_end
+global gdt_descriptor
+
+[bits 16]
+
+_main:
+_pm_bootstrap:
+	mov		dx, msg_title
+	call	putstr
+	mov		dx, msg_ldgdt
+	call	putstr
+
+	cli
+	lgdt	[gdt_descriptor]
+
+	in		al, 0x92
+	or		al, 2
+	out		0x92, al
+
+	mov		eax, cr0
+	or		eax, 0x1
+	mov		cr0, eax
+
+	jmp		dword CODE_SEGMENT:pmkernel
+
+msg_title: db 13, 10, 'YOTOS protected mode loader', 13, 10, 0
+msg_ldgdt: db 'Loading Global Descriptor Table (GDT)... ', 0
+
+putstr:				; dx=argument
+	mov		cx, bx	; we must preserve bx
+putstr_start:
+	mov		bx, dx	; [dx] is not a effective address
+	mov		al, byte [bx]
+	test	al, al
+	jz		putstr_end
+	mov		ah, 0x0e
+	mov		bx, 0x0007
+	int		0x10
+	inc		dx
+	jmp		putstr_start
+putstr_end:
+	mov		bx, cx
+	ret
+
+
+
+; GDT entry
+
+
+gdt_start:
+
+gdt_null:	; null descriptor
+	dd	0x00
+	dd	0x00
+
+gdt_code:	; code segment descriptor
+	dw	0xffff		; segment limit (bits 0-15)
+	dw	0x0			; base (bits 0-15)
+	db	0x0			; base (bits 16-23)
+
+	db	10011010b	; (present) 1,
+					; (privilege) 00,
+					; (descriptor type) 1,
+					; type = 
+					; (code) 1, 
+					; (conforming) 0, 
+					; (readable) 1,
+					; (accessed) 0
+
+	db	11001111b	; (granularity) 1,
+					; (32-bit default) 1,
+					; (64-bit segment) 0, 
+					; (AVL) 0,
+					; segment limit (bits 16-19)
+	
+	db	0x0			; base (bits 24-31)
+
+gdt_data:	; data segment descriptor
+	dw	0xffff		; segment limit (bits 0-15)
+	dw	0x0			; base (bits 0-15)
+	db	0x0			; base (bits 16-23)
+
+	db	10010010b	; (present) 1,
+					; (privilege) 00,
+					; (descriptor type) 1,
+					; type = 
+					; (code) 0, 
+					; (expand down) 0, 
+					; (writable) 1,
+					; (accessed) 0
+
+	db	11001111b	; (granularity) 1,
+					; (32-bit default) 1,
+					; (64-bit segment) 0, 
+					; (AVL) 0,
+					; segment limit (bits 16-19)
+	
+	db	0x0			; base (bits 24-31)
+
+gdt_user_code:	; user mode code segment descriptor
+	dw	0xffff		
+	dw	0x0			
+	db	0x0			
+	db	11111010b	
+	db	11001111b	
+	db	0x0			
+
+gdt_user_data:	; user mode data segment descriptor
+	dw	0xfff
+	dw	0x0
+	db	0x0
+	db	11110010b
+	db	11001111b  
+	db	0x0  
+
+gdt_end:
+
+gdt_descriptor:
+	dw	gdt_end - gdt_start - 1
+	dd	load_offset + gdt_start
+
+CODE_SEGMENT	equ		gdt_code - gdt_start
+DATA_SEGMENT	equ		gdt_data - gdt_start
+
+
diff --git a/pmint.c b/pmint.c
new file mode 100644
index 0000000..752cec1
--- /dev/null
+++ b/pmint.c
@@ -0,0 +1,46 @@
+#include <yotk32.h>
+
+typedef struct registers
+{
+	long ds;
+	long edi, esi, ebp, esp, ebx, edx, ecx, eax;
+	long int_no, err_code;
+	long eip, cs, eflags, useresp, ss;
+} registers_t; 
+
+
+void int_isr_handler(registers_t regs){
+	chv_putchar(regs.int_no);
+	chv_sync_cursor();
+}
+
+void timer_sleep_msg(void){
+	static int count = 0;
+	count++;
+	if(count % 100 == 0){
+		putstr("...");
+		putint(count / 100);
+		chv_sync_cursor();
+	}
+}
+
+void int_irq_handler(registers_t regs){
+	asm(".intel_syntax noprefix\n");
+
+	if(regs.int_no > 31 + 8){  /* Send reset signal to slave PIC (PIC2) */
+		asm volatile(
+			"mov dx, 0xA0\n"
+			"mov al, 0x20\n"
+			"out dx, al");
+	}
+
+	/* Send reset signal to master PIC (PIC1) */
+	asm volatile(
+		"mov dx, 0x20\n"
+		"mov al, 0x20\n"
+		"out dx, al");
+
+	if(regs.int_no == 32){ /* IRQ0 == Timer */
+		timer_sleep_msg();
+	}
+}
diff --git a/pmkern.s b/pmkern.s
new file mode 100644
index 0000000..da53094
--- /dev/null
+++ b/pmkern.s
@@ -0,0 +1,332 @@
+extern _putstr
+extern _chv_next_line
+extern _chv_init_cursor
+extern _chv_putchar
+extern _chv_sync_cursor
+extern _chv_next_line
+extern _int_isr_handler
+extern _int_irq_handler
+
+global _start
+global _pm_init
+global idt_start
+global idt_end
+global idt_descriptor
+
+CODE_SEGMENT		equ		0x08 ; gdt_code - gdt_start
+DATA_SEGMENT		equ		0x10 ; gdt_data - gdt_start
+USER_CODE_SEGMENT	equ		0x18 ; gdt_user_code - gdt_start
+USER_DATA_SEGMENT	equ		0x20 ; gdt_user_data - gdt_start
+
+[bits 32]
+
+%macro ISR_NOERRCODE 1
+	global _int_isr_%1
+	_int_isr_%1:
+		cli
+		push	byte 0
+		push	byte %1
+		jmp		_int_isr_common
+%endmacro
+
+%macro ISR_ERRCODE 1
+	global _int_isr_%1
+	_int_isr_%1:
+		cli
+		push	byte %1
+		jmp		_int_isr_common
+%endmacro
+
+%macro IDT_ISR_ENTRY 1
+	mov		eax, _int_isr_%1
+	mov		word [ebx], ax
+	mov		word [ebx+2], CODE_SEGMENT
+	mov		byte [ebx+4], 0
+	mov		byte [ebx+5], 0x80 | 14
+	mov		eax, _int_isr_%1
+	shr		eax, 16
+	mov		word [ebx+6], ax
+	add		ebx, 8
+%endmacro
+
+%macro IRQ 2
+	global _int_irq_%1
+	_int_irq_%1:
+		cli
+		push	byte 0
+		push	byte %2
+		jmp		_int_irq_common
+%endmacro
+
+%macro IDT_IRQ_ENTRY 1
+	mov		eax, _int_irq_%1
+	mov		word [ebx], ax
+	mov		word [ebx+2], CODE_SEGMENT
+	mov		byte [ebx+4], 0
+	mov		byte [ebx+5], 0x80 | 14
+	mov		eax, _int_irq_%1
+	shr		eax, 16
+	mov		word [ebx+6], ax
+	add		ebx, 8
+%endmacro
+
+
+_start:
+_pm_init:
+	mov		ax, DATA_SEGMENT
+	mov		ds, ax
+	mov		ss, ax
+	mov		es, ax
+	mov		fs, ax
+	mov		gs, ax
+
+	mov		ebp, 0x90500
+	mov		esp, ebp
+
+	call	_chv_init_cursor
+
+	call	_chv_next_line
+	push	msg_ldidt
+	call	_putstr
+	add		esp, 4
+	call	_chv_sync_cursor
+
+	; Create IDT entry
+	mov		ebx, idt_start
+
+%assign intcount 0
+%rep 32
+	IDT_ISR_ENTRY intcount
+%assign intcount intcount+1
+%endrep
+
+%assign intcount 0
+%rep 16
+	IDT_IRQ_ENTRY intcount
+%assign intcount intcount+1
+%endrep
+
+	; Load IDT descriptor
+	lidt	[idt_descriptor]
+
+	; ========== IDT OK ==========
+
+	call	_chv_next_line
+	push	msg_remap_irq
+	call	_putstr
+	add		esp, 4
+	call	_chv_sync_cursor
+
+	sub		esp, 2
+
+	; Save masks
+	mov		dx, 0x21	; PIC1
+	in		al, dx
+	mov		byte [esp], al
+
+	mov		dx, 0xA1	; PIC1
+	in		al, dx
+	mov		byte [esp+1], al
+
+	; Initialize two PICs
+	mov		dx, 0x20	; PIC1
+	mov		al, 0x11	
+	out		dx, al
+
+	mov		dx, 0xA0	; PIC2
+	mov		al, 0x11
+	out		dx, al
+
+	; Set vector offset
+	mov		dx, 0x21	; PIC1
+	mov		al, 0x20	; IRQ 0 -> INT 0x20
+	out		dx, al
+
+	mov		dx, 0xA1	; PIC2
+	mov		al, 0x28	; IRQ 8 -> INT 0x28
+	out		dx, al
+
+	; Master/Slave PIC
+	mov		dx, 0x21	; PIC1
+	mov		al, 0x04	; there is a slave PIC at IRQ2 (0000 0100)
+	out		dx, al
+
+	mov		dx, 0xA1	; PIC2
+	mov		al, 0x02	; tell Slave PIC its cascade identity (0000 0010)
+	out		dx, al
+
+	; Set 8086/88 mode
+	mov		dx, 0x21	; PIC1
+	mov		al, 0x01	
+	out		dx, al
+
+	mov		dx, 0xA1	; PIC2
+	mov		al, 0x01
+	out		dx, al
+
+	; Restore mask
+	mov		dx, 0x21	; PIC1
+	mov		al, byte [esp]
+	out		dx, al
+
+	mov		dx, 0xA1	; PIC2
+	mov		al, byte [esp+1]
+	out		dx, al
+
+	add		esp, 2
+
+	; ========== IRQ remap OK ==========
+
+	sti
+
+	call	_chv_next_line
+	call	_chv_next_line
+	push	msg_pmkernel
+	call	_putstr
+	add		esp, 4
+	call	_chv_next_line
+	call	_chv_next_line
+	call	_chv_sync_cursor
+
+sleep_forever:
+	call	_chv_next_line
+	push	msg_sleep_forever
+	call	_putstr
+	add		esp, 4
+	call	_chv_sync_cursor
+	
+	; Set timer
+	mov		dx, 0x43	; timer command port
+	mov		al, 0x36
+	out		dx, al
+
+	mov		ax, 11932
+	mov		dx, 0x40
+
+	out		dx, al
+	mov		ah, al
+	out		dx, al
+
+jump_forever:
+	hlt
+	hlt
+	hlt
+	hlt
+	hlt
+	jmp		jump_forever
+
+
+msg_ldidt: db 'Loading Interrupt Descriptor Table (IDT)... ', 0
+msg_remap_irq: db 'Remapping Interrupt requests (IRQ)... ', 0
+msg_pmkernel: db 'OK, YOT OS protected mode kernel is started', 0
+msg_sleep_forever: db 'No instruction available - sleep forever', 0
+
+idt_start:
+	times 256 dq 0
+idt_end:
+
+idt_descriptor:
+	dw	idt_end - idt_start - 1
+	dd	idt_start
+
+ISR_NOERRCODE 0
+ISR_NOERRCODE 1
+ISR_NOERRCODE 2
+ISR_NOERRCODE 3
+ISR_NOERRCODE 4
+ISR_NOERRCODE 5
+ISR_NOERRCODE 6
+ISR_NOERRCODE 7
+ISR_ERRCODE 8
+ISR_NOERRCODE 9
+ISR_ERRCODE 10
+ISR_ERRCODE 11
+ISR_ERRCODE 12
+ISR_ERRCODE 13
+ISR_ERRCODE 14
+ISR_NOERRCODE 15
+ISR_NOERRCODE 16
+ISR_NOERRCODE 17
+ISR_NOERRCODE 18
+ISR_NOERRCODE 19
+ISR_NOERRCODE 20
+ISR_NOERRCODE 21
+ISR_NOERRCODE 22
+ISR_NOERRCODE 23
+ISR_NOERRCODE 24
+ISR_NOERRCODE 25
+ISR_NOERRCODE 26
+ISR_NOERRCODE 27
+ISR_NOERRCODE 28
+ISR_NOERRCODE 29
+ISR_NOERRCODE 30
+ISR_NOERRCODE 31
+
+IRQ 0, 32
+IRQ 1, 33
+IRQ 2, 34
+IRQ 3, 35
+IRQ 4, 36
+IRQ 5, 37
+IRQ 6, 38
+IRQ 7, 39
+IRQ 8, 40
+IRQ 9, 41
+IRQ 10, 42
+IRQ 11, 43
+IRQ 12, 44
+IRQ 13, 45
+IRQ 14, 46
+IRQ 15, 47
+
+
+_int_isr_common:
+	pushad
+
+	mov		ax, ds
+	push	eax
+
+	mov		ax, DATA_SEGMENT
+	mov		ds, ax
+	mov		es, ax
+	mov		fs, ax
+	mov		gs, ax
+
+	call	_int_isr_handler
+
+	pop		eax
+	mov		ds, ax
+	mov		es, ax
+	mov		fs, ax
+	mov		gs, ax
+
+	popad
+
+	add		esp, 8
+	sti
+	iret
+
+_int_irq_common:
+	pushad
+
+	mov		ax, ds
+	push	eax
+
+	mov		ax, DATA_SEGMENT
+	mov		ds, ax
+	mov		es, ax
+	mov		fs, ax
+	mov		gs, ax
+
+	call	_int_irq_handler
+
+	pop		eax
+	mov		ds, ax
+	mov		es, ax
+	mov		fs, ax
+	mov		fs, ax
+
+	popad
+	add		esp, 8
+	sti
+	iret
diff --git a/yotk32/Makefile b/yotk32/Makefile
new file mode 100644
index 0000000..b077324
--- /dev/null
+++ b/yotk32/Makefile
@@ -0,0 +1,22 @@
+
+.PHONY: all clean
+.SUFFIXES: .c.o .s.o
+
+# some 32-bit function not implemented
+#OBJ=str_out.o char_in.o str_in.o char_vga.o char_vhl.o strbasic.o
+
+OBJ=str_out.o char_vga.o char_vhl.o strbasic.o
+LIB=yotk32.a
+
+all: $(LIB)
+
+$(LIB): $(OBJ)
+	ar rcs $@ $(OBJ)
+
+.s.o:
+	nasm -f elf $< -o $@
+.c.o:
+	gcc -m32 -ffreestanding -fleading-underscore -c $< -o $@
+
+clean:
+	rm -f $(LIB) $(OBJ)
diff --git a/yotk32/char_vga.s b/yotk32/char_vga.s
new file mode 100644
index 0000000..3352146
--- /dev/null
+++ b/yotk32/char_vga.s
@@ -0,0 +1,60 @@
+global _char_vga_get_cursor
+global _char_vga_set_cursor
+global _char_vga_cursor_x
+global _char_vga_cursor_y
+
+_char_vga_cursor_x: dd 0
+_char_vga_cursor_y: dd 0
+
+_char_vga_get_cursor:
+	push	ebp
+	mov		ebp, esp
+	xor		ecx, ecx			; cx=result
+
+	mov		dx, 0x3D4
+	mov		al, 0x0E
+	out		dx, al			; read high byte
+
+	mov		dx, 0x3D5
+	in		al, dx
+	mov		ch, al
+
+	mov		dx, 0x3D4
+	mov		al, 0x0F
+	out		dx, al			; read low byte
+
+	mov		dx, 0x3D5
+	in		al, dx
+	mov		cl, al
+
+	mov		eax, ecx			; set return value
+
+	mov		esp, ebp
+	pop		ebp
+	ret
+
+
+_char_vga_set_cursor:
+	push	ebp
+	mov		ebp, esp
+	mov		ecx, [ebp+8]		; cx=argument
+
+	mov		dx, 0x3D4
+	mov		al, 0x0E
+	out		dx, al			; send high byte
+
+	mov		dx, 0x3D5
+	mov		al, ch
+	out		dx, al
+
+	mov		dx, 0x3D4
+	mov		al, 0x0F
+	out		dx, al			; send low byte
+
+	mov		dx, 0x3D5
+	mov		al, cl
+	out		dx, al
+
+	mov		esp, ebp
+	pop		ebp
+	ret
diff --git a/yotk32/char_vhl.c b/yotk32/char_vhl.c
new file mode 100644
index 0000000..e02f2b1
--- /dev/null
+++ b/yotk32/char_vhl.c
@@ -0,0 +1,158 @@
+/* char_vhl = char VGA high level function */
+
+#include "yotk32.h"
+
+extern int char_vga_cursor_x;
+extern int char_vga_cursor_y;
+
+void chv_init_cursor(void){
+	int curpos = char_vga_get_cursor();
+	char_vga_cursor_x = CHAR_VGA_GETX(curpos);
+	char_vga_cursor_y = CHAR_VGA_GETY(curpos);
+}
+
+void chv_get_cursor(xycoord)
+	XYCOORD* xycoord;
+{
+	chv_init_cursor();
+	xycoord->x = char_vga_cursor_x;
+	xycoord->y = char_vga_cursor_y;
+}
+
+void chv_set_cursor(xycoord)
+	const XYCOORD* xycoord;
+{
+	char_vga_cursor_x = xycoord->x;
+	char_vga_cursor_y = xycoord->y;
+	char_vga_set_cursor(
+		CHAR_VGA_POSITION(char_vga_cursor_x, char_vga_cursor_y));
+}
+
+void chv_set_cursor_direct(x, y)
+	int x;
+	int y;
+{
+	char_vga_cursor_x = x;
+	char_vga_cursor_y = y;
+	char_vga_set_cursor(
+		CHAR_VGA_POSITION(char_vga_cursor_x, char_vga_cursor_y));
+}
+
+void chv_sync_cursor(void){
+	char_vga_set_cursor(
+		CHAR_VGA_POSITION(char_vga_cursor_x, char_vga_cursor_y));
+}
+
+void chv_reset_cursor(void){
+	chv_set_cursor_direct(0, 0);
+}
+
+void chv_movenext_cursor(void){
+	if(++char_vga_cursor_x >= CHAR_VGA_SCREENX){
+		char_vga_cursor_x -= CHAR_VGA_SCREENX;
+		char_vga_cursor_y++;
+	}
+	if(char_vga_cursor_y >= CHAR_VGA_SCREENY){
+		char_vga_cursor_y = CHAR_VGA_SCREENY;
+		chv_scroll(1);
+	}
+}
+
+void chv_moveprev_cursor(void){
+	if(--char_vga_cursor_x < 0){
+		char_vga_cursor_x += CHAR_VGA_SCREENX;
+		char_vga_cursor_y--;
+	}
+	if(char_vga_cursor_y < 0){
+		char_vga_cursor_y = 0;
+	}
+}
+
+void chv_move_cursor(count)
+	int count;
+{
+	int n;
+	n = CHAR_VGA_POSITION(char_vga_cursor_x, char_vga_cursor_y) + count;
+	char_vga_cursor_x = CHAR_VGA_GETX(n);
+	char_vga_cursor_y = CHAR_VGA_GETY(n);
+	if(char_vga_cursor_x > CHAR_VGA_SCREENX){
+		char_vga_cursor_x = CHAR_VGA_SCREENX - 1;
+	}else if(char_vga_cursor_x < 0){
+		char_vga_cursor_x = 0;
+	}
+	if(char_vga_cursor_y > CHAR_VGA_SCREENY){
+		char_vga_cursor_y = CHAR_VGA_SCREENY - 1;
+	}else if(char_vga_cursor_y < 0){
+		char_vga_cursor_y = 0;
+	}
+}
+
+void chv_next_line(void){
+	if(++char_vga_cursor_y >= CHAR_VGA_SCREENY){
+		char_vga_cursor_y--;
+		chv_scroll(1);
+		char_vga_cursor_y++;
+	}
+	char_vga_cursor_x = 0;
+}
+
+void chv_putchar(c)
+	int c;
+{
+	chv_memwrite(
+		CHAR_VGA_POSITION(char_vga_cursor_x, char_vga_cursor_y) * 2, c);
+	chv_movenext_cursor();
+}
+
+void chv_putchar_color(c, color)
+	int c;
+	int color;
+{
+	int pos = CHAR_VGA_POSITION(char_vga_cursor_x, char_vga_cursor_y) * 2;
+	chv_memwrite(pos++, c);
+	chv_memwrite(pos, color);
+	chv_movenext_cursor();
+}
+
+void chv_backspace(void){
+	chv_moveprev_cursor();
+	chv_memwrite(
+		CHAR_VGA_POSITION(char_vga_cursor_x, char_vga_cursor_y) * 2, ' ');
+}
+
+void chv_clear(void){
+	int i;
+	XYCOORD xycoord;
+	chv_memwrite(0, 'A');
+	for(i=0; i< CHAR_VGA_MMIOSIZE; ){
+		chv_memwrite(i++, ' ');
+		chv_memwrite(i++, CHV_COLORPAIR(
+			CHV_COLOR_LIGHT_GRAY, CHV_COLOR_BLACK));
+	}
+}
+
+void chv_scroll(line)
+	int line;
+{
+	int c, i;
+	int src, dest;
+	if(line > 0){
+		src = line * CHAR_VGA_SCREENX * 2;
+		for(dest = 0; dest < CHAR_VGA_MMIOSIZE && src < CHAR_VGA_MMIOSIZE; 
+			dest++, src++){
+			c = chv_memread(src);
+			chv_memwrite(dest, c);
+		}
+		for(; dest < CHAR_VGA_MMIOSIZE; ){
+			chv_memwrite(dest++, ' ');
+			chv_memwrite(dest++, CHV_COLORPAIR(
+				CHV_COLOR_LIGHT_GRAY, CHV_COLOR_BLACK));
+		}
+		char_vga_cursor_y -= line; 
+		if(char_vga_cursor_y < 0){
+			char_vga_cursor_y = 0;
+			chv_sync_cursor();
+		}
+	}
+}
+
diff --git a/yotk32/str_out.c b/yotk32/str_out.c
new file mode 100644
index 0000000..ada10e5
--- /dev/null
+++ b/yotk32/str_out.c
@@ -0,0 +1,29 @@
+#include "yotk32.h"
+
+void putint(unsigned long toprint){
+	char printbuf[12];
+	int i = 0;
+	do{
+		printbuf[i] = toprint % 10 + '0';
+		toprint /= 10;
+		i++;
+	}while(toprint > 0);
+	for(i--; i>=0; i--){
+		chv_putchar(printbuf[i]);
+	}
+}
+
+void putcharhex(char c){
+	char clist[] = {
+		'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 
+		'A', 'B', 'C', 'D', 'E', 'F'};
+
+	chv_putchar(clist[((c & 0xF0) >> 4)]);
+	chv_putchar(clist[(c & 0x0F)]);
+}
+
+void putstr(const char* s){
+	for(; *s; s++){
+		chv_putchar(*s);
+	}
+}
diff --git a/yotk32/strbasic.c b/yotk32/strbasic.c
new file mode 100644
index 0000000..25c039c
--- /dev/null
+++ b/yotk32/strbasic.c
@@ -0,0 +1,74 @@
+#include "yotk32.h"
+
+int strcmp(s1, s2)
+	const char* s1;
+	const char* s2;
+{
+	char* str1;
+	char* str2;
+	if((*s1 | *s2) && (!*s1 || !*s2)){
+		if(*s1){
+			return 1;
+		}else{
+			return -1;
+		}
+	}
+	for(str1=(char*)s1, str2=(char*)s2; 
+			*str1 != '\0' && *str2 != '\0'; str1++, str2++){
+		if(*str1 > *str2){
+			return 2;
+		}else if(*str1 < *str2){
+			return -2;
+		}
+	}
+	if(*str1 != '\0'){
+		return 3;
+	}
+	if(*str2 != '\0'){
+		return -3;
+	}
+	return 0;
+}
+
+int strtos(str, store)
+	const char* str;
+	unsigned int* store;
+{
+	unsigned int result = 0;
+	bool ishex = false;
+	if(*str == '0' && (*(str+1) == 'x' || *(str+1) == 'X')){
+		str += 2;
+		ishex = true;
+	}
+	for(; *str != '\0'; str++){
+		if(*str >= '0' && *str <= '9'){
+			if(ishex){
+				result <<= 4;
+				result += *str - '0';
+			}else{
+				result *= 10;
+				result += *str - '0';
+			}
+		}else if(*str >= 'A' && *str <= 'F'){
+			if(ishex){
+				result <<= 4;
+				result += *str - 'A' + 10;
+			}else{
+				return 0;
+			}
+		}else if(*str >= 'a' && *str <= 'f'){
+			if(ishex){
+				result <<= 4;
+				result += *str - 'a' + 10;
+			}else{
+				return 0;
+			}
+		}else if(*str == ' ' || *str == '\t' || *str == '\n'){
+			break;
+		}else{
+			return 0; /* Failed */
+		}
+	}
+	*store = result;
+	return 1;  /* OK */
+}
diff --git a/yotk32/yotk32.h b/yotk32/yotk32.h
new file mode 100644
index 0000000..289b7ee
--- /dev/null
+++ b/yotk32/yotk32.h
@@ -0,0 +1,154 @@
+#ifndef YOT_OS_KERNEL32_LIB
+#define YOT_OS_KERNEL32_LIB
+
+#ifndef NULL
+#define NULL ((char*)0)
+#endif
+
+#ifndef EOF
+#define EOF (-1)
+#endif
+
+#ifndef bool
+#define bool char
+#endif
+
+#ifndef true
+#define true 1
+#endif
+
+#ifndef false
+#define false 0
+#endif
+
+/* str_out.s */
+void putint(unsigned long);         /* 以 10 進位顯示一個 word (unsigned) */
+void putcharhex(char);      /* 以 16 進位顯示一個 byte */
+void putstr(const char*);   /* 顯示一個字串，'\0' 是結束 */
+
+/* char_in.s */
+#define GETCH_SCANCODE(code16) (((code16) & 0xff00) >> 8)
+#define GETCH_ASCII(code16)    ((code16) & 0x00ff)
+int getch(void);
+
+/* char_vga.s + char_vhl.c */
+#define CHAR_VGA_POSITION(x,y) (((y)*80)+(x))
+#define CHAR_VGA_GETX(n)       ((n)%80)
+#define CHAR_VGA_GETY(n)       ((n)/80)
+#define CHAR_VGA_SCREENX       80
+#define CHAR_VGA_SCREENY       25
+#define CHAR_VGA_SCREENSIZE    ((CHAR_VGA_SCREENX)*(CHAR_VGA_SCREENY))
+#define CHAR_VGA_MMIOSIZE      ((CHAR_VGA_SCREENSIZE)*2)
+
+#define CHV_COLORPAIR(fg,bg)     ((fg) | ((bg) << 4))
+#define CHV_COLOR_BLACK          0
+#define CHV_COLOR_BLUE           1
+#define CHV_COLOR_GREEN          2
+#define CHV_COLOR_CYAN           3
+#define CHV_COLOR_RED            4
+#define CHV_COLOR_MAGENTA        5
+#define CHV_COLOR_BROWN          6
+#define CHV_COLOR_LIGHT_GRAY     7
+#define CHV_COLOR_GRAY           8
+#define CHV_COLOR_LIGHT_BLUE     9
+#define CHV_COLOR_LIGHT_GREEN    10
+#define CHV_COLOR_LIGHT_CYAN     11
+#define CHV_COLOR_LIGHT_RED      12
+#define CHV_COLOR_LIGHT_MAGNETA  13
+#define CHV_COLOR_LIGHT_BROWN    14
+#define CHV_COLOR_WHITE          15
+
+typedef struct char_vga_position{
+	int x, y;
+} XYCOORD;
+
+void chv_init_cursor(void);
+void chv_sync_cursor(void);
+void chv_reset_cursor(void);
+void chv_get_cursor(XYCOORD*);
+void chv_set_cursor(const XYCOORD*);
+void chv_set_cursor_direct(int, int);
+void chv_movenext_cursor(void);
+void chv_moveprev_cursor(void);
+void chv_move_cursor(int);
+void chv_next_line(void);
+void chv_putchar(int);
+void chv_putchar_color(int, int);
+void chv_backspace(void);
+void chv_clear(void);
+void chv_scroll(int);
+
+#define chv_memread(position) \
+	(*((char*)((0xb8000)+(position))))
+#define chv_memwrite(position,byte) \
+	((*((char*)((0xb8000)+(position)))) = (byte))
+
+#define chv_screen_write_char(position,character) \
+	chv_memwrite(((position)*2), (character))
+#define chv_screen_write_color(position,color) \
+	chv_memwrite(((position)*2+1), (color))
+
+int  char_vga_get_cursor(void);
+void char_vga_set_cursor(int);
+
+/* keyboard scan codes */
+#define KEYDOWN_SCANCODE_ESC          0x01
+#define KEYDOWN_SCANCODE_BS           0x0e
+#define KEYDOWN_SCANCODE_TAB          0x0f
+#define KEYDOWN_SCANCODE_ENTER        0x1c
+#define KEYDOWN_SCANCODE_CTRL         0x1d
+#define KEYDOWN_SCANCODE_LEFT_SHIFT   0x2a
+#define KEYDOWN_SCANCODE_RIGHT_SHIFT  0x36
+#define KEYDOWN_SCANCODE_PRINT_SCREEN 0x37
+#define KEYDOWN_SCANCODE_ALT          0x38
+#define KEYDOWN_SCANCODE_SPACE        0x39
+#define KEYDOWN_SCANCODE_CAPS_LOCK    0x3a
+#define KEYDOWN_SCANCODE_FUNCTION(n)  (0x3a+(n))  /* F1 ~ F10，其他不適用 */
+#define KEYDOWN_SCANCODE_NUM_LOCK     0x45
+#define KEYDOWN_SCANCODE_SCROLL_LOCK  0x46
+#define KEYDOWN_SCANCODE_HOME         0x47
+#define KEYDOWN_SCANCODE_UP           0x48
+#define KEYDOWN_SCANCODE_PAGE_UP      0x49
+#define KEYDOWN_SCANCODE_LEFT         0x4b
+#define KEYDOWN_SCANCODE_RIGHT        0x4d
+#define KEYDOWN_SCANCODE_END          0x4f
+#define KEYDOWN_SCANCODE_DOWN         0x50
+#define KEYDOWN_SCANCODE_PAGE_DOWN    0x51
+#define KEYDOWN_SCANCODE_INSERT       0x52
+#define KEYDOWN_SCANCODE_DELETE       0x53
+
+/* keypad */
+#define KEYDOWN_SCANCODE_KEYPAD_ENTER 0x1c
+#define KEYDOWN_SCANCODE_KEYPAD_SLASH 0x35
+#define KEYDOWN_SCANCODE_KEYPAD_STAR  0x37
+#define KEYDOWN_SCANCODE_KEYPAD_7     0x47
+#define KEYDOWN_SCANCODE_KEYPAD_8     0x48
+#define KEYDOWN_SCANCODE_KEYPAD_9     0x49
+#define KEYDOWN_SCANCODE_KEYPAD_MINUS 0x4a
+#define KEYDOWN_SCANCODE_KEYPAD_4     0x4b
+#define KEYDOWN_SCANCODE_KEYPAD_5     0x4c
+#define KEYDOWN_SCANCODE_KEYPAD_6     0x4d
+#define KEYDOWN_SCANCODE_KEYPAD_ADD   0x4e
+#define KEYDOWN_SCANCODE_KEYPAD_1     0x4f
+#define KEYDOWN_SCANCODE_KEYPAD_2     0x50
+#define KEYDOWN_SCANCODE_KEYPAD_3     0x51
+#define KEYDOWN_SCANCODE_KEYPAD_0     0x52
+#define KEYDOWN_SCANCODE_KEYPAD_DOT   0x53
+
+/* str_in.c */
+int getstr(char*, int, int);
+/* 讀入一行的函式
+ * ARG1 = 要存到哪裡
+ * ARG2 = 最多可以讀多長（'\0' 不計入，但要自行保留空間）
+ * RVAL = 實際讀了幾個字 */
+
+int yotrl(char*, const char*, int, int);
+/* 同上，但是是進階版 */
+
+
+/* strbasic.c */
+int strcmp(const char*, const char*);
+int strtos(const char*, unsigned int*);
+
+#endif
+
diff --git a/yotsh.c b/yotsh.c
index f0f180d..5094ba7 100644
--- a/yotsh.c
+++ b/yotsh.c
@@ -199,9 +199,29 @@ int main(){
 		}else if(!strcmp(argcopy, "reboot")){
 			cp1 = 0;
 			asm "int 0x51";
-		}else if(!strcmp(argcopy, "reload")){
+		}else if(!strcmp(argcopy, "reload") ||
+				!strcmp(argcopy, "reload2") ||
+				!strcmp(argcopy, "yot16") ||
+				!strcmp(argcopy, "yotrm")){
 			cp1=0;
 			return 0;
+		}else if(!strcmp(argcopy, "yot32") ||
+				!strcmp(argcopy, "yotpm") ||
+				!strcmp(argcopy, "protect")){
+			putstr(
+				"WARNING: You cannot run any real mode program "
+				"unless rebooting!\r\n"
+				"Do you want to switch to protected mode ? [no] ");
+			yotrl(cmdline, NULL, 3, 7);
+			if(!strcmp(cmdline, "yes")){
+				return (3 << 12) | 101;
+			}else{
+				if(cmdline[0] == 'y' || cmdline[0] == 'Y'){
+					putstr("You should type `yes\'.\r\n");
+				}else{
+					putstr("Not confirmed.\r\n");
+				}
+			}
 		}else if(!strcmp(argcopy, "loadgarbage")){
 			cp1=0;
 			return 74;
@@ -211,10 +231,6 @@ int main(){
 		}else if(!strcmp(argcopy, "loadstupid")){
 			cp1=0;
 			return 73;
-		}else if(!strcmp(argcopy, "reload2")){
-			cp1=0;
-			/*envsave(env,sizeof(env));*/
-			return 0;
 		}else if(!strcmp(argcopy, "clear") || 
 				!strcmp(argcopy, "cls")){
 			chv_clear();
@@ -247,6 +263,8 @@ int main(){
 				putstr("Syntax: reboot\r\n");
 			}else if(!strcmp(cp2, "reload")){
 				putstr("Syntax: reload\r\n");
+			}else if(!strcmp(cp2, "yot32")){
+				putstr("Syntax: yot32\r\n");
 			}else if(!strcmp(cp2, "loadgarbage") ||
 					!strcmp(cp2, "loadstupid") ||
 					!strcmp(cp2, "loadnull")){
@@ -276,7 +294,9 @@ int main(){
 					"\r\n reboot      "
 					"Reboot the computer"
 					"\r\n reload      "
-					"Reload ??"
+					"Reload the shell"
+					"\r\n yot32       "
+					"Switch to protected mode"
 					"\r\n loadgarbage "
 					"Display some garbage to screen"
 					"\r\n loadstupid  "