Assembly 在保护模式下向屏幕ASM打印字符

我正在尝试进入保护模式，然后打印“嗨”

但它只是从我的bios中断调用（发生在进入pmode之前）打印“加载操作系统”，没有其他内容

我的引导加载程序.asm

%DEFINE KERNEL_LOAD_OFFSET 0x1000

org 0x7c00

bits 16

xor ax, ax
mov ds, ax

start: jmp main

Print:
 .print:
  lodsb
  or al, al
  je .done

  mov ah, 0x0E
  int 0x10

  .repeat:
   jmp .print

 .done:
  ret

ResetFloppy:
 mov ah, 0x0

 int 0x13
 jc ErrorFloppy
 .done:
  ret

ReadFloppy:

 mov ah, 0x02
 int 0x13

 jc ErrorFloppy

 .done:
  ret

ErrorFloppy:

 mov si, msgErrorFloppy
 call Print

 jmp hang


main: 
 .print:

  mov si, msg
  call Print

 .loadFile:
  mov al, 0xF
  mov ch, 0x0
  mov cl, 0x02
  mov dh, 0x0
  mov dl, 0x0
  mov bx, KERNEL_LOAD_OFFSET

  call ResetFloppy
  call ReadFloppy


 .loadGDT:
   lgdt [gdtr]
 .pM_start:
  cli
  pusha

  mov eax, cr0
  or al, 1
  mov cr0, eax

  popa

  jmp 0x08:ljmp_pM


 bits 32
 ljmp_pM: 
  mov ax, 0x10
  mov ds, ax
  mov ss, ax
  mov fs, ax
  mov es, ax
  mov gs, ax

  jmp KERNEL_LOAD_OFFSET

hang:
 jmp $

gdt:
NULL_DESC:
    dd 0            ; null descriptor
    dd 0

CODE_DESC:
    dw 0xFFFF       ; limit low
    dw 0            ; base low
    db 0            ; base middle
    db 10011010b    ; access
    db 11001111b    ; granularity
    db 0            ; base high

DATA_DESC:
    dw 0xFFFF       ; data descriptor
    dw 0            ; limit low
    db 0            ; base low
    db 10010010b    ; access
    db 11001111b    ; granularity
    db 0            ; base high

gdtr:
    Limit dw 24         ; length of GDT
    Base dd NULL_DESC   ; base of GDT

msg db "Loading OS", 13, 10, 0
msgErrorFloppy db "There was an error with the floppy", 13, 10, 0

FILL:
 times 510-($-$$) db 0

BOOTSECTOR:
 dw 0xAA55

bits 32

mov dword [0xB8000], 0x07690748

jmp $

Kernel.asm

%DEFINE KERNEL_LOAD_OFFSET 0x1000

org 0x7c00

bits 16

xor ax, ax
mov ds, ax

start: jmp main

Print:
 .print:
  lodsb
  or al, al
  je .done

  mov ah, 0x0E
  int 0x10

  .repeat:
   jmp .print

 .done:
  ret

ResetFloppy:
 mov ah, 0x0

 int 0x13
 jc ErrorFloppy
 .done:
  ret

ReadFloppy:

 mov ah, 0x02
 int 0x13

 jc ErrorFloppy

 .done:
  ret

ErrorFloppy:

 mov si, msgErrorFloppy
 call Print

 jmp hang


main: 
 .print:

  mov si, msg
  call Print

 .loadFile:
  mov al, 0xF
  mov ch, 0x0
  mov cl, 0x02
  mov dh, 0x0
  mov dl, 0x0
  mov bx, KERNEL_LOAD_OFFSET

  call ResetFloppy
  call ReadFloppy


 .loadGDT:
   lgdt [gdtr]
 .pM_start:
  cli
  pusha

  mov eax, cr0
  or al, 1
  mov cr0, eax

  popa

  jmp 0x08:ljmp_pM


 bits 32
 ljmp_pM: 
  mov ax, 0x10
  mov ds, ax
  mov ss, ax
  mov fs, ax
  mov es, ax
  mov gs, ax

  jmp KERNEL_LOAD_OFFSET

hang:
 jmp $

gdt:
NULL_DESC:
    dd 0            ; null descriptor
    dd 0

CODE_DESC:
    dw 0xFFFF       ; limit low
    dw 0            ; base low
    db 0            ; base middle
    db 10011010b    ; access
    db 11001111b    ; granularity
    db 0            ; base high

DATA_DESC:
    dw 0xFFFF       ; data descriptor
    dw 0            ; limit low
    db 0            ; base low
    db 10010010b    ; access
    db 11001111b    ; granularity
    db 0            ; base high

gdtr:
    Limit dw 24         ; length of GDT
    Base dd NULL_DESC   ; base of GDT

msg db "Loading OS", 13, 10, 0
msgErrorFloppy db "There was an error with the floppy", 13, 10, 0

FILL:
 times 510-($-$$) db 0

BOOTSECTOR:
 dw 0xAA55

bits 32

mov dword [0xB8000], 0x07690748

jmp $

和Compile.bat

nasm -f bin Dev/BootLoader.asm -o Bin/BootLoader.bin
nasm -f bin Dev/Kernel.asm -o Bin/Kernel.bin

dd if=Bin/BootLoader.bin of=Image/Image.img seek=0
dd if=Bin/Kernel.bin of=Image/Image.img seek=1 conv=notrunc

pause

---

我用bochs。我所得到的是：

在32位保护模式下，您无法使用BIOS，因为它是用16位实模式的代码编写的。因此，您必须像这样访问视频存储器：

    mov ebx,0xb8000    ; The video address
    mov al,'!'         ; The character to be print
    mov ah,0x0F        ; The color: white(F) on black(0)
    mov [ebx],ax        ; Put the character into the video memory

    mov dx,0x3D4       ; Tell the control I/O port to get the lower byte of
    mov al,0x0F        ; the cursor offset
    out dx,al
    mov dx,0x3D5       ; Switch to data I/O port
    in  al,dx          ; Get the cursor offset's lower byte

    mov dx,0x3D5       ; Tell the control I/O port to get the higher byte of
    mov al,0x0E        ; the cursor offset
    out dx,al
    mov dx,0x3D5       ; Switch to data I/O port
    in  al,dx          ; Get the higher byte

    imul ax,2           ; Because a character in video memory costs 2 bytes
                       ; (i.e character and attribute), we need to twice the cursor offset

然后您可能会看到一个

在屏幕的开头。如果只想在光标位置打印，可以按如下方式获得光标偏移：

    mov ebx,0xb8000    ; The video address
    mov al,'!'         ; The character to be print
    mov ah,0x0F        ; The color: white(F) on black(0)
    mov [ebx],ax        ; Put the character into the video memory

    mov dx,0x3D4       ; Tell the control I/O port to get the lower byte of
    mov al,0x0F        ; the cursor offset
    out dx,al
    mov dx,0x3D5       ; Switch to data I/O port
    in  al,dx          ; Get the cursor offset's lower byte

    mov dx,0x3D5       ; Tell the control I/O port to get the higher byte of
    mov al,0x0E        ; the cursor offset
    out dx,al
    mov dx,0x3D5       ; Switch to data I/O port
    in  al,dx          ; Get the higher byte

    imul ax,2           ; Because a character in video memory costs 2 bytes
                       ; (i.e character and attribute), we need to twice the cursor offset

在32位保护模式下，为了提高代码的效率，可以使用一些高级语言，如
C
来创建函数。这确实提高了代码的可读性

嗯，
Hi
就在左上角？哦，我的天啊，我真是太傻了：D谢谢：D把这篇文章作为答案发出去你的第一个代码块不会存储到内存中。我认为您遗漏了一个
mov[ebx]，ax
，因为您假设分页被禁用或直接映射。顺便说一句，您可以编写
mov-word[0xb8000]，（0x0F也是，
mul-ax，2
不是x86指令。
imul-ax，2
是有效的，但用它乘以一个愚蠢的幂。使用
shl-ax，1
。在写入
al
和移位之前，不要忘记将
eax
归零。使用
shl-ax，1
。这里没有理由使用
imul
的幂2.@PeterCordes我相信shift可能有一些错误。作为程序员，你应该知道第一位决定了符号，所以不使用shl更安全。