亲爱的 Stackoverflowers，
我写了一些汇编代码，最终应该读取根目录。然而问题是扩展读取功能没有将读取的数据放在正确的位置。或者我的段和偏移量有问题。
我从这段代码中得到的结果是：A| |，这意味着打印函数找到了一个 0，同时期望第一个扇区的一些随机值。
我真的不知道我做错了什么了
BIOS_ReadFile.inc
;*************************************************
; Name: BIOS_ReadFile.inc
; Description: Reads File from the FAT32 System
;*************************************************
[bits 16]
%ifndef BIOS_READFILE.INC
%define BIOS_READFILE.INC
%include "Constants.inc"
;-----------------------------------------------------------------
; BIOS_ReadSectors function
;-----------------------------------------------------------------
ReadStatus: db UNKNOWN ; 0 - Not Supported, 1 - Supported, 255 - Not known at given time
BIOS_ReadSectors:
mov si, DAPS ; Load DAPS Struct to DS:SI
mov ah, 0x42 ; Read Functions
int 0x13 ; Call the interrupt
jc .Failure ; If the read fails.
mov byte [ReadStatus], TRUE ; Set the ReadStatus to True
ret ; Return
.Failure:
mov byte [ReadStatus], FALSE ; Set the ReadStatus to False
mov ah, 0x0E ; Print Letter B, Gives Indication of Failure
mov bh, 0x00
mov bl, 0x07
mov al, 'B'
int 0x10
ret
; Return
;-----------------------------------------------------------------
; BIOS_ReadFile function
;-----------------------------------------------------------------
FirstDataSector: dw 0x0
RootDirectorySector: dw 0x0
BIOS_ReadFile:
; Calculating the First Data Sector
xor ax, ax
mov byte al, [Bios_Parameter_Block.FATS]
mul word [Extended_Bios_Parameter_Block.LargeSectorsPerFAT]
add word ax, [Bios_Parameter_Block.ReservedSectors]
mov word [FirstDataSector], ax
; Calculating the Root Directory Sector
mov word ax, [Extended_Bios_Parameter_Block.RootDirectory]
sub word ax, 2
mul byte [Bios_Parameter_Block.SectorsPerCluster]
add word ax, [FirstDataSector]
mov word [RootDirectorySector], ax
; Load Directory
;mov word [DAPS.SectorsToRead], 1
;mov word ax, [RootDirectorySector]
;mov word [DAPS.SectorStart], ax
call BIOS_ReadSectors
mov ah, 0x0E ; Print Letter A, Gives Indication of Failure
mov bh, 0x00
mov bl, 0x07
mov al, 'A'
int 0x10
ret
;-----------------------------------------------------------------
; Memory Data Structures and Other Variables
;-----------------------------------------------------------------
; Disk Address Packet Structure (Used For Loading Rest of OS)
DAPS: db 0x10 ; Size of Structure (16 bytes)
db 0 ; Always 0
.SectorsToRead dw 1 ; Number of Sectors to Read (1x512)
.Offset dw 0x7E00 ; Offset to load to.
.Segment dw 0x0000 ; Segment to load to.
.SectorStart dq 0 ; Read from Second Block
;----------------------------------------------------------------------------------------------------
%endif
引导加载程序.asm
[bits 16]
[org 0x0]
jmp Start
%include "BIOS_Parameter_Block.inc"
%include "BIOS_Extensions.inc"
%include "BIOS_ReadFile.inc"
%include "Print.inc"
; Prepare stack segment
;-----------------------------------------------------------------
Start:
cli
mov ax, 0x07C0
mov ds, ax ; Load segments with 0
mov fs, ax
mov es, ax
mov gs, ax
mov ax, 0x0000 ; set the stack
mov ss, ax
mov sp, 0xFFFF
mov bp, 0xFFFF
sti
; Check support for extensions
;-----------------------------------------------------------------
call CheckExtensions
cmp byte [ExtensionsSupported], FALSE
jz short unsupported
; Read from the device.
;-----------------------------------------------------------------
call BIOS_ReadFile
mov ah, 0x0E ; Print Letter B, Gives Indication of Failure
mov bh, 0x00
mov bl, 0x07
mov al, '|'
int 0x10
mov si, 0x200
call PrintString
mov ah, 0x0E ; Print Letter B, Gives Indication of Failure
mov bh, 0x00
mov bl, 0x07
mov al, '|'
int 0x10
cli
hlt
jmp 0x0:0x7E00 ; Jump to main
; Errors
;-----------------------------------------------------------------
unsupported:
mov ah, 0x0E ; Print Letter F, Gives Indication of Failure
mov bh, 0x00
mov bl, 0x07
mov al, 'F'
int 0x10
clc
hlt
; Fill Out Rest of Bootloader
;-----------------------------------------------------------------
times 510-($-$$) db 0
db 0x55, 0xAA ; Add Boot Record Signature
印刷公司
;*************************************************
; Name: Print.inc
; Description: Printing on console using INT 10h
; Function: PrintString(DS::SI nullTerminatedString)
;*************************************************
[bits 16]
%ifndef PRINT.INC
%define PRINT.INC
;---------------------------------------------------------------------------------
PrintString:
lodsb ; Load next byte from DI::SI to AL and increment SI by one
or al, al ; Null-Terminator check
jz .Done ; If found jump to end
mov ah, 0Eh ; Move Function number in AH
int 10h ; Else print character
jmp PrintString ; Repeat until null terminator found
.Done:
mov ah, 0x0E ; Print Letter B, Gives Indication of Failure
mov bh, 0x00
mov bl, 0x07
int 0x10
ret ; Return
;---------------------------------------------------------------------------------
％万一