print all cluster numbers ok
This commit is contained in:
ridethepig
parent
308d1caf1e
commit
a0dacc4b9e
136
loader.asm
136
loader.asm
@ -28,15 +28,15 @@ DispStr:
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pop bp
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ret
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;----------------------------------------------------------------------------
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; @param ax: the int to print
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; @param bp + 4: the word to print as uint_16t
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;----------------------------------------------------------------------------
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; print a word as decimal to current cursor
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DispInt:
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push bp
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mov bp, sp
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pusha
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mov di, 0
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mov ax, [bp + 4]
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.loop1:
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mov dx, 0
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mov bx, 10
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@ -61,8 +61,9 @@ DispInt:
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pop bp
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ret
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;----------------------------------------------------------------------------
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; give you a new line
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; no param
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;----------------------------------------------------------------------------
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; give you a new line
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DispNewline:
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push bp
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mov bp, sp
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@ -81,6 +82,27 @@ DispNewline:
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ret
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;----------------------------------------------------------------------------
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; @param bp + 4: low byte holds the ascii to print
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;----------------------------------------------------------------------------
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; putchar to current cursor pos
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DispPutchar:
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push bp
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mov bp, sp
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pusha
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; get cursor pos
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mov ax, 0300h
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mov bh, 0
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int 10h
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; putchar
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mov ax, [bp + 4]
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mov ah, 0Eh ; no need to set al, ax holds the param
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mov bl, 0Fh
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int 10H
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popa
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pop bp
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ret
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;----------------------------------------------------------------------------
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; 函数名: StringCmp
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;----------------------------------------------------------------------------
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; 作用:
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@ -143,11 +165,11 @@ ReadSector:
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pop bp
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ret
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.ReadFail:
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jmp $ ; 如果cf位置1，就意味着读入错误，这个时候建议直接开摆
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;------------------------------------------------------------------------------
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; 函数名: GetNextCluster
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; data => BaseOfSectorBuf : 0
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;------------------------------------------------------------------------------
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; 作用:
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; ax存放的是当前的簇(cluster)号，根据当前的簇号在fat表里查找，找到下一个簇的簇号，并将返回值存放在ax
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@ -176,9 +198,9 @@ GetNextCluster:
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mov ax, [es:bx]
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pop bx ; 取回奇数标识信息
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cmp bx, 0 ; 如果是第奇数个FAT项还得右移四位
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jz EvenCluster ; 可能是微软(FAT是微软创建的)第一个亲儿子的原因，有它的历史局限性
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jz .EvenCluster ; 可能是微软(FAT是微软创建的)第一个亲儿子的原因，有它的历史局限性
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shr ax, 4 ; 当时的磁盘很脆弱，经常容易写坏，所以需要两张FAT表备份，而且人们能够制作的存储设备的容量很小
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EvenCluster:
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.EvenCluster:
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and ax, 0FFFh ; 读完需要与一下，因为高位是未定义的，防止ax值有误
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mov word [bp - 2], ax ; 这里用了一个技巧，这样在popa的时候ax也顺便更新了
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@ -191,7 +213,7 @@ EvenCluster:
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; @retval ax: first cluster no
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;------------------------------------------------------------------------------
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; Find File by name, return first cluster no.
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; data => BaseOfSectorBuf:OffsetOfSectorBuf
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FuncFindFile:
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push bp
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mov bp, sp
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@ -247,58 +269,86 @@ FuncFindFile:
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pop bp
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ret
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;------------------------------------------------------------------------------
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; @param bp + 4: first cluster number
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;------------------------------------------------------------------------------
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; Find File by name, return first cluster no.
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; data => BaseOfSectorBuf:OffsetOfSectorBuf
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FuncPrintClusterNumbers:
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push bp
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mov bp, sp
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pusha
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mov ax, [bp + 4]
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.loop:
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mov ax, dx
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push ax
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call DispInt ; ax now holds the current cluster number
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add sp, 2
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push ' '
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call DispPutchar
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add sp, 2
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call GetNextCluster ; 根据数据区簇号获取文件下一个簇的簇号
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mov dx, ax ; dx <- 下一个簇的簇号
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cmp dx, 0FFFh ; 判断是否读完了（根据文档理论上dx只要在0xFF8~0xFFF都行，但是这里直接偷懒只判断0xFFF）
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jnz .loop
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popa
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pop bp
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ret
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MAIN:
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mov ax, cs ; cs <- 0
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mov ds, ax ; ds <- 0
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mov ss, ax ; ss <- 0
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mov ax, BaseOfSectorBuf
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mov es, ax ; es <- BaseOfSectorBuf
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; Display "This is {name}'s boot"
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call DispNewline
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mov ax, cs
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push ax
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mov ax, StudentString
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push ax
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mov ax, _endStudentString - StudentString
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push ax
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call DispStr
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add sp, 6 ; pop for 3 times
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mov ax, LoaderFileName
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push ax
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push cs
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push StudentString
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push _endStudentString - StudentString
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call DispStr
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add sp, 6 ; pop for 3 times
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; Read loader.bin's cluster number
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push LoaderFileName
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call FuncFindFile
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mov dx, ax ; temporarily save read result to dx
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pop ax
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add sp, 2
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mov dx, ax ; temporarily save read result to dx
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; Print first cluster number
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call DispNewline
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mov ax, cs
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push ax
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mov ax, clusternoString
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push ax
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mov ax, _endclusternoString - clusternoString
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push ax
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push cs
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push clusternoString
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push _endclusternoString - clusternoString
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call DispStr
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add sp, 6 ; pop for 3 times
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mov ax, dx ; dx holds the read result
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call DispInt
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mov ax, AA1FileName
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push ax
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push dx ; dx holds the read result
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call FuncPrintClusterNumbers
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add sp, 2
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; Read aA1.txt's cluster number
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push AA1FileName
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call FuncFindFile
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mov dx, ax ; temporarily save read result to dx
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pop ax
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add sp, 2
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mov dx, ax ; temporarily save read result to dx
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; Print first cluster number
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call DispNewline
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mov ax, cs
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push ax
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mov ax, clusternoString
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push ax
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mov ax, _endclusternoString - clusternoString
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push ax
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push cs
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push clusternoString
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push _endclusternoString - clusternoString
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call DispStr
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add sp, 6 ; pop for 3 times
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mov ax, dx ; dx holds the read result
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call DispInt
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add sp, 6
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push dx ; dx holds the read result
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call FuncPrintClusterNumbers
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add sp, 2
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jmp $
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;==============================================================================
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@ -307,7 +357,7 @@ MAIN:
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BaseOfStack equ 07c00h ; Boot状态下堆栈基地址(栈底, 从这个位置向低地址生长)
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; according to osdev, memory from 0x0000:0x7e00 to 0x7000:0xFFFF is free to use
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BaseOfSectorBuf equ 07000h ; diff from where we are here
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OffsetOfSectorBuf equ 0000h ; diff from where we are here
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OffsetOfSectorBuf equ 0400h ; the first 400h(=1024d) bytes left for fat1 read buf
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RootDirSectors equ 14 ; 19~32
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SectorNoOfRootDirectory equ 19 ; Root Sector starts from 19
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SectorNoOfFAT1 equ 1
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@ -335,7 +385,7 @@ LeftRootDirSectors dw RootDirSectors ; 还未搜索的根目录
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RootDirSectorNow dw SectorNoOfRootDirectory ; 目前正在搜索的根目录扇区
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BufferPacket times 010h db 0 ; ReadSector函数会用到的，用于向int 13h中断的一个缓冲区
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LoaderFileName db "LOADE BIN", 0 ; 8:3, fill with whitespace
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LoaderFileName db "LOADER BIN", 0 ; 8:3, fill with whitespace
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AA1FileName db "AA1 TXT", 0 ; the 0 at end is for StrCmp
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StudentString db "This is LiMaoliang's boot" ; size = 25
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_endStudentString
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