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Lot's of fixes for the FAT12/16 boot sector code.

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svn path=/trunk/; revision=4737
This commit is contained in:
Brian Palmer 2003-05-21 20:28:13 +00:00
parent faa8f94f27
commit f152732d04
1 changed files with 11 additions and 6 deletions
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17
freeldr/bootsect/fat.asm
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@ -144,6 +144,7 @@ CalcDriveSize:
; DX:AX now has the number of the starting sector of the root directory ; DX:AX now has the number of the starting sector of the root directory
; Now calculate the size of the root directory ; Now calculate the size of the root directory
xor dx,dx
mov ax,0020h ; Size of dir entry mov ax,0020h ; Size of dir entry
mul si ; Times the number of entries mul si ; Times the number of entries
mov bx,[BYTE bp+BytesPerSector] mov bx,[BYTE bp+BytesPerSector]
@ -257,7 +258,7 @@ ReadCluster:
add ax,[BYTE bp-DataAreaStartLow] ; Add start of data area add ax,[BYTE bp-DataAreaStartLow] ; Add start of data area
adc dx,[BYTE bp-DataAreaStartHigh] ; Now we have DX:AX with the logical start sector of OSLOADER.SYS adc dx,[BYTE bp-DataAreaStartHigh] ; Now we have DX:AX with the logical start sector of OSLOADER.SYS
xor bx,bx ; We will load it to [ES:0000], ES loaded before function call xor bx,bx ; We will load it to [ES:0000], ES loaded before function call
mov cl,BYTE [BYTE bp+SectsPerCluster] ;mov cl,BYTE [BYTE bp+SectsPerCluster]; Sectors per cluster still in CX
;call ReadSectors ;call ReadSectors
;ret ;ret
@ -277,12 +278,14 @@ ReadSectors:
adc dx,byte 0 adc dx,byte 0
cmp dx,WORD [BYTE bp-BiosCHSDriveSizeHigh] ; Check if they are reading a sector within CHS range cmp dx,WORD [BYTE bp-BiosCHSDriveSizeHigh] ; Check if they are reading a sector within CHS range
jb ReadSectorsCHS ; Yes - go to the old CHS routine ja ReadSectorsLBA ; No - go to the LBA routine
jb ReadSectorsCHS ; Yes - go to the old CHS routine
cmp ax,WORD [BYTE bp-BiosCHSDriveSizeLow] ; Check if they are reading a sector within CHS range cmp ax,WORD [BYTE bp-BiosCHSDriveSizeLow] ; Check if they are reading a sector within CHS range
jbe ReadSectorsCHS ; Yes - go to the old CHS routine jbe ReadSectorsCHS ; Yes - go to the old CHS routine
ReadSectorsLBA: ReadSectorsLBA:
popa popa
ReadSectorsLBALoop:
pusha ; Save logical sector number & sector count pusha ; Save logical sector number & sector count
o32 push byte 0 o32 push byte 0
@ -323,11 +326,13 @@ ReadSectorsLBA:
inc ax ; Increment Sector to Read inc ax ; Increment Sector to Read
adc dx,byte 0 adc dx,byte 0
mov dx,es push bx
add dx,byte 20h ; Increment read buffer for next sector mov bx,es
mov es,dx add bx,byte 20h ; Increment read buffer for next sector
mov es,bx
pop bx
loop ReadSectorsLBA ; Read next sector loop ReadSectorsLBALoop ; Read next sector
ret ret