source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Boot/BootInfo.asm@ 99

; File name     :   BootInfo.asm
; Project name  :   XTIDE Universal BIOS
; Description   :   Functions for generating and accessing drive
;                   information to be displayed on boot menu.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Creates new BOOTNFO struct for detected hard disk.
;
; BootInfo_CreateForHardDisk
;   Parameters:
;       DL:     Drive number
;       DS:DI:  Ptr to Disk Parameter Table
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;   Returns:
;       ES:BX:  Ptr to BOOTNFO (if successful)
;       CF:     Cleared if BOOTNFO created succesfully
;               Set if any error
;   Corrupts registers:
;       AX, BX, CX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
BootInfo_CreateForHardDisk:
    call    BootInfo_GetOffsetToBX      ; ES:BX now points to new BOOTNFO
    call    BootInfo_StoreSectorCount
    jmp     SHORT BootInfo_StoreDriveName


;--------------------------------------------------------------------
; Returns offset to BOOTNFO for wanted drive.
;
; BootInfo_GetOffsetToBX
;   Parameters:
;       DL:     Drive number
;       DS:     RAMVARS segment
;   Returns:
;       BX:     Offset to BOOTNFO struct
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
BootInfo_GetOffsetToBX:
    mov     bl, dl                      ; Copy drive number to BL
    mov     al, BOOTNFO_size            ; Size of struct
    sub     bl, [RAMVARS.bFirstDrv]     ; Drive number to index
    mul     bl                          ; AX = Offset inside BOOTNFO array
    add     ax, BOOTVARS.rgBootNfo      ; Add offset to BOOTNFO array
    xchg    bx, ax                      ; Copy result to BX
    ret


;--------------------------------------------------------------------
; Stores total sector count to BOOTNFO.
;
; BootInfo_StoreSectorCount
;   Parameters:
;       ES:BX:  Ptr to BOOTNFO
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       CF:     Cleared if variables stored succesfully
;               Set if any error
;   Corrupts registers:
;       AX, CX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
BootInfo_StoreSectorCount:
    push    bx
    call    AtaID_GetTotalSectorCount       ; Get to BX:DX:AX
    mov     cx, bx                          ; Now in CX:DX:AX
    pop     bx
    mov     [es:bx+BOOTNFO.twSectCnt], ax
    mov     [es:bx+BOOTNFO.twSectCnt+2], dx
    mov     [es:bx+BOOTNFO.twSectCnt+4], cx
    clc
    ret


;--------------------------------------------------------------------
; Stores drive name to BOOTNFO.
;
; BootInfo_StoreDriveName
;   Parameters:
;       ES:BX:  Ptr to BOOTNFO
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       CF:     Cleared if variables stored succesfully
;               Set if any error
;   Corrupts registers:
;       AX, CX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
BootInfo_StoreDriveName:
    push    ds
    push    si
    push    di

    ; DS:SI to ATA source string
    push    es
    pop     ds
    add     si, BYTE ATA1.strModel

    ; ES:DI to BOOTNFO destination string
    lea     di, [bx+BOOTNFO.szDrvName]

    ; Read string
    mov     cx, LEN_BOOTNFO_DRV>>1
    call    BootInfo_StoreAtaString
    pop     di
    pop     si
    pop     ds
    clc
    ret

;--------------------------------------------------------------------
; Stores ATA string.
; Byte ordering will be corrected and string will be STOP terminated.
;
; BootInfo_StoreAtaString
;   Parameters:
;       CX:     Maximum number of WORDs to copy (without STOP)
;       DS:SI:  Ptr to ATA string
;       ES:DI:  Ptr to destination string
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, CX, SI, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
BootInfo_StoreAtaString:
    lodsw                           ; Load WORD from DS:SI to AX
    xchg    al, ah                  ; Change byte order
    call    BootInfo_StoreAtaChar
    jc      SHORT .Return           ; Return if invalid character
    mov     al, ah                  ; Write next char
    call    BootInfo_StoreAtaChar
    jc      SHORT .Return           ; Return if invalid character
    loop    BootInfo_StoreAtaString ; Loop while words left
.Return:
    xor     ax, ax                  ; Terminate string with NULL
    stosb
    ret

;--------------------------------------------------------------------
; Stores ATA character.
;
; BootInfo_StoreAtaChar
;   Parameters:
;       AL:     Character to store
;       ES:DI:  Ptr to destination character
;   Returns:
;       DI:     Incremented to next character
;       CF:     Set if non writable ASCII character
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
BootInfo_StoreAtaChar:
    cmp     al, 20h                 ; First allowed ASCII char?
    jb      SHORT .SkipStoring      ;  If below, end string
    cmp     al, 7Eh                 ; Last allowed ASCII char?
    ja      SHORT .SkipStoring      ;  If above, end string
    stosb                           ; Store character
    clc                             ; Clear CF to continue with next char
    ret
.SkipStoring:
    stc
    ret


;--------------------------------------------------------------------
; Finds BOOTNFO for drive and return total sector count.
;
; BootInfo_GetTotalSectorCount
;   Parameters:
;       DL:     Drive number
;       DS:     RAMVARS segment
;   Returns:
;       BX:DX:AX:   48-bit sector count
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------   
ALIGN JUMP_ALIGN
BootInfo_GetTotalSectorCount:
    push    ds
    call    BootInfo_GetOffsetToBX
    LOAD_BDA_SEGMENT_TO ds, ax
    mov     ax, [bx+BOOTNFO.twSectCnt]
    mov     dx, [bx+BOOTNFO.twSectCnt+2]
    mov     bx, [bx+BOOTNFO.twSectCnt+4]
    pop     ds
    ret