source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm @ 173

; Project name  :   XTIDE Universal BIOS
; Description   :   Functions for creating Disk Parameter Table.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Creates new Disk Parameter Table for detected hard disk.
; Drive is then fully accessible using any BIOS function.
;
; CreateDPT_FromAtaInformation
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;       CS:BP:  Ptr to IDEVARS for the controller
;       DS:     RAMVARS segment
;       ES:     BDA Segment
;   Returns:
;       DL:     Drive number for new drive
;       DS:DI:  Ptr to Disk Parameter Table (if succesfull)
;       CF:     Cleared if DPT created successfully
;               Set if any error
;   Corrupts registers:
;       AX, BX, CX, DH
;--------------------------------------------------------------------
CreateDPT_FromAtaInformation:
    call    FindDPT_ForNewDriveToDSDI
    ; Fall to .InitializeDPT

;--------------------------------------------------------------------
; .InitializeDPT
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       DS:DI:  Ptr to Disk Parameter Table
;       CS:BP:  Ptr to IDEVARS for the controller
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
.InitializeDPT:
    mov     [di+DPT.bIdevarsOffset], bp ; IDEVARS must start in first 256 bytes of ROM
    ; Fall to .StoreDriveSelectAndDriveControlByte

;--------------------------------------------------------------------
; .StoreDriveSelectAndDriveControlByte
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       DS:DI:  Ptr to Disk Parameter Table
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;       CS:BP:  Ptr to IDEVARS for the controller
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
.StoreDriveSelectAndDriveControlByte:
    mov     al, bh
    and     ax, BYTE FLG_DRVNHEAD_DRV       ; AL now has Master/Slave bit
    cmp     [cs:bp+IDEVARS.bIRQ], ah        ; Interrupts enabled?
    jz      SHORT .StoreFlags               ;  If not, do not set interrupt flag
    or      al, FLGL_DPT_ENABLE_IRQ
.StoreFlags:
    mov     [di+DPT.wFlags], ax
    ; Fall to .StoreAddressing

;--------------------------------------------------------------------
; .StoreAddressing
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;       CS:BP:  Ptr to IDEVARS for the controller
;   Returns:
;       DX:AX or AX:    Number of cylinders
;       BH:             Number of sectors per track
;       BL:             Number of heads
;   Corrupts registers:
;       CX, (DX)
;--------------------------------------------------------------------
.StoreAddressing:
    ; Check if CHS defined in ROMVARS
    mov     al, FLG_DRVPARAMS_USERCHS   ; User specified CHS?
    call    AccessDPT_TestIdeVarsFlagsForMasterOrSlaveDrive
    jnz     SHORT .StoreUserDefinedCHSaddressing

    ; Check if LBA supported
    call    AtaID_GetPCHStoAXBLBHfromAtaInfoInESSI
    test    BYTE [es:si+ATA1.wCaps+1], A1_wCaps_LBA>>8
    jz      SHORT .StoreCHSaddressing

    ; Check if 48-bit LBA supported
    test    BYTE [es:si+ATA6.wSetSup83+1], A6_wSetSup83_LBA48>>8
    jz      SHORT .StoreLBA28addressing
    or      BYTE [di+DPT.bFlagsLow], ADDRESSING_MODE_LBA48<<ADDRESSING_MODE_FIELD_POSITION
.StoreLBA28addressing:
    or      BYTE [di+DPT.bFlagsLow], ADDRESSING_MODE_LBA28<<ADDRESSING_MODE_FIELD_POSITION
    call    AtaID_GetTotalSectorCountToBXDXAXfromAtaInfoInESSI
    call    AtaID_GetLbaAssistedCHStoDXAXBLBH
    jmp     SHORT .StoreChsFromDXAXBX

    ; Check if P-CHS to L-CHS translation required
.StoreUserDefinedCHSaddressing:
    call    AccessDPT_GetPointerToDRVPARAMStoCSBX
    mov     ax, [cs:bx+DRVPARAMS.wCylinders]
    mov     bx, [cs:bx+DRVPARAMS.wHeadsAndSectors]
.StoreCHSaddressing:
    cmp     ax, MAX_LCHS_CYLINDERS
    jbe     SHORT .StoreChsFromAXBX     ; No translation required

    ; We need to get number of bits to shift for translation
    push    bx
    push    ax
    eMOVZX  dx, bl                      ; Heads now in DX
    xchg    bx, ax                      ; Sectors now in BX
    call    AccessDPT_ShiftPCHinBXDXtoLCH
    or      cl, ADDRESSING_MODE_PCHS<<ADDRESSING_MODE_FIELD_POSITION
    or      [di+DPT.bFlagsLow], cl      ; Store bits to shift
    pop     ax
    pop     bx
    ; Fall to .StoreChsFromAXBX

;--------------------------------------------------------------------
; .StoreChsFromAXBX
; .StoreChsFromDXAXBX
;   Parameters:
;       DX:AX or AX:    Number of cylinders
;       BH:     Number of sectors per track
;       BL:     Number of heads
;       DS:DI:  Ptr to Disk Parameter Table
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;       CS:BP:  Ptr to IDEVARS for the controller
;   Returns:
;       Nothing
;   Corrupts registers:
;       DX
;--------------------------------------------------------------------
.StoreChsFromAXBX:
    xor     dx, dx
.StoreChsFromDXAXBX:
    mov     [di+DPT.dwCylinders], ax
    mov     [di+DPT.dwCylinders+2], dx
    mov     [di+DPT.wHeadsAndSectors], bx
    ; Fall to .StoreBlockMode

;--------------------------------------------------------------------
; .StoreBlockMode
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;       CS:BP:  Ptr to IDEVARS for the controller
;   Returns:
;       Nothing
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
.StoreBlockMode:
    cmp     BYTE [es:si+ATA1.bBlckSize], 1  ; Max block size in sectors
    jbe     SHORT .BlockModeTransfersNotSupported
    or      BYTE [di+DPT.bFlagsHigh], FLGH_DPT_BLOCK_MODE_SUPPORTED
.BlockModeTransfersNotSupported:
    ; Fall to .StoreDeviceSpecificParameters

;--------------------------------------------------------------------
; .StoreDeviceSpecificParameters
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;       CS:BP:  Ptr to IDEVARS for the controller
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX
;--------------------------------------------------------------------
.StoreDeviceSpecificParameters:
    call    Device_FinalizeDPT
    ; Fall to .StoreDriveNumberAndUpdateDriveCount

;--------------------------------------------------------------------
; .StoreDriveNumberAndUpdateDriveCount
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;       CS:BP:  Ptr to IDEVARS for the controller
;       ES:     BDA Segment
;   Returns:
;       DL:     Drive number for new drive
;       CF:     Always cleared
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
.StoreDriveNumberAndUpdateDriveCount:
    mov     dl, [es:BDA.bHDCount]
    or      dl, 80h                     ; Set bit 7 since hard disk

    inc     BYTE [RAMVARS.bDrvCnt]      ; Increment drive count to RAMVARS
    inc     BYTE [es:BDA.bHDCount]      ; Increment drive count to BDA

    cmp     BYTE [RAMVARS.bFirstDrv], 0 ; First drive set?
    ja      SHORT .AllDone              ;  If so, return
    mov     [RAMVARS.bFirstDrv], dl     ; Store first drive number
    clc
.AllDone:
    ret