source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm @ 258

; 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:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX
;--------------------------------------------------------------------
.StoreAddressing:
    ; Check if CHS defined in ROMVARS
    call    AccessDPT_GetPointerToDRVPARAMStoCSBX
    test    byte [cs:bx+DRVPARAMS.wFlags], FLG_DRVPARAMS_USERCHS    ; User specified CHS?
    jnz     SHORT .StoreUserDefinedPCHS

    ; Check if LBA supported
    call    AtaID_GetPCHStoAXBLBHfromAtaInfoInESSI
    test    BYTE [es:si+ATA1.wCaps+1], A1_wCaps_LBA>>8
    jz      SHORT .StoreCHSfromAXBHBL       ; Small old drive with CHS addressing only

    ; 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
    mov     [di+DPT.twLbaSectors], ax
    mov     [di+DPT.twLbaSectors+2], dx
    mov     [di+DPT.twLbaSectors+4], bx
    call    AtaID_GetLbaAssistedCHStoDXAXBLBH
    mov     [di+DPT.bLbaHeads], bl
    jmp     SHORT .StoreBlockMode

;--------------------------------------------------------------------
; .StoreUserDefinedPCHS
;   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:
;       AX:     Number of P-CHS cylinders
;       BH:     Number of P-CHS sectors per track
;       BL:     Number of P-CHS heads
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
.StoreUserDefinedPCHS:
    call    AccessDPT_GetPointerToDRVPARAMStoCSBX
    mov     ax, [cs:bx+DRVPARAMS.wCylinders]
    mov     bx, [cs:bx+DRVPARAMS.wHeadsAndSectors]
    ; Fall to .StoreCHSfromAXBHBL

;--------------------------------------------------------------------
; .StoreCHSfromAXBHBL
;   Parameters:
;       AX:     Number of P-CHS cylinders
;       BH:     Number of P-CHS sectors per track
;       BL:     Number of P-CHS 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:
;       AX:     Number of P-CHS cylinders
;       BH:     Number of P-CHS sectors per track
;       BL:     Number of P-CHS heads
;   Corrupts registers:
;       CX
;--------------------------------------------------------------------
.StoreCHSfromAXBHBL:
    push    ax
    push    bx
    call    AccessDPT_ShiftPCHinAXBLtoLCH   ; Get number of bits to shift
    pop     bx
    pop     ax
    jcxz    .StorePCHSfromAXDX              ; Small drive so use L-CHS addressing

    ; Store P-CHS addressing mode and number of bits to shift in L-CHS to P-CHS translation
    or      cl, ADDRESSING_MODE_PCHS<<ADDRESSING_MODE_FIELD_POSITION
    or      [di+DPT.bFlagsLow], cl
    ; Fall to .StoreChsFromAXBLBH

;--------------------------------------------------------------------
; .StoreChsFromAXBLBH
;   Parameters:
;       AX:     Number of P-CHS cylinders
;       BH:     Number of P-CHS sectors per track
;       BL:     Number of P-CHS 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:
;       Nothing
;--------------------------------------------------------------------
.StorePCHSfromAXDX:
    mov     [di+DPT.wPchsCylinders], ax
    mov     [di+DPT.wPchsHeadsAndSectors], 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

%ifdef MODULE_SERIAL_FLOPPY
;
; These two instructions serve two purposes:
; 1. If the drive is a floppy drive (CF set), then we effectively increment the counter.
; 2. If this is a hard disk, and there have been any floppy drives previously added, then the hard disk is 
;    effectively discarded.  This is more of a safety check then code that should ever normally be hit (see below).
;    Since the floppy DPT's come after the hard disk DPT's, without expensive (code size) code to relocate a DPT, 
;    this was necessary.  Now, this situation shouldn't happen in normal operation, for a couple of reasons:
;       A. xtidecfg always puts configured serial ports at the end fo the IDEVARS list
;       B. the auto serial code is always executed last
;       C. the serial server always returns floppy drives last
;
    adc     byte [RAMVARS.xlateVars+XLATEVARS.bFlopCreateCnt], 0
    jnz     .AllDone    
%else
;
; Even without floppy support enabled, we shouldn't try to mount a floppy image as a hard disk, which
; could lead to unpredictable results since no MBR will be present, etc.  The server doesn't know that 
; floppies are supported, so it is important to still fail here if a floppy is seen during the drive scan.
;
    jc      .AllDone
%endif

    ; 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

.AllDone:
    clc
    ret