source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm @ 421

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

;
; XTIDE Universal BIOS and Associated Tools 
; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team.
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
; 
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.      
; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;       

; 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:
;       DS:DI:  Ptr to Disk Parameter Table (if successful)
;       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
%ifdef MODULE_IRQ
    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:
%endif
    mov     [di+DPT.wFlags], ax
    ; Fall to .StoreCHSparametersAndAddressingMode

;--------------------------------------------------------------------
; .StoreCHSparametersAndAddressingMode
;   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
;--------------------------------------------------------------------
.StoreCHSparametersAndAddressingMode:
    ; Check if CHS defined in ROMVARS
    call    AccessDPT_GetPointerToDRVPARAMStoCSBX
    test    byte [cs:bx+DRVPARAMS.wFlags], FLG_DRVPARAMS_USERCHS    ; User specified P-CHS?
    jz      SHORT .AutodetectPCHSvalues

    ; Use DRVPARAMS P-CHS values instead of autodetected
    mov     ax, [cs:bx+DRVPARAMS.wCylinders]
    mov     bx, [cs:bx+DRVPARAMS.wHeadsAndSectors]
    call    AtaGeometry_GetLCHStoAXBLBHfromPCHSinAXBLBH
    jmp     SHORT .StoreLCHStoDPT

    ; Get L-CHS parameters and addressing mode
.AutodetectPCHSvalues:
    call    AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSI

.StoreLCHStoDPT:
    eSHL_IM dl, ADDRESSING_MODE_FIELD_POSITION
    or      cl, dl
    or      [di+DPT.bFlagsLow], cl      ; Shift count and addressing mode
    mov     [di+DPT.wLchsCylinders], ax
    mov     [di+DPT.wLchsHeadsAndSectors], bx

    ; Store P-CHS to DPT
    call    AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI
    mov     [di+DPT.bPchsHeads], bl
%ifdef MODULE_EBIOS
    mov     [di+DPT.wPchsCylinders], ax
    mov     [di+DPT.bPchsSectorsPerTrack], bh
    ; Fall to .StoreNumberOfLbaSectors

;--------------------------------------------------------------------
; .StoreNumberOfLbaSectors
;   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
;--------------------------------------------------------------------
    ; Check if LBA supported
    test    BYTE [es:si+ATA1.wCaps+1], A1_wCaps_LBA>>8
    jz      SHORT .NoLbaSupportedSoNoEBIOS

    ; Store LBA 28/48 total sector count
    call    AtaGeometry_GetLbaSectorCountToBXDXAXfromAtaInfoInESSI
    call    StoreLba48AddressingFromCLandTotalSectorCountFromBXDXAX

    ; Load user defined LBA
    call    AccessDPT_GetPointerToDRVPARAMStoCSBX
    test    BYTE [cs:bx+DRVPARAMS.wFlags], FLG_DRVPARAMS_USERLBA
    jz      SHORT .KeepTotalSectorsFromAtaID
    mov     ax, [cs:bx+DRVPARAMS.dwMaximumLBA]
    mov     dx, [cs:bx+DRVPARAMS.dwMaximumLBA+2]
    xor     bx, bx

    ; Compare user defined and ATA-ID sector count and select smaller
    cmp     bx, [di+DPT.twLbaSectors+4]
    jb      SHORT .StoreUserDefinedSectorCountToDPT
    cmp     dx, [di+DPT.twLbaSectors+2]
    jb      SHORT .StoreUserDefinedSectorCountToDPT
    ja      SHORT .KeepTotalSectorsFromAtaID
    cmp     ax, [di+DPT.twLbaSectors]
    jae     SHORT .KeepTotalSectorsFromAtaID
.StoreUserDefinedSectorCountToDPT:
    xor     cx, cx      ; Always LBA28 for user defined values
    call    StoreLba48AddressingFromCLandTotalSectorCountFromBXDXAX

.KeepTotalSectorsFromAtaID:
.NoLbaSupportedSoNoEBIOS:
%endif ; MODULE_EBIOS
    ; 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

;----------------------------------------------------------------------
; Update drive counts (hard and floppy)
;----------------------------------------------------------------------

%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 of 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

    inc     BYTE [RAMVARS.bDrvCnt]      ; Increment drive count to RAMVARS

.AllDone:
    clc
    ret


%ifdef MODULE_EBIOS
;--------------------------------------------------------------------
; StoreLba48AddressingFromCLandTotalSectorCountFromBXDXAX
;   Parameters:
;       BX:DX:AX:   Total Sector Count
;       CL:         FLGL_DPT_LBA48 if LBA48 supported
;       DS:DI:      Ptr to Disk Parameter Table
;   Returns:
;       Nothing
;   Corrupts registers:
;       CL
;--------------------------------------------------------------------
StoreLba48AddressingFromCLandTotalSectorCountFromBXDXAX:
    or      cl, FLGL_DPT_LBA_AND_EBIOS_SUPPORTED
    and     BYTE [di+DPT.bFlagsLow], ~FLGL_DPT_LBA48
    or      [di+DPT.bFlagsLow], cl
    mov     [di+DPT.twLbaSectors], ax
    mov     [di+DPT.twLbaSectors+2], dx
    mov     [di+DPT.twLbaSectors+4], bx
    ret
%endif ; MODULE_EBIOS