source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm@ 590

; 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, 2011-2013 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
;       DX:     Autodetected port (for devices that support autodetection)
;       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
;       CF:     Cleared
;   Corrupts registers:
;       AX, BX, CX, DX
;--------------------------------------------------------------------
CreateDPT_FromAtaInformation:
    call    FindDPT_ForNewDriveToDSDI
    ; Fall to .InitializeDPT

;--------------------------------------------------------------------
; .InitializeDPT
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       DX:     Autodetected port (for devices that support autodetection)
;       DS:DI:  Ptr to Disk Parameter Table
;       CS:BP:  Ptr to IDEVARS for the controller
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
.InitializeDPT:
    call    CreateDPT_StoreIdevarsOffsetAndBasePortFromCSBPtoDPTinDSDI
    ; 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:
    ; Apply any user limited values to ATA ID
    call    AtaID_ModifyESSIforUserDefinedLimitsAndReturnTranslateModeInDX

    ; Translate P-CHS to L-CHS
    call    AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIwithTranslateModeInDX
    mov     [di+DPT.wLchsCylinders], ax
    mov     [di+DPT.wLchsHeadsAndSectors], bx
    mov     al, dl
    eSHL_IM al, TRANSLATEMODE_FIELD_POSITION
    or      cl, al

    ; Store P-CHS and flags
    call    AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI
    dec     dl                      ; Set ZF if TRANSLATEMODE_LARGE, SF if TRANSLATEMODE_NORMAL
    jle     SHORT .JumpOverSetBitForAssistedLBA

    ; Set LBA bit for Assisted LBA
    or      cl, FLGL_DPT_LBA
.JumpOverSetBitForAssistedLBA:
    jnz     SHORT .NothingToChange

    ; We cannot have 16 P-Heads heads in Revised ECHS mode (8193 or more cylinders)
    ; but 16 heads are allowed when there are 8192 or less cylinders (ECHS).
    ; Both of these are LARGE modes so do not confuse with NORMAL mode.
    call    AtaGeometry_IsDriveSmallEnoughForECHS
    adc     bx, -1                  ; Adjust 16 P-Heads to 15 if needed

.NothingToChange:
    or      [di+DPT.bFlagsLow], cl  ; Shift count and addressing mode
    mov     [di+DPT.wPchsHeadsAndSectors], bx
%ifdef MODULE_COMPATIBLE_TABLES OR MODULE_EBIOS
    ; Store P-Cylinders here for Compatible DPTs when FLGL_DPT_LBA is not set
    ; or when drive has over 15,482,880 sectors
    mov     [di+DPT.wPchsCylinders], ax
%endif

%ifdef MODULE_EBIOS
    test    cl, FLGL_DPT_LBA
    jz      SHORT .NoLbaSoNoEBIOS

    ; Store P-Cylinders but only if we have 15,482,880 or less sectors since
    ; we only need P-Cylinders so we can return it from AH=48h
    call    AtaGeometry_GetLbaSectorCountToBXDXAXfromAtaInfoInESSI
    sub     ax, (MAX_SECTOR_COUNT_TO_RETURN_PCHS+1) & 0FFFFh
    sbb     dx, (MAX_SECTOR_COUNT_TO_RETURN_PCHS+1) >> 16
    sbb     bx, BYTE 0
    jnc     SHORT .StoreNumberOfLbaSectors

    ; Since we might have altered the default P-CHS parameters to be
    ; presented to the drive (AH=09h), we need to calculate new
    ; P-Cylinders. It could be read from the ATA ID after
    ; COMMAND_INITIALIZE_DEVICE_PARAMETERS but that is too much trouble.
    ; P-Cyls = MIN(16383*16*63, LBA sector count) / (P-Heads * P-Sectors per track)
    call    AtaGeometry_GetLbaSectorCountToBXDXAXfromAtaInfoInESSI
    xchg    cx, ax                          ; Sector count to DX:CX
    mov     al, [di+DPT.bPchsHeads]
    mul     BYTE [di+DPT.bPchsSectorsPerTrack]
    xchg    cx, ax
    div     cx                              ; AX = new P-Cylinders

    ; We could remove wPchsCylinders from DPT if we calculate it on AH=48h
    ; (and for compatible DPTs) but that would require extra code so we save ROM space instead.
    mov     [di+DPT.wPchsCylinders], ax

    ; Store CHS sector count as total sector count. We must not use
    ; LBA sector count if it is 15,482,880 or less.
    mul     cx
    xor     bx, bx
    jmp     SHORT .StoreTotalSectorsFromBXDXAX


;--------------------------------------------------------------------
; .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
;--------------------------------------------------------------------
.StoreNumberOfLbaSectors:
    ; Store LBA 28/48 total sector count
    call    AtaGeometry_GetLbaSectorCountToBXDXAXfromAtaInfoInESSI
    or      [di+DPT.bFlagsLow], cl      ; LBA48 flag
.StoreTotalSectorsFromBXDXAX:
    mov     [di+DPT.twLbaSectors], ax
    mov     [di+DPT.twLbaSectors+2], dx
    mov     [di+DPT.twLbaSectors+4], bx
.NoLbaSoNoEBIOS:
%endif ; MODULE_EBIOS
    ; 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
; Device_FinalizeDPT returns with CF set only when a floppy was found which can't happen without MODULE_SERIAL
%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 ; ~MODULE_SERIAL_FLOPPY
;
; 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 ; MODULE_SERIAL_FLOPPY
%endif ; MODULE_SERIAL

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

%ifdef MODULE_SERIAL
.AllDone:
    clc
%endif

    ret


;--------------------------------------------------------------------
; CreateDPT_StoreIdevarsOffsetAndBasePortFromCSBPtoDPTinDSDI
;   Parameters:
;       DX:     Autodetected port (for devices that support autodetection)
;       DS:DI:  Ptr to Disk Parameter Table
;       CS:BP:  Ptr to IDEVARS for the controller
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
CreateDPT_StoreIdevarsOffsetAndBasePortFromCSBPtoDPTinDSDI:
    mov     [di+DPT.bIdevarsOffset], bp     ; IDEVARS must start in first 256 bytes of ROM
    mov     ax, [cs:bp+IDEVARS.wBasePort]
    mov     [di+DPT.wBasePort], ax
    ret