source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/AccessDPT.asm@ 546

; Project name  :   XTIDE Universal BIOS
; Description   :   Functions for accessing DPT data.

;
; 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

;--------------------------------------------------------------------
; AccessDPT_GetDriveSelectByteToAL
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       AL:     Drive Select Byte
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AccessDPT_GetDriveSelectByteToAL:
    mov     al, [di+DPT.bFlagsLow]
    and     al, FLGL_DPT_SLAVE | FLGL_DPT_LBA
    or      al, MASK_DRVNHEAD_SET   ; Bits set to 1 for old drives
    ret


;--------------------------------------------------------------------
; AccessDPT_GetDeviceControlByteToAL
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       AL:     Device Control Byte
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AccessDPT_GetDeviceControlByteToAL:
%ifdef MODULE_IRQ

%ifndef USE_UNDOC_INTEL
    xor     al, al
%endif

    test    BYTE [di+DPT.bFlagsLow], FLGL_DPT_ENABLE_IRQ    ; Clears CF

%ifdef USE_UNDOC_INTEL
    eSALC   ; Clears AL using CF while preserving flags
%endif

    jnz     SHORT .EnableDeviceIrq
    or      al, FLG_DEVCONTROL_nIEN ; Disable IRQ
.EnableDeviceIrq:
%else
    mov     al, FLG_DEVCONTROL_nIEN ; Disable IRQ
%endif ; MODULE_IRQ
    ret


;--------------------------------------------------------------------
; AccessDPT_GetLCHStoAXBLBH
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       AX:     Number of L-CHS cylinders
;       BL:     Number of L-CHS heads
;       BH:     Number of L-CHS sectors per track
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
AccessDPT_GetLCHStoAXBLBH:
    mov     ax, [di+DPT.wLchsCylinders]
    mov     bx, [di+DPT.wLchsHeadsAndSectors]
    ret


%ifdef MODULE_8BIT_IDE_ADVANCED
;--------------------------------------------------------------------
; AccessDPT_IsThisDeviceXTCF
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       AH:     Device Type
;       ZF:     Set if XTCF
;               Cleared if some other device
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
AccessDPT_IsThisDeviceXTCF:
    mov     ah, [di+DPT_ATA.bDevice]
    cmp     ah, DEVICE_8BIT_XTCF_PIO8
    je      SHORT .DeviceIsXTCF
    cmp     ah, DEVICE_8BIT_XTCF_PIO8_WITH_BIU_OFFLOAD
    je      SHORT .DeviceIsXTCF
    cmp     ah, DEVICE_8BIT_XTCF_DMA
.DeviceIsXTCF:
    ret
%endif ; MODULE_8BIT_IDE_ADVANCED


%ifdef MODULE_EBIOS
;--------------------------------------------------------------------
; AccessDPT_GetLbaSectorCountToBXDXAX
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       BX:DX:AX:   48-bit sector count
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
AccessDPT_GetLbaSectorCountToBXDXAX:
    mov     ax, [di+DPT.twLbaSectors]
    mov     dx, [di+DPT.twLbaSectors+2]
    mov     bx, [di+DPT.twLbaSectors+4]
    ret
%endif ; MODULE_EBIOS


;--------------------------------------------------------------------
; Returns pointer to DRVPARAMS for master or slave drive.
;
; AccessDPT_GetPointerToDRVPARAMStoCSBX
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       CS:BX:  Ptr to DRVPARAMS
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
AccessDPT_GetPointerToDRVPARAMStoCSBX:
    call    AccessDPT_GetIdevarsToCSBX
    add     bx, BYTE IDEVARS.drvParamsMaster    ; CS:BX points to Master Drive DRVPARAMS
    test    BYTE [di+DPT.bFlagsLow], FLGL_DPT_SLAVE
    jz      SHORT .ReturnPointerToDRVPARAMS
    add     bx, BYTE DRVPARAMS_size             ; CS:BX points to Slave Drive DRVPARAMS
.ReturnPointerToDRVPARAMS:
    ret


;--------------------------------------------------------------------
; Needed many times during initialization so it is better to
; make it as a function to save bytes.
;
; AccessDPT_GetIdevarsToCSBX
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       CS:BX:  Ptr to IDEVARS for the drive
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
AccessDPT_GetIdevarsToCSBX:
    eMOVZX  bx, BYTE [di+DPT.bIdevarsOffset]
    ret


;--------------------------------------------------------------------
; ACCESSDPT__GET_UNSHIFTED_TRANSLATE_MODE_TO_AXZF
;   Parameters:
;       DS:DI:  Ptr to Disk Parameter Table
;   Returns:
;       AX:     Translate Mode (TRANSLATEMODE_NORMAL, TRANSLATEMODE_LARGE or TRANSLATEMODE_ASSISTED_LBA)
;               unshifted (still shifted where it is in bFlagsLow)
;       ZF:     Set based on value in AL
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
;
; Converted to a macro since only called in two places, and the call/ret overhead
; is not worth it for these two instructions (4 bytes total)
;
%macro ACCESSDPT__GET_UNSHIFTED_TRANSLATE_MODE_TO_AXZF 0
    mov     al, [di+DPT.bFlagsLow]
    and     ax, BYTE MASKL_DPT_TRANSLATEMODE
%endmacro