source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/EBIOS/AH41h_CheckIfExtensionsPresent.asm@ 545

; Project name  :   XTIDE Universal BIOS
; Description   :   Int 13h function AH=41h, Check if Extensions Present.

;
; 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

;--------------------------------------------------------------------
; Int 13h function AH=41h, Check if Extensions Present.
;
; AH41h_HandlerForCheckIfExtensionsPresent
;   Parameters:
;       DL:     Translated Drive number
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to IDEPACK
;   Parameters on INTPACK:
;       BX:     55AAh
;   Returns with INTPACK:
;       AH:     Major version of EBIOS extensions
;       BX:     AA55h
;       CX:     Support bits
;       CF:     0 if successful, 1 if error
;--------------------------------------------------------------------
AH41h_HandlerForCheckIfExtensionsPresent:
    cmp     WORD [bp+IDEPACK.intpack+INTPACK.bx], 55AAh
    jne     SHORT .EbiosNotSupported

    mov     BYTE [bp+IDEPACK.intpack+INTPACK.ah], EBIOS_VERSION
    mov     WORD [bp+IDEPACK.intpack+INTPACK.bx], 0AA55h

%ifdef CREATE_COMPATIBLE_DPT
    call    AH41h_GetSupportBitsToCX
    mov     [bp+IDEPACK.intpack+INTPACK.cx], cx
%else
    mov     WORD [bp+IDEPACK.intpack+INTPACK.cx], ENHANCED_DRIVE_ACCESS_SUPPORT
%endif

    and     BYTE [bp+IDEPACK.intpack+INTPACK.flags], ~FLG_FLAGS_CF  ; Return with CF cleared
    jmp     Int13h_ReturnFromHandlerWithoutStoringErrorCode
.EbiosNotSupported:
    jmp     Int13h_DirectCallToAnotherBios


%ifdef CREATE_COMPATIBLE_DPT
;--------------------------------------------------------------------
; AH41h_GetSupportBitsToCX
;   Parameters:
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;   Returns:
;       CX:     Support bits returned by AH=41h
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
AH41h_GetSupportBitsToCX:
    mov     cx, ENHANCED_DRIVE_ACCESS_SUPPORT

    ; DPTE needs buffer from RAM so do not return it in lite mode
%ifndef USE_AT
    test    BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
    jz      SHORT .DoNotSetEDDflag
%endif

%ifdef MODULE_8BIT_IDE OR MODULE_SERIAL
    ; DPTE contains information for device drivers. We should not return
    ; DPTE for 8-bit devices since software would think they are 16-bit devices.
    cmp     BYTE [di+DPT_ATA.bDevice], DEVICE_8BIT_ATA
    jae     SHORT .DoNotSetEDDflag
%endif

    or      cl, ENHANCED_DISK_DRIVE_SUPPORT ; AH=48h returns DPTE
.DoNotSetEDDflag:
    ret

%endif ; CREATE_COMPATIBLE_DPT