source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/BootVars.asm@ 557

; Project name  :   XTIDE Universal BIOS
; Description   :   Functions for accessings BOOTVARS.

;
; 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

;--------------------------------------------------------------------
; BootVars_Initialize
;   Parameters:
;       DS:     RAMVARS Segment
;       ES:     BDA Segment
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, CX, DX, DI
;--------------------------------------------------------------------
BootVars_Initialize:
    ; Clear all DRVDETECTINFO structs to zero
    mov     al, DRVDETECTINFO_size
    mul     BYTE [cs:ROMVARS.bIdeCnt]
    mov     di, BOOTVARS.rgDrvDetectInfo    ; We must not initialize anything before this!
    xchg    cx, ax
%ifndef MODULE_HOTKEYS
    jmp     Memory_ZeroESDIwithSizeInCX

%else ; if MODULE_HOTKEYS
    call    Memory_ZeroESDIwithSizeInCX

    ; Initialize HOTKEYVARS by storing default drives to boot from
    call    BootVars_StoreDefaultDriveLettersToHotkeyVars
    mov     dl, [cs:ROMVARS.bBootDrv]
    jmp     HotkeyBar_StoreHotkeyToBootvarsForDriveNumberInDL


;--------------------------------------------------------------------
; BootVars_StoreDefaultDriveLettersToHotkeyVars
;   Parameters:
;       ES:     BDA Segment
;   Returns:
;       Nothing
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
BootVars_StoreDefaultDriveLettersToHotkeyVars:
    call    BootVars_GetLetterForFirstHardDriveToAX
    mov     ah, DEFAULT_FLOPPY_DRIVE_LETTER
    xchg    al, ah
    mov     [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wFddAndHddLetters], ax
    ret

%endif ; MODULE_HOTKEYS


;--------------------------------------------------------------------
; Returns letter for first hard disk. Usually it will be 'C' but it
; can be higher if more than two floppy drives are found.
;
; BootVars_GetLetterForFirstHardDriveToAX
;   Parameters:
;       DS:     RAMVARS segment
;   Returns:
;       AX:     Upper case letter for first hard disk
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
BootVars_GetLetterForFirstHardDriveToAX:
    call    FloppyDrive_GetCountToAX
    add     al, DEFAULT_FLOPPY_DRIVE_LETTER     ; First Hard Drive letter comes after last floppy drive letter...
    MAX_U   al, DEFAULT_HARD_DRIVE_LETTER       ; ...but it can never be 'A' or 'B'
    ret