source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Initialization/Initialize.asm

; Project name  :   XTIDE Universal BIOS
; Description   :   Functions for initializing the BIOS.

;
; 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

;--------------------------------------------------------------------
; Initializes the BIOS.
; This function is called from main BIOS ROM search routine.
;
; Initialize_FromMainBiosRomSearch
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
Initialize_FromMainBiosRomSearch:       ; unused entrypoint ok
    pushf                               ; To store IF
    sti                                 ; Enable interrupts for keystrokes
    push    ds
    push    ax                          ; We use AX to install very late init handler
    LOAD_BDA_SEGMENT_TO ds, ax

    test    BYTE [BDA.bKBFlgs1], (1<<2) ; Clears ZF if CTRL is held down
    jnz     SHORT .SkipRomInitialization

    ; Install INT 19h handler (boot loader) where drives are detected
    mov     WORD [BIOS_BOOT_LOADER_INTERRUPT_19h*4], Int19h_BootLoaderHandler
    mov     [BIOS_BOOT_LOADER_INTERRUPT_19h*4+2], cs

%ifdef MODULE_VERY_LATE_INIT
    push    es
    ; Install special INT 13h handler that initializes XTIDE Universal BIOS
    ; when our INT 19h is not called
    les     ax, [BIOS_DISK_INTERRUPT_13h*4] ; Load system INT 13h handler
    mov     WORD [BIOS_DISK_INTERRUPT_13h*4], Int13hBiosInit_Handler
    mov     [BIOS_DISK_INTERRUPT_13h*4+2], cs
    mov     [TEMPORARY_VECTOR_FOR_SYSTEM_INT13h*4], ax
    mov     [TEMPORARY_VECTOR_FOR_SYSTEM_INT13h*4+2], es
    pop     es
%endif

.SkipRomInitialization:
    pop     ax
    pop     ds
    popf
    retf


;--------------------------------------------------------------------
; Initializes the BIOS variables and detects IDE drives.
;
; Initialize_AndDetectDrives
;   Parameters:
;       ES:     BDA Segment
;   Returns:
;       DS:     RAMVARS segment
;   Corrupts registers:
;       All, except ES
;--------------------------------------------------------------------
Initialize_AndDetectDrives:
    call    DetectPrint_InitializeDisplayContext
    call    DetectPrint_RomFoundAtSegment
    call    RamVars_Initialize
    call    BootVars_Initialize
%ifdef MODULE_HOTKEYS
    ; This is a simple fix for the so called "No Fixed Disk Present in FDISK"-bug introduced in r551. MODULE_HOTKEYS includes the internal
    ; module MODULE_DRIVEXLATE which is needed if interrupt handlers are installed before drive detection. The reason for this is that
    ; Interrupts_InitializeInterruptVectors won't install our interrupt 13h handler if no drives were detected (unless MODULE_DRIVEXLATE is included).
    ; Since the drive detection hasn't been done yet, the handler will not be installed, causing the above mentioned bug.
    call    Interrupts_InitializeInterruptVectors   ; HotkeyBar requires INT 40h so install handlers before drive detection
    call    DetectDrives_FromAllIDEControllers
%else
    ; Without MODULE_HOTKEYS (or actually MODULE_DRIVEXLATE) we *must* use this call order.
    call    DetectDrives_FromAllIDEControllers
    call    Interrupts_InitializeInterruptVectors
%endif
    mov     [RAMVARS.wDrvDetectSignature], es       ; No longer in drive detection mode (set normal timeouts)
    ; Fall to .StoreDptPointersToIntVectors

;--------------------------------------------------------------------
; .StoreDptPointersToIntVectors
;   Parameters:
;       DS:     RAMVARS segment
;       ES:     BDA and interrupt vector segment (zero)
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX, SI, DI
;--------------------------------------------------------------------
%ifdef MODULE_COMPATIBLE_TABLES
.StoreDptPointersToIntVectors:
%ifndef USE_AT
    test    BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
    jz      SHORT .SkipToReturn             ; Only Full operating mode has extra RAM to spare
%endif

    mov     bx, HD0_DPT_POINTER_41h * 4
    mov     dl, 80h
.FindForNextDrive:
    call    FindDPT_ForDriveNumberInDL      ; DPT to DS:DI
    jc      SHORT .NextDrive                ; Store nothing if not our drive

    push    dx
    call    CompatibleDPT_CreateToAXSIforDriveDL
    pop     dx

    mov     [es:bx], si
    mov     [es:bx+2], ax

.NextDrive:
    inc     dx
    add     bx, (HD1_DPT_POINTER_46h - HD0_DPT_POINTER_41h) * 4
    cmp     dl, 82h
    jb      SHORT .FindForNextDrive

.SkipToReturn:
%endif ; MODULE_COMPATIBLE_TABLES
    ret