source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Inc/BootVars.inc

; Project name  :   XTIDE Universal BIOS
; Description   :   Defines for BOOTVARS struct used by boot menu
;                   and drive initialization.

;
; 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
;

%ifndef BOOTVARS_INC
%define BOOTVARS_INC


; Temporary locations for system interrupt handlers. Stored during ROM initialization
; and needed when we do full initialization and drive detection on INT 19h
TEMPORARY_VECTOR_FOR_SYSTEM_INT13h      EQU     32h ; Unused by BIOS (reserved for DOS)
TEMPORARY_VECTOR_FOR_SYSTEM_INT19h      EQU     33h ; Unused by BIOS (reserved for DOS)


; Default drives
DEFAULT_FLOPPY_DRIVE_LETTER             EQU 'A'
DEFAULT_HARD_DRIVE_LETTER               EQU 'C'

; Number of times to retry booting before accepting error
BOOT_READ_RETRY_TIMES       EQU     3


%ifdef MODULE_HOTKEYS

struc HOTKEYVARS
    .fpPrevTimerHandler resb    4       ; Previous 08h timer handler
    .wTimeWhenDisplayed resb    2       ; System time (ticks) when Hotkey bar was first displayed
    .wFddAndHddLetters:
    .bFddLetter         resb    1       ; Floppy Drive letter hotkey (upper case)
    .wHddLetterAndFlags:
    .bHddLetter         resb    1       ; Hard Drive letter hotkey (upper case). Must be after .bFddLetter!
    .bFlags             resb    1       ; Must be just after .bHddLetter!  (dependency in Hotkeybar.asm)
    .bScancode          resb    1       ; Function hotkey scancode, must be just after .bFlags!
endstruc

%ifndef CHECK_FOR_UNUSED_ENTRYPOINTS
%if HOTKEYVARS.bFddLetter+1 != HOTKEYVARS.bHddLetter || HOTKEYVARS.bHddLetter+1 != HOTKEYVARS.bFlags || HOTKEYVARS.bFlags+1 != HOTKEYVARS.bScancode
%error "HOTKEYVARS: bytes need to come in the order .bFddLetter, then .bHddLetter, then .bFlags, then .bScancode"
%endif
%endif

; Bit defines for HOTKEYVARS.bFlags
FLG_HOTKEY_HD_FIRST         EQU     (1<<0)  ; First try to boot from HDD, then FDD

%endif ; MODULE_HOTKEYS


; Pre-boot variables. These do not exist after successful boot to OS.
; Segment is always 0000h, same as BDA segment
struc BOOTVARS
                        resb    7C00h
    .rgbAtaInfo:                        ; 7C00h, ATA Information for drive detection
    .rgbBootSect        resb    512     ; 7C00h, Boot sector
                        resb    256     ; Boot Menu stack
    .rgbMnuStack:
    .dwPostStack        resb    4       ; POST stack pointer when entering INT 19h
%ifdef MODULE_HOTKEYS
    .hotkeyVars         resb    HOTKEYVARS_size ; Must be located just before DRVDETECTINFO structs
%endif
    .rgDrvDetectInfo:                   ; Array containing DRVDETECTINFO structs
endstruc


; MAX_HARD_DISK_NAME_LENGTH must be defined ahead of the DRVDETECTINFO structure to avoid problems with NASM
MAX_HARD_DISK_NAME_LENGTH   EQU     30  ; Bytes reserved for drive name

struc DRVDETECTINFO
    .StartOfDrvDetectInfo:
    .szDrvName              resb    MAX_HARD_DISK_NAME_LENGTH
                            resb    2   ; Zero word (ensures string terminates)
    .wInitErrorFlags        resb    2   ; Errors during initialization

    ; DRVDETECTINFO's size must be an even multiple of DPT's size
    .EndOfDriveDetectInfo:  resb    LARGEST_DPT_SIZE - (.EndOfDriveDetectInfo % LARGEST_DPT_SIZE)
endstruc

DPT_DRVDETECTINFO_SIZE_MULTIPLIER   EQU     DRVDETECTINFO_size / LARGEST_DPT_SIZE

%ifndef CHECK_FOR_UNUSED_ENTRYPOINTS
%if MAX_HARD_DISK_NAME_LENGTH % 2 <> 0
    %error "MAX_HARD_DISK_NAME_LENGTH needs to be a multiple of 2, memory is moved with word operations."
%endif
%endif


;--------------------------------------------------------------------
; Stores POST stack pointer to BOOTVARS.
;
; STORE_POST_STACK_POINTER
;   Parameters:
;       ES:     BDA and Interrupt Vector segment (zero)
;   Returns:
;       Nothing
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%macro STORE_POST_STACK_POINTER 0
    mov     [es:BOOTVARS.dwPostStack], sp
    mov     [es:BOOTVARS.dwPostStack+2], ss
%endmacro


;--------------------------------------------------------------------
; Initializes stack for boot menu usage.
; POST stack is not large enough when DPTs are stored to 30:0h.
;
; Note regarding LOAD_BDA_SEGMENT_TO: If you force the use of SP
; then you also have to unconditionally enable the CLI/STI pair.
; The reason for this is that only some buggy 808x CPU:s need the
; CLI/STI instruction pair when changing stacks. Other CPU:s disable
; interrupts automatically when SS is modified for the duration of
; the immediately following instruction to give time to change SP.
;
; SWITCH_TO_BOOT_MENU_STACK
;   Parameters:
;       Nothing
;   Returns:
;       SS:SP:  Pointer to top of Boot Menu stack
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%macro SWITCH_TO_BOOT_MENU_STACK 0
%ifndef USE_186
    cli                                 ; Disable interrupts
%endif
    LOAD_BDA_SEGMENT_TO ss, sp
    mov     sp, BOOTVARS.rgbMnuStack    ; Load offset to stack
%ifndef USE_186
    sti                                 ; Enable interrupts
%endif
%endmacro


;--------------------------------------------------------------------
; Restores SS and SP to initial boot loader values.
;
; Note! Must return with AX=0 and CF preserved.
; See Int19hMenu_JumpToBootSector_or_RomBoot.
;
; SWITCH_BACK_TO_POST_STACK
;   Parameters:
;       AX:     BDA and Interrupt Vector segment (zero)
;   Returns:
;       SS:SP:  Ptr to POST stack
;   Corrupts registers:
;       Nothing (not even FLAGS)
;--------------------------------------------------------------------
%macro SWITCH_BACK_TO_POST_STACK 0
%ifndef USE_386
    cli
    mov     ss, ax
    mov     sp, [ss:BOOTVARS.dwPostStack]
    mov     ss, [ss:BOOTVARS.dwPostStack+2]
    sti
%else
    mov     ss, ax
    lss     sp, [ss:BOOTVARS.dwPostStack]
%endif
%endmacro


%endif ; BOOTVARS_INC