Windows 95 Secrets (4th Edition)/Windows95Secrets4thEdition.iso/utility/configur/cmossave/cmos.asm

Assembly Source File | 1995-05-11 | 17.3 KB | 779 lines

    PAGE    60,132
NAME    CMOSSAVE
    TITLE    CMOSSave Save CMOS to a file on disk or floppy
Comment |
    Version 2.2 1995 April 14 Roedy Green
    works with MASM 6.0 and Optasm
    This assembler code generates all three programs:
    CMOSSAVE.COM CMOSREST.COM and CMOSCHK.COM.

See CMOS.TXT for details on use.

  USAGE:

Examples:
*********

CMOSSave A:\MyCMOS.Sav

CMOSRest A:\MyCMOS.Sav

CMOSChk  A:\ByCMOS.Sav

Syntax errors or missing file trouble generates an ERRORLEVEL 4.
CMOSChk generates an ERRORLEVEL 1 if the CMOS has changed since
the CMOSSave was done.

Version History
***************

Version 1.0
- released to BIX 91/09/07

Version 1.1
- released to BIX 91/09/18
- added special check for small 64 character CMOSes.

Version 1.2
- fix spelling errors
- use CMOS.SAV instead of MyCMOS.SAV in examples

Version 1.3
- now consider fewer bytes volatile, restore more stuff.
- hints in docs about clearing CMOS.

Version 1.4
- now consider flags Status register C, offset 0C as volatile.
  fixes false alarms.

Version 1.5 1994 June 1
- change of address and phone number
- address now appears in the banner.

Version 1.6 1994 August 29
- more information about how CMOS bits are used.

Version 2.0 1994 October 1
- easier configuration of CHKCMOS volatile bytes.
- smarter bat files.
- docs on different ways to use.

Version 2.2 1995 April 16
- docs on use before experimentation

CMOS Usage - see also CMOS.OFS

How to Assemble
***************

Manually set the GENERATING equate embedded in this code, then:

to assemble with MASM 6.0 use:
ML.EXE /AT /c /Fl /VM /Zf /Zm CMOS.Asm
LINK.EXE /TINY /MAP CMOS.Obj,CMOS.com,CMOS.map;
copy cmos.com cmossave.com

to assemble with OPTASM use:
Optasm     CMOS.Asm,CMOS.Obj,CMOS.Lst/L/N/G/S
OLINK     CMOS.Obj,CMOS.COM,/MAP/TINY;
copy cmos.com cmossave.com

Register Conventions
********************

Subroutines may trash all registers except those explicity
documented as input or output.

| ; end of comment


;    E Q U A T E S

CMOSSAVE    EQU    1
CMOSREST    EQU    2
CMOSCHK     EQU    3

; use /DGenerating#CMOSSAVE
;     /DGenerating#CMOSREST
;     /DGenerating#CMOSCHK
; on the assembler command line to select which version
; of the code to assemble.
;    Or add code following of the form:

; GENERATING EQU CMOSSave


    If    Generating eq CMOSSave
%OUT Generating CMOSSave.Com
    Endif

    If    Generating eq CMOSRest
%OUT Generating CMOSRest.Com
    endif

    If    Generating eq CMOSChk
%OUT Generating CMOSChk.Com
    endif
;==============================================================


stack    segment stack        ; keep MS link happy by providing null stack
stack    ends

CODE    SEGMENT PARA        ; start off in code.

;==============================================================

data    segment byte        ; provide a separate DATA segment
                ; actually all come after the code
;==============================================================
;  V A R I A B L E S


    If    Generating eq CMOSSave

BannerMsg    DB '░▒▓█ CMOSSave 2.2 █▓▒░',13d,10d
        DB 13d,10d
        DB 'Saves contents of CMOS to a file on hard disk or floppy.',13,10
        DB 'Copyright (c) 1991,1995 Roedy Green Canadian Mind Products [phone].',13,10
        DB '#601 - 1330 Burrard, Vancouver BC CANADA  V6Z 2B8',13,10
        DB 'Shareware to freely distribute and use for any purpose except military.',13,10
        DB 13,10
        db '$'

UsageMsg    DB '░▒▓█ Error █▓▒░',7,13,10
        DB 'Insert a formatted diskette.',13,10
        DB 'then try:',13,10
        DB 'CMOSSave A:\CMOS.Sav',13,10
        DB 'or if want to save on hard disk try:',13,10
        DB 'CMOSSave C:\CMOS.Sav',13,10
        DB 'Read CMOS.TXT to find how to use it properly.',13,10
        db '$'

FileTroubleMsg    DB '░▒▓█ Error █▓▒░',7,13,10
        DB 'Cannot create the disk file.',13,10
        db '$'

WorkedMsg    DB 'CMOS successfully saved',13,10
        db '$'

    EndIf


    If    Generating eq CMOSRest
BannerMsg    DB '░▒▓█ CMOSRest 2.2 █▓▒░',13d,10d
        DB 13d,10d
        DB 'Restores CMOS from a CMOSSave file on hard disk or floppy.',13,10
        DB 'Copyright (c) 1991,1995 Roedy Green Canadian Mind Products [phone].',13,10
        DB '#601 - 1330 Burrard, Vancouver BC CANADA  V6Z 2B8',13,10
        DB 'Shareware to freely distribute and use for any purpose except military.',13,10
        DB 13,10
        db '$'

UsageMsg    DB '░▒▓█ Error █▓▒░',13,10
        DB 'Insert the diskette you used for CMOSSave.',13,10
        DB 'then try:',13,10
        DB 'CMOSRest A:\CMOS.Sav',13,10
        DB 'or if the file is on hard disk try:',13,10
        DB 'CMOSRest C:\CMOS.Sav',13,10
        DB 'Read CMOS.TXT to find how to use it properly.',13,10
        db '$'

FileTroubleMsg    DB '░▒▓█ Error █▓▒░',7,13,10
        DB 'Cannot find/read the disk file.',13,10
        db '$'

WorkedMsg    DB 'CMOS successfully restored',13,10
        db '$'

    EndIf

    If    Generating eq CMOSChk
BannerMsg    DB '░▒▓█ CMOSChk 2.2 █▓▒░',13d,10d
        DB 13d,10d
        DB 'Ensures CMOS not corrupted or changed.',13,10
        DB 'Copyright (c) 1991,1995 Roedy Green Canadian Mind Products [phone].',13,10
        DB '#601 - 1330 Burrard, Vancouver BC CANADA  V6Z 2B8',13,10
        DB 'Shareware to freely distribute and use for any purpose except military.',13,10
        DB 13,10
        db '$'

UsageMsg    DB '░▒▓█ Error █▓▒░',7,13,10
        DB 'Insert the diskette you used for CMOSSave.',13,10
        DB 'then try:',13,10
        DB 'CMOSChk A:\CMOS.Sav',13,10
        DB 'or if you have the file on hard disk try:',13,10
        DB 'CMOSChk C:\CMOS.Sav',13,10
        DB 'Read CMOS.TXT to find how to use it properly.',13,10
        db '$'

FileTroubleMsg    DB '░▒▓█ Error █▓▒░',7,13,10
        DB 'Cannot find/read the disk file.',13,10
        db '$'

MatchTroubleMsg DB '░▒▓█ Error █▓▒░',7,13,10
        DB 'CMOS has been corrupted! at hex offset:value:expected ',13,10
        db '$'

ColonMsg    db ':','$'

NextTripleMsg    db 13,10,'$'


WorkedMsg    DB 'CMOS is OK, i.e. unchanged since the last CMOSSave.',13,10
        db '$'

    EndIf


FilenamePtr    DW    0
            ; pointer to filename in command line

CMOSSize    DB    0
            ; size of cmos in bytes

CMOSBuff    db 0    ; dynamic buffer will grow to 128
            ; it hangs out past the end of the program

data        ends

com    group    code,data    ; force data segment to go at the end

    ASSUME    CS:com,DS:com,ES:com,SS:com
                ; seg regs cover everything
    ORG    100H        ; in Code segment

;==========================

Main    proc    far

;    M A I N L I N E   R O U T I N E
Start:
    lea    dx,BannerMsg    ; display the banner
    Call    Say
    Call    Parse        ; get filename from command line

    If    Generating eq CMOSSave
    call    GetCMOS     ; fetch CMOS to buffer
    call    WriteCMOS    ; write CMOS contents to file
    EndIf

    If    Generating eq CMOSRest
    call    ReadCMOS    ; read CMOS contents from file
    call    CalcCMOSSize    ; it is 64 or 128 bytes long?
    call    PutCMOS     ; store buffer to CMOS
    EndIf

    If    Generating eq CMOSChk
    call    ReadCMOS    ; read CMOS contents from file
    call    CalcCMOSSize    ; it is 64 or 128 bytes long?
    call    CompareCMOS    ; compare CMOS with buffer
    EndIf

    lea    dx,WorkedMsg    ; crow about success
    Call    Say
Done:
    mov    ax,4c00h
    int    21h        ;normal termination

Main    EndP

;===============================================================

Trouble proc    near

FileTrouble:
    Lea    dx,FileTroubleMsg    ; display file trouble
    Call    Say
    Jmp    Abort

abort:
                ; error exit
    mov    ax, 4c04h    ; ERRORLEVEL = 4
    int    21h        ; DIE

Trouble endp

;===============================================================

MLeading    PROC    Near

;    Remove leading blanks
;    on entry BX is addr of string, CX its length
;    trims off any leading blanks, leaving result in BX CX
;    length may also be 0 or 1, but not -ve
;    If the entire string is blank the result is the null string
    mov    di,bx
    mov    al,20H        ; AL = blank  -- the search char
    jcxz    mleading2    ; jump if null string
    repe    scasb        ; scan ES:DI forwards till hit non blank
                ; DI points just after it (wrap ok)
                ; cx IS ONE TOO SMALL, OR 0 IF NONE FOUND
    je    mleading1    ; jump if entire string was blank
    inc    cx        ; CX is length of remainder of string
mleading1:
    dec    di        ; DI points to non-blank
mleading2:
    mov    bx,di        ; put address back
    ret

MLeading    ENDP

;========================================

MTrailing    PROC    Near

;    Remove trailing blanks.
;    on entry BX is addr of string, CX its length
;    trims off any trailing blanks, leaving result in BX CX
;    length may also be 0 or 1, but not -ve
;    If the entire string is blank the result is the null string
    mov    di,bx
    add    di,cx        ; calc addr last char in string
    dec    di
    mov    al,20H        ; AL = blank  -- the search char
    jcxz    mtrailing1    ; jump if null string
    std
    repe    scasb        ; scan ES:DI backwards till hit non blank
                ; DI points just ahead of it (wrap ok)
                ; CX is one too small, or 0 if none found
    cld
    je    mtrailing1    ; jump if whole string was blank
    inc    cx
mtrailing1:
    ret

MTrailing    ENDP

;========================================

Parse        PROC    NEAR
;    Parse the command line to remove lead/trail blanks from
;    the single drive parameter and terminate it by 2 nulls.
;    sample inputs
;    CMOSRest A:\CMOS.SAV
;    CMOSRest    B:\MySub\MyCMOS.SAV
;
;    When Done DS:BX points to start of string.
;    String will be terminated by 2 nulls
;    CX counts bytes in string exclusive of nulls
                ; counted string at HEX 80 PSP
                ; contains command line.
                ; Preceeded by unwanted spaces.
                ; possibly followed by unwanted spaces.
                ; currently missing a trailing null.
    xor    ch,ch
    mov    cl,ds:80H
    mov    bx,81H
    call    Mleading    ; get rid of leading blanks
    call    MTrailing    ; get rid of trailing blanks
    mov    di,bx        ; calc addr of byte just past end
    add    di,cx
    mov    word ptr [di],0 ; plop in pair of nulls after string
    mov    FileNamePtr,bx    ; remember where filename was
    jcxz    SyntaxTrouble    ; missing parm.
    ret

SyntaxTrouble:
    lea    dx,UsageMsg        ; display usage message
    Call    Say
    Jmp    Abort

Parse        ENDP

;======================================

Say    Proc

;    on entry DX points to a string to display
    push    ax
    MOV    AH,9
    Int    21h
    pop    ax
    ret

Say    EndP

;======================================

    If    Generating eq CMOSSave

GetCMOS Proc    Near

;    Get 128 byte contents of CMOS into a buffer.

    mov    cx,128        ; count of times through loop
    lea    bx,CMOSBuff    ; where to put the contents
    sub    al,al        ; start offset in CMOS
GetLoop:
    Call    PeekCmos    ; al=offset ah=contents
    mov    byte ptr[bx],ah
    inc    al
    inc    bx
    loop    GetLoop
    ret

GetCMOS EndP

    EndIf

;===============================================================

    If    Generating eq CMOSRest

PutCMOS Proc    Near

;    Put 128-byte contents of buffer into CMOS.
;    do not touch the volatile bytes

    mov    cx,128        ; count of times through loop
    lea    bx,CMOSBuff    ; where to put the contents
    sub    al,al        ; start offset in CMOS
PutLoop:
    call    Volatile    ; test if this is a volatile byte
                ; test offset in al
    jc    LeaveItAlone
    mov    ah,byte ptr[bx]
    Call    PokeCMOS    ; al=offset ah=contents

LeaveItAlone:
    inc    bx
    inc    al
    loop    PutLoop
    ret

PutCMOS EndP

    EndIf

;===============================================================

    If    Generating eq CMOSChk

hexPAD    DB    '00$'    ; where numeric output built by SayHexByte

SayHexByte    proc    Near
    ;    al contains hex byte to display:

    push    ax        ; preserve regs
    push    bx
    push    cx
    push    dx
    mov    dl,al        ; save input
;    Do first (leftmost digit)
    mov    cl,4
    shr    al,cl
    and    al,0fh        ; get first digit
    cmp    al,9
    jg    HexChar1
    add    al,'0'        ; convert digit to ASCII
    jmp    StoreChar1
HexChar1:
    add    al,'A'-0AH    ; convert to uppercase A..H
StoreChar1:
    mov    hexPad,al

;    Do second (rightmost digit)
    mov    al,dl
    and    al,0fh        ; get last digit
    cmp    al,9
    jg    HexChar2
    add    al,'0'        ; convert digit to ASCII
    jmp    StoreChar2
HexChar2:
    add    al,'A'-0AH    ; convert to uppercase A..H
StoreChar2:
    mov    hexPad+1,al

;    Number is ready
    lea    dx,Hexpad
    mov    AH,09h        ; BIOS put string terminated by $
    int    21h
    pop    dx
    pop    cx
    pop    bx
    pop    ax
    ret

SayHexByte    ENDP

    EndIf

;===============================================================

    If    Generating eq CMOSChk
CompareCMOS    proc    Near

;    compares buffer version of CMOS with contents of actual CMOS
;    ignores mismatches of volatile bytes.
;    Aborts if finds a mismatch

    mov    cx,128        ; count of times through loop
    lea    bx,CMOSBuff    ; where to find comparison set
    sub    al,al        ; start offset in CMOS
    push    si
    sub    si,si        ; count of mismatches
CompLoop:
    call    Volatile    ; test if this is a volatile byte
                ; test offset in al
    jc    MatchedOk
    Call    PeekCMOS    ; al=offset ah=contents
    cmp    ah,byte ptr[bx] ; compare CMOS with buffer
    je    MatchedOk

;    Mismatch
    test    si,si            ; only complain on first mismatch
    jnz    AlreadyComplained
    lea    dx,MatchTroubleMsg    ; display CMOS mismatch
    call    Say
AlreadyComplained:
    push    ax
    inc    si        ; count of how many mismatches found
    Call    SayHexByte    ; report offset
    lea    dx,ColonMsg
    call    Say
    mov    al,ah        ; report bad value in CMOS
    Call    SayHexByte
    lea    dx,ColonMsg
    call    Say
    mov    al,byte ptr[bx] ; report what value should be from file.
    call    SayHexByte
    lea    dx,NextTripleMsg
    call    Say
    pop    ax

MatchedOk:
    inc    bx
    inc    al
    loop    CompLoop

    test    si,si
    jz    NoMismatches

    mov    ax, 4c01h        ; ERRORLEVEL = 1
    int    21h            ; DIE

NoMisMatches:
    pop    si
    ret

CompareCMOS    EndP

    EndIf

;===============================================================

    If    Generating ne CMOSSave

;    Add to this list if you need more volatile bytes.
;    Remember the trailing h.

VolatileList    db    0ch,032h

VolatileCount    equ    $-VolatileList


Volatile    Proc    near

;    Is cmos offset in AL volatile?    If so set carry.
;    These bytes will be undisturbed.
;    Preserves all registers.
;    00..09, 0C and 32 are volatile, rest are not.
;    0A 0B 0D 0E 0F used to be considered volatile, now are not.
;    if cmos is small, all bytes past end are considered volatile

    cmp    al,CMOSSize        ; bytes past end are volatile
    jae    IsVolatile
    cmp    al,09h
    jbe    IsVolatile        ; early bytes are for timing
    push    cx
    push    di
    mov    cx,VolatileCount
    lea    di,VolatileList
    repne    scasb            ; search till find a match
    pop    di
    pop    cx
    je    IsVolatile

IsNotVolatile:
    clc                ; clear carry
    ret

IsVolatile:
    stc
    ret

Volatile    EndP
    EndIf

;===============================================================

    If    Generating ne CMOSSave

CalcCMOSSize    Proc    near

;    Is CMOS 64 or 128 bytes long?
;    It is 64 if bytes at 10..2F match those at 50..6F.
;    Otherwise it is 128 bytes.
;    Preserves all registers.

    push    si
    push    di
    push    cx
    lea    si,CMOSBuff+10h
    lea    di,CMOSBuff+50h
    mov    cx,02fh+1-10h
    repe    cmpsb
    je    IsCMOS64

IsCMOS128:
    mov    CMOSSize,128    ; differ, must be a big CMOS
    jmp    CalcCMOSSizeDone

IsCMOS64:
    mov    CMOSSize,64    ; all same, small CMOS

CalcCMOSSizeDone:
    pop    cx
    pop    di
    pop    si

    ret

CalcCMOSSize    EndP
    EndIf

;===============================================================

    if    Generating ne CMOSRest

PeekCMOS    proc    near

;    Reads one byte from cmos.
;    on entry al has offset desired
;    on exit ah has the contents of that byte.
;    preserves all registers

;    See page 5-81 IBM AT Tech ref BIOS listing for how to read CMOS
;    We always enable the NMI with bit 7 on.

    push    bx
    push    ax
    cli                ; disable interrupts
    or    al,80h            ; disable NMI
    out    70h,al            ; output the byte address to CMOS
    jmp    $+2            ; delay, safer than nop
    in    al,71h            ; read the CMOS byte
    jmp    $+2            ; delay, safer than nop
    mov    bl,al
                    ; re-enable the NMI
    mov    al,0dh            ; point to battery status register
    out    70h,al            ; leave pointing at a safe r/o register
    sti                ; restore interrupts
    pop    ax
    mov    ah,bl
    pop    bx
    ret

PeekCMOS    EndP

    EndIf

;===============================================================

    If    Generating eq CMOSRest

PokeCMOS    proc    near

;    Stuffs one byte into cmos.
;    on entry al has offset desired, ah has the value to stuff.
;    Preserves all registers.

;    See page 5-81 IBM AT Tech ref BIOS listing for how to write CMOS
;    We always enable the NMI with bit 7 on.

    push    ax
    cli                ; disable interrupts
    or    al,80h            ; disable NMI
    out    70h,al            ; output the byte address to CMOS
    jmp    $+2            ; delay, safer than nop

    mov    al,ah            ; get contents
    out    71h,al            ; poke the CMOS byte
    jmp    $+2            ; delay, safer than nop
                    ; re-enable the NMI
    mov    al,0dh            ; point to battery status register
    out    70h,al            ; leave pointing at a safe r/o register
    sti                ; restore interrupts
    pop    ax
    ret

PokeCMOS    EndP

    EndIf

;===============================================================

    If    Generating ne CMOSSave

ReadCMOS    Proc    Near

;    Open a file read the CMOS into a buffer

    mov    dx,FileNamePtr    ; DS:DX point to file
    xor    al,al        ; AL=0 is attribute read/only
    mov    ah,03Dh     ; DOS open function
    int    21h
    jc    FileTrouble
    mov    bx,ax        ; save handle
    mov    cx,128        ; read 128 bytes
    lea    dx,CMOSBuff    ; buffer address
    mov    ah,3fH        ; DOS read
    int    21h
    jc    FileTrouble
    cmp    ax,128
    jne    FileTrouble
    mov    ah,3eh        ; DOS close
    int    21h
    jc    FileTrouble
    ret

ReadCMOS    EndP

    EndIf

;===============================================================

    if    Generating eq CMOSSave

WriteCMOS    Proc    Near

;    Create a file write CMOS to it

    mov    dx,FileNamePtr    ; DS:DX point to file
    xor    cx,cx        ; CX=0 is attribute
    mov    ah,03ch     ; DOS create function
    int    21h
    jc    FileTrouble
    mov    bx,ax        ; SAVE HANDLE
    MOV    CX,128        ; write 128 bytes
    lea    dx,CMOSBuff    ; buffer address
    mov    ah,40h        ; DOS write
    int    21h
    jc    FileTrouble
    cmp    ax,128
    jne    FileTrouble
    mov    ah,3eh        ; DOS close
    int    21h
    jc    FileTrouble
    ret

WriteCMOS    EndP

    EndIf

;===============================================================

CODE    ends            ; end of code segment
    end    Start