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415 lines
10 KiB
415 lines
10 KiB
PAGE ,132
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TITLE DXEMM.ASM -- Dos Extender MEMM Disable Code
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; Copyright (c) Microsoft Corporation 1989-1991. All Rights Reserved.
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;***********************************************************************
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;
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; DXEMM.ASM -- Dos Extender MEMM Disable Code
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;
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;-----------------------------------------------------------------------
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;
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; This module provides routines that attempt to disable MEMM/CEMM/EMM386
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; drivers. DOSX tries to disable MEMM when starting up, and enables MEMM
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; when terminating.
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;
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; NOTE: All the code in this module is consider initialization, and
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; is discarded before going operational. This includes code
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; segment variables. The MEMM enable code is not in this file
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; since that cannot be discarded.
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;
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;-----------------------------------------------------------------------
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;
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; 12/08/89 jimmat Minor changes so enable code could be finished.
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; 07/14/89 jimmat Original version - but largely taken from Windows/386
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; code from ArronR
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;
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;***********************************************************************
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.286p
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; -------------------------------------------------------
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; INCLUDE FILE DEFINITIONS
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; -------------------------------------------------------
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.xlist
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.sall
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include segdefs.inc
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include gendefs.inc
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.list
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if NOT VCPI
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; -------------------------------------------------------
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; GENERAL SYMBOL DEFINITIONS
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; -------------------------------------------------------
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EMM_OK equ 0
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; Device driver header for Microsoft 386 EMM drivers
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;
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emm_hdr STRUC
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;
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DW ? ;Null segment address
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DW ? ;Null offset address
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DW ? ;Attribute - Char
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DW ? ;Strategy routine entry
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DW ? ;Interrupt routine entry
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DB 'EMMXXXX0' ;Character device name
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;
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; GENERAL FUNCTIONS ENTRY POINT
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; ELIM_Entry is a entry point for executing general MEMM
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; functions. (e.g. ON, OFF function).
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;
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ELIM_Entry_off dw ? ; general entry point
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;
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; MEMM signature
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;
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emmsig db ? ; MEMM signature
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emm_hdr ENDS
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; -------------------------------------------------------
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; EXTERNAL SYMBOL DEFINITIONS
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; -------------------------------------------------------
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; -------------------------------------------------------
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; DATA SEGMENT DEFINITIONS
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; -------------------------------------------------------
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DXDATA segment
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extrn MEMM_State:BYTE ; initial on/off/auto state
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extrn MEMM_Call:DWORD ; far call address into MEMM driver
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extrn fMEMM_Disabled:BYTE ; NZ if MEMM was disabled
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DXDATA ends
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; -------------------------------------------------------
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; CODE SEGMENT VARIABLES
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; -------------------------------------------------------
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DXCODE segment
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extrn segDXData:WORD
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EMMDevNameRM DB "EMMXXXX0" ;Character device name
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MEMMsig db 'MICROSOFT EXPANDED MEMORY MANAGER 386'
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MEMMsiglen equ $ - MEMMsig
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CEMMsig db 'COMPAQ EXPANDED MEMORY MANAGER 386'
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CEMMsiglen equ $ - CEMMsig
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DXCODE ends
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DXPMCODE segment
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DXPMCODE ends
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; -------------------------------------------------------
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subttl MEMM/CEMM/EMM386 Disable Routines
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page
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; -------------------------------------------------------
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; MEMM/CEMM/EMM386 DISABLE ROUTINES
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; -------------------------------------------------------
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DXCODE segment
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assume cs:DXCODE
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; -------------------------------------------------------
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; EMMDisable -- This routine attempts to disable any installed
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; MEMM/CEMM/EMM386 driver.
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;
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; Input: none
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; Output: CY off - EMM driver disabled (or not installed)
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; CY set - EMM installed, and can't disable
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; Errors:
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; Uses: All registers preserved
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assume ds:DGROUP,es:NOTHING,ss:NOTHING
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public EMMDisable
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EMMDisable proc near
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pusha
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push ds
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push es
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call Check_for_EMM_Driver ;is there and EMM driver?
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jc emmd_ok ; no, then we're already done
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call MEMM_Inst_chk ;is it one we know about?
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jc emmd_bad ; no, then we can't disable it
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; Get the current EMM driver state before checking for open handles. The
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; process of checking for handles may change the driver from AUTO to ON.
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xor ax,ax ; get & save current emm state
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call [MEMM_Call] ; returns ah = 0 - on, 1 - off,
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mov MEMM_state,ah ; 2 - auto & off, 3 - auto & on
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call AnyMEMMHandles ;does it have any handles allocated?
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jc emmd_bad ; yes, then we can't disable it
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call TurnMEMMOff ;try to disable it
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jc emmd_bad
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mov fMEMM_Disabled,1 ;remember that we disabled MEMM
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emmd_ok:
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clc ;indicate disabled (or not installed)
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emmd_ret:
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pop es
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pop ds
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popa
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ret
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emmd_bad:
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stc ;can't disable!
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jmp short emmd_ret
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EMMDisable endp
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; -------------------------------------------------------
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; Windows/386 EMM Disable Code
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; -------------------------------------------------------
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assume ds:NOTHING,es:NOTHING,ss:NOTHING
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BeginProc macro name
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name proc near
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endm
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EndProc macro name
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name endp
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endm
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;--------------------------------------------------------
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;******************************************************************************
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;
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; MEMM_Inst_chk - Check to see if MEMM/CEMM is already installed
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;
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; ENTRY:
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; Know there is an EMM driver so INT 67 vector points to something
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;
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; EXIT:
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; Carry set
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; No MEMM/CEMM driver
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; Carry Clear
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; [entry_seg] = segment of driver header
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; [entry_off] = offset of status routine in MEMM
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;
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; USES: AX,CX,SI,DI,FLAGS
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;
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;******************************************************************************
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assume ds:NOTHING, es:NOTHING
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BeginProc MEMM_Inst_chk
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push ds
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push es
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xor ax,ax
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mov ds,ax
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mov ax,word ptr ds:[(67h * 4)+2] ; get segment pointed to by int 67
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mov ds,ax
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mov si,emmsig
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cld ; strings foward
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mov di,offset MEMMsig
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push cs
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pop es
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mov cx,MEMMsiglen
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cld
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repe cmpsb ; q: is the MEMM signature out there?
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je short found_sig ; y: return one
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mov si,emmsig
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mov di,offset CEMMsig
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mov cx,CEMMsiglen
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cld
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repe cmpsb ; q: is the CEMM signature out there?
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jne short Not_Found ; n: done, not found
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found_sig:
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mov es,segDXData
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xor si,si
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mov word ptr es:[MEMM_Call+2],ds ; save segment for far call
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mov cx,ds:[si.ELIM_Entry_off]
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mov word ptr es:[MEMM_Call],cx ; Offset for far call
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clc
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MEMM_Inst_Done:
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pop es
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pop ds
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ret
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Not_Found:
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stc
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jmp short MEMM_Inst_Done
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EndProc MEMM_Inst_chk
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;******************************************************************************
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;
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; TurnMEMMOff
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;
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; Turn MEMM off (CEMM, IEFF, MEMM)
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;
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; ENTRY:
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; entry_seg entry_off set to CEMM/MEMM enable disable routine
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;
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; EXIT:
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; Carry Set
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; Could not disable EMM
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; Carry Clear
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; MEMM CEMM EMM turned off
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;
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; USES: EAX,FLAGS
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;
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;******************************************************************************
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assume ds:DGROUP, es:NOTHING
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BeginProc TurnMEMMOff
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cmp MEMM_state,1 ; MEMM already off?
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jz short memm_off ; yes, nothing to do
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mov AX,0101h ; no, turn it OFF
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call [MEMM_Call]
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jc short memm_err
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memm_off:
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clc
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memm_done:
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ret
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memm_err:
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stc ; Error, set carry
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jmp short memm_done
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EndProc TurnMEMMOff
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;******************************************************************************
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;
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; AnyMEMMHandles/Check_For_EMM_Handles
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;
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; Are there any open MEMM handles
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;
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; ENTRY:
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; entry_seg entry_off set to CEMM/MEMM enable disable routine
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;
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; EXIT:
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; Carry Set
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; There are open handles
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; Carry Clear
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; There are no open handles
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;
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; USES: EAX,EBX,ECX,FLAGS
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;
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;******************************************************************************
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assume ds:DGROUP, es:NOTHING
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BeginProc AnyMEMMHandles
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mov ax,4600h
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int 67h
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cmp ah,EMM_OK
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jne short memm_is_off
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mov cx,ax
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mov ax,4B00h
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int 67h
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cmp ah,EMM_OK
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jne short memm_is_off
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cmp cl,40h
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jb short Check_Cnt
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or bx,bx ; Don't dec through 0!!!
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jz short Check_Cnt
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dec bx ; Do not include handle 0 on 4.0 drivers
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Check_Cnt:
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cmp bx,0
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stc
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jne short HaveHandles
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memm_is_off:
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clc
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HaveHandles:
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ret
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EndProc AnyMEMMHandles
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;******************************************************************************
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;
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; Check_For_EMM_Driver
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;
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; See if an EMM driver is around
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;
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; ENTRY:
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; None
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;
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; EXIT:
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; Carry Set
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; No EMM driver around
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; Carry Clear
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; EMM driver is around
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;
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; USES: AX,CX,SI,DI,FLAGS
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;
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;******************************************************************************
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assume ds:NOTHING,es:NOTHING
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BeginProc Check_For_EMM_Driver
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push ds
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push es
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; Note, DS:SI & ES:DI used to be swapped, but on at least one system where
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; Int 67h pointed to F000 and there was not ram or rom at F000:000A (rom
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; started at F0000:8000), bus noise made the compare work when it shouldn't
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; have. Swapping ES:DI / DS:SI corrected this.
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xor ax,ax
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mov es,ax
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mov ax,word ptr es:[(67h * 4)+2] ; get segment pointed to by int 67
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mov es,ax
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mov di,000Ah ; Offset of device name
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mov si,offset EMMDevNameRM
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push cs
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pop ds
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mov cx,8
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cld
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repe cmpsb
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jne short NoEMM_Seen
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clc
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EMMTstDone:
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pop es
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pop ds
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ret
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NoEMM_Seen:
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stc
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jmp short EMMTstDone
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EndProc Check_For_EMM_Driver
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; -------------------------------------------------------
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DXCODE ends
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;****************************************************************
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endif ; NOT VCPI
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end
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