; ; File: ; kernel.asm ; Description: ; kernel start-up code ; ; Copyright (c) 1995, 1996 ; Pasquale J. Villani ; All Rights Reserved ; ; This file is part of DOS-C. ; ; DOS-C 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, or (at your option) any later version. ; ; DOS-C 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. ; ; You should have received a copy of the GNU General Public ; License along with DOS-C; see the file COPYING. If not, ; write to the Free Software Foundation, 675 Mass Ave, ; Cambridge, MA 02139, USA. ; ; $Id$ ; %include "segs.inc" %include "ludivmul.inc" segment PSP extern _ReqPktPtr:wrt LGROUP STACK_SIZE equ 384/2 ; stack allocated in words ;************************************************************ ; KERNEL BEGINS HERE, i.e. this is byte 0 of KERNEL.SYS ;************************************************************ ..start: entry: jmp short realentry ;************************************************************ ; KERNEL CONFIGURATION AREA ; this is copied up on the very beginning ; it's a good idea to keep this in sync with KConfig.h ;************************************************************ global _LowKernelConfig _LowKernelConfig: db 'CONFIG' ; constant dw configend-configstart; size of config area ; to be checked !!! configstart: DLASortByDriveNo db 0 ; sort disks by drive order InitDiskShowDriveAssignment db 1 ; SkipConfigSeconds db 2 ; ForceLBA db 0 ; GlobalEnableLBAsupport db 1 ; configend: ;************************************************************ ; KERNEL CONFIGURATION AREA END ;************************************************************ ;************************************************************ ; KERNEL real entry (at ~60:20) ; ; moves the INIT part of kernel.sys to high memory (~9000:0) ; then jumps there ; to aid debugging, some '123' messages are output ; this area is discardable and used as temporary PSP for the ; init sequence ;************************************************************ realentry: ; execution continues here push ax push bx pushf mov ax, 0e31h ; '1' Tracecode - kernel entered mov bx, 00f0h int 010h popf pop bx pop ax jmp far kernel_start beyond_entry: resb 256-(beyond_entry-entry) ; scratch area for data (DOS_PSP) segment INIT_TEXT extern _FreeDOSmain ; ; kernel start-up ; kernel_start: push ax push bx pushf mov ax, 0e32h ; '2' Tracecode - kernel entered mov bx, 00f0h int 010h popf pop bx pop ax mov ax,cs cli mov ss,ax mov sp,init_tos int 12h ; move the init code to higher memory mov cl,6 shl ax,cl mov dx,init_end+15 mov cl,4 shr dx,cl sub ax,dx mov es,ax mov ax,cs mov ds,ax xor si,si xor di,di mov cx,init_end+1 shr cx,1 cld rep movsw push es mov ax,cont push ax retf cont: mov ax,cs mov ss,ax ; Now set up call frame mov ds,[cs:_INIT_DGROUP] mov bp,sp ; and set up stack frame for c sti ; now enable them push ax push bx pushf mov ax, 0e33h ; '3' Tracecode - kernel entered mov bx, 00f0h int 010h popf pop bx pop ax inc bl jns floppy mov bl,3 ; set to C: if hard disk floppy: mov byte [_BootDrive],bl ; tell where we came from ;!! int 11h ;!! mov cl,6 ;!! shr al,cl ;!! inc al ;!! mov byte [_NumFloppies],al ; and how many mov ax,ss mov ds,ax mov es,ax jmp _FreeDOSmain %ifdef WATCOM global _IU4M _IU4M: LMULU global _IU4D _IU4D: LDIVMODU %endif segment INIT_TEXT_END ;************************************************************ ; KERNEL CODE AREA END ; the NUL device ;************************************************************ segment CONST ; ; NUL device strategy ; global _nul_strtgy _nul_strtgy: mov word [cs:_ReqPktPtr],bx ;save rq headr mov word [cs:_ReqPktPtr+2],es retf ; ; NUL device interrupt ; global _nul_intr _nul_intr: push es push bx les bx,[cs:_ReqPktPtr] ;es:bx--> rqheadr or word [es:bx+3],100h ;set "done" flag pop bx pop es retf segment _LOWTEXT ; floppy parameter table global _int1e_table _int1e_table: times 0eh db 0 ;************************************************************ ; KERNEL FIXED DATA AREA ;************************************************************ segment _FIXED_DATA ; Because of the following bytes of data, THIS MODULE MUST BE THE FIRST ; IN THE LINK SEQUENCE. THE BYTE AT DS:0004 determines the SDA format in ; use. A 0 indicates MS-DOS 3.X style, a 1 indicates MS-DOS 4.0-6.X style. global DATASTART DATASTART: global _DATASTART _DATASTART: dos_data db 0 dw kernel_start db 0 ; padding dw 1 ; Hardcoded MS-DOS 4.0+ style times (0eh - ($ - DATASTART)) db 0 global _NetBios _NetBios dw 0 ; NetBios Number times (26h - 0ch - ($ - DATASTART)) db 0 ; Globally referenced variables - WARNING: DO NOT CHANGE ORDER ; BECAUSE THEY ARE DOCUMENTED AS UNDOCUMENTED (?) AND HAVE ; MANY MULTIPLEX PROGRAMS AND TSR'S ACCESSING THEM global _NetRetry _NetRetry dw 3 ;-000c network retry count global _NetDelay _NetDelay dw 1 ;-000a network delay count global _DskBuffer _DskBuffer dd -1 ;-0008 current dos disk buffer global _inputptr _inputptr dw 0 ;-0004 Unread con input global _first_mcb _first_mcb dw 0 ;-0002 Start of user memory global _DPBp global MARK0026H ; A reference seems to indicate that this should start at offset 26h. MARK0026H equ $ _DPBp dd 0 ; 0000 First drive Parameter Block global _sfthead _sfthead dd 0 ; 0004 System File Table head global _clock _clock dd 0 ; 0008 CLOCK$ device global _syscon _syscon dw _con_dev,seg _con_dev ; 000c console device global _maxbksize _maxbksize dw 512 ; 0010 maximum bytes/sector of any block device dd 0 ; 0012 pointer to buffers info structure global _CDSp _CDSp dd 0 ; 0016 Current Directory Structure global _FCBp _FCBp dd 0 ; 001a FCB table pointer global _nprotfcb _nprotfcb dw 0 ; 001e number of protected fcbs global _nblkdev _nblkdev db 0 ; 0020 number of block devices global _lastdrive _lastdrive db 0 ; 0021 value of last drive global _nul_dev _nul_dev: ; 0022 device chain root extern _con_dev:wrt LGROUP dw _con_dev, seg _con_dev ; next is con_dev at init time. dw 8004h ; attributes = char device, NUL bit set dw _nul_strtgy dw _nul_intr db 'NUL ' global _njoined _njoined db 0 ; 0034 number of joined devices dw 0 ; 0035 DOS 4 pointer to special names (always zero in DOS 5) setverPtr dw 0,0 ; 0037 setver list dw 0 ; 003B cs offset for fix a20 dw 0 ; 003D psp of last umb exec global _LoL_nbuffers _LoL_nbuffers dw 1 ; 003F number of buffers dw 1 ; 0041 size of pre-read buffer global _BootDrive _BootDrive db 1 ; 0043 drive we booted from %IFNDEF I386 db 0 ; 0044 cpu type (1 if >=386) %ELSE db 1 ; 0044 cpu type (1 if >=386) %ENDIF dw 0 ; 0045 Extended memory in KBytes buf_info: global _firstbuf _firstbuf dd 0 ; 0047 disk buffer chain dw 0 ; 004B Number of dirty buffers dd 0 ; 004D pre-read buffer dw 0 ; 0051 number of look-ahead buffers db 0 ; 0053 00=conv 01=HMA deblock_buf dd 0 ; 0054 deblock buffer times 3 db 0 ; 0058 unknown dw 0 ; 005B unknown db 0, 0FFh, 0 ; 005D unknown global _VgaSet _VgaSet db 0 ; 0060 unknown dw 0 ; 0061 unknown global _uppermem_link _uppermem_link db 0 ; 0063 upper memory link flag _min_pars dw 0 ; 0064 minimum paragraphs of memory ; required by program being EXECed global _uppermem_root _uppermem_root dw 0ffffh ; 0066 dmd_upper_root (usually 9fff) _last_para dw 0 ; 0068 para of last mem search SysVarEnd: ;; FreeDOS specific entries global _os_setver_minor _os_setver_minor db 0 global _os_setver_major _os_setver_major db 5 global _os_minor _os_minor db 0 global _os_major _os_major db 5 global _rev_number _rev_number db 0 global _version_flags _version_flags db 0 global _f_nodes _f_nodes dw 0 global _f_nodes_cnt _f_nodes_cnt dw 0 global os_release extern _os_release os_release dw _os_release ;; The first 5 sft entries appear to have to be at DS:00cc times (0cch - ($ - DATASTART)) db 0 global _firstsftt _firstsftt: dd -1 ; link to next dw 5 ; count ; Some references seem to indicate that this data should start at 01fbh in ; order to maintain 100% MS-DOS compatibility. times (01fbh - ($ - DATASTART)) db 0 global MARK01FBH MARK01FBH equ $ global _local_buffer ; local_buffer is 256 bytes long ; so it overflows into kb_buf!! ; only when kb_buf is used, local_buffer is limited to 128 bytes. _local_buffer: times 128 db 0 global _kb_buf _kb_buf db 128,0 ; initialise buffer to empty times 128+1 db 0 ; room for 128 byte readline + LF ; ; Variables that follow are documented as part of the DOS 4.0-6.X swappable ; data area in Ralf Browns Interrupt List #56 ; ; this byte is used for ^P support global _PrinterEcho _PrinterEcho db 0 ;-34 - 0 = no printer echo, ~0 echo global _verify_ena _verify_ena db 0 ; ~0, write with verify ; this byte is used for TAB's global _scr_pos _scr_pos db 0 ; Current Cursor Column global _switchar _switchar db '/' ;-31 - switch char global _mem_access_mode _mem_access_mode db 0 ;-30 - memory allocation strategy global sharing_flag sharing_flag db 0 ; 00 = sharing module not loaded ; 01 = sharing module loaded, but ; open/close for block devices ; disabled ; FF = sharing module loaded, ; open/close for block devices ; enabled (not implemented) global _net_set_count _net_set_count db 1 ;-28 - count the name below was set global _net_name _net_name db ' ' ;-27 - 15 Character Network Name db 00 ; Terminating 0 byte ; ; Variables contained the the "STATE_DATA" segment contain ; information about the STATE of the current DOS Process. These ; variables must be preserved regardless of the state of the INDOS ; flag. ; ; All variables that appear in "STATE_DATA" **MUST** be declared ; in this file as the offsets from the INTERNAL_DATA variable are ; critical to the DOS applications that modify this data area. ; ; global _ErrorMode, _InDOS global _CritErrLocus, _CritErrCode global _CritErrAction, _CritErrClass global _CritErrDev, _CritErrDrive global _dta global _cu_psp, _default_drive global _break_ena global _return_code global _internal_data global _CritPatch _CritPatch dw 0d0ch ;-11 zero list of patched critical dw 0d0ch ; section variables dw 0d0ch dw 0d0ch dw 0d0ch db 0 ;-01 - unknown _internal_data: ; <-- Address returned by INT21/5D06 _ErrorMode db 0 ; 00 - Critical Error Flag _InDOS db 0 ; 01 - Indos Flag _CritErrDrive db 0 ; 02 - Drive on write protect error _CritErrLocus db 0 ; 03 - Error Locus _CritErrCode dw 0 ; 04 - DOS format error Code _CritErrAction db 0 ; 06 - Error Action Code _CritErrClass db 0 ; 07 - Error Class _CritErrDev dd 0 ; 08 - Failing Device Address _dta dd 0 ; 0C - current DTA _cu_psp dw 0 ; 10 - Current PSP break_sp dw 0 ; 12 - used in int 23 _return_code dw 0 ; 14 - return code from process _default_drive db 0 ; 16 - Current Drive _break_ena db 1 ; 17 - Break Flag (default TRUE) db 0 ; 18 - flag, code page switching db 0 ; 19 - flag, copy of 18 on int 24h abort global _swap_always, _swap_indos _swap_always: global _Int21AX _Int21AX dw 0 ; 1A - AX from last Int 21 global owning_psp, _MachineId owning_psp dw 0 ; 1C - owning psp _MachineId dw 0 ; 1E - remote machine ID dw 0 ; 20 - First usable mcb dw 0 ; 22 - Best usable mcb dw 0 ; 24 - Last usable mcb dw 0 ; 26 - memory size in paragraphs dw 0 ; 28 - unknown db 0 ; 2A - unknown db 0 ; 2B - unknown db 0 ; 2C - unknown global _break_flg _break_flg db 0 ; 2D - Program aborted by ^C db 0 ; 2E - unknown db 0 ; 2F - not referenced global _DayOfMonth _DayOfMonth db 1 ; 30 - day of month global _Month _Month db 1 ; 31 - month global _YearsSince1980 _YearsSince1980 dw 0 ; 32 - year since 1980 daysSince1980 dw 0FFFFh ; 34 - number of days since epoch ; force rebuild on first clock read global _DayOfWeek _DayOfWeek db 2 ; 36 - day of week _console_swap db 0 ; 37 console swapped during read from dev global _dosidle_flag _dosidle_flag db 1 ; 38 - safe to call int28 if nonzero _abort_progress db 0 ; 39 - abort in progress global _CharReqHdr _CharReqHdr: global _ClkReqHdr _ClkReqHdr times 30 db 0 ; 3A - Device driver request header dd 0 ; 58 - pointer to driver entry global _MediaReqHdr _MediaReqHdr times 22 db 0 ; 5C - Device driver request header global _IoReqHdr _IoReqHdr times 30 db 0 ; 72 - Device driver request header times 6 db 0 ; 90 - unknown global _ClkRecord _ClkRecord times 6 db 0 ; 96 - CLOCK$ transfer record dw 0 ; 9C - unknown global __PriPathBuffer __PriPathBuffer times 80h db 0 ; 9E - buffer for file name global __SecPathBuffer __SecPathBuffer times 80h db 0 ;11E - buffer for file name global _sda_tmp_dm _sda_tmp_dm times 21 db 0 ;19E - 21 byte srch state global _SearchDir _SearchDir times 32 db 0 ;1B3 - 32 byte dir entry global _TempCDS _TempCDS times 88 db 0 ;1D3 - TemporaryCDS buffer global _DirEntBuffer _DirEntBuffer times 32 db 0 ;22B - space enough for 1 dir entry global _wAttr _wAttr dw 0 ;24B - extended FCB file attribute global _SAttr _SAttr db 0 ;24D - Attribute Mask for Dir Search global _OpenMode _OpenMode db 0 ;24E - File Open Attribute times 3 db 0 global _Server_Call _Server_Call db 0 ;252 - Server call Func 5D sub 0 db 0 ; Pad to 05CCh times (25ch - ($ - _internal_data)) db 0 global _tsr ; used by break and critical error _tsr db 0 ;25C - handlers during termination db 0 ;25D - padding global term_psp term_psp dw 0 ;25E - 0?? global int24_esbp int24_esbp times 2 dw 0 ;260 - pointer to criticalerr DPB global _user_r, int21regs_off, int21regs_seg _user_r: int21regs_off dw 0 ;264 - pointer to int21h stack frame int21regs_seg dw 0 global critical_sp critical_sp dw 0 ;268 - critical error internal stack global current_ddsc current_ddsc times 2 dw 0 ; Pad to 059ah times (27ah - ($ - _internal_data)) db 0 global current_device current_device times 2 dw 0 ;27A - 0?? global _lpCurSft _lpCurSft times 2 dw 0 ;27e - Current SFT global _current_ldt _current_ldt times 2 dw 0 ;282 - Current CDS global _lpFcb _lpFcb times 2 dw 0 ;286 - pointer to callers FCB global _current_sft_idx _current_sft_idx dw 0 ;28A - SFT index for next open ; used by MS NET ; Pad to 05b2h times (292h - ($ - _internal_data)) db 0 dw __PriPathBuffer ; 292 - "sda_WFP_START" offset in DOS DS of first filename argument dw __SecPathBuffer ; 294 - "sda_REN_WFP" offset in DOS DS of second filename argument ; Pad to 05ceh times (2aeh - ($ - _internal_data)) db 0 global _current_filepos _current_filepos times 2 dw 0 ;2AE - current offset in file ; Pad to 05f0h times (2d0h - ($ - _internal_data)) db 0 global _prev_user_r global prev_int21regs_off global prev_int21regs_seg _prev_user_r: prev_int21regs_off dw 0 ;2D0 - pointer to prev int 21 frame prev_int21regs_seg dw 0 ; Pad to 05fdh times (2ddh - ($ - _internal_data)) db 0 global _ext_open_action global _ext_open_attrib global _ext_open_mode _ext_open_action dw 0 ;2DD - extended open action _ext_open_attrib dw 0 ;2DF - extended open attrib _ext_open_mode dw 0 ;2E1 - extended open mode ; Pad to 0620h times (300h - ($ - _internal_data)) db 0 global _szNames _szNames: ;; times 11 db 0 global _FcbSearchBuffer ; during FCB search 1st/next use bottom _FcbSearchBuffer: ; of error stack as scratch buffer ; times 43 db 0 ; - only used during int 21 call ; stacks are made to initialize to no-ops so that high-water ; testing can be performed global apistk_bottom apistk_bottom: times STACK_SIZE dw 0x9090 ;300 - Error Processing Stack global _error_tos _error_tos: times STACK_SIZE dw 0x9090 ;480 - Disk Function Stack global _disk_api_tos _disk_api_tos: times STACK_SIZE dw 0x9090 ;600 - Char Function Stack global _char_api_tos _char_api_tos: apistk_top: db 0 ; 780 ??? _VolChange db 0 ;781 - volume change _VirtOpen db 0 ;782 - virtual open flag ; controlled variables end at offset 78Ch so pad to end times (78ch - ($ - _internal_data)) db 0 ; ; end of controlled variables ; segment _BSS ;!! global _NumFloppies ;!!_NumFloppies resw 1 ;!!intr_dos_stk resw 1 ;!!intr_dos_seg resw 1 ; mark front and end of bss area to clear segment IB_B global __ib_start __ib_start: segment IB_E global __ib_end __ib_end: ;; do not clear the other init BSS variables + STACK: too late. ; kernel startup stack global init_tos resw 512 init_tos: ; the last paragraph of conventional memory might become an MCB resb 16 global __init_end __init_end: init_end: segment _DATA ; blockdev private stack global blk_stk_top times 192 dw 0 blk_stk_top: ; clockdev private stack global clk_stk_top times 64 dw 0 clk_stk_top: ; have a jump to the real thing here for AARD compliance global _CharMapSrvc ; in _DATA (see AARD) _CharMapSrvc: jmp 0x70:CharMapSrvc2 ; Dynamic data: ; member of the DOS DATA GROUP ; and marks definitive end of all used data in kernel data segment ; segment _DATAEND _swap_indos: ; we don't know precisely what needs to be swapped before this, so set it here. ; this is just after FIXED_DATA+BSS+DATA and before (D)CONST+BSS ; probably, the clock and block stacks and disktransferbuffer should go past ; _swap_indos but only if int2a ah=80/81 (critical section start/end) ; are called upon entry and exit of the device drivers segment DYN_DATA global _Dyn _Dyn: DynAllocated dw 0 segment ID_B global __INIT_DATA_START __INIT_DATA_START: segment ID_E global __INIT_DATA_END __INIT_DATA_END: segment INIT_TEXT_START global __InitTextStart __InitTextStart: ; and c version ; ; start end end of HMA area segment HMA_TEXT_START global __HMATextAvailable __HMATextAvailable global __HMATextStart __HMATextStart: ; ; the HMA area is filled with 1eh+3(=sizeof VDISK) = 33 byte dummy data, ; so nothing will ever be below 0xffff:0031 ; segment HMA_TEXT begin_hma: times 10h db 0 ; filler [ffff:0..ffff:10] times 20h db 0 db 0 %ifdef WATCOM ; 32 bit multiplication + division global __U4M __U4M: LMULU global __U4D __U4D: LDIVMODU %endif ;End of HMA segment segment HMA_TEXT_END global __HMATextEnd __HMATextEnd: ; and c version ; The default stack (_TEXT:0) will overwrite the data area, so I create a dummy ; stack here to ease debugging. -- ror4 segment _STACK class=STACK stack segment _LOWTEXT ; dummy interrupt return handlers global _int22_handler global _int28_handler global _int2a_handler global _empty_handler _int22_handler: _int28_handler: _int2a_handler: _empty_handler: iret global _initforceEnableA20 initforceEnableA20: call near forceEnableA20 retf global __HMARelocationTableStart __HMARelocationTableStart: global _int2f_handler extern reloc_call_int2f_handler _int2f_handler: jmp 0:reloc_call_int2f_handler call near forceEnableA20 global _int20_handler extern reloc_call_int20_handler _int20_handler: jmp 0:reloc_call_int20_handler call near forceEnableA20 global _int21_handler extern reloc_call_int21_handler _int21_handler: jmp 0:reloc_call_int21_handler call near forceEnableA20 global _low_int25_handler extern reloc_call_low_int25_handler _low_int25_handler: jmp 0:reloc_call_low_int25_handler call near forceEnableA20 global _low_int26_handler extern reloc_call_low_int26_handler _low_int26_handler: jmp 0:reloc_call_low_int26_handler call near forceEnableA20 global _int27_handler extern reloc_call_int27_handler _int27_handler: jmp 0:reloc_call_int27_handler call near forceEnableA20 global _int0_handler extern reloc_call_int0_handler _int0_handler: jmp 0:reloc_call_int0_handler call near forceEnableA20 global _int6_handler extern reloc_call_int6_handler _int6_handler: jmp 0:reloc_call_int6_handler call near forceEnableA20 global _cpm_entry extern reloc_call_cpm_entry _cpm_entry: jmp 0:reloc_call_cpm_entry call near forceEnableA20 global _reloc_call_blk_driver extern _blk_driver _reloc_call_blk_driver: jmp 0:_blk_driver call near forceEnableA20 global _reloc_call_clk_driver extern _clk_driver _reloc_call_clk_driver: jmp 0:_clk_driver call near forceEnableA20 ; global _CharMapSrvc ; in _DATA (see AARD) extern _reloc_call_CharMapSrvc CharMapSrvc2: jmp 0:_reloc_call_CharMapSrvc call near forceEnableA20 global __HMARelocationTableEnd __HMARelocationTableEnd: ; ; if we were lucky, we found all entries from the outside to the kernel. ; if not, BUMS ; ; ; this routine makes the HMA area available. PERIOD. ; must conserve ALL registers ; will be only ever called, if HMA (DOS=HIGH) is enabled. ; for obvious reasons it should be located at the relocation table ; global _XMSDriverAddress _XMSDriverAddress: dw 0 ; XMS driver, if detected dw 0 global __EnableA20 __EnableA20: mov ah,3 UsingXMSdriver: push bx call far [cs:_XMSDriverAddress] pop bx retf global __DisableA20 __DisableA20: mov ah,4 jmp short UsingXMSdriver dslowmem dw 0 eshighmem dw 0ffffh global forceEnableA20 forceEnableA20: push ds push es push ax forceEnableA20retry: mov ds, [cs:dslowmem] mov es, [cs:eshighmem] mov ax, [ds:00000h] cmp ax, [es:00010h] jne forceEnableA20success mov ax, [ds:00002h] cmp ax, [es:00012h] jne forceEnableA20success mov ax, [ds:00004h] cmp ax, [es:00014h] jne forceEnableA20success mov ax, [ds:00006h] cmp ax, [es:00016h] jne forceEnableA20success ; ; ok, we have to enable A20 )at least seems so ; call far __EnableA20 jmp short forceEnableA20retry forceEnableA20success: pop ax pop es pop ds ret ; ; global f*cking compatibility issues: ; ; very old brain dead software (PKLITE, copyright 1990) ; forces us to execute with A20 disabled ; global _ExecUserDisableA20 _ExecUserDisableA20: cmp word [cs:_XMSDriverAddress],0 jne NeedToDisable cmp word [cs:_XMSDriverAddress+2],0 je noNeedToDisable NeedToDisable: push ax call far __DisableA20 pop ax noNeedToDisable: iret segment _LOWTEXT ; ; Default Int 24h handler -- always returns fail ; so we have not to relocate it (now) ; FAIL equ 03h global _int24_handler _int24_handler: mov al,FAIL iret ; ; this makes some things easier ; ; to minimize relocations segment HMA_TEXT global _DGROUP_ _DGROUP_ dw DGROUP segment _LOWTEXT global _TEXT_DGROUP _TEXT_DGROUP dw DGROUP segment INIT_TEXT global _INIT_DGROUP _INIT_DGROUP dw DGROUP