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Assembly Source File | 1985-03-26 | 22.6 KB | 1,088 lines

Page 80,132 Title LUE - Extract LBR Member Comment | Version 1.93, February 22, 1985 LUE Command ----------- Purpose: Extract a file (member) from an LU or LAR type library. Format: LUE [d:][path]filename[.ext] filename[.ext] Remarks: The library name must be supplied. If the member file name is omitted, all files are extracted. Notes: Written for the IBM PC using DOS 2.0 or later. Copyright 1984 Vernon Buerg, for public domain use. LUE duplicates the A and E function of LU. The advantages of LUE are: - smaller, so a copy can be kept on the "system" disk - faster, mucho - handles paths and wildcards. - retains input file or member date/time 1.7 updates: - checks for CRC in bytes 16-17 - allocate more memory for buffers, up to 60K 1.8 updates: - extracts members in LU86 format 1.9 updates: - default library extension to LBR - allow multiple filenames on command line ----------| DirNtry Struc ;LU/LAR directory entries D_Stat Db 0 ;File status D_File Db 8 Dup (' ') ;File name (FCB format) D_Ext Db 3 Dup (' ') ;Extension part D_Ptr Dw 0 ;Offset to data (mod 128) D_Len Dw 0 ;Length, 128-byte sectors D_CRC Dw 0 ;CRC check bytes D_Cdate Dw 0 ;Create date D_Udate Dw 0 ;Update date D_Ctime Dw 0 ;Create time D_Utime Dw 0 ;Update time D_Pad Dw 0,0,0 ;Pad bytes in last block DirNtry Ends Page ; ; Extract an LU member file Cseg Segment Public Para 'CODE' Assume CS:Cseg,DS:Cseg,ES:Cseg,SS:Cseg Org 100h Lue Proc Far Lea SP,Stackx ; Use local stack Push DS ; Standard entry Sub AX,AX ; for DOS return Push AX Mov StkTop,SP ; Save stack ptr for return Call ChkVer ; Check DOS version Call Alloc ; Get buffers Call GetParm ; Get LBR and file name Call OpenLbr ; Access library Call LoadDir ; Load directory Call Search ; Find and extract file(s) Call CloseLbr ; Final close Mov DX,Offset EofMsg Error: Mov AX,CS ;Insure DS Mov DS,AX Mov SP,StkTop ;Insure stack is proper Call PrintS ;Display a message Ret ;Return to DOS Page ; ; Messages, Constants, and Work Areas Active Equ 0 Deleted Equ 254 Unused Equ 255 Dir_Len Equ Size DirNtry Sector Equ 128 ; Logical sector size MaxPara Equ (60*1024)/16 ; Maximum buffer size MinPara Equ (12*1024)/16 ; Minumum buffer size CR Equ 13 LF Equ 10 Stopper Equ 255 ; Ends message text Mode Db 0 ;Library format ; 01 = ***DIR format 02 = CRC included ; 04 = LU86 format 08 = CRC invalid IHandle Dw 0 ;Input file handle OHandle Dw 0 ;Output file handle SecSize Dw Sector BufSize Dw 0 ;Block size to use BufSec Dw 0 ;Sectors in a block S_Dir Dw 0 ;Addr of DIR segment S_Buf Dw 0 ;Addr of buffer segment StkTop Dw 0 ParmNxt Dw 0 ; Pointer to next filename operand FilePtr Dw 0 ; Pointer to current filename FileNm Db 13 Dup (0) ; File name from command line LbrPtr Dw Offset LbrName ; Offset to file name part Entries Dw 0 ; Number of directory entries Counter Dw 0 ; for search loop NumSecs Dw 0 ; Number of data sectors DirPtr Dw 0 ; Points to next dir entry LenDir Dw 0 ; Total directory size Blanks Db 13 Dup (' ') ; Name in old format files DirKey Db '********DIR' ; in new format libs Year Dw 0 Msg10 Db CR,LF,'Requested member file not found ' Member Db 8 Dup (' ') ;Requested member file Ext Db 3 Dup (' '),0,255 MsgE Db CR,LF,'Extracting ' NewName Db 13 Dup (0),255,' - from ',Stopper ; ; Error messages Msg2 Db CR,LF,'I/O error reading',CR,LF,255 Msg7 Db CR,LF,'LSEEK failed',CR,LF,255 Msg8 Db CR,LF,'CREATE failed for ',255 EofMsg Db CR,LF,'End of file',CR,LF,255 Page ; ; Insure Usable DOS version ChkVer Proc Near Mov DX,Offset Version ; Show current program version Call PrintS Mov AH,30h ; Get DOS version Int 21h Cmp AL,2 ; Insure 2.0 or later Jb VerBad Ret VerBad: Mov DX,Offset Sorry Jmp Error Sorry Db CR,LF,'Sorry, PC DOS Version 2 required',CR,LF,255 Version Db 'LUE - Version 1.92 - V.Buerg',CR,LF,Stopper ChkVer Endp Page ; ; Allocate directory and I/O buffer Alloc Proc Near Mov BX,Paras_C ;Add up program size Mov AH,4Ah ;Shrink memory Int 21h Alloc1: Mov BX,MaxPara ;Maximum memory requested Mov AH,48h Int 21h Jc Alloc1 ;Get what there is Cmp BX,MinPara ;Have enough? Jb Alloc6 Mov S_Dir,AX ;Set directory segment Mov CX,512 ;Paras in DIR Add AX,CX ;Bump over 8k Mov S_Buf,AX ; as I/O buffer Sub BX,CX ;Paras in buffer Mov CL,3 ; into sectors Shr BX,CL Mov BufSec,BX Mov AX,CS ; Get offset to directory Mov DX,S_Dir ; rather than use segment addresses Sub DX,AX Mov CL,4 Shl DX,CL Mov S_Dir,DX Mov DirPtr,DX Ret Alloc6: Mov DX,Offset AlocMsg ;Insufficient memory Jmp Error AlocMsg Db CR,LF,'Insufficient memory',255 Alloc Endp Page ; ; Get Command Tail Operands ; ; Input: DS must point to program PSP ; Output: ; Carry flag if any errors encountered, message sent ; LbrName - receives the first operand, library file name ; FileNm - receives the second operand, a member name ; FilePtr - points to the first member name GetParm Proc Near ; First operand is LBR name Mov SI,82h ; Second is requested member Sub CX,CX Or CL,DS:[80h] ; Length of command operands Jnz Parm0 Jmp Parm_Error ; Library name missing Parm0: Mov DI,Offset ParmFld ; Save command operands Rep Movsb Mov CX,129 ; and pad with CRs Sub CL,DS:[80h] Mov AL,CR Rep Stosb Mov SI,Offset ParmFld ; Point to operands Mov CL,DS:[80h] ; and get length Parm1: Lodsb ; Skip leading blanks Cmp AL,' ' ; while Parming LBR name Loope Parm1 Mov DI,Offset LbrName ; Copy library name operand Parm2: Stosb Lodsb Cmp AL,0Dh ; The library name operand may end Je Parm20 ; in a blank but not a CR, because Cmp AL,'.' ; a CR means there are no filenames Je Parm2a Cmp AL,' ' ; Copy the first operand and check for Loopne Parm2 ; an extension delimiter. Jcxz Parm_Error Parm20: Mov AX,'L.' ; If no extension is supplied, Stosw ; supply a default of .LBR Mov AX,'RB' Stosw Jmp Short Parm2d Parm2a: Stosb ; Copy the extension Lodsb Cmp AL,0Dh ; End of lbr name? Je Parm2d Cmp AL,' ' Loopne Parm2a Parm2d: Mov AX,0FF00h ; Append ASCIIZ and print stopper Stosw Parm2e: Mov ParmNxt,SI ; Set pointer to next operand Mov SI,DI ; Look for path or drive Sub SI,2 Mov CX,SI Sub CX,Offset LbrName Std Parm23: Lodsb Cmp AL,':' ; drive specifier? Je Parm24 ; yes, may be start of file name part Cmp AL,'\' ; path specifier? Je Parm24 Loop Parm23 Mov SI,Offset LbrName ; Simple filename Jmp Short Parm25 Parm24: Add SI,2 Parm25: Mov LbrPtr,SI ; followed by a filename Cld Clc Ret Parm_Error: ; Library name missing Mov DX,Offset Usage ; or member name(s) missing Jmp Error ; Send usage message Usage Db CR,LF,'Usage: LUE library[.LBR] filename(s)',CR,LF,Stopper GetParm Endp Page ; ; Open the Library OpenLbr Proc Near ;Open the library Mov DX,Offset MyDta ; Set local data transfer area Mov AH,1Ah Int 21h Mov AH,4Eh ; Find first matching file Mov DX,Offset LbrName Sub CX,CX Int 21h Jc Error9 ; Library file not found Mov CX,13 ; Copy first file name Mov SI,Offset MyDta+30 Mov DI,LbrPtr Openl1: Lodsb ; Copy until null found Stosb Cmp AL,0 Loopne Openl1 Mov AL,Stopper Stosb Mov AX,3D00h ; Open library file for reading Mov DX,Offset LbrName Int 21h Jc Error1 ; Library failed to open Mov IHandle,AX ; yes, save handle Mov DX,Offset MsgU ; Show name of library in use Call PrintS Mov DX,Offset LbrName Call PrintS Ret ; and return Error9: Mov DX,Offset Msg9 ; Say LIBRARY not found Jmp Short Errorl Error1: Mov DX,Offset Msg1 ; Say OPEN FAILED Errorl: Call PrintS Mov DX,Offset LbrName ; and add file name Jmp Error Msg9 Db CR,LF,'Library not found: ',Stopper Msg1 Db CR,LF,'Unable to open:',Stopper MsgU Db CR,LF,'Using: ',Stopper OpenLbr Endp Page ; ; Get pointer to next command operand GetNext Proc Near ; Returns ZF if there's an operand Mov Filenm,0 Mov CX,14 Mov DI,Offset FileNm ; Copy the next operand as a Mov SI,ParmNxt ; member file name Cmp Byte Ptr [SI],CR ; No more operands? Je Parm7 Parm3a: Lodsb Cmp AL,' ' ; Skip leading blanks Loope Parm3a Dec SI Parm3: Mov ParmNxt,SI Lodsb Cmp AL,' ' ; Multiple member names are separated Je Parm4 ; by blanks. The last one ends in a CR. Cmp AL,CR Je Parm4 Stosb Loop Parm3 Parm4: Mov AX,0FF00h ; Append ASCIIZ and print stopper Stosw Mov SI,DI ; Each member filename may include Std ; a drive and/or path names, need to Dec SI ; the address of the filename part Parm5: Lodsb Cmp AL,':' ; Check for drive Je Parm6 Cmp AL,'\' ; Check for paths Je Parm6 Cmp AL,'/' Je Parm6 Cmp SI,Offset Filenm-1 Ja Parm5 Dec SI Parm6: Inc SI ; Save a pointer to the filename Inc SI Parm7: Mov FilePtr,SI ; part of the member name Cld Clc Cmp Byte Ptr FileNm,0 ; Set ZF to indicate whether Ret ; there is a file name GetNext Endp Page ; ; Load entire directory into memory LoadDir Proc Near Call ReadMst ;Get master DIR entry Jnc Load2 Mov DX,Offset Msg3 ;Say I/O ERROR Jmp Errmsg Load2: Call Verify ;Validate master entry Jnc Load3 Mov DX,Offset Msg6 ;Say INVALID LBR FORMAT Jmp Errmsg Load3: Call ReadLib ;Read remainder of directory Jnc Load4 Mov DX,Offset Msg3 Jmp ErrMsg Load4: Call ChkCRC ;Validate directory CRC Test Mode,8 ; is it okay? Jz Load5 ; yup Mov DX,Offset CRC_Bad Call PrintS Load5: Ret ErrMsg: Call PrintS ;Display error message Mov DX,Offset LbrName Jmp Error Msg3 Db CR,LF,'I/O error writing',CR,LF,Stopper Msg6 Db CR,LF,'Invalid LBR format: ',Stopper CRC_Bad Db CR,LF,'Directory CRC invalid',CR,LF,Stopper LoadDir Endp Page ; ; Search for requested file Search Proc Near ; First member from FilePtr Call GetNext ; Any members specified? Jz Search0 ; no, extract all members Call Fcbname ; yes, change name to FCB format Search0: Mov AX,S_Dir ; Offset to DIR in memory Add AX,Dir_Len ; bump over master entry Mov DirPtr,AX Mov AX,Entries ; Reset directory entries counter Mov Counter,AX Search1: Mov BX,DirPtr ;Point to current entry Cmp [BX].D_Stat,Deleted ;Entry deleted? Je Search2 ; yes, skip it Cmp [BX].D_Stat,Active ;Is entry in use? Jne Search2 ; no, skip it Cmp Member,' ' ; Want all files? Je Search3 ; yes, extract it Lea DI,[BX].D_File-1 ; Directory file name Mov SI,Offset Member ; Selected member name Mov CX,11 Search7:Lodsb Inc DI Cmp AL,'?' ; Wildcard? Je Search5 ; yup, consider a match Cmp AL,Byte Ptr [DI] Jne Search2 Search5:Loop Search7 ; No match Search3:Call Extract ; Matched, extract it Search2:Add DirPtr,Size DirNtry ; Next directory entry Dec Counter ; Number of dir entries Jnz Search1 ; not found, try next entry Cmp NewName,0 ; Extracted any files? Jne Search4 ; yes, normal exit Mov DX,Offset Msg10 ; no, say file not found Jmp Error Search4: Call GetNext ; Any more to select? Jz Search9 ; no, done Call FcbName Jmp Search0 ; yes, all again Search9: Ret Search Endp Page ; ; Extract the requested file Extract Proc Near ;BX points to directory entry Mov AX,[BX].D_Len ;Number of sectors Mov NumSecs,AX Mov AX,[BX].D_Ptr ;Get offset to data Mul SecSize Mov CX,DX ; in CX:DX for LSEEK Mov DX,AX Call Lseek ;Reposition input Call FixName ;Format FCB file name Call Create ;Create output file Mov DX,Offset MsgE ;Say extracting Call PrintS Ext3: Mov AX,NumSecs ;Total data sectors Cmp AX,BufSec ;Will fit in one buffer? Jbe Ext4 ; yes, just one r/w Mov AX,BufSec ; no, set max size to read Ext4: Mul SecSize ;Sectors*size = bytes to read Mov BufSize,AX Call Read ;Read a block Mov AX,BufSec Cmp NumSecs,AX ;Last block? Ja Ext6 ; no, full block Test Mode,4 ;LU86 format? Jz Ext6 ; no, use entire size Mov DL,Byte Ptr [BX].D_Pad ; yes, less pad Sub DH,DH Sub BufSize,DX Ext6: Call Write ;Write a block Mov AX,BufSec Sub NumSecs,AX ;Get number of sectors left Js Ext7 ; no more, return Jnz Ext3 ; more, read next block Ext7: Call GetDate ;Original member date Call SetDate ; as new file date Call CloseO ;Close output Ret Extract Endp Subttl --- Subroutines Page ; ; Read a Sector Subroutine Read Proc Near ;Read a sector Push BX Mov BX,IHandle ;File handle Mov CX,BufSize ;Number of bytes Mov DX,S_Buf Push DS Mov DS,DX Sub DX,DX Mov AH,3Fh ;Read from file Int 21h Pop DS Jc Err2 Or AX,AX ;Any data read? Jz Err2 ; no, send message Pop BX Ret Err2: Mov DX,Offset Msg2 ;Say I/O error reading Jmp Error Read Endp ; ; Write a Sector Subroutine Write Proc Near ;Write a sector Push BX Mov BX,OHandle ;File handle Mov CX,BufSize ;Bytes to write Push DS Mov DX,S_Buf Mov DS,DX Sub DX,DX Mov AH,40h ;Write to a file Int 21h Pop DS Jc Err3 Pop BX Ret Err3: Mov DX,Offset Msg3 ;Say I/O error writing Jmp Error Write Endp ; ; Create File Subroutine Create Proc Near ;Create output file Sub CX,CX ;Normal attribute Mov DX,Offset NewName ;New file name Mov AH,3Ch ;Create a file Int 21h Jc Err8 Mov OHandle,AX ;Save file handle Ret ; and return Err8: Mov DX,Offset Msg8 ;Say CREATE failed Call PrintS Mov DX,Offset NewName Jmp Error Create Endp ; ; Position File Subroutine Lseek Proc Near Push BX Mov AX,4200h ;Reposition to member data Mov BX,IHandle Int 21h ; pointed to by CX:DX Jc Err7 Pop BX Ret Err7: Mov DX,Offset Msg7 ;Say LSEEK FAILED Jmp Error Lseek Endp ; ; Close file handle CloseLbr Proc Near ;Close input (library) Push BX Mov BX,Ihandle Mov AH,3Eh Int 21h Pop BX Ret CloseLbr Endp CloseO Proc Near ;Close output Push BX Mov BX,OHandle Mov AH,3Eh Int 21h Pop BX Ret CloseO Endp Page ; ; Get original member/file date/time GetDate Proc Near ;Determine original date Push BX Test Mode,5 ;Date in directory? Jz GetDat1 ; no, use LBR file date Test Mode,1 ;ASCII stamps? Jnz GetDat2 ; no, maybe LU86 format Mov CX,Word Ptr [BX].D_Utime Mov DX,Word Ptr [BX].D_Udate Or CX,CX ;Any update time? Jnz GetDat3 Mov CX,Word Ptr [BX].D_Ctime Mov DX,Word Ptr [BX].D_Cdate GetDat3:Call CPM_Date Pop BX Ret ; Convert ASCII date/time to DOS date format GetDat2:Sub Byte Ptr [BX].D_Ctime,'8' ;Adjust year Mov AX,Word Ptr [BX].D_Ctime Call Cnvrt Mov DH,AL Shl DH,1 Mov AX,Word Ptr [BX].D_CRC ; Month Call Cnvrt Mov DL,AL Mov CL,5 Shl DL,CL Mov CL,3 Shr AL,CL Or DH,AL Mov AX,Word Ptr [BX].D_CRC+3 ; Day Call Cnvrt Or DL,AL Push DX Mov AX,Word Ptr [BX].D_Utime ; Hour Call Cnvrt Mov CL,3 Shl AL,CL Mov DH,AL Mov AX,Word Ptr [BX].D_Utime+3 ; Minute Call Cnvrt Mov DL,AL Mov CL,5 Shl DL,CL Mov CL,3 Shr AL,CL Or DH,AL Mov AX,Word Ptr [BX].D_Utime+6 ; Second Call Cnvrt Or DL,AL Mov CX,DX Pop DX Pop BX Ret GetDat1: Mov BX,IHandle Mov AX,5700h ;Get input file date/time Int 21h ; in DX:CX Pop BX Ret GetDate Endp Page ; ; Set output file date/time SetDate Proc Near ;Set output date/time Push BX ; from DX:CX Mov BX,OHandle Mov AX,5701h ;Change output file date Int 21h Pop BX Ret SetDate Endp Cnvrt Proc Near ;Convert ASCII to binary Xchg AH,AL And AH,0Fh And AL,0Fh Aad Ret Cnvrt Endp Page ; ; Convert CPM date CPM_Date Proc Near ;Convert CP/M date Push AX ; to DOS format in DX Push BX Push CX Push SI Mov AX,DX ;Days since 12/31/77 Sub CX,CX ;Years since Mov DX,OneYear CD1: Sub AX,DX ; for 1978 Jle CD2 Inc CL Sub AX,DX ; for 1979 Jle CD2 Inc CL Inc DX Sub AX,DX ; for next leap year Jle CD2 Dec DX Inc CL Sub AX,DX ; and year after Jle CD2 Inc CL Jmp Short CD1 CD2: Add AX,DX Mov DX,AX ;Save days left over CD3: Mov AX,CX ;Adjust year Add AL,78 ; plus base year Mov Days+1,28 ;Days in Feb Test AL,3 ;Is it leap year? Jnz CD4 ; no, has 28 Mov Days+1,29 ; yes, has one more CD4: Mov Year,AX ;Save year Mov SI,Offset Days ; point to days/month Sub AX,AX Sub BX,BX Mov BL,1 ; month number CD5: Lodsb Sub DX,AX ; days into month Jle CD6 ; within month Inc BL Jmp Short CD5 CD6: Add DX,AX Mov AX,Year ;Combine into DOS format Sub AX,80 Mov CL,9 Shl AX,CL Mov CL,5 Shl BX,CL Add AX,BX ; year and month Add DX,AX ; and day Pop SI Pop CX Pop BX Pop AX Ret Days Db 31,28,31,30,31,30,31,31,30,31,30,31 OneYear Equ 365 ;Days in normal year CPM_Date Endp Page ; ; Format new file name FixName Proc Near Mov DI,Offset NewName ;Clear target name Mov SI,Offset Blanks Mov CX,12 Rep Movsb Lea SI,[BX].D_File ;Must convert FCB name format Mov DI,Offset NewName ; to ASCIIZ format for Int 21 Mov CX,8 Fix5: Lodsb ;Copy name part Cmp AL,' ' Je Fix7 Stosb Loop Fix5 Fix7: Cmp Byte Ptr [BX].D_Ext,' ' Je Fix9 ;If not extension Mov AL,'.' ;Otherwise, dlimit the parts Stosb Mov CX,3 Lea SI,[BX].D_Ext ;Extension part in dir name Fix8: Lodsb Cmp AL,' ' ;Copy non-blank chars Je Fix9 Stosb Loop Fix8 Fix9: Mov AL,0 ;Final ASCIIZ stopper Stosb Ret FixName Endp ; ; Change filename to FCB format FcbName Proc Near Mov SI,Offset Blanks ; Clear target MEMBER field Mov DI,Offset Member Mov CX,11 Rep Movsb Mov SI,Offset FileNm ; Reformat to FCB style Mov DI,Offset Member Mov CX,9 Fcbnm1: Lodsb ; Next filename char Cmp AL,'a' ; Insure in upper case Jb FcbNm2 Cmp AL,'z' Ja FcbNm2 Sub AL,32 ; Make it upper case FcbNm2: Cmp AL,'.' Je Fcbnm3 Cmp AL,'*' ; Wildcard? Je FcbNm8 ; yes, expand it Cmp AL,0 ; End of ASCIIZ name? Je FcbNm7 Stosb ; Copy name part Loop Fcbnm1 FcbNm7: Jmp Short Fcbnm9 ; If no extension FcbNm8: Mov AL,'?' ; Expand * wildcard Rep Stosb Lodsb Cmp AL,'.' ; Is there one? Jne FcbNm9 ; no, have it all Fcbnm3: Mov DI,Offset Ext ; Copy extension Mov CX,3 Fcbnm4: Lodsb ; Copy extension Cmp AL,'a' ; Insure in upper case Jb FcbNm5 Cmp AL,'z' Ja FcbNm5 Sub AL,32 ; Make it upper case FcbNm5: Cmp AL,'*' ; Have wildcard? Je FcbNm6 ; yes, expand it Cmp AL,0 ; End of ASCIIZ name? Je FcbNm9 Stosb Loop Fcbnm4 Jmp Short FcbNm9 FcbNm6: Mov AL,'?' ; Expand ext wildcards Rep Stosb Fcbnm9: Ret FcbName Endp Page ; ; Print String PrintS Proc Near ;Print string like Int 21h (9) Push BX ;DX points to string Push BP Push SI Mov SI,DX PS1: Lodsb Cmp AL,0 ;Skip zeros Je PS1 Cmp AL,255 ;String ends in a hex FF Je PS9 ; so can print $ Mov AH,2 ;Use std output device Mov DL,AL Int 21h Jmp Short PS1 PS9: Pop SI Pop BP Pop BX Ret PrintS Endp Page ; ; Build directory in memory ReadMst Proc Near Mov BX,Ihandle ;Read master directory entry Mov CX,32 ; first 32-byte record Mov DX,S_Dir Mov AH,3Fh Int 21h Jc Error3 Cmp AX,CX ;Got all of it? Jne Error3 Ret ReadLib: ;Read remaining entries Mov BX,S_Dir Mov AX,Word Ptr [BX].D_Len ;Sectors for direc. Sub DX,DX Shl AX,1 ;Calc number of entries Shl AX,1 ; four per sector Dec AX ; less master entry Mov Entries,AX Mov CL,5 ;Calc size remaining Shl AX,CL Mov CX,AX Mov LenDir,CX ;Save length Add LenDir,Dir_Len ; of entire directory Mov BX,IHandle ;Read rest of directory Mov DX,S_Dir Add DX,Dir_Len Mov AH,3Fh Int 21h Jc Error3 Cmp AX,CX ;Got all of it? Jne Error3 Ret Error3: Clc Ret ReadMst Endp Page ; ; Validate master directory entry Verify Proc Near Mov BX,S_Dir Sub AX,AX Cmp Byte Ptr [BX].D_Stat,AL ;Active first entry? Jne NotLBR Cmp Word Ptr [BX].D_Ptr,AX ;Valid index pointer? Jne NotLBR Mov Mode,AL ;Init LBR type and Mov CX,11 ;Check name of blanks Lea SI,Word Ptr [BX].D_File Mov DI,Offset Blanks Repe Cmpsb Jne Ver4 Cmp Word Ptr [BX].D_CRC,CX ;Any CRC? Je Ver2 Or Mode,2 ; yes... Ver2: Cmp Word Ptr [BX].D_Ctime,CX Je Ver9 ;Any LU86 stamps? Or Mode,4 ; yes... Jmp Short Ver9 Ver4: Mov CX,11 ;May be new format Lea SI,Byte Ptr [BX].D_File Mov DI,Offset DirKey Repe Cmpsb Jne NotLBR Mov Mode,1 ;Indicate ***DIR format Ver9: Clc ;Return CD=0 Ret NotLBR: Stc ;or CF=1 if not LBR Ret Verify Endp Page ; ; Check CRC for directory ChkCRC Proc Near And Mode,0FFh-8 ;Clear error indication Test Mode,2 ;LU86 CRC included? Jz ChkCRC9 ; no, skip it Mov SI,S_Dir ;Calculate directory CRC Mov BX,SI Mov CX,LenDir Mov DX,Word Ptr [BX].D_CRC ;Save original CRC Or DX,DX ; any used? Jz ChkCRC9 ; nope, skip check Mov Word Ptr [BX].D_CRC,0 Call GetCRC ;CRC for directory block Call UpdCRC ; and for end-of-block Mov Word Ptr [BX].D_CRC,DX Cmp AX,DX ;CRC correct? Je ChkCRC9 Or Mode,8 ; no, indicate error ChkCRC9:Ret ChkCRC Endp ; ; Calculate CRC for a block from CCIT polynomial ; ; CRC = x^16 + x^12 + x^5 + 1 GetCRC Proc Near ;SI points to data Push BX ;CX contains length Push DX Sub BX,BX ;Zero resultant CRC GetCRCs:Mov DX,CX GetCRC0:Mov CX,8 ; bits in a byte Lodsb ; get next byte GetCRC1:Rol AL,1 ;MSB -> carry Rcl BX,1 ; -> CRC LSB Jnc GetCRC2 Xor BX,1021h GetCRC2:Loop GetCRC1 Dec DX Jnz GetCRC0 Mov AX,BX ;Return CRC in AX Pop DX Pop BX Ret GetCRC Endp ; Update CRC at end of block UpdCRC Proc Near ;CRC in AX Push BX Push DX Mov BX,AX ;Current CRC Mov CX,2 ;Last two bytes Mov SI,Offset Zero ; of zero Jmp Short GetCRCs Zero Dw 0 UpdCRC Endp Page Lue Endp Storage Equ This Byte Stackx Equ Storage+256 ; Local stack end ParmFld Equ Stackx+4 ; Command line operands MyDta Equ ParmFld+128 ; Disk data transfer area LbrName Equ MyDta+48 WorkEnd Equ LbrName+77 Paras_C Equ (WorkEnd-Cseg+2048)/16 ; Paragraphs in program and stack Cseg Ends End Lue