Power CD-ROM!! 8

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Assembly Source File | 1994-09-27 | 37.2 KB | 770 lines

_TEXT SEGMENT PUBLIC 'CODE' ASSUME CS:_TEXT,DS:_TEXT,ES:_TEXT,SS:_TEXT ORG 100H START: JMP MAIN ; DATA AREA ; --------- SIGNATURE DB CR,SPACE,SPACE,SPACE,CR,LF COPYRIGHT DB "SHRED 1.0 (c) 1995 Michael J. Mefford",CR,LF First_Rights DB "First Published in PC Magazine, " DB "January 10, 1995",CR,LF,LF DB "Syntax: SHRED [d:] [filespec] [/S] [/F | /D] [/C]",CR,LF,LF DB "Insures confidentiality by writing zeros over sensitive data",CR,LF DB "/S Subdirectories.",CR,LF DB "/F Free space on disk shredded.",CR,LF DB "/D Delete only; no shredding.",CR,LF DB "/C Confirmation before shredding suppressed." DOUBLE_SPACE DB LF CR_LF DB CR,LF,0,CTRL_Z CR EQU 13 LF EQU 10 CTRL_Z EQU 26 SPACE EQU 32 BOX EQU 254 Y_SCAN EQU 15H N_SCAN EQU 31H ESC_SCAN EQU 01H CTRL_C EQU 03H ENTER_SCAN EQU 1CH DIRECTORY EQU 10H MATCHING STRUC RESERVED DB 21 DUP (?) ATTRIBUTE DB ? FILE_TIME DW ? FILE_DATE DW ? SIZE_LOW DW ? SIZE_HIGH DW ? FILE_NAME DB 13 DUP (?) MATCHING ENDS BYTES_PER_CLUSTER DW ? AVAILABLE_HIGH DW ? AVAILABLE_LOW DW ? ZERO_SEG DW ? CTRL_BREAK DB ? CURRENT_DISK DB ? FILESPEC DW ? DIRECTORY_LINE DW ? OPEN_FORMAT DW 3C00H ;Create file. SWITCH_FLAG DB 0 SUBDIRS EQU 01H FREE EQU 02H DELETE_ONLY EQU 04H CONFIRM EQU 08H DISK EQU 10H NOT_FOUND DB CR,LF,"File not found",0 NOT_ENOUGH DB "Not enough memory",0 DIRECTORY_OF DB "Directory of ",0 SHREDDING DB "Shredding ",0 DELETING DB "Deleting ",0 FREE_SPACE DB "All the FREE space of drive ",0 WILL_BE DB "will be ",0 SHREDDED DB "shredded. ",0 DELETED DB "deleted. ",0 WORKING DB "... working",0 WARNING DB "WARNING: ",0 CONTINUE DB "Continue? (Y/N or Esc to Quit) ",0 TO_CONFIRM DB CR,LF,"(Press ",17,217," to confirm, Esc to cancel) ",0 ABORTED DB CR,LF,LF,"Aborted",CR,LF,0 TEMP DB "SHRED.TMP",0 STAR_DOT_STAR DB "*.*",0 DOT_DOT DB "..",0 PROTECTED_FILE DB "is a read-only and can't be shredded. Press any key.",0 ; CODE AREA ; --------- MAIN PROC NEAR CLD ;String moves forward. MOV AX,500H INT 10H ;Select active page zero. MOV AH,0FH INT 10H ;Get current video mode. CMP AL,7 ;If it's MONO, JZ CK_CURSOR CMP AL,2 ; CO80, JZ CK_CURSOR CMP AL,3 ; or BW80, then OK mode. JZ CK_CURSOR MOV AX,3 ;Else, change to CO80. INT 10H CK_CURSOR: CALL GET_CURSOR ;Read cursor position. CMP DH,1 ;If DOS prompt already JZ SIGN_ON ; at top, skip move. MOV AH,8 ;Else, read attr/char INT 10H ; at cursor position. MOV BH,AH ;Move DOS command line to top XOR CX,CX ; of screen by scrolling active MOV DL,80 - 1 ; page with current attribute. MOV AL,DH DEC AL MOV AH,6 INT 10H SIGN_ON: MOV DX,100H ;Set cursor to line 2 (logical 1) CALL SET_CURSOR MOV SI,OFFSET SIGNATURE ;And display copyright CALL PRINT_STRING ; and syntax. MOV BX,OFFSET ZEROS ;Allocate memory for code, stack ADD BX,15 ; and 64K for a segment of zeros. MOV CL,4 SHR BX,CL MOV AX,DS ADD AX,BX MOV ZERO_SEG,AX ;Save address of segment of zeros ADD BX,4096 MOV AH,4AH INT 21H JNC SETUP_STACK MOV SI,OFFSET NOT_ENOUGH ;Error msg if not enough memory. JMP MSG_EXIT SETUP_STACK: MOV SP,OFFSET STACK_PTR ;Move stack pointer down. MOV DX,OFFSET DTA ;To preserve command line, change MOV AH,1AH ; DTA from PSP to end of code. INT 21H MOV ES,ZERO_SEG ;Fill extra segment with zeros. XOR DI,DI XOR AX,AX MOV CX,32768 REP STOSW PUSH CS POP ES MOV AX,3300H ;Retrieve current Ctrl INT 21H ; break state and store. MOV CTRL_BREAK,DL XOR DL,DL MOV AX,3301H ;Turn Ctrl break off. INT 21H MOV AH,19H ;Get current drive INT 21H MOV CURRENT_DISK,AL ; and save. ;----------------------------------------------; PARSE: MOV SI,81H ;Point to command line parameter. FIND_SWITCH: LODSB ;Get a byte. CMP AL,CR ;Carriage return marks end. JZ FIND_FILESPEC ;If end, done here. CMP AL,"/" ;Is it a switch character? JNZ FIND_SWITCH ;If no, next byte. LODSB ;Else, retrieve switch. AND AL,5FH ;Else, capitalize. CMP AL,"S" ;Is it subdirectories? JNZ CK_FREE ;If no, check free switch. OR SWITCH_FLAG,SUBDIRS ;Else, flag to do subdirectories. CK_FREE: CMP AL,"F" ;Is it disk free switch? JNZ CK_DELETE ;If no, check delete switch. OR SWITCH_FLAG,FREE ;Else, flag to zero free space. CK_DELETE: CMP AL,"D" ;Is it delete-only switch? JNZ CK_CONFIRM ;If no, check confirm switch. OR SWITCH_FLAG,DELETE_ONLY ;Else, flag to delete-only. CK_CONFIRM: CMP AL,"C" ;Is it suppress confirm switch? JNZ BAD_SWITCH ;If no, exit. OR SWITCH_FLAG,CONFIRM ;Else, flag to suppress prompts. JMP FIND_SWITCH ;Next switch. BAD_SWITCH: MOV AL,1 JMP RESTORE ;------------------------------------------------------------------; ; Parse drive and/or path delimiters. Convert filespec to ASCIIZ. ; ; If drive delimiter found (:), change to requested drive. ; ;------------------------------------------------------------------; FIND_FILESPEC: MOV SI,81H ;Point to command line parameter. PARSE_LEADING: LODSB ;Get a byte. CMP AL,SPACE ;Is it a space char or below? JA LEADING_END ;If no, done here. CMP AL,CR ;Is it carriage return? JNZ PARSE_LEADING ;If no, get next byte. LEADING_END: DEC SI ;Adjust pointer to string start. MOV BP,SI ;Save start of filespec. MOV BX,SI ;Use BX as filename start pointer FIND_END: LODSB ;Get a byte. CMP AL,":" ;Is it a drive delimiter? JNZ CK_SLASH ;If no, check path delimiter. MOV DL,[SI-2] ;Else, retrieve drive specifier. AND DL,5FH ;Capitalize. SUB DL,"A" ;Convert to DOS format. MOV AH,0EH ;Change drive. INT 21H MOV BX,SI ;Save as filename start. JMP FIND_END ;Continue parsing. CK_SLASH: CMP AL,"\" ;Is it a path delimiter? JNZ CK_DELIMITER ;If no, check switch character. MOV BX,SI ;Else, save as filename start. CK_DELIMITER: CMP AL,"/" ;Is it a switch delimiter? JZ FOUND_END ;If yes, end of filespec. CMP AL,SPACE ;Is it above space character? JA FIND_END ;If yes, continue until find end. FOUND_END: DEC SI ;Adjust. PUSH SI ;Save filespec end. PUSH BX ;Save filespec start. MOV BYTE PTR [SI],0 ;Convert to ASCIIZ. CMP BP,SI ;Any filespec? JZ NO_SPEC ;If no, treat as /F. CMP BYTE PTR [SI - 1],":" ;Drive specifier only? JNZ GET_CURRENT ;If no, skip NO_SPEC: OR SWITCH_FLAG,DISK GET_CURRENT: MOV SI,OFFSET CURRENT_DIR ;Retrieve current directory. CALL GET_DIR MOV AH,19H ;Retrieve current disk. INT 21H ADD AL,"A" ;Convert to ASCII. MOV BYTE PTR WORKING_DIR,AL ;Save drive MOV BYTE PTR WORKING_DIR + 1,":" ; and colon delimiter. CALL GET_AVAILABLE ;Get disk free space. TEST SWITCH_FLAG,FREE OR DISK ;Was there /F or no filespec JZ FIND_PATH ; or drive-only?; If no, skip. TEST SWITCH_FLAG,DELETE_ONLY ;Was there /D delete only? JNZ FIND_PATH ;If yes, skip. CALL SHRED_FREE ;Else, shred free disk space. MOV SI,OFFSET DOUBLE_SPACE ;Add double space CALL PRINT_STRING ; between outputs. ;-------------------------------------------------; FIND_PATH: POP BX ;Retrieve filename start. POP SI ;Retrieve filespec end. TEST SWITCH_FLAG,DISK ;Was filespec drive-only? JZ CK_ROOT ;If no, continue. JMP GOOD_EXIT ;Else, done. CK_ROOT: MOV CX,1 ;CX=1:"\"not=root; CX=0:"\"=root. CMP BYTE PTR [BX - 1],"\" ;Filespec start path delimiter? JNZ CK_PATH ;If no, not root. CMP BYTE PTR [BX - 2],":" ;Else, is it prefaced with colon? JZ ROOT ;If yes, then root. CMP BYTE PTR [BX - 2],SPACE ;Is it prefaced with white space? JA CK_TRAILING ;If no, then trailing slash? ROOT: DEC CX ;Else, root; CX=0 for root flag. JMP SHORT CK_PATH ;Change default path. CK_TRAILING: CMP BX,SI ;Filename start = filespec end? JNZ CK_PATH ;If no, not trailing slash. MOV BYTE PTR [BX - 1],0 ;Else, zero out trailing slash MOV BX,OFFSET STAR_DOT_STAR ; and use global filespec. CK_PATH: MOV DX,BP ;See if filespec is a path CALL CHANGE_DIR ; by changing directory. JC CK_FILESPEC ;If failed, remove filename. MOV BX,OFFSET STAR_DOT_STAR ;Else, use global for filename. JMP SHORT GOT_FILESPEC ;Done here. CK_FILESPEC: JCXZ SAVE_DELIMIT ;Is path root?; If yes leave "\". DEC BX ;Else, point to slash. SAVE_DELIMIT: PUSH [BX] ;Preserve filename start. MOV BYTE PTR [BX],0 ;Temp ASCIIZ twixt path and name. CALL CHANGE_DIR ;Change directory. POP [BX] ;Restore first byte of filename. JCXZ GOT_FILESPEC ;If root, done here. INC BX ;Else, readjust filename pointer. GOT_FILESPEC: MOV FILESPEC,BX ;Save filename. ;----------------------------------------------; MOV BP,OFFSET TREE_LEVEL ;Initialize directory tree MOV DI,BP ; level array to level one. MOV AX,0101H MOV CX,50 REP STOSW CALL GET_CURSOR ;Get relative line for MOV DIRECTORY_LINE,DX ; directory display. MOV OPEN_FORMAT,3D01H ;Open file for writing. NEXT_LEVEL: MOV SI,OFFSET WORKING_DIR + 2 ;Display current directory. CALL GET_DIR MOV SI,OFFSET DIRECTORY_OF CALL PRINT_STRING MOV SI,OFFSET WORKING_DIR CALL PRINT_STRING FIND_FIRST: MOV DX,FILESPEC ;Find first matching normal XOR CX,CX ; file to filespec. MOV AH,4EH INT 21H JNC CK_READ_ONLY MOV SI,OFFSET NOT_FOUND ;If failed, display message. CALL PRINT_STRING JMP SHORT CK_SUBDIRS ;Check /Subdir switch. FIND_NEXT: MOV AH,4FH ;Find next matching file. INT 21H JC CK_SUBDIRS ;If failed, check /Subdir switch. CK_READ_ONLY: TEST BYTE PTR DTA.ATTRIBUTE, 1 JZ CK_WARNING MOV DX,DIRECTORY_LINE INC DH CALL BLANK_LINE CALL DISPLAY_NAME MOV SI,OFFSET PROTECTED_FILE CALL PRINT_STRING CALL CLEAR_KEY CALL GET_KEY JMP FIND_NEXT CK_WARNING: MOV DX,DIRECTORY_LINE ;Move cursor to line below INC DH ; directory. CALL BLANK_LINE ;Blank out last display. TEST SWITCH_FLAG,CONFIRM ;Did user suppress prompts? JNZ NO_WARNING ;If yes, no warning. MOV SI,OFFSET WARNING ;Else, display warning message. CALL PRINT_STRING CALL DISPLAY_NAME ;Display complete stats of file. MOV SI,OFFSET WILL_BE CALL PRINT_STRING ;Display message. TEST SWITCH_FLAG,DELETE_ONLY JZ MESSAGE1 MOV SI,OFFSET DELETED MESSAGE1: CALL PRINT_STRING CALL PROMPT ;Ask user if should continue. JC FIND_NEXT ;If no, find next matching. CALL SHRED_FILE ;Else, shred the file. JMP FIND_NEXT ;Find next matching file. NO_WARNING: CALL CK_KEY ;Let user abort the /C suppress JNZ ERROR_EXIT ; confirm mode with any keypress. MOV SI,OFFSET SHREDDING ;Display message TEST SWITCH_FLAG,DELETE_ONLY JZ MESSAGE2 MOV SI,OFFSET DELETING MESSAGE2: CALL PRINT_STRING CALL DISPLAY_NAME ; and file stats. CALL SHRED_FILE ;Shred the file. JMP FIND_NEXT ;Next matching. ;----------------------------------------------; CK_SUBDIRS: TEST SWITCH_FLAG,SUBDIRS ;Was there a /Subdir switch? JNZ FIRST_DIR ;If yes, continue. JMP SHORT GOOD_EXIT ;Else, exit. PARENT_DIR: CMP BP,OFFSET TREE_LEVEL ;Are we at tree level where we JZ GOOD_EXIT ; started? If yes, done here. MOV BYTE PTR [BP],1 ;Else, first dir of this level. DEC BP ;Go down a level. MOV DX,OFFSET DOT_DOT ;Change to parent directory. CALL CHANGE_DIR FIRST_DIR: XOR BL,BL ;BL = directory number. MOV DX,OFFSET STAR_DOT_STAR ;Global search. MOV CX,DIRECTORY ;Ask for directories. MOV AH,4EH INT 21H JC PARENT_DIR ;If no match, down a level. JMP SHORT CK_DIR ;Else, see if it's a directory. NEXT_DIR: MOV AH,4FH ;Get all subdirectories in INT 21H ; current directory then JC PARENT_DIR ; to parent. CK_DIR: CMP BYTE PTR DTA.ATTRIBUTE,DIRECTORY ;Is it a directory? JNZ NEXT_DIR ;If no, next matching. CMP BYTE PTR DTA.FILE_NAME,'.' ;is it a dot directory? JZ NEXT_DIR ;If no, next matching. INC BL ;Increment position in directory. CMP BL,[BP] ;Continue until new directory. JNZ NEXT_DIR INC BYTE PTR DS:[BP] ;Update this level dir count. MOV DX,OFFSET DTA.FILE_NAME CALL CHANGE_DIR ;Change the directory. INC BP ;Up a level. MOV DX,DIRECTORY_LINE ;Blank out last display. CALL BLANK_LINE JMP NEXT_LEVEL ;Get all files in new directory. ;----------------------------------------------; ERROR_EXIT: MOV SI,OFFSET ABORTED ;Display abort message. MSG_EXIT: CALL PRINT_STRING MOV AL,1 ;ERRORLEVEL = 1. JMP SHORT RESTORE ;Restore defaults. GOOD_EXIT: XOR AL,AL ;ERRORLEVEL = 0. RESTORE: PUSH AX ;Save ERRORLEVEL. MOV DL,CTRL_BREAK ;Restore break state. MOV AX,3301H INT 21H MOV DX,OFFSET CURRENT_DIR ;Restore default directory. CALL CHANGE_DIR MOV DL,CURRENT_DISK ;Restore default drive. MOV AH,0EH INT 21H POP AX ;Retrieve ERRORLEVEL. EXIT: MOV AH,4CH INT 21H ;Terminate. MAIN ENDP ;***************; ;* SUBROUTINES *; ;***************; SHRED_FREE: PUSH BP ;Preserve base pointer. MOV DX,OFFSET TEMP ;See if temporary file exits. MOV CX,1FH ;Use all attributes. NEXT_TEMP: MOV AH,4EH INT 21H JC GOT_TEMP ;If it doesn't, OK. MOV BX,DX INC BYTE PTR [BX] ;Else, change name. JNZ NEXT_TEMP ;Give up after several name JMP ERROR_EXIT ; changes and abort. GOT_TEMP: MOV BP,DX ;Point to temporary filename. TEST SWITCH_FLAG,CONFIRM ;Do we need user permission to JNZ NO_PROMPT ; continue? If no, no prompt. CALL FREE_MSG ;Else, display message. MOV SI,OFFSET WILL_BE CALL PRINT_STRING MOV SI,OFFSET WILL_BE CALL PRINT_STRING CALL PRINT_STRING MOV SI,OFFSET CR_LF CALL PRINT_STRING CALL PROMPT ;Ask user if should continue. JC FREE_END ;If no, done here. JMP SHORT DO_FREE ;Else, shred the disk free space. NO_PROMPT: CALL CK_KEY ;Let user abort the /C suppress JNZ ERROR_EXIT ; confirm mode with any keypress. MOV SI,OFFSET SHREDDING ;Display message. CALL PRINT_STRING CALL FREE_MSG MOV SI,OFFSET WORKING ;Display "... working" message. CALL PRINT_STRING DO_FREE: MOV SI,AVAILABLE_HIGH ;Create a temporary file and MOV DI,AVAILABLE_LOW ; write zeros bytes equal to CALL WRITE_ZEROS ; the amount of free space. FREE_END: POP BP ;Restore base pointer. RET ;----------------------------------------------; FREE_MSG: MOV SI,OFFSET FREE_SPACE ;Display free space message. CALL PRINT_STRING MOV AL,BYTE PTR WORKING_DIR ;Display the working drive. MOV AH,0EH INT 10H MOV AX,0EH SHL 8 + SPACE INT 10H RET ;----------------------------------------------; SHRED_FILE: PUSH BP ;Preserve base pointer. MOV BP,OFFSET DTA.FILE_NAME ;Point to filename. MOV SI,DTA.SIZE_HIGH ;Retrieve size of file. MOV DI,DTA.SIZE_LOW MOV DX,SI MOV AX,DI MOV CX,BYTES_PER_CLUSTER ;Round up file size to nearest DIV CX ; whole cluster by dividing by SUB CX,DX ; bytes per cluster and ADD DI,CX ; adding remainder to size. ADC SI,0 CALL WRITE_ZEROS ;Write zeros over the file. POP BP ;Restore base pointer. RET ;---------------------------------------------------------------; ; INPUT: BP -> filename; SI:DI = number of zero bytes to write. ; ;---------------------------------------------------------------; WRITE_ZEROS: TEST SWITCH_FLAG,DELETE_ONLY ;Is the delete-only flag set? JNZ DELETE_FILE ;If yes, don't write zeros. MOV DX,BP ;Filename pointer. XOR CX,CX ;Normal attribute. MOV AX,OPEN_FORMAT ;Create new or open existing. INT 21H JC WRITE_FAIL ;If failed, exit. MOV BX,AX ;Else, save filehandle. NEXT_WRITE: MOV CX,DI ;Retrieve low half of byte count. OR SI,SI ;Is high half zero? JZ SUBTRACT ;If yes, continue. MOV CX,0FFFFH ;Else, write full word (65535). SUBTRACT: SUB DI,CX ;Subtract from running count. SBB SI,0 ;If borrow, adjust high half. JCXZ CLOSE_FILE ;If zero bytes, done here. PUSH DS ;Preserve data segment. MOV DS,ZERO_SEG ;Use segment of zeros. XOR DX,DX ;Offset of zero. MOV AH,40H ;Write to file. INT 21H POP DS ;Restore data segment. JC WRITE_FAIL ;If failed, exit. CMP AX,CX ;Did we write what we asked? JNZ WRITE_FAIL ;If no, failed; exit. JMP NEXT_WRITE ;Else, write next chunk. CLOSE_FILE: MOV AH,3EH ;Close file. INT 21H JC WRITE_FAIL ;If failed, exit. DELETE_FILE: MOV DX,BP MOV AH,41H ;Delete file. INT 21H JC WRITE_FAIL ;If failed, exit. ZEROS_END: RET WRITE_FAIL: MOV DX,OFFSET NOT_FOUND ;With all failures, display CALL PRINT_STRING ; generic "file not found" JMP ERROR_EXIT ; message and abort. ;----------------------------------------------------------------------; ; OUTPUT: CY = 0: Yes; CY = 1: No; If Esc or ^C, go directly to exit. ; ;----------------------------------------------------------------------; PROMPT: MOV SI,OFFSET CONTINUE ;Display message. CALL PRINT_STRING CALL CLEAR_KEY ;Clear keyboard buffer. GET_INPUT: CALL GET_KEY ;Now get a keystroke. CMP AH,Y_SCAN ;Was it "Y"? JNZ CK_NO MOV AH,0EH ;If yes, display "Y" and INT 10H CALL PRINT_STRING ; ask for confirmation. GET_CONFIRM: CALL GET_KEY CMP AH,ESC_SCAN STC JZ PROMPT_END CMP AH,ENTER_SCAN JNZ GET_CONFIRM MOV SI,OFFSET WORKING CALL PRINT_STRING CLC JMP SHORT PROMPT_END CK_NO: CMP AH,N_SCAN ;Was it "N"? STC JZ PROMPT_END CMP AH,ESC_SCAN ;Was it Esc? JZ BREAK OR AH,AH ;Was it Ctrl Break? JZ BREAK CMP AL,CTRL_C ;Was it Ctrl C? JNZ GET_INPUT ;If Esc, Ctrl Break or Ctrl C, BREAK: JMP ERROR_EXIT ; immediate exit. PROMPT_END: RET ;Else, return keystroke. ;----------------------------------------------; GET_AVAILABLE: XOR DL,DL ;Default drive. MOV AH,36H ;Get disk free space. INT 21H MUL CX ;Bytes/sector * sectors/cluster MOV BYTES_PER_CLUSTER,AX ; equals bytes/cluster. MUL BX ;Avail clusters * bytes/cluster MOV AVAILABLE_HIGH,DX ; equals available bytes. MOV AVAILABLE_LOW,AX RET ;----------------------------------------------; DISPLAY_NAME: MOV SI,OFFSET DTA.FILE_NAME ;Point to filename. MOV DI,OFFSET RESULTS ;And storage area. MOV AX,SPACE SHL 8 + SPACE ;Initiate storage with spaces. MOV CX,20 REP STOSW MOV DI,OFFSET RESULTS ;Point to start of storage again. MOV CX,12 ;Store 12 bytes of filename. NEXT_STORE: LODSB ;Get a byte. OR AL,AL ;End of filename? JZ END_STORE ;If yes, finish with blanks. CMP AL,"." ;Is it the period? JNZ STORE_BYTE ;If no, store. SUB CX,3 ;Else store 3 spaces. MOV AL,SPACE REP STOSB ADD CX,3 JMP SHORT NEXT_STORE ;Get next byte. STORE_BYTE: STOSB ;Store byte. LOOP NEXT_STORE ;Get next byte. END_STORE: MOV AL,SPACE ;Pad balance with spaces. REP STOSB PUSH DI ;Save pointer. ADD DI,8 ;Move to end of bytes field. MOV DX,DTA.SIZE_LOW ;Retrieve high and low words MOV AX,DTA.SIZE_HIGH ; of size in bytes. MOV BX,10 ;Convert to decimal. STD ;Reverse direction. NEXT_SIZE: MOV CX,DX ;Low word in CX. XOR DX,DX ;Zero in high half. DIV BX ;Convert to decimal. XCHG AX,CX ;Retrieve low word. DIV BX XCHG AX,DX ;Retrieve remainder. ADD AL,"0" ;Convert to ASCII. STOSB ;Store it. MOV AX,CX ;Are we done? OR CX,DX JNZ NEXT_SIZE ;If no, divide again. CLD ;Back to forward direction. POP DI ;Retrieve pointer. ADD DI,11 ;Move to date field. DATE: MOV DX,DTA.FILE_DATE ;Retrieve date. MOV AX,DX MOV CL,5 ;Shift to lowest bits. SHR AX,CL AND AX,1111B ;Mask off all but month. MOV CL,0FFH ;Flag as no leading zeros. MOV CH,"-" ;Delimiting character. CALL STORE_WORD ;Store it. MOV AX,DX ;Retrieve date. AND AX,11111B ;Mask off all but day. XOR CL,CL ;Flag include leading zeros. MOV CH,"-" CALL STORE_WORD ;Store it. MOV AX,DX ;Retrieve date for last time. MOV CL,9 SHR AX,CL ;Mask off all but year. ADD AX,80 ;Adjust to ASCII. CMP AX,100 ;Past year 2000? JB DISPLAY_DATE ;If no, display. Else, adjust for SUB AX,100 ; next century. (Planning ahead!) DISPLAY_DATE: XOR CL,CL ;Display leading zeros. MOV CH,SPACE CALL STORE_WORD ;Store it. TIME: INC DI ;Move to time field. MOV DX,DTA.FILE_TIME ;Retrieve time. MOV AX,DX MOV CL,11 ;Shift to hours bits. SHR AX,CL PUSH AX CMP AX,12 ;Past noon? JBE MERIDIAN SUB AX,12 ;If yes, adjust. MERIDIAN: CMP AX,0 ;Midnight? JNZ NOT_MIDNIGHT MOV AX,12 ;If yes, adjust. NOT_MIDNIGHT: MOV CL,0FFH ;Suppress leading zeros. MOV CH,":" CALL STORE_WORD ;Store it. MOV AX,DX ;Retrieve time. MOV CL,5 ;Shift to minutes bits. SHR AX,CL AND AX,111111B ;Mask off all but minutes. XOR CL,CL POP DX ;Retrieve hours. MOV CH,"p" ;Assume PM. CMP DX,12 ;Is it PM? JAE PM MOV CH,"a" ;If no, AM. PM: CALL STORE_WORD ;Store it. XOR AL,AL STOSB MOV SI,OFFSET RESULTS ;Print out results CALL PRINT_STRING MOV SI,OFFSET CR_LF CALL PRINT_STRING RET ;Done here. ;-----------------------------------------------------------------------; ; Converts a two byte hex number to decimal followed by delimiter. ; ; INPUT: AX = hex number; BL = 10; CH = delimiter character to store. ; ; CL = 0 if zeros are to be stored; CL = -1 if leading zeros ignored. ; ; ES:DI points to storage. ; ;-----------------------------------------------------------------------; STORE_WORD: DIV BL ;Divide by ten. ADD AX,"00" ;Convert to ASCII. CMP CL,0 ;Are we to display leading zero? JZ STORE_IT ;If yes, store as is. CMP AL,"0" ;Is it a leading zero? JNZ STORE_IT ;If no, store it. MOV AL,SPACE ;Else, store a space. STORE_IT: STOSW MOV AL,CH ;Store delimiter character also. STOSB RET ;----------------------------------------------; ; INPUT: DX = first row to write spaces. ; ;----------------------------------------------; BLANK_LINE: PUSH DX CALL SET_CURSOR MOV CX,80 * 4 NEXT_BLANK: MOV AX,0EH SHL 8 + SPACE ;Write spaces via BIOS. INT 10H LOOP NEXT_BLANK POP DX CALL SET_CURSOR RET ;----------------------------------------------; GET_DIR: MOV BYTE PTR [SI],"\" ;DOS doesn't preface directory INC SI ; with slash so we must. XOR DL,DL MOV AH,47H ;Get current directory. INT 21H RET CHANGE_DIR: MOV AH,3BH ;Change current directory. INT 21H RET ;----------------------------------------------; SET_CURSOR: XOR BH,BH ;Video page zero. MOV AH,2 ;Set cursor position. INT 10H RET GET_CURSOR: XOR BH,BH MOV AH,3 ;Get cursor position. INT 10H RET ;----------------------------------------------; GET_KEY: XOR AH,AH ;Get a keystroke. INT 16H RET CK_KEY: MOV AH,1 ;ZR = 1 if no keystroke available INT 16H ;ZR = 0 if keystroke is available RET CLEAR_IT: CALL GET_KEY CLEAR_KEY: CALL CK_KEY ;If any keystrokes available, JNZ CLEAR_IT ; remove them. RET ;----------------------------------------------; WRITE_TTY: MOV AH,0EH ;Write TTY via BIOS. INT 10H PRINT_STRING: LODSB OR AL,AL ;ASCIIZ string. JNZ WRITE_TTY RET CURRENT_DIR = $ WORKING_DIR = CURRENT_DIR + 68 RESULTS = WORKING_DIR + 68 DTA = RESULTS + 41 TREE_LEVEL = DTA + SIZE MATCHING STACK_PTR = TREE_LEVEL + 100 + 256 ZEROS = STACK_PTR _TEXT ENDS END START