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Assembly Source File | 1988-06-14 | 59.4 KB | 1,350 lines

TITLE COMPARE.ASM PAGE 60,132 ;-------------------------------------------; ; COMPARE - Compares text and binary files ; ; PC Magazine - Michael J. Mefford ; ;-------------------------------------------; _TEXT SEGMENT PUBLIC 'CODE' ;********************************; ASSUME CS:_TEXT,DS:_TEXT ;* *; ASSUME ES:_TEXT,SS:_TEXT ;* Requires MASM 2.0 or later *; ;* Remember to EXE2BIN *; ORG 100H ;* *; START: JMP MAIN ;********************************; ; DATA AREA ; --------- SYNTAX_MSG DB CR,SPACE,SPACE,SPACE,CR,LF COPYRIGHT DB "COMPARE 1.0 (C) 1988 Ziff Communications Co.",CR,LF PROGRAMMER DB "PC Magazine ",BOX," Michael J. Mefford",CR,LF,CR,LF DB "Syntax: COMPARE filespec filespec[/B][/W]",CR,LF DB "/B = Binary /W = WordStar$",CTRL_Z TAB EQU 9 CR EQU 13 LF EQU 10 CTRL_Z EQU 26 SPACE EQU 32 BOX EQU 254 CRT_MODE EQU 49H CRT_COLS EQU 4AH ADDR_6845 EQU 63H TEN_K EQU 10 * 1024 _64K_PARA EQU 64 * (1024 / 16) SPEC_LENGTH EQU 80 LINE_CHAR EQU 0CDH LF_BAR_CHAR EQU 0B5H RT_BAR_CHAR EQU 0C6H BLINKING EQU 10000000B STATUS_REG DW ? VIDEO_SEG DW 0B000H COLS DW ? ROWS DB 24 NORMAL_ATTRIB DB 07H INVERSE_ATTRIB DB 70H STRIP_MASK DB 0FFH SYNTAX_FLAG DB 0 DISPLAY_FLAG DB 1 MISMATCH_FLAG DB 0 WINDOW_FULL DB 0 FILE_START DW FILE1_BUFFER2, FILE2_BUFFER2 ;CONSTANT FILE_POS DW 2 DUP (?) FILE_END DW 2 DUP (?) BUFFER_END DW FILE1_BUFFER2 + TEN_K, FILE2_BUFFER2 + TEN_K WINDOW_POS DW 2 DUP (?) WINDOW_COL DW 2 DUP (?) WINDOW_LINE DW 2 DUP (?) WINDOW_SIZE DB ? SAVE_COL DW 80,80 SAVE_POS DW FILE1_BUFFER2, FILE2_BUFFER2 SYNC_POS DW 2 DUP (?) LINE_ARRAY DW 2 DUP (4 DUP (?)) LINE_CAPACITY DW ? STATUS_LINE DW ? HEX_SEGMENT DW 2 DUP (0) HEX_OFFSET DW 2 DUP (0) FILENAME DW FILESPEC + 2, FILESPEC + SPEC_LENGTH + 2 FILE_HANDLE DW 2 DUP (?) NOT_ENOUGH DB "Requires 64K free RAM$" BAD_MODE_MSG DB "Unsupported video mode$" BINARY_NAME DB "COMEXE" PROMPT DW PROMPT1, PROMPT2 PROMPT1 DB CR,LF,LF,"Enter first file name",CR,LF,"$" PROMPT2 DB CR,LF,LF,"Enter second file name",CR,LF,"$" NOT_FOUND_MSG DB CR,LF,"File not found$" MENU DB "Press any key for next compare Esc to Exit",0 MENU_LENGTH EQU $ - MENU - 1 WORKING_MSG DB "Working",0 WORKING_LENGTH EQU $ - WORKING_MSG - 1 DIFF_MSG DB "Files significantly different",0 DIFF_LENGTH EQU $ - DIFF_MSG - 1 SAME_MSG DB "Files are effectively identical",0 SAME_LENGTH EQU $ - SAME_MSG - 1 DONE_MSG DB "Compare completed",0 DONE_LENGTH EQU $ - DONE_MSG - 1 ; CODE AREA ; --------- MAIN PROC NEAR CLD ;String instructions forward. MOV BX,_64K_PARA ;Make sure we have 64K to MOV AH,4AH ; to work in. INT 21H MOV DX,OFFSET NOT_ENOUGH ;Exit if cramped, else continue. JNC CK_SWITCH JMP ERROR_EXIT ;--------------------------------------------------------; ; Check for /B Binary and /W WordStar switch characters. ; ;--------------------------------------------------------; CK_SWITCH: MOV SI,81H ;Point to command line. NEXT_SWITCH: LODSB ;Get a byte. CMP AL,CR ;Is it carriage return? JZ PARSE ;If yes, done here. CMP AL,"/" ;Is it switch delimiter? JNZ NEXT_SWITCH ;If no, next byte. MOV BYTE PTR [SI-1],0 ;Else, ASCIIZ it out. LODSB ;Get the switch character. CMP AL,CR ;Make sure it's not CR JZ PARSE ; so we don't go past end. MOV BYTE PTR [SI-1],0 ;ASCIIZ switch character also. AND AL,5FH ;Capitalize. CMP AL,"W" JNZ CK_BINARY ;If it's not "W", then skip. MOV STRIP_MASK,7FH ;Else, we will strip high bit. CK_BINARY: CMP AL,"B" ;Is it "B"? JNZ NEXT_SWITCH ;If no, next byte. MOV LINE_CAPACITY,16 ;Else, do hex compare. JMP SHORT NEXT_SWITCH ;Next byte. ;---------------------------------------------------------------; ; Parse the command line for filespecs. If one or both missing ; ; or file can't be opened, prompt the user for filespec. ; ;---------------------------------------------------------------; PARSE: MOV SI,81H ;Point to command line again. XOR BP,BP ;Initialize filespec counter. NEXT_PARSE: LODSB ;Get a byte. CMP AL,SPACE ;Parse off leading delimiters JA LEADING_END CMP AL,CR ; as long as it's not ending JNZ NEXT_PARSE ; carriage return. LEADING_END: DEC SI ;Adjust pointer. MOV DI,SI ;Save as filespec start position. MOV DX,SI FIND_END: LODSB ;Get a byte. CMP AL,SPACE ;Are we at end of filespec? JA FIND_END MOV BYTE PTR [SI-1],0 ;If yes, make ASCIIZ. PUSH SI ;Save our place. PUSH AX ;And save the character. CALL OPEN_FILE ;Try to open the file. JNC RESTORE_PARSE ;If successful, get next filespec CALL PROMPT_USER ; else, prompt user for filespec. RESTORE_PARSE: POP AX ;Restore last parsed character POP SI ; and position. STORE_START: MOV FILENAME[BP],DI ;Store pointer to filename. ADD BP,2 ;Next filespec. CMP BP,2 JA CAP CMP AL,CR ;Was last character parsed CR? JNZ NEXT_PARSE ;If no, get next. CALL PROMPT_USER ;Else prompt user for filespec JMP SHORT STORE_START ; and store pointer to it. ;----------------------------------------------------------------------------; ; Capitalize filenames so parameter parsing can be done with one compare. ; ;----------------------------------------------------------------------------; CAP: MOV BP,2 ;Two filenames to capitalize. CAPITALIZE: MOV SI,FILENAME[BP] ;Point to filename. NEXT_CAP: LODSB ;Get a byte. CMP AL,0 ;Is it ASCIIZ? JZ LOOP_CAP ;If yes, next name. CMP AL,"a" ;Is it a lower case a - z? JB NEXT_CAP CMP AL,"z" JA NEXT_CAP AND BYTE PTR [SI-1],5FH ;If yes, capitalize. JMP SHORT NEXT_CAP LOOP_CAP: SUB BP,2 ;Capitalize both names. JNC CAPITALIZE ;-----------------------------------------------------------------------------; ; Automatically do a binary compare if filespec has a .COM or .EXE extension. ; ;-----------------------------------------------------------------------------; MOV BP,2 BINARY: MOV SI,FILENAME[BP] ;Point to filename. NEXT_BINARY: LODSB ;Get a byte. CMP AL,0 ;Is it ASCIIZ? JZ LOOP_BINARY ;If yes, done here. CMP AL,"." ;Is it delimiting dot char? JNZ NEXT_BINARY ;If no, next byte. MOV BX,2 ;Two possible binary names -- MOV DI,OFFSET BINARY_NAME ; .COM and .EXE. NEXT_EXEC: PUSH SI ;Save our place. PUSH DI MOV CX,3 ;Do we have a match? REP CMPSB POP DI ;Restore our place. POP SI JZ BINARY_FILE ;If match, mark a binary compare. ADD DI,3 ;Else point to next extension DEC BX JNZ NEXT_EXEC ; and check if it matches. JMP SHORT NEXT_BINARY LOOP_BINARY: SUB BP,2 ;Do both filenames. JNC BINARY JMP SHORT READY BINARY_FILE: MOV LINE_CAPACITY,16 ;Else, do hex compare. ;---------------------------------------------------------------------; ; Line array is used to keep track of the start of file line displays ; ; so we can display three lines preceeding mismatch for context. ; ;---------------------------------------------------------------------; READY: MOV AX,FILE_START[0] ;Initalize current line-starts MOV LINE_ARRAY[6],AX ; of array to start of file. MOV AX,FILE_START[2] MOV LINE_ARRAY[14],AX CALL VIDEO_SETUP ;Prepare for video environment. CALL DISPLAY_SETUP ;Initialize display with heading ; and window delimiting lines. ;---------------------------------------------------------------------------; ; We will loop here filling the window with mismatches until all displayed. ; ;---------------------------------------------------------------------------; DO_SEARCH: CALL SEARCH ;Search for mismatches. JNC GET_KEY ;If not carry, not done yet. CALL CLS_MENU ;If done, clear menu. MOV DI,STATUS_LINE ADD DI,COLS MOV BH,NORMAL_ATTRIB CMP MISMATCH_FLAG,1 ;Display appropriate message JZ DO_DONE_MSG MOV SI,OFFSET SAME_MSG SUB DI,SAME_LENGTH AND NOT 1 JMP SHORT MESSAGE_EXIT DO_DONE_MSG: MOV SI,OFFSET DONE_MSG SUB DI,DONE_LENGTH AND NOT 1 JMP SHORT MESSAGE_EXIT GET_KEY: CALL DISPLAY_MENU ;If not done, display menu. CALL CLEAR_KEY ;Clear any awaiting keystroke. CALL READ_KEY ;Get a keystroke. CMP AH,1 ;Is it Esc? JNZ DO_SEARCH ;If no, search for next mismatch. CALL CLS_MENU ;Else, clear menu JMP SHORT GOOD_EXIT ; and exit. ;--------------------------------------------------------------; ; Exit with appropriate message and put cursor back on screen. ; ;--------------------------------------------------------------; ERROR_EXIT: CALL PRINT_STRING ;Print error message. MOV AL,1 ;Exit with error level one. JMP SHORT EXIT MESSAGE_EXIT: CALL WRITE_STRING ;Display exit message. GOOD_EXIT: MOV DH,ROWS ;Move cursor to next to last DEC DH ; line of screen. XOR DL,DL XOR BH,BH MOV AH,2 INT 10H XOR AL,AL ;Error level zero. EXIT: MOV AH,4CH ;Terminate. INT 21H MAIN ENDP ; *************** ; * SUBROUTINES * ; *************** ;-------------------------------------; ; INPUT ; ; None ; ; ; ; OUTPUT ; ; Carry flag = 1 if search complete ; ; Carry flag = 0 if more to search. ; ; ; ; All registers destroyed. ; ;-------------------------------------; SEARCH PROC NEAR ;--------------------------------------------------------; ; Display "Working" message and initialization variables ; ;--------------------------------------------------------; CALL CLS_MENU ;Clear the menu. MOV SI,OFFSET WORKING_MSG ;Display "Working" MOV DI,STATUS_LINE ADD DI,80 - WORKING_LENGTH AND NOT 1 MOV BH,NORMAL_ATTRIB OR BH,BLINKING ; with blinking attribute. CALL WRITE_STRING MOV AX,COLS SHL AX,1 ;Double for attribute. MOV DI,AX SHL DI,1 ;Second line. MOV WINDOW_POS[0],DI ;Initialize window pointers MOV DL,WINDOW_SIZE INC DL MUL DL ; to top left corner of ADD DI,AX ; each window. MOV WINDOW_POS[2],DI MOV BP,2 ;Restore the window columns, RESTORE_WIN: MOV AX,SAVE_COL[BP] ; window lines and file MOV WINDOW_COL[BP],AX ; positions to what they were MOV AX,SAVE_POS[BP] ; when one of the windows MOV FILE_POS[BP],AX ; was filled last search. MOV AL,WINDOW_SIZE XOR AH,AH MOV WINDOW_LINE[BP],AX SUB BP,2 JNC RESTORE_WIN MOV DI,OFFSET LINE_ARRAY ;Initialize the array of MOV AX,LINE_ARRAY[6] ; line starts to the last MOV CX,4 ; line start from previous REP STOSW ; search. MOV AX,LINE_ARRAY[14] MOV CX,4 REP STOSW MOV WINDOW_FULL,0 ;Flag that windows are not full. MOV DISPLAY_FLAG,0 ;No display during search. ;------------------------------------------------------------------------------; ; Check to see if End of File has been reached and/or windows have been filled ; ;------------------------------------------------------------------------------; NEXT_SEARCH: MOV SI,FILE_POS[0] ;Get current file position. MOV DI,FILE_POS[2] CALL STORE_WINDOW ;See if current postion to be CALL CK_EOF1 ; frozen for next search. JNC CK_WINDOW2 ;If both End of Files reached CALL CK_EOF2 ; then compare complete. JNC CK_WIN_FULL STC RET CK_WINDOW2: CALL CK_EOF2 ;If neither EOF then continue. JNC BOTH_WINDOWS CK_WIN_FULL: TEST WINDOW_FULL,111B ;If one EOF and windows full JZ COMPARE ; then return, else continue. JMP SHORT SEARCH_END BOTH_WINDOWS: CMP WINDOW_FULL,111B ;If both windows full, return. JZ SEARCH_END ;------------------------------------------------------------------------; ; Files are compared a byte at a time until mismatch is found. ; ; In comparing text files, if one byte is a carriage return and it is ; ; mismatch with a space then both are ignored (line wrap); else just ; ; the CR is ignored (word wrap). No special treatment for binary files. ; ;------------------------------------------------------------------------; COMPARE: MOV BH,NORMAL_ATTRIB ;Use normal attribute. CALL CK_EOF1 ;If either EOF then match JC DO_MISMATCH ; not possible. CALL CK_EOF2 JC DO_MISMATCH MOV AL,[SI] ;Get a byte from each file. MOV AH,[DI] CMPSB ;Are they the same? JZ FORMAT_BOTH ;If yes, format display. CMP LINE_CAPACITY,16 ;If no, is it a binary compare? JZ DO_MISMATCH ;If yes, mismatch. CMP AL,LF ;Else, is it linefeed? JZ ADJUST_2A ;If yes, ignore. CMP AL,CR ;If CR, check if matched JZ CK_ADJUST_2A ; with a space character. CMP AH,LF ;Do the same for both files. JZ FORMAT_1A CMP AH,CR JNZ DO_MISMATCH CK_ADJUST_1A: CMP AL,SPACE ;If CR matched with space, JZ FORMAT_BOTH ; format both characters. ADJUST_1A: JMP SHORT FORMAT_1A ;Else, just format the CR. CK_ADJUST_2A: CMP AH,SPACE ;Do the same for other file. JZ FORMAT_BOTH ADJUST_2A: XOR BP,BP ;File one index. JMP SHORT FORMAT_2A FORMAT_BOTH: XOR BP,BP CALL FORMAT FORMAT_1A: MOV BP,2 ;File two index. MOV AL,AH ;Call format with character FORMAT_2A: CALL FORMAT ; in AL. JMP NEXT_SEARCH ;Check next bytes. DO_MISMATCH: MOV MISMATCH_FLAG,1 ;Flag that mismatch found. CALL MISMATCH ;Go highlight the mismatch. JMP NEXT_SEARCH ;Check next bytes. SEARCH_END: CLC RET SEARCH ENDP ;------------------------------------; ; INPUT ; ; AL = Character to format. ; ; BP = Index to file. ; ; ; ; OUTPUT ; ; WINDOW_COL[BP] WINDOW_LINE[BP] ; ; WINDOW_FULL FILE_POS[BP] ; ; are updated. ; ; ; ; AX, BX, CX, SI and DI preserved. ; ;------------------------------------; FORMAT PROC NEAR PUSH AX ;Preserve registers. PUSH CX PUSH SI PUSH DI MOV CX,WINDOW_COL[BP] ;Retrieve current column. CMP LINE_CAPACITY,16 ;Are we working on a binary file? JZ DO_HEX ;If yes, do a hex display. CALL LINES ;Else, display text lines. JMP SHORT CK_LINE_START DO_HEX: CALL HEX CK_LINE_START: INC FILE_POS[BP] ;Increment file position. JCXZ LINE_START ;End of a display line? MOV WINDOW_COL[BP],CX ;If no, store column postion JMP SHORT FORMAT_END ; and return. LINE_START: MOV AX,LINE_CAPACITY ;Else, go to next column. MOV WINDOW_COL[BP],AX CMP AX,16 ;Are we doing a binary compare? JZ CK_ARRAY ;If yes, skip CR check. OR BP,BP ;Else, check if EOF. JNZ CK_CR2 CALL CK_EOF1 JMP SHORT CK_CR CK_CR2: CALL CK_EOF2 CK_CR: JC CK_ARRAY ;If EOF, skip CR check. MOV DI,FILE_POS[BP] ;Else, if byte at end of an 80 CMP BYTE PTR [DI],CR ; column display is CR, bump JNZ CK_ARRAY ; file postion past it so INC FILE_POS[BP] ; don't double space display. CK_ARRAY: CMP DISPLAY_FLAG,1 ;Are we displaying? JNZ ADJUST_ARRAY ;If no, skip line check. CMP WINDOW_LINE[BP],0 ;Else, is window full? JZ FORMAT_END ;If yes, done here. DEC WINDOW_LINE[BP] ;Else, decrement line display. JNZ ADJUST_ARRAY ;If window not full, skip next. MOV CX,BP ;Else, mark appropriate ADD CL,2 ; WINDOW_FULL bit as full. OR WINDOW_FULL,CL JMP SHORT FORMAT_END ADJUST_ARRAY: TEST WINDOW_FULL,001B ;Has window been stored? JNZ FORMAT_END ;If yes, skip array indexing. CALL ARRAY_INDEX ;Else, index into array. MOV SI,DI ADD SI,2 MOV CX,3 REP MOVSW ;Move all line starts up one MOV AX,FILE_POS[BP] MOV [DI],AX ; and store new line start. FORMAT_END: POP DI ;Restore registers. POP SI POP CX POP AX RET FORMAT ENDP ;------------------------------; ; INPUT ; ; AL = Character to display. ; ; CX = current column. ; ; BP = Index to file. ; ; ; ; OUTPUT ; ; CX = new column. ; ; WINDOW_POS[BP] is updated. ; ; ; ; BX preserved. ; ;------------------------------; LINES PROC NEAR CMP AL,CR ;Carriage return? JZ PAD_SPACES ;If yes, pad balance of line. CMP AL,TAB ;Is it tab character? JZ EXPAND_TAB ;If yes, expand to spaces. CMP AL,LF ;Is it linefeed? JZ LINES_END ;If yes, skip. PUSH CX ;Save column. MOV CX,1 ;Display one character. CALL CK_DISPLAY POP CX ;Restore column and decrement. DEC CX RET EXPAND_TAB: PUSH CX ;Save column. DEC CX ;Adjust column counter. AND CX,7 ;Get bottom three bits. INC CX ;Adjust. PUSH CX ;Save. CALL PAD_SPACES ;Move to next tab position. POP AX POP CX SUB CX,AX ;Adjust column counter. RET PAD_SPACES: MOV AL,SPACE ;If CR display spaces. CK_DISPLAY: CMP DISPLAY_FLAG,1 ;Are we to write it to screen? JNZ DISPLAY_END ;If no, return. CMP WINDOW_LINE[BP],0 ;Window full? JZ DISPLAY_END ;If yes, return. MOV DI,WINDOW_POS[BP] ;Else, retrieve display position. WRITE_VIEW: CALL WRITE_SCREEN ;Write character CX times. LOOP WRITE_VIEW MOV WINDOW_POS[BP],DI ;Store new display position. DISPLAY_END: XOR CX,CX LINES_END: RET LINES ENDP ;------------------------------; ; INPUT ; ; AL = Character to display. ; ; CX = current column. ; ; BP = Index to file. ; ; ; ; OUTPUT ; ; CX = new column. ; ; WINDOW_POS[BP] is updated. ; ; ; ; BX preserved. ; ;------------------------------; HEX PROC NEAR CMP DISPLAY_FLAG,1 ;Are we to write to screen? JNZ DEC_COLUMN ;If no, just update column. CMP WINDOW_LINE[BP],0 ;Else, is window full? JNZ GO_HEX ;If yes, continue. DEC_COLUMN: DEC CX ;Else, update column and return. RET GO_HEX: PUSH CX ;Save some registers. PUSH AX PUSH CX MOV DI,WINDOW_POS[BP] ;Retrieve window position. CMP CX,16 ;Is it first column? JNZ DISP_NUMBERS ;If no, just display the byte. PUSH AX ;Else, save character and PUSH BX ; attribute. MOV AX,FILE_POS[BP] ;Retrieve file position SUB AX,FILE_START[BP] ;Subtract the starting position. ADD AX,HEX_OFFSET[BP] ;Add the 64K offset. PUSH AX ;Save the offset. MOV AX,HEX_SEGMENT[BP] ;Retrieve segment. JNC DISP_SEGMENT ;Did offset carry? ADD AX,1000H ;If yes, add 1000h to segment. DISP_SEGMENT: MOV BH,NORMAL_ATTRIB ;Yes normal attribute. MOV CX,1 ;Segment and offset counter. NEXT_ADDRESS: XCHG AH,AL ;AL = byte to display. CALL DISPLAY_HEX XCHG AH,AL ;Get second byte to display. CALL DISPLAY_HEX OR CX,CX ;Segment and offset displayed? JZ ADDRESS_END ;If yes, done here. MOV AL,":" ;Else, display delimiting colon. CALL WRITE_SCREEN POP AX ;Retrieve offset. DEC CX ;Decrement counter. JMP SHORT NEXT_ADDRESS ;Display segment. ADDRESS_END: ADD DI,4 ;Move right two spaces. POP BX ;Retrieve attribute. POP AX ;Retrieve character. DISP_NUMBERS: CALL DISPLAY_HEX ;Display the hex number. MOV AL,SPACE ;Delimit with a space. POP CX ;Retrieve column counter. CMP CX,9 ;Is it half way? JNZ DELIMITER MOV AL,"-" ;If yes, display delimiting dash DELIMITER: PUSH BX ; with normal attribute. MOV BH,NORMAL_ATTRIB CALL WRITE_SCREEN POP BX ;Restore attribute. MOV WINDOW_POS[BP],DI ;Store window position. SHL CX,1 ;Multiply column by 8. SHL CX,1 ADD DI,CX ;Add to current window postion. ADD DI,30 ;Tab over additional 15. POP AX ;Retrieve character and display. CALL WRITE_SCREEN POP CX ;Restore column counter DEC CX ; and update. JNZ HEX_END ;If last column, bump window MOV AX,COLS ; to next line. SUB AX,59 SHL AX,1 ADD WINDOW_POS[BP],AX HEX_END: RET HEX ENDP ;-------------------------------; ; INPUT ; ; AL = Hex number to display. ; ; ; ; OUTPUT ; ; none ; ; ; ; BX and CX preserved. ; ;-------------------------------; DISPLAY_HEX PROC NEAR PUSH CX ;Preserve CX. MOV CX,0204H ;2 char/byte; 4 bits/byte. ROTATE_HEX: ROL AL,CL ;Get next four bits. PUSH AX ;Save number. AND AL,00001111B ;Mask off high bits. ADD AL,30H ;Convert to ASCII. CMP AL,"9" ;Is it above 9? JLE PRINT_HEX ADD AL,7 ;If yes, convert to hex alpha. PRINT_HEX: CALL WRITE_SCREEN POP AX ;Restore number. DEC CH ;Do both hex characters. JNZ ROTATE_HEX POP CX RET DISPLAY_HEX ENDP ;----------------------------; ; INPUT ; ; BH = Display attribute. ; ; ; ; OUTPUT ; ; None ; ; ; ; All registers destroyed. ; ;----------------------------; MISMATCH PROC NEAR CMP DISPLAY_FLAG,1 ;Is this first time here? JZ SYNCHRONIZE ;If yes no context to display. MOV DISPLAY_FLAG,1 ;Else, flag to display. CALL CLS_WINDOWS ;Clear the windows. MOV BP,2 ;Two windows. NEXT_WINDOW: MOV AX,LINE_CAPACITY ;Restore line to first column. MOV WINDOW_COL[BP],AX MOV CX,FILE_POS[BP] ;Save current position. CALL ARRAY_INDEX MOV AX,[DI] ;Retrieve third line back. MOV FILE_POS[BP],AX NEXT_CONTEXT: MOV SI,FILE_POS[BP] ;Display context until current CMP SI,CX ; mismatch position. JAE LOOP_WINDOW LODSB CALL FORMAT JMP SHORT NEXT_CONTEXT LOOP_WINDOW: SUB BP,2 ;Do both windows. JNC NEXT_WINDOW ;-----------------------------------------------------------------------------; ; Try to synchronize by matching 10 bytes up to 200 postions away from ; ; current position. In text files, ignore spaces so won't get false matches. ; ;-----------------------------------------------------------------------------; SYNCHRONIZE: MOV BX,FILE_POS[0] ;File 1 postion in BX. MOV CX,400 ;400 byte reach. NEXT_SYNC: PUSH CX ;Save counter. MOV DX,FILE_POS[2] ;Second file position in DX. MOV CX,400 ;Also a 400 byte reach. NEXT_TRY: PUSH CX ;Save counter. MOV CX,10 ;Require 10 bytes for match. MOV SI,BX ;Initialize pointers. MOV DI,DX NEXT_CHAR: CALL CK_EOF1 ;EOF of file one? JC NEXT_TRY_END ;If yes, increment file 2. CALL CK_EOF2 ;EOF of file two? JC FILE2_END ;If yes, increment file 1. MOV AL,[SI] ;Retrieve characters. MOV AH,[DI] CMPSB ;Do they match? JZ POSSIBLE_SYNC ;If yes, poss. synchronization. CMP LINE_CAPACITY,16 ;Else, is it binary compare? JZ NEXT_TRY_END ;If yes, no match. CMP AL,LF ;Else, if linefeed, ignore. JZ ADJUST_2B CMP AL,CR ;If carriage return, ignore JZ CK_ADJUST_2B ; and ignore any match space. CMP AH,LF ;Do same check for both files. JZ ADJUST_1B CMP AH,CR JNZ NEXT_TRY_END CK_ADJUST_1B: CMP AL,SPACE ;If CR with space, ignore both. JZ NEXT_CHAR ADJUST_1B: DEC SI ;Else, ignore CR only. JMP SHORT NEXT_CHAR CK_ADJUST_2B: CMP AH,SPACE ;Do same for both files. JZ NEXT_CHAR ADJUST_2B: DEC DI JMP SHORT NEXT_CHAR POSSIBLE_SYNC: CMP AL,SPACE ;If sync char is space, ignore. JZ NEXT_CHAR LOOP NEXT_CHAR ;Need ten matches for sync. JMP SHORT EVALUATE FILE2_END: POP CX ;If file 2 EOF, skip to JMP SHORT NEXT_SYNC_END ; next file 1 postion. NEXT_TRY_END: INC DX ;Increment file 2 postion. POP CX ;Decrement reach counter. LOOP NEXT_TRY ;Keep trying up to 400 positions. NEXT_SYNC_END: INC BX ;Increment file 1 position. POP CX ;Decrement reach counter. LOOP NEXT_SYNC ;Keep trying up to 400 positions. PUSH SI ;Save pointers. PUSH DI MOV SI,OFFSET DIFF_MSG MOV DI,STATUS_LINE MOV AX,COLS SHL AX,1 SUB AX,DIFF_LENGTH * 2 ADD DI,AX PUSH BX PUSH DX ;Display "Files significantly MOV BH,NORMAL_ATTRIB ; different" if didn't find CALL WRITE_STRING ; a match. POP DX POP BX POP DI POP SI JMP SHORT EVALUATE_EOF ;--------------------------------------------; ; Display mismatch until EOF or window full. ; ;--------------------------------------------; EVALUATE: POP CX ;Fix stack. POP CX EVALUATE_EOF: CALL CK_EOF1 ;EOF of file 1? JNC EOF2 MOV BX,FILE_END[0] ;If yes, use file end pointer. EOF2: CALL CK_EOF2 ;EOF of file 2? JNC INVERSE MOV DX,FILE_END[2] ;If yes, use file end pointer. INVERSE: MOV SYNC_POS[0],BX ;Save synchronization position. MOV SYNC_POS[2],DX MOV BH,INVERSE_ATTRIB ;Display in inverse attribute. MOV BP,2 ;Two windows to display. HIGHLIGHT: MOV SI,FILE_POS[BP] ;Is current postion = sync pos? CMP SI,SYNC_POS[BP] JZ LOOP_INVERSE ;If yes, done. CMP WINDOW_LINE[BP],0 ;Is window full? JZ LOOP_INVERSE ;If yes, done. LODSB ;Else, display mismatch. CALL FORMAT JMP SHORT HIGHLIGHT LOOP_INVERSE: SUB BP,2 ;Do both windows. JNC HIGHLIGHT EVALUATE_END: CALL STORE_WINDOW ;Freeze postion if window full. MOV BP,2 ;Restore current position. RESTORE_POS: MOV AX,SYNC_POS[BP] MOV FILE_POS[BP],AX SUB BP,2 JNC RESTORE_POS RET MISMATCH ENDP ;----------------------------; ; INPUT ; ; None ; ; ; ; OUTPUT ; ; None ; ; ; ; AX and BP destroyed. ; ;----------------------------; STORE_WINDOW PROC NEAR ;------------------------------------------------------------------------; ; As soon as a window becomes full, freeze the position for next search. ; ;------------------------------------------------------------------------; TEST WINDOW_FULL,110B ;Either window full? JZ STORE_END ;If no, done. TEST WINDOW_FULL,001B ;Else, have we already stored? JNZ STORE_END ;If yes, done. OR WINDOW_FULL,001B ;Else, flag stored. MOV BP,2 FREEZE_POS: MOV AX,FILE_POS[BP] ;And store current position MOV SAVE_POS[BP],AX MOV AX,WINDOW_COL[BP] ; and column. MOV SAVE_COL[BP],AX SUB BP,2 JNC FREEZE_POS STORE_END: RET STORE_WINDOW ENDP ;---------------------------------; ; INPUT ; ; SI and DI = current position. ; ; Two entry points: ; ; CK_EOF1 and CK_EOF2 ; ; ; ; OUTPUT ; ; Carry flag = 1 if EOF. ; ; Carry flag = 0 if not EOF. ; ; ; ; BP destroyed. ; ;---------------------------------; CK_EOF PROC NEAR ;-----------------------------------------------------------------; ; These two subroutines read the next 10K bytes if end of buffer ; ; reached and EOF not reached. The second buffer is moved to the ; ; first buffer and all appropriate pointers are adjusted. ; ;-----------------------------------------------------------------; CK_EOF1: XOR BP,BP ;File index pointer. CMP SI,FILE_END[BP] ;Is position = EOF? JB NOT_EOF ;If no, not EOF. CMP SI,BUFFER_END[BP] ;Else, is it at end of buffer? JB EOF ;If no, EOF. JMP SHORT MOVE_BUFFER ;Else, more to file; read it. CK_EOF2: MOV BP,2 ;Do same for file 2. CMP DI,FILE_END[BP] JB NOT_EOF CMP DI,BUFFER_END[BP] JB EOF MOVE_BUFFER: PUSH AX ;Save registers. PUSH BX PUSH CX PUSH DX PUSH SI PUSH DI MOV SI,FILE_START[BP] ;Retrieve buffer start address. MOV DI,SI SUB DI,TEN_K MOV CX,TEN_K / 2 ;And move data to buffer REP MOVSW ; 10K below. CALL READ_FILE ;Read the next 10K. SUB SAVE_POS[BP],TEN_K ;Adjust all the pointers by 10K. SUB SYNC_POS[BP],TEN_K SUB FILE_POS[BP],TEN_K ADD HEX_OFFSET[BP],TEN_K ;Add 10K to offset. JNC DO_ARRAY ;If carry, add 1000h to segment. ADD HEX_SEGMENT[BP],1000H DO_ARRAY: CALL ARRAY_INDEX ;Adjust line start array. MOV CX,4 SUB_ARRAY: SUB [DI],TEN_K INC DI INC DI LOOP SUB_ARRAY POP DI POP SI POP DX POP CX POP BX POP AX OR BP,BP ;If file 1, adjust DI and DX. JZ ADJUST_FILE1 SUB DI,TEN_K SUB DX,TEN_K JMP SHORT NOT_EOF ADJUST_FILE1: SUB SI,TEN_K ;Else, adjust SI and BX. SUB BX,TEN_K NOT_EOF: CLC RET EOF: STC RET CK_EOF ENDP ;-----------------------------------; ; INPUT ; ; BP = file index. ; ; ; ; OUTPUT ; ; DI = start of line-start array. ; ; ; ; All registers preserved. ; ;-----------------------------------; ARRAY_INDEX PROC NEAR MOV DI,BP SHL DI,1 ;Multiply file index by 4 SHL DI,1 ; to index into index. ADD DI,OFFSET LINE_ARRAY RET ARRAY_INDEX ENDP ;-----------------------------------; ; INPUT ; ; BP = file index ; ; DX = points to ASCIIZ filename. ; ; ; ; OUTPUT ; ; Carry flag = 1 if failed. ; ; Carry flag = 0 if successful. ; ; ; ; BP preserved. ; ;-----------------------------------; OPEN_FILE PROC NEAR MOV AX,3D00H ;Open file for reading. INT 21H JC OPEN_END MOV FILE_HANDLE[BP],AX ;Save file handle if successful CALL READ_FILE ; and read 10K. OPEN_END: RET OPEN_FILE ENDP ;-----------------------------------; ; INPUT ; ; BP = file index ; ; DX = points to ASCIIZ filename. ; ; ; ; OUTPUT ; ; Carry flag = 1 if failed. ; ; Carry flag = 0 if successful. ; ; ; ; BP preserved. ; ;-----------------------------------; READ_FILE PROC NEAR MOV BX,FILE_HANDLE[BP] ;Retrieve filehandle. MOV DX,FILE_START[BP] ;Point to storage buffer. MOV SI,DX ;Save it. MOV CX,TEN_K ;Read maximum of 10K. MOV AH,3FH ;Read file. INT 21H JC READ_FILE_END ;If failed, exit. ADD DX,AX ;Else, add bytes read to buffer MOV FILE_END[BP],DX ; address and store as file end. MOV CX,AX ;Bytes read in counter. JCXZ READ_END ;Skip if zero bytes read. MOV AL,STRIP_MASK ;Else, retrieve strip mask. CMP AL,0FFH ;If not WordStar, skip. JZ READ_END WORDSTAR: AND DS:[SI],AL ;Else, strip the high bit INC SI ; of all bytes read. LOOP WORDSTAR READ_END: CLC READ_FILE_END: RET READ_FILE ENDP ;-----------------------------------; ; INPUT ; ; None ; ; ; ; OUTPUT ; ; None ; ; ; ; ES preserved. ; ;-----------------------------------; VIDEO_SETUP PROC NEAR PUSH ES ;Preserve ES. MOV AX,500H ;Make sure active page is zero. INT 10H MOV AX,40H ;Point to the ROM BIOS data area MOV ES,AX MOV AL,ES:CRT_MODE ;Retrieve current video mode. CMP AL,7 ;Is it mono mode? JZ SUPPORTED ;If yes, continue. CMP AL,3 ;Is it text? JBE SUPPORTED ;If yes, continue. UNSUPPORTED: MOV DX,OFFSET BAD_MODE_MSG ;Else, do not pass GO. JMP ERROR_EXIT ;Go directly to jail. SUPPORTED: MOV AH,12H MOV BL,10H INT 10H CMP BL,10H ;Is there an EGA? JZ CK_CGA ;If no, check if CGA. TEST ES:BYTE PTR [87H],8 ;Else, EGA_info; Is it active? JNZ CK_CGA ;If no, check CGA. XOR BH,BH ;Else, retrieve CRT rows. MOV AX,1130H PUSH ES INT 10H POP ES MOV ROWS,DL ;Save CRT rows. CK_CGA: MOV AL,ES:CRT_COLS ;Retrieve CRT cols. XOR AH,AH ;Zero in high half. MOV DX,AX ;Save it. MOV BX,LINE_CAPACITY ;Retrieve line capacity. CMP BX,16 ;Are we displaying hex? JNZ CAPACITY ;If no, store. MOV DX,BX ;Else, use 16 as capacity. CMP AL,40 ;Are we in 40 column mode? JZ UNSUPPORTED ;If yes, useless display. CAPACITY: MOV LINE_CAPACITY,DX ;Store capacity and initialize MOV SAVE_COL[0],DX ; columns. MOV SAVE_COL[2],DX MOV COLS,AX ;Store columns. SHL AX,1 ;Times two for attribute. MOV DL,ROWS ;Retrieve rows MUL DL ; and multiply. MOV STATUS_LINE,AX ;Save as address of status line. SUB DL,4 ;Subtract 4 from CRT rows SHR DL,1 ; and divide by two MOV WINDOW_SIZE,DL ; and save as window size. MOV AX,ES:ADDR_6845 ;Retrieve display card. ADD AX,6 ;Add six to get status register MOV STATUS_REG,AX ;Store as status register. CMP AX,3BAH ;Is it monochrome? JZ VIDEO_END ;If yes, done here. ADD VIDEO_SEG,800H ;Else, adjust video segment. MOV AH,8 ;Get attribute at cursor postion. INT 10H MOV NORMAL_ATTRIB,AH ;And save as forground. XOR AH,01110111B ;Flip color bits. MOV INVERSE_ATTRIB,AH ;And save as highlight attribute. VIDEO_END: POP ES ;Restore ES. RET VIDEO_SETUP ENDP ;-----------------------------------; ; INPUT ; ; AL = character to write. ; ; BH = attribute. ; ; ; ; OUTPUT ; ; None ; ; ; ; AL, BH, CX preserved. ; ;-----------------------------------; WRITE_SCREEN PROC NEAR PUSH ES MOV DX,VIDEO_SEG ;Point to screen segment. MOV ES,DX MOV DX,STATUS_REG ;Retrieve status register. MOV BL,AL ;Store character in BL. HORZ_RET: IN AL,DX ;Get status. RCR AL,1 ;Is it low? JC HORZ_RET ;If not, wait until it is. CLI ;No more interrupts. HWAIT: IN AL,DX ;Get status. RCR AL,1 ;Is it high? JNC HWAIT ;If no, wait until it is. MOV AX,BX ;Retrieve character; now it's OK STOSW ; to write to screen buffer. STI ;Interrupts back on. POP ES RET ;Return WRITE_SCREEN ENDP ;-----------------------------------; ; INPUT ; ; None ; ; ; ; OUTPUT ; ; None ; ; ; ; All registers destroyed. ; ;-----------------------------------; DISPLAY_SETUP PROC NEAR CALL CLS ;Clear screen. MOV DH,ROWS ;Retrieve CRT rows. INC DH ;Move one line below off screen. XOR DL,DL ;Column zero. XOR BH,BH ;Page zero. MOV AH,2 ;Set cursor position. INT 10H XOR DI,DI ;Point to top left of display. MOV SI,OFFSET COPYRIGHT ;Point to copyright message. MOV BH,NORMAL_ATTRIB ;And display it. CALL WRITE_STRING MOV DI,COLS ;Retrieve columns. SHL DI,1 ;Double for attribute. SUB DI,64 ;Right justify my name. INC SI ;Bump pointer past linefeed. CALL WRITE_STRING MOV BP,0 ;Initialize counter. NEXT_LINE: MOV CX,COLS ;Write line characters PUSH DI ;Save position. MOV AL,LINE_CHAR ; to screen. NEXT_WRITE: CALL WRITE_SCREEN LOOP NEXT_WRITE POP DI ;Retrieve position. CMP BP,2 ;Do two windows. JA SETUP_END PUSH DI ;Save screen pointer. ADD DI,10 ;Tab in five spaces MOV AL,LF_BAR_CHAR ; and print a left bar char. CALL WRITE_SCREEN MOV SI,FILENAME[BP] ;Point to filename and print it. CALL WRITE_STRING MOV AL,RT_BAR_CHAR ;Finish frame with right bar char CALL WRITE_SCREEN POP DI ;Restore display pointer. MOV AX,COLS SHL AX,1 MOV DL,WINDOW_SIZE INC DL ;Multiply line length by window MUL DL ; size plus one and add to ADD DI,AX ; current position to get to ADD BP,2 ; next position to display line. JMP SHORT NEXT_LINE SETUP_END: RET DISPLAY_SETUP ENDP ;-----------------------------------; ; INPUT ; ; None ; ; ; ; OUTPUT ; ; None ; ; ; ; All registers destroyed. ; ;-----------------------------------; DISPLAY_MENU PROC NEAR MOV SI,OFFSET MENU ;Point to menu. MOV DI,STATUS_LINE ;Point to status line. MOV BH,NORMAL_ATTRIB ;Use normal attribute CALL WRITE_STRING ; and display menu. RET DISPLAY_MENU ENDP ;-----------------------------------; ; INPUT ; ; BP = file index ; ; ; ; OUTPUT ; ; None ; ; ; ; All registers destroyed. ; ;-----------------------------------; PROMPT_USER PROC NEAR CMP SYNTAX_FLAG,1 ;If first time through, display JZ NEXT_PROMPT ; syntax message. MOV SYNTAX_FLAG,1 MOV DX,OFFSET SYNTAX_MSG CALL PRINT_STRING NEXT_PROMPT: MOV DX,PROMPT[BP] ;Retrieve appropriate prompt CALL PRINT_STRING ; and display. MOV DI,FILENAME[BP] ;Retrieve address of filename MOV DX,DI ; storage and save. SUB DX,2 ;Put in first byte of filename MOV BX,DX ; buffer, the buffer length (80). MOV BYTE PTR [BX],SPEC_LENGTH MOV AH,0AH INT 21H ;Buffered Keyboard Input. PUSH DI ;Save filename pointer. MOV AL,CR ;Carriage return points ASCIIZ: SCASB ; to last byte of input. JNZ ASCIIZ MOV BYTE PTR [DI-1],0 ;Replace it with zero (ASCIIZ). POP DI ;Retrieve filename pointer. MOV DX,DI CALL OPEN_FILE ;Attempt to open the file. JNC PROMPT_END ;If successful, done here. MOV DX,OFFSET NOT_FOUND_MSG ;Else, display "Not found" CALL PRINT_STRING ; message JMP SHORT NEXT_PROMPT ; and prompt user again. PROMPT_END: RET PROMPT_USER ENDP ;-------------------------------------; ; INPUT ; ; SI = points to string to display. ; ; Entry point is WRITE_STRING. ; ; ; ; OUTPUT ; ; None ; ; ; ; All registers destroyed. ; ;-------------------------------------; WRITE_IT: CALL WRITE_SCREEN ;Write a character. WRITE_STRING: LODSB ;Retrieve a character. CMP AL,SPACE ;Keep writing until a carriage JAE WRITE_IT ; return or space encountered. RET ;-------------------; ; BIOS Keyboard I/O ; ;-------------------; READ_KEY: MOV AH,0 ;Wait for next keyboard INT 16H ; input. RET CK_KEY: MOV AH,1 ;See if character ready. INT 16H RET CLEAR_IT: CALL READ_KEY ;If characters are ready CLEAR_KEY: CALL CK_KEY ; read them to clear keyboard JNZ CLEAR_IT ; buffer. RET ;---------------------------; ; Screen clearing routines. ; ;---------------------------; CLS: XOR CX,CX ;Top left corner. MOV DX,COLS ;Right corner DEC DL MOV DH,ROWS ;Bottom row. JMP SHORT CLEAR_WINDOW ;Clear the screen. CLS_WINDOWS: MOV CX,0200H ;Row 3; column zero. MOV DX,COLS ;Right corner. DEC DL MOV DH,WINDOW_SIZE ;Bottom of window one. INC DH CALL CLEAR_WINDOW ;Clear the window. ADD CH,WINDOW_SIZE ;Increment a window size INC CH ; and a delimiting line. ADD DH,WINDOW_SIZE INC DH JMP SHORT CLEAR_WINDOW ;Clear second window. CLS_MENU: MOV CH,ROWS ;Bottom row. XOR CL,CL ;Column zero. MOV DH,CH MOV DL,2CH ;To column 44. CLEAR_WINDOW: PUSH BX ;Preserve BX. MOV BH,NORMAL_ATTRIB ;Normal attribute. MOV AX,600H ;Scroll active page. INT 10H POP BX ;Restore BX. RET ;-------------------; ; DOS print string. ; ;-------------------; PRINT_STRING PROC NEAR MOV AH,9 INT 21H RET PRINT_STRING ENDP ;----------------------------------------------------------; ; Buffered keyboard input and file buffers at end of code. ; ;----------------------------------------------------------; EVEN FILESPEC EQU $ FILE1_BUFFER1 EQU FILESPEC + 2 * (SPEC_LENGTH + 2) FILE1_BUFFER2 EQU FILE1_BUFFER1 + TEN_K FILE2_BUFFER1 EQU FILE1_BUFFER2 + TEN_K FILE2_BUFFER2 EQU FILE2_BUFFER1 + TEN_K _TEXT ENDS END START