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Assembly Source File | 1991-01-10 | 39.6 KB | 828 lines

;-------------------------------------------------------------------------- ; SMOOTH * PC Magazine * Feb 14, 1989 ; Provides forward, backward and variable speed smooth scrolling ; of a file to the display. Requires Ega or Vga. ; Syntax: SMOOTH filespec ;-------------------------------------------------------------------------- _TEXT SEGMENT PUBLIC 'CODE' ASSUME CS:_TEXT,DS:_TEXT,ES:_TEXT,SS:_TEXT ORG 100H START: JMP MAIN ; DATA AREA ; --------- DB CR,SPACE,SPACE,SPACE COPYRIGHT DB CR,LF,"SMOOTH 1.0 (C) 1989 Ziff Communications Co." PROGRAMMER DB CR,LF,"PC Magazine ",BOX," Michael J. Mefford",CR,LF,LF DB "Syntax: SMOOTH filespec [/W][/Snn][Cmmm]",CR,LF DB "/W = Wordstar; /S = nn Speed; /C = mmm Color",CR,LF,LF DB "Use: ",24,25,", PgUp, PgDn, Home, End; Esc to Exit",CR,LF DB "+ = faster; - = slower; Space bar = pause; (0-9) = speed" COPY_LENGTH EQU $ - COPYRIGHT DB CR,LF,LF,"$",CTRL_Z NOT_ENOUGH DB "Not enough memory$" NOT_EGA_VGA DB "Requires Ega/Vga$" NOT_FOUND DB "File not found$" CR EQU 13 LF EQU 10 TAB EQU 9 CTRL_Z EQU 26 SPACE EQU 32 BOX EQU 254 STATUS_REG DW 3BAH VIDEO_SEGMENT DW 0B000H INDEX_SEGMENT DW ? CRT_COLS DW ? CRT_LINE DW ? CRT_LEN DW ? CRT_START DW 0 CRT_END DW ? LAST_LINE DW ? STRIP_MASK DB 0FFH ATTRIBUTE DB 07H DISPLAY_ROWS DW ? SCAN_LINESx2 DW ? UP EQU 0 DOWN EQU 1 DIRECTION DB UP CURRENT_SCANx2 DW 0 SCAN_SPEED DW 3 THIRTY_K EQU 30 * 1024 FILE_HANDLE DW ? FILE_END DW ? STORE_FLAG DB 1 DISPATCH_KEY DB 1, 48H, 50H, 49H, 51H, 47H, 4FH, 39H, 0DH, 0CH, 4EH, 4AH DISPATCH_CNT EQU $ - DISPATCH_KEY DISPATCH_TABLE DW EXIT, UP_ARROW, DOWN_ARROW, PGUP, PGDN, HOME DW END_KEY, SPACE_BAR, PLUS, MINUS, PLUS, MINUS DISPATCH_END EQU $ - 2 ; CODE AREA ; --------- MAIN PROC NEAR CLD ;All string operations forward. MOV BX,2000H ;Allocate 128K of memory. MOV AH,4AH INT 21H MOV DX,OFFSET NOT_ENOUGH ;Exit with message if not enough. JC ERROR_MSG MOV SP,0FFFEH ;Stack to top of code segment. MOV AX,CS ADD AX,1000H ;Use 2nd 64K for line indices. MOV INDEX_SEGMENT,AX MOV AX,40H ;Point to BIOS data area. MOV ES,AX MOV AX,500H ;Make sure zero video page. INT 10H MOV AX,1A00H ;Get display info. INT 10H CMP AL,1AH ;Function supported? JNZ CK_EGA ;If no, not VGA; check EGA. CMP BL,7 ;Else, monochrome VGA? JZ GET_CRT_MODE ;If yes, OK. CMP BL,8 ;Else, color VGA? JZ GET_CRT_MODE ;If yes, OK. CK_EGA: MOV AH,12H MOV BL,10H ;Get EGA information. INT 10H MOV DX,OFFSET NOT_EGA_VGA CMP BL,10H ;Is there an EGA? JZ ERROR_MSG ;If no, exit with message. TEST ES:BYTE PTR [87H],8 ;Is EGA active? JZ GET_CRT_MODE ;If yes, continue. ERROR_MSG: PUSH DX ;Else, exit with message. MOV DX,OFFSET COPYRIGHT ;Display copyright and syntax. CALL PRINT_STRING POP DX CALL PRINT_STRING MOV AL,1 ;ERRORLEVEL = 1 JMP TERMINATE ;Exit. GET_CRT_MODE: MOV BL,ES:[49H] ;Retrieve CRT_MODE. CMP BL,7 ;Is it mono? JZ GET_COLS ;If yes, use defaults. MOV STATUS_REG,3DAH ;Else, mono status register. MOV VIDEO_SEGMENT,0B800H ;And mono video segment. CMP BL,2 ;Is mode BW80? JZ GET_COLS ;If yes, defaults. OR BL,BL ;Is mode BW40? JZ GET_COLS ;If yes, continue. MOV ATTRIBUTE,17H ;Else, use color attribute. CMP BL,3 ;Are we in CO80 or CO40? JBE GET_COLS ;If yes, done here. MOV AX,3 ;Else, change to CO80. INT 10H GET_COLS: MOV AX,ES:[4AH] ;Retrieve CRT_COLS MOV CRT_COLS,AX ; and save. SHL AX,1 ;Double for attribute MOV CRT_LINE,AX ; and save. PUSH AX ;Save line length. MOV BH,2 ;Get font information. MOV AX,1130H INT 10H SHL CX,1 ;Double scan lines/character. MOV SCAN_LINESx2,CX ; and save. INC DL ;Adjust character rows. XOR DH,DH MOV DISPLAY_ROWS,DX ;Store rows on screen. POP AX ;Retrieve screen width. MUL DL ; Times rows MOV CRT_LEN,AX ; equals CRT length. ;-------------------------------------------------------; ; Check for /W WordStar, /S speed or /C color switches. ; ;-------------------------------------------------------; 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. AND AL,5FH ;Capitalize. CMP AL,"W" ;Is it "W"? JNZ CK_S ;If not, check "S". MOV STRIP_MASK,7FH ;Else, we will strip high bit. CK_S: CMP AL,"S" ;Is it "S"? JNZ CK_C ;If no, check "C". CALL DECIMAL_INPUT ;Else, get speed request. XOR BH,BH MOV AX,SCAN_LINESx2 CMP BX,AX ;If greater than maximum, JBE SAVE_SPEED MOV BX,AX ; use maximum, else use request. SAVE_SPEED: MOV SCAN_SPEED,BX JMP SHORT NEXT_SWITCH ;Get next switch. CK_C: CMP AL,"C" ;Is it "C"? JNZ NEXT_SWITCH ;If no, next switch. CALL DECIMAL_INPUT ;Else, get color request. OR BL,BL ;If black on black, skip. JZ NEXT_SWITCH MOV ATTRIBUTE,BL ;Else, save color request. JMP NEXT_SWITCH ;Next switch. ;---------------------------------------; ; Parse the command line for filespec. ; ;---------------------------------------; PARSE: MOV SI,81H ;Point to command line again. NEXT_PARSE: LODSB ;Get a byte. CMP AL,SPACE ;Parse off leading delimiters. JA LEADING_END OR AL,AL ;If ASCIIZ reached, done. JNZ NEXT_PARSE LEADING_END: MOV DX,SI DEC DX ;Adjust pointer. FIND_END: LODSB ;Find end of filespec. CMP AL,SPACE ;If none white space, continue. JAE FIND_END MOV BYTE PTR [SI-1],0 ;ASCIIZ filespec. MOV AX,3D00H ;Open file for reading. INT 21H MOV DX,OFFSET NOT_FOUND ;If fail, exit with message. JNC SAVE_HANDLE JMP ERROR_MSG SAVE_HANDLE: MOV FILE_HANDLE,AX ;Else, save handle. CALL FIRST_READ ;Read 30K. MOV ES,VIDEO_SEGMENT ;Clear the screen by writing MOV CX,CRT_LEN ; the CRT length / 2 words SHR CX,1 XOR DI,DI MOV AH,ATTRIBUTE ; with spaces of attribute. MOV AL,SPACE REP STOSW MOV BL,ATTRIBUTE ;Add border with same attribute. CALL SET_BORDER MOV DX,DISPLAY_ROWS ;Place cursor in middle of row XCHG DH,DL ; of display. SHR DH,1 CALL SET_CURSOR PUSH SI ;Save file pointer. MOV SI,OFFSET COPYRIGHT ;Display copyright and syntax MOV CX,COPY_LENGTH ; with attribute. NEXT_COPY: LODSB MOV AH,0EH INT 10H LOOP NEXT_COPY POP SI ;Retrieve file pointer. XOR BP,BP ;Use BP as line file pointer. CALL ADVANCE ;Write first line. MOV CRT_END,DI ;Save CRT end. ;*************** MAIN LOOP *****************; ; Poll the keyboard then scroll the screen. ; ;*******************************************; INPUT: MOV AH,1 ;Is there a keystroke ready? INT 16H JZ SCROLL_PAGE ;If no, scroll the page. GET_KEY: XOR AH,AH ;Else, get the keystroke. INT 16H SUB AL,"0" ;If not number, check functions. JC FUNCTION CMP AL,9 JA FUNCTION XOR AH,AH ;Else, change speed to number. CALL DO_SPEED JMP SHORT SCROLL_PAGE FUNCTION: PUSH DI ;Save some registers. PUSH ES PUSH CS POP ES MOV AL,AH ;Scan code in AL. MOV DI,OFFSET DISPATCH_KEY ;Check dispatch table. MOV CX,DISPATCH_CNT REPNZ SCASB POP ES ;Restore registers. POP DI JNZ INPUT ;Skip keystroke if no match. SHL CX,1 ;Else, look up subroutine MOV BX,OFFSET DISPATCH_END SUB BX,CX CALL [BX] ; and process command. SCROLL_PAGE: CALL SCROLL ;Scroll the page. JMP SHORT INPUT ;Next input. ;---------------------------------------------------; EXIT: MOV BX,FILE_HANDLE ;Retrieve file handle MOV AH,3EH ; and close the file. INT 21H MOV BX,CRT_LINE MOV SI,CRT_START ;Point to current visible page. MOV AX,SCAN_LINESx2 ;If current scan line is more SHR AX,1 ; than half of character scan CMP CURRENT_SCANx2,AX ; lines, move to next line. JB MOVE_PAGE ADD SI,BX MOVE_PAGE: XOR DI,DI MOV CX,CRT_LEN SUB CX,BX SHR CX,1 MOV AH,ATTRIBUTE ;Value to be used on last line. XOR AL,AL PUSH DS MOV DS,VIDEO_SEGMENT REP MOVSW ;Move the active page to page 0. MOV CX,BX SHR CX,1 REP STOSW ;Clear the last line. POP DS XOR BX,BX ;Return to a normal scan line of XOR CX,CX ; zero and an offset of zero. CALL SET_CRT XOR BL,BL ;Border back to black. CALL SET_BORDER MOV DX,DISPLAY_ROWS ;Put cursor on bottom of screen. XCHG DH,DL DEC DH ;Up a line so screen won't scroll DEC DH ; with new DOS prompt. CALL SET_CURSOR XOR AL,AL ;ERRORLEVEL zero. TERMINATE: MOV AH,4CH ;Return to DOS. INT 21H MAIN ENDP ; *************** ; * SUBROUTINES * ; *************** ;-----------------------------------------; ; What follows is the keyboard functions. ; ;-----------------------------------------; UP_ARROW: CMP DIRECTION,DOWN ;Are we already scrolling down? JZ CK_SPEED ;If yes, skip and go check speed. CALL CK_PAGE ;Else, is a full page displayed? JBE ARROW_END ;If no, ignore. INC BX ;Else, move file pointer up CALL PAGE_UP ; display rows plus one. MOV DIRECTION,DOWN ;Change scroll direction to down. JMP SHORT CK_SPEED ;Check if speed is zero. ARROW_END: RET DOWN_ARROW: CMP DIRECTION,UP ;Are we already scrolling up? JZ CK_SPEED ;If yes, skip and go check speed. CALL MOVE_DOWN ;Else, move file pointer to MOV DIRECTION,UP ; bottom of page; direction down. CK_SPEED: CMP SCAN_SPEED,0 ;If scroll speed non-zero, JNZ ARROW_END ; done, else increase by one. PLUS: MOV AX,SCAN_SPEED ;Increase scan speed by one INC AX ; scan line unless already DO_SPEED: CMP AX,SCAN_LINESx2 ; maximum speed. JBE STORE_SPEED RET MINUS: MOV AX,SCAN_SPEED ;Decrease scan speed by one DEC AX ; scan line unless already JS MINUS_END ; speed of zero (stationary). STORE_SPEED: MOV SCAN_SPEED,AX MINUS_END: RET PGUP: CMP DIRECTION,DOWN ;Are we scrolling opposite of JZ REVERSE_UP ; page request? If yes, reverse. CALL CK_PAGE ;Else, is a full page displayed? JBE PGUP_END ;If no, ignore. INC BX ;Else, move file pointer to top CALL PAGE_UP ; of page. CALL CK_PAGE ;Retrieve page length. JA DO_PAGE_UP ;Can we page up a full page? CALL PARTIAL_PAGE ;If no, partial page. JZ DO_WRITE ;If already home, skip. DO_PAGE_UP: CALL PAGE_UP ;Else, move to top of prev. page. DO_WRITE: CALL WRITE_DOWN ;Write the page. File pointer JMP SHORT PGUP_END ; ends up back at bottom so done. REVERSE_UP: CALL CK_PAGE ;If full page continue, JAE DO_REVERSE ; else use partial page. CALL PARTIAL_PAGE JZ PGUP_END ;If already home, ignore. DO_REVERSE: MOV SI,LAST_LINE ;Else, retrieve last line. CALL PAGE_UP ;Move up a page. CALL WRITE_DOWN ;Write that page. CALL MOVE_UP ;Move file pointer back to top. PGUP_END: RET PGDN: CMP DIRECTION,DOWN ;Are we scrolling opposite of JZ REVERSE_DN ; page request? If yes, reverse. CALL NEW_PAGE ;Else, move to next page. RET REVERSE_DN: CALL MOVE_DOWN ;Else, move to bottom of page. CALL NEW_PAGE ;Display next page. CALL MOVE_UP ;Move file pointer back to top. PGDN_END: RET HOME: MOV CURRENT_SCANx2,0 ;Move to scan line zero. CMP DIRECTION,DOWN ;Are we scrolling opposite of JZ REVERSE_HOME ; page request? If yes, reverse. CALL CK_PAGE ;Is a full page displayed? JA GO_HOME ;If yes, continue, else ignore. RET REVERSE_HOME: OR BP,BP ;Are we already home? JZ HOME_END ;If yes, ignore. MOV SI,LAST_LINE ;Else, retrieve last line. GO_HOME: MOV BX,BP ;Move up the number of lines SHR BX,1 ; currently displayed. CALL PAGE_UP CALL WRITE_DOWN ;Write the first page. CK_REVERSE: CMP DIRECTION,DOWN ;Scrolling down? JNZ HOME_END ;If no, done. CALL MOVE_UP ;Else, move file pointer to top. HOME_END: RET END_KEY: MOV BX,0FFFFH ;Move down until bottom reached. CMP DIRECTION,DOWN ;Are we scrolling opposite of JNZ DO_END ; page request? If yes, reverse. MOV SI,LAST_LINE ;Retrieve last line. DO_END: CALL NO_WRITE ;Top of last page and write. JMP SHORT CK_REVERSE ;Check if file pointer correction SPACE_BAR: MOV AH,1 ;Wait until keystroke ready INT 16H JZ SPACE_BAR CMP AL,SPACE ;If space bar, eat keystroke. JNZ SPACE_END ;Else, return to process. XOR AH,AH INT 16H SPACE_END: RET ;-----------------------------; ; Function support routines. ; ;-----------------------------; PARTIAL_PAGE: MOV CURRENT_SCANx2,0 ;Move to scan line zero. MOV BX,BP ;Return with number of lines SHR BX,1 ; displayed. OR BX,BX ;Zero flag if already home. RET WRITE_DOWN: CALL CK_PAGE ;Write a full page plus one INC BX ; line to display. MOV STORE_FLAG,1 CALL WRITE_PAGE RET MOVE_UP: CALL CK_PAGE ;Move up a full page plus one. INC BX CALL PAGE_UP MOV LAST_LINE,SI RET MOVE_DOWN: CALL CK_PAGE ;Move down a full page. INC BX MOV SI,LAST_LINE MOV STORE_FLAG,0 CALL WRITE_PAGE RET NEW_PAGE: CALL CK_PAGE ;Get page size. NO_WRITE: PUSH BX ;Save. MOV STORE_FLAG,0 ;Move down the page request. CALL WRITE_PAGE MOV CX,BX ;Save lines moved. CALL CK_PAGE ;Get page size. POP AX ;Retrieve page request. JBE SHORT_PAGE ;If short page, special. INC BX ;Else, move up page plus one. CALL PAGE_UP CALL WRITE_DOWN ;And write the page. CALL CK_FILE_END JNC NEW_PAGE_END MOV AX,SCAN_LINESx2 ;Change scan line to last line. DEC AX MOV CURRENT_SCANx2,AX RET SHORT_PAGE: MOV BX,AX ;For short files, move back SUB BX,CX ; up the number of lines JZ NEW_PAGE_END ; moved down. Zero net result CALL PAGE_UP ; same as ignore. NEW_PAGE_END: RET ;------------------------------------------------------------; ; OUTPUT: BX = Display rows + 1; JBE set if not a full page ; ;------------------------------------------------------------; CK_PAGE: MOV BX,DISPLAY_ROWS ;Retrieve rows on screen. SHL BX,1 ;Double for word index. CMP BP,BX ;Is there a full page? PUSHF ;Preserve results. SHR BX,1 ;Return BX = rows. POPF ;Restore flags. RET ;------------------------------------------------; ; INPUT: BX = number of lines to move backward. ; ;------------------------------------------------; PAGE_UP: DEC BP ;Index back one line. DEC BP ;It's a word index. CALL CK_BACKWARD ;Move back one line. DEC BX ;Continue until requested lines. JNZ PAGE_UP RET ;----------------------------------------; ; INPUT: BX = Number of lines to write. ; ;----------------------------------------; WRITE_PAGE: MOV DI,CRT_START ;Point to CRT start. NEXT_WRITE: CALL CK_FILE_END ;End of file? JC WRITE_END ;If yes, done. CALL ADVANCE ;Else, write a line. DEC BX ;Continue until requested lines. JNZ NEXT_WRITE WRITE_END: RET ;******************************************; SCROLL: MOV AX,SCAN_LINESx2 ;Retrieve scan lines times two. MOV BX,CURRENT_SCANx2 ;Retrieve current scan line X 2. CMP DIRECTION,DOWN ;Are we scrolling down? JZ SCROLL_DOWN ;If yes scroll down. ADD BX,SCAN_SPEED ;Else, scroll up; add speed. CMP BX,AX ;Is it a wrap? JB SCROLL_IT ;If no, display new scan line. CALL CK_FILE_END ;Are we at end of file? JNC CK_CRT_UP ;If no, continue MOV BX,AX ;Else, move to last scan line. DEC BX JMP SHORT SCROLL_IT CK_CRT_UP: SUB BX,AX ;Subtract scan lines. MOV AX,CRT_LINE ;Retrieve CRT line length. ADD CRT_START,AX ;Move CRT start to next line. CALL CK_CRT_END ;Check if end of video memory. MOV STORE_FLAG,1 ;Write a new line. CALL ADVANCE MOV CRT_END,DI ;Save new CRT end. SCROLL_IT: MOV CURRENT_SCANx2,BX ;Store new scan line. MOV CX,CRT_START ;Program registers to CALL SET_CRT ; new CRT start and scan line. SCROLL_END: RET SCROLL_DOWN: SUB BX,SCAN_SPEED ;Scroll down; subtract speed. JNC SCROLL_IT ;If not wrap, display new scan. ADD BX,AX ;Else, add scan lines. OR BP,BP ;Are we at home position? JNZ CK_CRT_DN ;If no, continue. XOR BX,BX ;Else, set scan line to zero. JMP SHORT SCROLL_IT CK_CRT_DN: CALL CK_CRT_START ;Check if start of video memory. MOV SI,LAST_LINE ;Retrieve last line. DEC BP ;Decrement file pointer DEC BP ; line start index. CALL CK_BACKWARD ;Move file pointer up one line. MOV DI,CRT_START ;Point to start of CRT. MOV STORE_FLAG,1 ;Write the line at top. CALL LINES JMP SHORT SCROLL_IT ;Set new scan line. ;------------------------------; ; Scroll support subroutines. ; ;------------------------------; CK_CRT_START: MOV AX,CRT_LINE ;Retrieve bytes in CRT line. MOV DI,CRT_START ;Retrieve current CRT start. OR DI,DI ;Is it offset of zero? JNZ MOVE_CRT ;If no, move down one line. PUSH SI ;Else, save file pointer. PUSH DS ;Preserve data segment. XOR SI,SI ;Move page zero to top MOV DI,THIRTY_K ; of video memory. MOV CX,CRT_LEN SUB DI,CX MOV CRT_START,DI SHR CX,1 MOV DS,VIDEO_SEGMENT REP MOVSW POP DS ;Restore registers. POP SI ADD DI,AX ;Adjust for extra line. MOV CRT_END,DI ;Store as new CRT end. MOVE_CRT: SUB CRT_END,AX ;Move CRT end up one line. SUB CRT_START,AX ;Move CRT start up one line. RET ;---------------------------------; CK_CRT_END: MOV DI,CRT_END ;Retrieve current CRT end. CMP DI,THIRTY_K ;End of video memory? JB CK_END ;If no, done here. PUSH SI ;Else, save file pointer PUSH DS ; and data segment. MOV SI,CRT_START ;Move page down to start XOR DI,DI ; of video memory. MOV CRT_START,DI MOV CX,CRT_LEN SHR CX,1 MOV DS,VIDEO_SEGMENT REP MOVSW POP DS ;Restore registers. POP SI CK_END: RET ;---------------------------------; CK_BACKWARD: CALL GET_INDEX ;Set file pointer to SUB SI,AX ; previous line. CMP SI,OFFSET FILE_BUFFER ;Out of range of buffer? JAE BACKWARD_END ;If no, done here. PUSH SI ;Else, preserve registers. PUSH BX CALL BACKWARD ;Rearrange buffer and read POP BX ; in previous 30K of file. POP SI ADD SI,THIRTY_K ;Adjust file pointer. BACKWARD_END: MOV LAST_LINE,SI ;Save last line. RET ;-------------------------------------------------; ; OUTPUT: AX = length in bytes of previous line. ; ;-------------------------------------------------; GET_INDEX: PUSH DS ;Preserve data segment. MOV DS,INDEX_SEGMENT ;Second 64K is used for MOV AX,DS:[BP] ; index of line length. POP DS RET ;-----------------------------------------------------------------------; ; INPUT: BX = Desired scan line times two; CX = Offset of video start. ; ;-----------------------------------------------------------------------; SET_CRT: MOV DX,CS:STATUS_REG ;Retrieve status register. CLI ;No interrupts. HORIZONTAL: IN AL,DX ;Wait for horizontal trace TEST AL,8 ; so will catch vertical JZ HORIZONTAL ; retrace at start. VERTICAL: IN AL,DX ;Wait for vertical retrace. RCR AL,1 JC VERTICAL SUB DX,6 ;Point to CRT index register. MOV AL,8 ;Index to preset row scan. OUT DX,AL INC DX SHR BX,1 ;Convert scan line times two MOV AL,BL ; to actual scan line (div 2). OUT DX,AL DEC DX ;Back to index register. MOV BX,0D0CH ;Set video offset. CALL SET_ADDRESS DEC DX ;Back to index register. MOV BX,0F0EH ;Hide cursor by setting MOV CX,CRT_END ; CRT end. CALL SET_ADDRESS STI RET ;Interrupts back on. SET_ADDRESS: SHR CX,1 ;Address has to be divided by 2. MOV AL,BL ;Most significant byte. OUT DX,AL INC DX MOV AL,CH ;Write it. OUT DX,AL DEC DX ;Next index. MOV AL,BH OUT DX,AL INC DX MOV AL,CL ;Least significant byte. OUT DX,AL ;Write it. RET ;---------------------------------------------------------------------------; ; A line is marked by either a carriage return or reaching the last column. ; ;---------------------------------------------------------------------------; ADVANCE: XOR DX,DX ;Use DX as counter. CALL LINES ;Write a line. PUSH DS MOV DS,INDEX_SEGMENT MOV DS:[BP],DX ;Save length of line. POP DS INC BP ;Move to new index. INC BP JNZ ADVANCE_END ;If 32K lines exceeded, JMP EXIT ; too much; give up. ADVANCE_END: RET ;---------------------------------; LINES: MOV CX,CRT_COLS ;Retrieve columns. MOV LAST_LINE,SI ;Save current line as new last. NEXT_LINES: CMP SI,FILE_END ;End of buffer?; If no, continue. JB GET_LINES CMP FILE_END,OFFSET FILE_BUFFER + (THIRTY_K * 2) JB PAD_SPACES ;If end of file, pad with spaces. PUSH BX ;If end of buffer, save PUSH CX ; our pointers and PUSH DX PUSH DI ; read next 30K. CALL FORWARD POP DI ;Restore pointers. POP DX POP CX POP BX GET_LINES: MOV AH,ATTRIBUTE ;Retrieve attribute. LODSB ;Get a byte. INC DX ;Increment counter. AND AL,STRIP_MASK ;Strip high bit for WordStar? CMP AL,CR ;Carriage return? JZ PAD_SPACES ;If yes, pad balance of line. CMP AL,TAB ;Is it tab character? JZ DO_TAB ;If yes, tab. CMP AL,LF ;Is it linefeed? JZ NEXT_LINES ;If yes, skip. CMP STORE_FLAG,1 ;Else, write to video memory? JNZ NEXT_BYTES ;If no, next byte. STOSW ;Else, store the byte/attribute. NEXT_BYTES: LOOP NEXT_LINES ;Get next byte. CMP BYTE PTR [SI],CR ;Adjust if next byte CR after JNZ END_LINES ; complete line to avoid double INC SI ; spacing. INC DX END_LINES: RET DO_TAB: PUSH CX ;Save counter. DEC CX ;Adjust column counter. AND CX,7 ;Get bottom three bits. INC CX ;Adjust. PUSH CX CALL PAD_SPACES ;Move to next tab position. POP AX POP CX SUB CX,AX ;Adjust counter. JNZ NEXT_LINES ;Next byte if last column. RET PAD_SPACES: MOV AL,SPACE ;Space character. CK_DISPLAY: CMP STORE_FLAG,1 ;Are we to write it to screen? JNZ CK_DISP_END ;If no, return. WRITE_VIEW: REP STOSW ;Else, write CX spaces/attribute. CK_DISP_END: RET ;-----------------------------------------------------; ; OUTPUT: CY = 0 if not file end; CY = 1 if file end. ; ;-----------------------------------------------------; CK_FILE_END: CMP SI,FILE_END JB NOT_FILE_END CMP FILE_END,OFFSET FILE_BUFFER + (THIRTY_K * 2) JAE NOT_FILE_END STC RET NOT_FILE_END: CLC RET ;-------------------------------------------------------------------; ; These two subroutines read either the next or previous 30K bytes. ; ;-------------------------------------------------------------------; FORWARD: XOR CX,CX ;Zero in high half; Move file MOV DX,THIRTY_K ; pointer forward 30K. SUB LAST_LINE,DX ;Adjust last line 30K. CALL MOVE_POINTER FIRST_READ: MOV SI,OFFSET FILE_BUFFER + THIRTY_K MOV DI,OFFSET FILE_BUFFER ;Move second half of buffer CALL MOVE_BUFFER ; to first half and read 30K. MOV CX,-1 ;Move file pointer back. NEG DX MOVE_POINTER: MOV BX,FILE_HANDLE MOV AX,4201H ;Move file pointer via DOS. INT 21H RET BACKWARD: MOV CX,-1 ;Move pointer back 30K. MOV DX,- (THIRTY_K * 2) CALL MOVE_POINTER MOV SI,OFFSET FILE_BUFFER ;Move first half of MOV DI,OFFSET FILE_BUFFER + THIRTY_K ; buffer to second. MOVE_BUFFER: PUSH ES ;Preserve extra segment. PUSH CS POP ES MOV DX,SI ;Save file pointer. MOV CX,THIRTY_K / 2 ;Move 15K words (30K bytes). REP MOVSW MOV BX,FILE_HANDLE MOV CX,THIRTY_K ;Read 30K. MOV AH,3FH INT 21H MOV SI,DX ;Restore file pointer. MOV DX,AX ADD AX,OFFSET FILE_BUFFER + THIRTY_K MOV FILE_END,AX ;Store end of buffer offset. POP ES RET ;--------------------------------------------------; ; INPUT: SI points to parameter start. ; ; OUTPUT: SI points to parameter end; BX = number. ; ;--------------------------------------------------; DECIMAL_INPUT: XOR BL,BL ;Start with zero. NEXT_DECIMAL: LODSB ;Get a character. SUB AL,"0" ;ASCII to binary. JC DECIMAL_END ;If not between 0 and 9, skip. CMP AL,9 JA DECIMAL_END XCHG AL,BL MOV CL,10 ;Multiply current by 10 to MUL CL ; shift left one decimal. ADD BL,AL ;Add new number and store in BX. JMP SHORT NEXT_DECIMAL DECIMAL_END: DEC SI ;Adjust pointer. RET ;------------------------; ; INPUT: BL = Attribute. ; ;------------------------; SET_BORDER: XOR BH,BH MOV CL,4 ;Use background attribute SHR BL,CL ; for border. MOV AH,0BH INT 10H RET SET_CURSOR: XOR BH,BH MOV AH,2 ;Set cursor position. INT 10H RET PRINT_STRING: MOV AH,9 INT 21H RET FILE_BUFFER = $ _TEXT ENDS END START