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Assembly Source File | 1998-01-14 | 15.3 KB | 454 lines

; BROWSE.ASM -- Full Screen File Pager ; ==================================== CSEG Segment Assume CS:CSEG, DS:CSEG, ES:CSEG, SS:CSEG Org 0080h Parameter Label Byte Org 0100h Entry: Jmp Begin ; All Data ; -------- db 'ATTR=' Attribute db 0 ; Current screen attribute db 'SHIFT=' ShiftHoriz db 8 ; Horizontal shift screen default DosVersionFail db 'Requires DOS 2.0 or above$' NoSpaceFail db 'Not enough memory$' FileFail db 'File Not Found$' ScreenFail db 'Unsupported video mode$' Delimiters db 9,' ,;=/' ; Delimiters in parameter FileHandle dw ? ; Use for saving file handle WSMode db 0FFh ; AND value for non-WordStar mode LineLength db ? ; Length of line (from BIOS) NumberLines db 25,0 ; Number of lines (check EGA BIOS) ScreenSize dw ? ; Size of screen in bytes CheckRetrace db 1 ; Flag zero if EGA or MONO used Addr6845 dw ? ; Could use for retrace check ScreenAddr Label DWord ; Address of screen ScreenOff dw 0 ; Higher for non-page 0 ScreenSeg dw 0B800h ; Set to B000h for Mono Mode 7 ScreenStart dw ? ; Points within buffer EndOfFile dw ? ; Points within buffer FileOffset dw -1, -1 ; Address within file of buffer data HorizOffset dw 0 ; Horizontal offset for display RightMargin dw 0 ; Right margin for offset display Dispatch dw Home, Up, PgUp, Dummy, Left dw Dummy, Right, Dummy, End, Down, PgDn ; Check DOS Version for 2.0 or above ; ---------------------------------- Begin: Cld ; All string directions forward Mov AH,30h Int 21h ; Get DOS Version Number Cmp AL,2 ; Check for 2.0 or later Jae DOSVerOK Mov DX,Offset DOSVersionFail ErrorExit: Mov AH,9 ; Write error message Int 21h Int 20h ; Parse Command Line to get File Name and WordStar flag ; ----------------------------------------------------- DOSVerOK: Mov SI,1 + Offset Parameter ; Points to parameter NameSearch: Lodsb ; Get byte Cmp AL,13 ; Check if carriage return Jz NoFileFound ; If so, no file name Mov DI,Offset Delimiters ; String of delimiters Mov CX,5 ; Number of delimiters (no /) Repne Scasb ; See if a match Je NameSearch ; If a delimiter, keep looking Mov DX,SI ; Otherwise found file name Dec DX ; Points to beginning of it EndSearch: Lodsb ; Get next byte Cmp AL,13 ; See if carriage return Je GotFileEnd ; If so, we're all done Mov DI,Offset Delimiters ; String of delimiters Mov CX,6 ; Number (including /) Repne Scasb ; See if a match Jne EndSearch ; If not, still in file name Mov Byte Ptr [SI - 1],0 ; If so, mark end of file name Jcxz GotFlag ; If slash, check for W Jmp EndSearch ; Or continue flag search GotFlag: Lodsb ; Get byte after / flag Or AL,20h ; Uncapitalize Cmp AL,'w' ; See if w for WordStar mode Jnz GotFileEnd ; If not, just ignore it Mov [WSMode],7Fh ; AND value for WordStar ; Open the File ; ------------- GotFileEnd: Mov Byte Ptr [SI - 1],0 ; Mark end of file name ; DX still points to name Mov AX,3D00h ; Open file for reading Int 21h ; by calling DOS Jnc GotTheFile ; If no error, continue NoFileFound: Mov DX,Offset FileFail ; Otherwise print a message Jmp ErrorExit GotTheFile: Mov [FileHandle],AX ; Save the file handle ; Get Screen Mode Information from BIOS Data Area ; ----------------------------------------------- Push ES ; Save register Sub AX,AX Mov ES,AX ; Set ES to 0 (BIOS Data) Mov AL,ES:[0449h] ; Current Video Mode Cmp AL,3 ; Check if Color Alpha Jbe DisplayOK ; Continue if so Cmp AL,7 ; Check if monochrome display Je Monochrome ; If so, branch Mov DX,Offset ScreenFail ; We can't handle graphics Jmp ErrorExit ; So print an error message Monochrome: Mov [ScreenSeg],0B000h ; Use Monochrome Segment Mov [CheckRetrace],0 ; Don't have to check retrace DisplayOK: Mov AL,ES:[044Ah] ; Number of Columns Mov [LineLength],AL ; Save it Mov AX,ES:[044Eh] ; Offset into screen buffer Mov [ScreenOff],AX ; Save it Mov AX,ES:[0463h] ; Address of 6845 Regsiter Mov [Addr6845],AX ; Save it Push ES Sub DL,DL ; Set Rows to zero first Sub BH,BH Mov AX,1130h ; EGA BIOS: Get Information Int 10h Pop ES Or DL,DL ; Check if DL is still zero Jz NoEGA ; If so, skip rest of stuff Inc DL Mov [NumberLines],DL ; Save Number of Lines Test Byte Ptr ES:[0487h],4 ; Check if must check retrace Jnz NoEGA Mov [CheckRetrace],0 ; EGA says we don't have to NoEGA: Mov BH,ES:[0462h] ; Get Current Page (use later) Pop ES Mov AL,[LineLength] ; Length of each line Mul [NumberLines] ; Total chars on screen Add AX,AX ; Double for attributes Mov [ScreenSize],AX ; And Save it ; See if enough memory is left ; ---------------------------- Add AX,Offset ScreenHold ; Add ScreenSize to code end Add AX,256 ; Add a little stack room Cmp AX,SP ; Check against stack pointer Jbe GotEnufMemory ; Continue if OK Mov DX,Offset NoSpaceFail ; Otherwise end program Jmp ErrorExit ; with error messae ; Get Current Screen Attribute ; ---------------------------- GotEnufMemory: Cmp [Attribute],0 ; Check if attribute pre-set Jnz GotAttribute ; If so, move on Mov DL,' ' ; Write out a byte Mov AH,2 ; using DOS Int 21h Mov AL,8 ; Now backspace Mov AH,14 ; using BIOS call Int 10h Mov AH,8 ; Read character & attribute Int 10h ; using BIOS call (BH = pg) Mov [Attribute],AH ; And save attribute ; Save Current Screen ; ------------------- GotAttribute: Mov DX,Offset Terminate ; Set Ctrl-Break exit Mov AX,2523h ; to terminate that way Int 21h Mov DI,Offset ScreenHold ; Destination of screen Mov CX,[ScreenSize] ; Size of screen Push DS ; Save Source Segment Lds SI,[ScreenAddr] ; Get screen address Rep Movsb ; Move in the bytes Pop DS ; Restore Source Segment ; Get Keyboard Key and Decide on Action ; ------------------------------------- Call Home ; Read file in Mov [ScreenStart],SI ; Set buffer address KeyLoop: Call UpDateScreen ; Write file to screen GetKey: Mov AH,8 ; Get key Int 21h ; by calling DOS Cmp AL,27 ; Check if ESC Je Terminate ; If so, terminate Cmp AL,0 ; Check if extended Jnz GetKey ; If not, try again Mov AH,8 ; Get extended code Int 21h ; by calling DOS Sub AL,71 ; Subtract Home key value Jb GetKey ; If below that, not valid Cmp AL,(81 - 71) ; Check if above PgDn Ja GetKey ; If so, ignore it Sub AH,AH ; Zero out top byte Add AX,AX ; Double for word access Mov BX,AX ; Offset in dispatch table Mov SI,[ScreenStart] ; Set current buffer pointer Call [Dispatch + BX] ; Do the call Mov [ScreenStart],SI ; Set new buffer pointer Jmp KeyLoop ; And update the screen ; Terminate -- Restore screen and close file ; ------------------------------------------ Terminate: Mov SI,Offset ScreenHold ; Address of Saved Screen Les DI,[ScreenAddr] ; Address of Display Mov CX,[ScreenSize] ; Number of characters Rep Movsb ; Move them back Mov BX,[FileHandle] ; Get File Handle Mov AH,3Eh ; Close File Int 21h Int 20h ; Terminate ; Cursor Key Routines -- Home Key ; ------------------------------- Home: Sub BX,BX ; For zeroing out values Mov AX,[FileOffset] ; Check if read in file Or AX,[FileOffset + 2] Mov [FileOffset],BX ; Zero out file address Mov [FileOffset + 2],BX Mov [HorizOffset],BX ; Zero out horizontal offset Mov SI,Offset Buffer ; Reset buffer pointer Jz Dummy ; Skip file read if in already Mov DX,Offset Buffer ; Area to read file in Mov CX,32768 ; Number of bytes to read Call FileRead ; Read in file Dummy: Ret ; Up and PgUp Keys ; ---------------- Up: Call GetPrevChar ; Get previous char in buffer Jc UpDone ; If none available, finish UpLoop: Call GetPrevChar ; Get previous char again Jc UpDone ; if none, we're done Cmp AL,10 ; Check if line feed Jnz UpLoop ; If not, try again Call GetNextChar ; Get char after line feed UpDone: Ret PgUp: Mov CX,Word Ptr [NumberLines] ; Number of lines PgUpLoop: Call Up ; Do UP that many times Loop PgUpLoop Ret ; Left and Right Keys ; ------------------- Left: Mov [HorizOffset],0 ; Reset Horizontal Offset Ret Right: Mov AL,[ShiftHoriz] ; Get places to shift Sub AH,AH Add [HorizOffset],AX ; Move that many right Ret ; End, Down, and PgDn Keys ; ------------------------ End: Mov BX,SI ; Save buffer pointer Call PgDn ; Go page down Cmp BX,SI ; Check if we did so Jnz End ; If so, do it again Ret Down: Call GetNextChar ; Get next character Jc NoMoreDown ; If no more, we're done DownLoop: Call GetNextChar ; Get one again Jc UpLoop ; If no more, find prev LF Cmp AL,10 ; See if line feed Jnz DownLoop ; If not, continue NoMoreDown: Ret PgDn: Mov CX,Word Ptr [NumberLines] ; Number of lines PgDnLoop: Call Down ; Do DOWN that many times Loop PgDnLoop Ret ; Update Screen ; ------------- UpdateScreen: Push ES Mov SI,[ScreenStart] ; Address of data in buffer Les DI,[ScreenAddr] ; Address of display Mov CX,ScreenSize ; Number of bytes in screen Shr CX,1 ; Half for number of chars Mov AL,' ' ; Will blank screen Mov AH,[Attribute] ; With screen attribute Rep Stosw ; Blank it Mov AL,[LineLength] ; Length of display line Sub AH,AH Add AX,[HorizOffset] ; Add Horizontal Offset Mov [RightMargin],AX ; That's right display margin Sub DL,DL ; Line Number LineLoop: Sub BX,BX ; Column Number Mov AL,[LineLength] ; Use Line Length Mul DL ; and Line Number Add AX,AX ; to recalculate Mov DI,AX ; display destination Add DI,[ScreenOff] ; Add beginning address CharLoop: Call GetNextChar ; Get next character Jc EndOfScreen ; If no more, we're done And AL,[WSMode] ; Will be 7Fh for WordStar Cmp AL,13 ; Check for carriage return Je CharLoop ; Do nothing if so Cmp AL,10 ; Check for line feed Je LineFeed ; Do routine if so Cmp AL,9 ; Check for tab Je Tab ; Do routine if so Mov CX,1 ; Just 1 char to display PrintChar: Cmp BX,[HorizOffset] ; See if we can print it Jb NoPrint Cmp BX,[RightMargin] ; See if within margin Jae NoPrint Mov AH,[Attribute] ; Attribute for display Cmp [CheckRetrace],0 ; See if must stop snow Jz WriteIt ; If not, skip retrace wait Push BX Push DX Mov BX,AX ; Save character and attribute Mov DX,[Addr6845] ; Set up I/O address Add DX,6 RetraceWait1: In AL,DX ; Check until Shr AL,1 ; vertical retrace Jc RetraceWait1 ; ends Cli ; Clear interrupts RetraceWait2: In AL,DX ; Check until Shr AL,1 ; vertical retrace Jnc RetraceWait2 ; begins Mov AX,BX ; Get back character & attr Stosw ; Write to display Sti ; Enable interrupts again Pop DX Pop BX Jmp Short NoPrint ; Skip around "no snow" write WriteIt: Stosw ; Write without retrace wait NoPrint: Inc BX ; Bump up line counter Loop PrintChar ; Do it CX times Jmp CharLoop ; Then go back to top Tab: Mov AX,BX ; Current column number And AX,07h ; Take lower three bits Mov CX,8 Sub CX,AX ; Subtract from 8 Mov AL,' ' ; Will print CX blanks Jmp PrintChar LineFeed: Inc DL ; Next line Cmp DL,[NumberLines] ; See if down at bottom Jb LineLoop ; If not, continue EndOfScreen: Pop ES ; All done -- leave Ret ; Get Next Character from buffer ; ------------------------------ ; (Input is SI pointing to buffer, Returns AL, CY if no more) GetNextChar: Cmp SI,[EndOfFile] ; See if at end of file Jae NoMoreNext ; If so, no more chars Cmp SI,Offset BufferEnd ; See if at end of buffer Jb CanGetNext ; If not, just get character Push CX ; Otherwise save registers Push DX Push DI Push ES Push DS ; Set ES to DS Pop ES ; (could be different) Mov SI,Offset BufferMid ; Move 2nd buffer half Mov DI,Offset Buffer ; to 1st buffer half Mov CX,16384 Sub [ScreenStart],CX ; New buffer pointer Rep Movsb ; Move them Mov SI,DI ; SI also buffer pointer Add [FileOffset],32768 ; Adjust file addr to read Adc [FileOffset + 2],0 Mov DX,Offset BufferMid ; Place to read file Mov CX,16384 ; Number of bytes Call FileRead ; Read the file Sub [FileOffset],16384 ; Now adjust so reflects Sbb [FileOffset + 2],0 ; 1st half of buffer Pop ES ; Get back registers Pop DI Pop DX Pop CX Jmp GetNextChar ; And try again to get char CanGetNext: Lodsb ; Get the character NoMoreNext: Cmc ; So CY set if no more Ret ; Get Previous Character from buffer ; ---------------------------------- GetPrevChar: Cmp SI,Offset Buffer ; See if at top of buffer Ja CanGetPrev ; If not, just get character Mov AX,[FileOffset] ; See if at top of file Or AX,[FileOffset + 2] Jz AtTopAlready ; If so, can't get anymore Push CX ; Save some registers Push DX Mov SI,Offset Buffer ; Move 1st half of buffer Mov DI,Offset BufferMid ; to 2nd half of buffer Mov CX,16384 Add [ScreenStart],CX ; New buffer pointer Rep Movsb ; Do the move Sub [FileOffset],16384 ; Adjust file addr for read Sbb [FileOffset + 2],0 Mov DX,Offset Buffer ; Area to read file into Mov CX,16384 ; Number of bytes Call FileRead ; Read the file Pop DX ; Get back registers Pop CX Jmp Short CanGetPrev ; Now get character AtTopAlready: Stc ; CY flag set for no more Ret CanGetPrev: Dec SI ; Move pointer back Mov AL,[SI] ; Get the character Clc ; CY flag reset for success Ret ; Read CX bytes from the file into DX buffer ; ------------------------------------------ FileRead: Push AX ; Save some registers Push BX Push CX Push DX Mov [EndOfFile],-1 ; Initialize this Mov DX,[FileOffset] ; Get file address to read Mov CX,[FileOffset + 2] Mov BX,[FileHandle] ; Get file Handle Sub AL,AL ; Do LSEEK from beginning Mov AH,42h ; LSEEK call Int 21h Pop DX ; Get back destination Pop CX ; Get back count Mov AH,3Fh ; Read file function call Int 21h Jnc NoReadError ; If no error, continue Sub AX,AX ; Otherwise read zero bytes NoReadError: Cmp AX,CX ; See if 32K has been read Je GotItAll ; If so, we're home free Add AX,DX ; Otherwise add to buffer addr Mov [EndOfFile],AX ; And save as end of file GotItAll: Pop BX Pop AX Ret ; File Buffer and Screen Hold Areas ; --------------------------------- Buffer Label Byte ; Area for file reads BufferMid equ Buffer + 16384 ; Halfway through it BufferEnd equ BufferMid + 16384 ; At end of it ScreenHold equ BufferEnd ; Area for holding screen CSEG EndS ; End of segment End Entry ; Denotes entry point