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Text File | 1990-05-28 | 17.2 KB | 441 lines

zavt - enhanced MS-DOS ansi/avatar console driver SYNOPSIS Include in \config.sys the line device=zavt.sys DESCRIPTION Zavt.sys is a console driver which understands ANSI control sequences as well as Avatar level 0. It has several advantages over most other drivers. 1. It supports any display mode the BIOS can set up (see below) 2. It can be addressed by two different names so the default output can be left in raw mode (see below) 3. The blasted bell is now 1/9 second 4. Any DOS console entry may make use of a full-screen editor One trivial advantage is the allowing of backspaces across the left margin. I don't know what problems this may create, but it is nice for the command line. COMPATABILITY ------------- Zavt gets all its information about the console from the BIOS data area - nothing is assumed other than that modes 0-3 and 7 are text modes. Other drivers assume your screen is 25 lines long, and that the video card is always left on page 0. This is a safe assumption most of the time, but bad practice. AutoCAD 2.5 for example is more efficient in switching between graphics and text when you configure it to write text on page one and use page 0 for its graphics, but will not give a usable text page with other drivers. Nansi has code in it to switch an EGA to 43 line mode, or an AT&T display to 50 line mode, but if you switch back by any means other than Nansi's own facilities, Nansi continues to assume 43 lines. Zavt responds to changes in display size very well. If you switch to a mode with more lines on screen (not by means of the driver - system specifics I leave to other software), Zavt will use them immediately. If you switch to a mode with fewer lines and the cursor is off the new screen, the next scroll will bring it along with the screen region around it into view. The best way to get a feel for this if you have an EGA is to play with the xxLINE.COM programs included. The names are for EGA, and will work for VGA, but will give you more lines than advertised. DEVICE DRIVERS -------------- When you, for example, type C:> type foo.txt COMMAND.COM opens the file foo.txt, reads it, and writes it to the console driver, which puts it up on the screen. DOS has two ways of writing to the console driver: raw/binary mode: where the device driver is called once for a group of characters letting the device driver handle them all at once, or cooked/ASCII mode: where DOS calls the device driver once for each character to be sent, expanding any tabs. Raw mode is much faster as the device driver is called fewer times requiring less overhead all together. However, you lose the ability to abort in the middle of output. If you TYPE a large file, COMMAND.COM sends it to the console driver 32K at a time, so if you Ctrl-Break, you'll have to wait until the first 32K have been displayed. DOS also no longer expands tabs, but this is easily handled by the device driver. Run RAW.COM then type C:> dir /w and rather than tabs between filenames, the tab character is displayed. Run COOKED.COM before continuing. When DOS wants input from the console (such as when reading input for a filter such as MORE), raw and cooked mode also apply. In cooked mode, DOS will echo each character you enter, and interpret the cursor keys and f-keys allowing you to edit what you enter. DOS will also end entry when you hit CR, returning what you typed up to that point, even if more characters were requested. To demonstrate this, type C:> more and type some gibberish. DOS is requesting 4096 characters, but as soon as you type <enter>, entry ends and more prints out what you typed. Press f6 and enter to end. When the console is in raw mode however, DOS does not echo characters, check for ^C, ^S, or ^P, and asks of the driver however many characters the calling program wants. The driver has no choice but to oblige, and without feedback, the computer seems frozen. Run RAW.COM included in this archive, then try MORE. Unless you type 4096 characters, with a ^Z included to flag end of file, the computer is for all intents and purposes crashed. So while setting the console to raw mode lets you display text *MUCH* faster, you have a potential trap if you run into software which requests data from the default input. The solution would seem to be to write in raw mode, and read on cooked mode, but DOS will speak to a device driver in only one way at a time. The solution? Use a second device driver. The console is normally addressed as CON, but Zavt has a secondary handler which allows it to be addressed as KEYB as well. The problem is how to change the default input to KEYB. CTTY will change both the default input, but it will change the default output and error output as well. In DOS versions up to 3.3, CTTY has a bug which will allow you to C:> CTTY <KEYB DOS will say 'Invalid Device' but otherwise acts as expected. DOS 4.0 users will have to live with the risk (it's not that great). Once the default input is set to the alternate handler, you can go ahead and set the default output (and with it, the error output) to raw mode. ANSI (taken from documentation for NANSI 2.4) ---- While putting text up on the screen, zavt.sys keeps a lookout for the escape character (chr(27), known as ESC); this character signals the start of a terminal control sequence. Terminal control sequences follow the format ESC [ param; param; ...; param cmd where ESC is the escape character chr$(27). [ is the left bracket character. param is an ASCII decimal number, or a string in quotes. cmd is a case-specific letter identifying the command. Usually, zero, one, or two parameters are given. If parameters are omitted, they usually default to 1. Spaces are not allowed between parameters. For example, both ESC[1;1H and ESC[H send the cursor to the home position (1,1), which is the upper left. Either single or double quotes may be used to quote a string. Each character inside a quoted string is equivalent to one numeric parameter. Quoted strings are normally used only for the Keyboard Key Reassignment command. ESCAPE.COM from PC-Magazine is included as an easy way to send these control sequences, sending the ESC and [ followed immediately by whatever is given to it on the command line. Control Sequences The following table lists the sequences understood by nansi.sys. Differences between nansi.sys and the standard ansi.sys are marked with a vertical bar (|). Cursor Positioning Short Long name Format Notes CUP cursor position ESC[y;xH Sets cursor position. HVP cursor position ESC[y;xf Same as CUP; not recommended. CUU cursor up ESC[nA n = # of lines to move CUD cursor down ESC[nB CUF cursor forward ESC[nC n = # of columns to move CUB cursor backward ESC[nD DSR Device Status, Report! ESC[6n Find out cursor position. CPR Cursor Position report ESC[y;xR<CR> Response to DSR, as if typed. SCP Save Cursor Position ESC[s Not nestable. RCP Restore Cursor Position ESC[u Editing EID Erase in Display ESC[J Clears screen to cursor EID Erase in Display ESC[1J Clears screen from cursor. EID Erase in Display ESC[2J Clears screen. EIL Erase in Line ESC[K Clears to end of line. EIL Erase in Line ESC[1K Clears line up to cursor. EIL Erase in Line ESC[2K Clears entire line. IL Insert Lines ESC[nL Inserts n blank lines at cursor line. DL Delete Lines ESC[nM Deletes n lines, including cursor line. IC Insert Characters ESC[n@ Inserts n blank chars at cursor. DC Delete Characters ESC[nP Deletes n chars, including cursor char. Mode-Setting SGR Set Graphics Rendition ESC[n;n;...nm See character attribute table. SM Set Mode ESC[=nh See screen mode table. RM Reset Mode ESC[=nl See screen mode table. IBMKKR Keyboard Key Reass. ESC["string"p The first char of the string gives the key to redefine; the rest of the string is the key's new value. To specify unprintable chars, give the ASCII value of the char outside of quotes, as a normal parameter. IBM function keys are two byte strings; see the IBM Basic manual. For instance, ESC[0;59;"dir a:";13;p redefines function key 1 to have the value "dir a:" followed by the ENTER key. If no parameters given, all keys are reset to their default values. Character Attributes The Set Graphics Rendition command is used to select foreground and background colors or attributes. When you use multiple parameters, they are executed in sequence, and the effects are cumulative. Attrib code Value 0 All attributes off (normal white on black) 1 Bold 2 Bold off 4 Underline 5 Blink 7 Reverse Video 8 Invisible (but why?) 30-37 foregnd blk/red/grn/yel/blu/magenta/cyan/white 40-47 background (no effect in graphics modes) Screen Modes The Set Mode and Reset Mode sequences both accept one parameter, with the following values: Mode Code Value (same for Set and for Reset) 0 text 40x25 Black & White 1 text 40x25 Color 2 text 80x25 Black & White 3 text 80x25 Color 4 bitmap 320x200 4 bits/pixel 5 bitmap 320x200 1 bit/pixel 6 bitmap 640x200 1 bit/pixel 13 EGA graphics 320x200 4 bits/pixel 14 EGA graphics 640x200 4 bits/pixel 15 EGA [ IBM Monochrome display 640x350 2 bits/pixel?] 16 EGA graphics 640x350 4 bits/pixel [with full 256K] Mode Code Set Reset 7 *Wrap at end of line No wrap at EOL 45 *Graphics Cursor No simulated graphics cursor Note: Modes other than the two set codes are BIOS display modes and modes not listed which may be supported by new cards (VGA for example) can also be selected by these functions. [ * = default ] Little Dead Blobs If you are using a graphics mode, and the cursor leaves little dead blobs behind when it moves, you are probably using a program which bypasses DOS (naughty, naughty). It might help to tell Nansi to turn off its graphics cursor by sending the string ESC [ = 45 l (The last character in that string is a lowercase "L".) AVATAR ------ While putting text up on the screen, Zavt.sys also looks out for ^V, ^Y, ^L and ^P. The following is taken from documentation for OANSI. ALIASING In an Avatar sequence, the DLE character is "escaped." That's a scheme to let you use characters normally not available to an editor. DLE Hex=10 Decimal=16 Here are some examples of character aliases: Hex Decimal Real character ---------------------------------- 10 83 16 131 3 (^c) 10 9a 16 154 1a (^z) 10 90 16 144 10 (^p) 10 10 16 16 10 (^p) When an Avatar terminal runs into a DLE character, it grabs the next available byte and strips off the high-order bit. CONTROL CODES Command Description ----------------------------------------------- ^v ^a <a> attribute The "<a>" is a single byte. The value of this attribute byte corresponds to the video attributes used by IBM on their CGA monitors. (Intense video is supported, black-on-black is not.) ^v ^b blinking on blinking is turned off by the next "^v^a" command ^v ^c move cursor up a line ^v ^d move cursor down a line ^v ^e move cursor left a line ^v ^f move cursor right a line ^v ^g clear to end of line ^v ^h <r> <c> set cursor position These are 1-based numbers with the "Y" (row) coordinate first. The upper left of the display is "1,1." The start of the second line would be "2,1." ^l set current attribute to cyan on black, home cursor and clear screen Avatar is a binary based protocol while ANSI is ASCII based. As a result, control codes which may have other meanins may end up part of an Avatar control sequnce. This is not a problem except when something tries to interpret a control code without realizing it is to be preserved. The only situation where this occurs that is of any concern is with DOS. If the console is in cooked mode, any ^i will become some number of spaces as DOS considers it to be a tab. This will corrupt any Avatar code with a ^i in it. The solution is to set the console to raw mode, which is the reccommended setup for speed as well. Full-Screen input ----------------- Code for the full-screen editor was mostly taken from PC-Magazine's DOS-EDIT and thus the mechanics are virtually identical. Being part of the console handler rather than a TSR however allows the editor to be used for any DOS input rather than only the command line. For those not familiar, pressing cursor-up on the command line with DOS-EDIT loaded would move the cursor up one line and put you into the full-screen editor. From there, the special keys are Escape leave the fullscreen routine Cursor keys move the cursor accordingly Home move the cursor to the left margin End leave the full-screen routine, putting what is on the screen under and following the cursor into a buffer to be read as keyboard input PgUp move the cursor to its original column PgDn delete all characters on and following the cursor Insert toggle insert/delete mode Delete delete character to left of cursor and move text under and to the right of the cursor one space left Enter same as End but adds a CR to the end of the data The alpha-numeric keys print to screen while control codes may or may not depending on whether or not they have other purposes. Alt-<num> input always prints however, so it is possible to queue a sequence of strings by putting typing them on one line and typing 13 on the numeric keypad while holding Alt in between each string. Since ZAVT treats all console input the same, using cursor-up as the full-screen key may preclude software such as 4DOS which uses the key for its own purposes. In ZAVT without keyboard remapping Ctrl-PgUp is used in its place as it is reasonably obscure but still accessible. In ZAVT with keyboard mapping, there is no default. When a key maps a double-null, that is taken as the hotkey. Thus to define Ctrl-PgUp as the hotkey with ESCAPE.COM, type c:>ESCAPE 0;132;0;0p BUGS The Set Mode and Reset Mode code 45 was chosen to match what was used in NANSI 2.4 which in turn was chosen without even looking to see if there were established codes for those functions. Insert and delete character do not work in graphics modes because BIOS does not include a scroll left/right function. Cursor Position Report has a carriage return in it, which is what ansi.sys does, but is nonstandard. Avatar RLE doesn't handle control characters - it assumes whatever you give it to repeat is printable and prints it, also assuming the repeat will not result in wrapping past the right margin. Wrap around left margin is nice, but nonstandard. NOTE While I polished off this code and added some of my own, the bulk of it was written by Daniel Kegel, and Thomas Hanlin III to whom credit is due. My distribution policy is the same as for the formentioned authors' drivers, which is as follows as taken from the documentation for NANSI24. This program and all files associated with it are hereby placed in the public domain, and thus may be freely copied and distributed. If you really like this program, either (a) improve it, and place your improvements in the public domain, (b) write a neat program which uses Zavt's unique speed, and place your program in the public domain, (c) tip the author (Tip; contraction for "To Inspire Programmer"; traditionally, a contribution of $5 per copy), or (d) resolve to become a better human being in the future. Any problems or suggestions can be made to the 'author', Luns Tee 32 Thyra Ave. Toronto, Ontario, M4C-5G5 Canada FOR PROGRAMMERS If the code seems to be a mess, that's because it is. Code from ZANSI has been juggled around so as to minimize the number of JMPs that are not JMP SHORT. Just a few hints: Search for "90" in the .LST files. If any follow a JMP instruction, make the JMP a JMP SHORT as these are NOPs to pad the size difference between the two variants of this instruction. When writing anything which writes to the console, use an IOCTL call to get the driver's attributes, save them, and set the console to raw mode. Do not write to the console by calling Int 21h function 2 once for each character (it's not that uncommon) but rather function 40h for each string. Buffering strings larger than about 10 characters starts diminishing returns. Just remember to return the console to its original state before exiting. The file ZAVT.MAK has switches for Turbo Assembler and not Microsoft MASM which NANSI was compiled under. The .MAK file itself is for Microsoft's MAKE utility however. FILES ZAVT*.ASM - console driver source files ZAVT.MAK - make file for ZAVT.SYS ZAVT.SYS - full-featured driver ZAVTNK.SYS - driver with keyboard remapping disabled FONTS.ZIP - assortment of ega/vga fonts RAW.COM - program to set console to raw COOKED.COM - and cooked mode ESCAPE.COM - program to send escape sequences to console ZAVT.DOC - this file