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Text File | 1986-11-13 | 25.9 KB | 597 lines

Ded - the Draco Screen Editor Ded is a screen editor for CP/M-80 systems which can be configured to run on a variety of terminals. Also, it's 62 commands can be assigned by the user to any desired keystroke or keystroke sequence. It is NOT a word processor. It has no concept of boldface, italics, footnotes, etc. It does have some commands and features (such as automatic word-wrap) which are useful in editing text files. It has several commands and features (such as automatic indentation and block shifts) which are designed specifically for working with source files for structured programming languages. Ded is invoked from CP/M by the command ded file.typ where 'file.typ' is the name of the file to be edited. If the file doesn't exist, it will be created. If the file does exist then it will be renamed as 'file.BAK' and a new file called 'file.typ' will be created. When Ded terminates normally, it writes the new version of the file to the newly created file, thus the entire editing session can be later discarded by ERAsing 'file.typ' and RENameing 'file.BAK' to be 'file.typ'. Note, however than any existing 'file.BAK' is deleted when Ded first reads in 'file.typ'. If more than one file is given on the command line then Ded edits them one after another. Internally, Ded is a line editor. This means that it treats a file as a sequence of lines of text. This has little effect on the user, but will show up in some situations. One minor point is that Ded will always put a CR/LF sequence at the end of each line of text in a file. One aspect of this nature is that Ded does not handle lines longer than 79 characters. The user will be warned when an operation attempts to make a longer line. Similarly, lines are truncated to 79 characters when files are read in. Ded does not do disk buffering. This means that the entire file being edited must fit in memory. Ded uses a compressed form of internal storage in which sequences of blanks are stored as single bytes (the high order bit is set and the remaining 7 bits are a count of the number of blanks). This compressed form can be used for file storage, to reduce the space used by files containing a lot of whitespace. Ded will also generate standard 8-column tabs or fully expanded blanks. If Ded runs out of memory space, it will inform the user gracefully, and allow editing to continue. User-settable typewriter-style tabstobs are available in Ded. When it is initially run, the tab-stops are set at the standard 8-column boundary, but they can be cleared and set to any arbitrary columns. The TAB key causes blanks to be generated until the cursor is at the next tab-stop. When not in insert mode, the character under the cursor is replaced by the blanks. Since Ded uses special characters internally to represent sequences of blanks, these characters should not appear (as other than the intended compressed blanks) in any files edited with Ded. As a special case, if these characters are between matching quotes (as scanned left-to-right), they are acceptable and will be displayed in highlighted mode on the screen. The ASCII HT character is similarly restricted. Control characters other than CR, LF, SUB and HT can appear anywhere in a line with no ill effects. They will be displayed in reverse video as their non-control forms. One of the concepts used in Ded is that of a region of lines. Such a region can be shifted, aligned, printed, written to a file, etc. A region is defined by first selecting the start point of the region with the POINT command, moving to the end-point of the region, and then executing the command which is to affect the entire region. Regions must be marked in the forward direction, i.e. the end-point must be later in the file than the start point, whether on the same line or on a later line. Ded's screen display consists of 23 lines for the text of the file, each of which is 79 columns long (the last column is not used other than by the cursor). Also present is a status line at the bottom of the screen. This line contains 7 indicators, the name of the file being edited, the line and column of the cursor and an area which is used for error messages, status messages, and user prompts. The 7 indicators are as follows: 1 - the first end of a region has been marked T - there is currently text in the 'text buffer' I - insert mode is enabled W - word-wrap mode is enabled M - multi-column mode is enabled S - a search subject has been given C - a global change 'to' has been given Insert mode should be familiar to all computer users: characters typed are inserted before the one under the cursor instead of replacing the ones currently on the line. Characters to the right are moved over to make room. Word-wrap is also fairly common - when typing, if a character is about to be typed just beyond the word-wrap column, then an automatic carriage return is generated. Also, if the character to be typed is a non-blank, then the full word which that character is part of is moved down to the new line. Any left indent set is applicable to the newly inserted line. Multi-column mode is a special feature of Ded. It interacts with the carriage return and word-wrap operations. Instead of causing a new line to be inserted, these operations move the cursor to the left indent column of an existing next line. Blanks are added to that line only as needed to reach the left indent and any word carried over by word-wrap is moved to the next line replacing any text that might have been there. Multiple columns can be easily made by setting the left indent at the desired left edge of the column (remember that the left indent is the number of spaces before the first character of the column) and the word-wrap column to the desired right edge of the column. Such columns can be entered in any order, and with careful typing and the use of insert mode, columns can even be inserted. Since the keystrokes which select the various commands can be modified by the user, it is not possible to discuss the commands based on the keys typed to execute them. Thus, all of the commands in Ded have been named. The detailed description of the commands is arranged in several related groups. A separate page included with this writeup lists the commands in a short form, with space in which the user can write in the keystrokes which have been selected to perform the commands. Cursor Movement Commands LEFT - the cursor moves left one column. Moving left past the first column will cause the cursor to wrap to the next available column in the previous line. RIGHT - the cursor moves right one column. Moving right past the right-hand edge of the screen causes the cursor to wrap to the first column of the next line. UP - the cursor moves up one line. If the cursor was originally on the top line of the screen, then the file is windowed backwards one line first. DOWN - the cursor moves down one line. If the cursor was originally on the last line of the screen, then the file is scrolled up one line first. SKIPWORD - the cursor moves forward to the beginning of the next word. It will not move past the end of the line. BACKWORD - the cursor moves backward to the beginning of the previous word. It will not move past the beginning of the line. BOL - the cursor moves to the first column of the current line. EOL - the cursor moves to the next free column of the line. (Just past the last character on the line.) NEXTLINE - the cursor moves to the first column of the next line. TOP - the cursor moves to the top line on the screen. BOTTOM - the cursor moves to the bottom line on the screen. PAGEUP - the screen is scrolled backwards 20 lines through the file. The cursor will stay at the same screen position unless the full 20 line scroll was not possible. PAGEDOWN - the screen is scrolled forwards 20 lines through the file. The cursor will stay at the same screen position unless the full 20 line scroll was not possible. HOME - the cursor (and screen window if necessary) is moved to the first column of the first line in the file. GOTO - the user is asked to enter a number. The cursor (and screen window if necessary) is moved to that line. GOPOINT - the cursor is moved to the position last set using the POINT command. The presence of a marked point is indicated by a highlighted '1' (for 1st region end) in the status line. Commands Which Change the Current Line DELCHAR - the character under the cursor is deleted. Characters which were to the right of it are moved left one space. BACKSPACE - the character before the cursor is deleted and the cursor backs up one column. TAB - if insert mode is active (an 'I' is showing in the status line), then blanks are inserted before the character under the cursor to move that character to the next tab-stop. If insert mode is not active, the character under the cursor is deleted first (it is replaced or typed over by the TAB). DELWORD - the next word is deleted. If the cursor is within a word, then the trailing portion of that word is deleted. DELBACKWORD - the previous word is deleted. If the cursor is within a word, then the leading portion of that word is deleted. DELEOL - the characters from the current position to the end of the line are deleted. INSERTSPECIAL - a special character is inserted before the current character. The user is asked for the decimal value of the character to be inserted. Characters with the high-order bit set, or the ASCII HT character, should only be inserted inside matching quotes, else they will be expanded into blanks. CP/M end-of-file characters (decimal 26), carriage returns (decimal 13) or linefeeds (decimal 10) should never be inserted into the file. UNDO - any changes made to the current line since the cursor was moved onto that line are undone. Commands which require user input or redraw the screen will finalize the line so that changes made before then cannot be undone. REDRAW - the entire screen is redrawn. This is useful if your terminal goes bonkers. Commands Which Affect Entire Lines DELLINE - the current line is deleted. RETURN (this key cannot be redefined) - the normal action here is to insert a new line after the current one, add blanks to that line to make up the current left indent, and leave the cursor after the indent column. The cursor does not have to be at the end of a line for RETURN to work. The new line is considered to be inserted, since that is the action when RETURN is given when the cursor is not on the last line of the file. The action of RETURN is modified when the multi- column flag is set (an 'M' appears in the status line). INSERTLINE - a new line is inserted after the current one, and blanks will be added to it to come up to the current left indent column. This command is NOT affected by the multi- column flag. JOIN - the next line is joined to the end of the current line. SPLIT - the current line is split into two lines. The characters from the cursor position onwards are moved to the next line. The left indent column is ignored. INDENT - the left indent is incremented by the current value of the indent increment. The current line is adjusted to the new indent amount if the line is longer than the new indent. OUTDENT - the left indent is decremented by the current value of the indent increment. The current line is adjusted to the new indent amount if the line is longer than the old indent. ADJUSTLINE - the current line is adjusted to the current indent amount. Commands for Doing Global Changes and Searches CHANGE - the user is asked for a subject ('from') string, a 'to' string, and a count. The first 'count' occurrences of the 'from' string are changed to the 'to' string. The cursor will be left at the end of the last changed string. If not enough are found, the cursor will be left at the end of the file. The changes done by CHANGE cannot be undone by UNDO even if the last change is on the line the cursor ends up on. The presence of a 'to' change string is indicated by a highlighted 'C' in the status line. CHANGENEXT - the previously selected 'from' and 'to' (if still active), are used for a single further search. CHANGENEXT freezes changes to the line before it operates, but the single change it makes can be undone using UNDO. CHANGENEXT can only be done if the 'C' and 'S' indicators are on. FIND - the user is asked to enter a subject string and Ded searches for the first occurence of that string after the current position. The cursor is moved to just after the first found occurrence. If none is found, the cursor is left at the end of the file. FINDNEXT - the next occurrence of the given search subject is scanned for. The presence of a search subject is indicated by an 'S' in the status line. Commands Dealing With Entire Regions of the File POINT - this command marks the first end of a region. The presence of such a first end is indicated by the presence of a '1' in the status line. ADJUST - the lines in the selected region are adjusted to the current left indent. SHIFTLEFT - the lines in the selected region are shifted left by 'IndentIncrement' characters, where 'IndentIncrement' is the current value of the indent increment (default 4). SHIFTRIGHT - the lines in the selected region are shifted right by 'IndentIncrement' characters (blanks are inserted at the beginning of the lines). YANK - the text in the selected region is removed from the file and put into the 'text buffer'. If the two end points are in the same line and the same column, then the entire line is taken. If they are in the same line but different columns, then the text moved is a string from the single line. If the end points are in different lines, then the entire region between the end points (inclusive) is moved. This is the quickest way to delete a large group of lines from the file. Any previous text in the text buffer is freed first. The presence of text in the 'text buffer' is indicated by a 'T' in the status line. COPY - a copy of the selected region is made in the 'text buffer'. Other than copying instead of moving, this command is the same as the YANK command. PUT - a copy of the text in the 'text buffer' is inserted into the file. If the buffered text is a string from a single line, then it is inserted into the current line at the current cursor position. If the buffered text is a group of lines, then a copy of those lines is inserted before the current line. FORMAT - the format command is fairly simple in what it does, but the effects of it can be quite complex. Basically, it takes the text in the 'text buffer' and feeds it through the input routine just as if the user had typed it in. Initially, the user is asked whether or not to do line-by-line formatting. If the answer is no, then the text on the saved lines is pushed through in a single stream. Multiple blanks in the buffered text are replaced by a single blank. If a line being processed doesn't end in a blank, then a blank is generated (this prevents words from being joined together). If the line- by-line mode is selected, the further option of deleting instead of inserting is offered. Ignore the delete option for now. In line-by-line mode, a carriage return is generated at the end of each of the processed lines. The key to this command (and why it is called FORMAT) is that the word-wrap flag is forced on during the processing, thus the text being processed is formatted within the current left-indent to wrap margin space. The multi-column flag is also respected, so FORMAT can be used to create new columns. Paragraph indents and hanging indents can be created in the new text by properly positioning the cursor when issuing the FORMAT command - the first character will be placed at the cursor position, and the left indent will not take effect until the next line. See the section on hints for more information on using the FORMAT command. Currently, the FORMAT command has some minor problems concerning the definition of "words". PRINT - the selected group of lines is printed on the printer. Output to the printer always uses fully expanded blanks. WRITE - the user is asked for a file name, and the selected group of lines is written to that file. The file is deleted and re-created first. A disk-full condition during this operation will be reported. READ - the user is asked for a file name and a first and last line number in that file. Those lines are copied into the current file before the current line. Commands for Manipulating Files DELETEFILE - the user is asked for the name of a file to delete. This is useful for handling the 'disk full' condition. NEWFILEEXIT - the user is asked for the name of another file to edit. The current file is written out and the new file is read in and edited. The sequence of files given on the CP/M command line which ran Ded is not disturbed. A disk-full condition during the write operation will be reported and the user will be left editing the original file. NEWFILEQUIT - the user is asked for the name of another file to edit. All changes made to the current file in this editing session are abandoned. EXIT - the current file is written out, and the next one in Ded's parameter list is read in and edited. If no more files remain in the list (the usual case), Ded returns to CP/M. Again, the disk-full condition is reported and the user is left still editing the intact file. QUIT - all changes made to the current file in this editing session are abandoned and Ded moves on to the next file. Commands for Setting Options and Tabstops SET - this command is used to set any of 3 different numeric values, depending on the character typed after the SET command (this character will not be echoed anywhere, but the appropriate prompt will appear). The 3 parameters and their code letters are: i - indent increment (any value from 0 to 70, default 4) l - the current left margin (any value from 0 to 1 less than the current wrap column, default 0) w - the current word-wrap column (any value from 1 greater than the current left margin to 79, default 79) BLANKMODE - this command cycles through the three modes of storing blanks in disk files. The default mode, that of using standard 8-column tabs, is compatible with CP/M, MSDOS, Dec operating systems, etc. Blank-count mode is compatible only with Ded, but is handled by the Draco compiler also. Fully expanded mode is handled by everything, but takes up more disk space and I/O time. CLEARALL - all tabstops are cleared TABSET - a tabstop is set for the current column TABCLEAR - any tabstop in the current column is cleared INSERT - the character insert mode is toggled between on and off. Insert mode on is indicated by an 'I' in the status line. WRAP - the word-wrap mode is toggled between on and off. Wrap mode on is indicated by a 'W' in the status line. For the purposes of word wrapping, along with word movement and word deletion, characters of a word are letters, digits, '_', '^', '"', ''', and '$'. MULTICOLUMN - the multicolumn mode is toggled between on and off. Multi-column mode on is indicated by an 'M' in the status line. Some Hints and Tricks The left margin is of great use when typing in structured program source. Indentation tends to change a lot, so the INDENT and UNDENT commands should be on easily reached keys. Similarly the ADJUST, SHIFTLEFT and SHIFTRIGHT commands are of great use when modifying programs. A useful(?) trick involves the combination of word-wrap and multi-column mode. Set the left indent and wrap-column 1 column apart, then pick a key (say the vertical bar) and let it auto-repeat. You will get a column of that character stretching vertically down the file. Such a column can be inserted as a separator by setting insert mode on also. Because of the way the INDENT and OUTDENT commands operate, they can be used to create hanging indents in text. When a hanging indent is desired, use carriage return to go to the line to be hanging left, then use OUTDENT to move left to the desired outdent position. Type in the first few words of the line and then use INDENT to re-set the proper indent level. The current line will not move since the cursor is beyond the indent column. You can then continue typing and word-wrap will take over. Similarly, when entering structured program text, the INDENT or OUTDENT commands for the next line can be entered before hitting return or after hitting return. After is usually easiest. Additional capabilities of the FORMAT command can be used to manipulate columns of text. An example should suffice to illustrate some of the possibilities. Enter Ded editing a new file and enter the following (Ded command names are in upper case, comments are indicated by a '*', and additional instructions are indicated by ':'): SET w 20 WRAP Now is the time for all good men to come to the aid of their party. Now is the time for all good men to come to the aid of their party. Now is the time for all good men to come to the aid of their party. HOME EOL WRAP : space to column 22 (cursor in column 22) SET w 79 SET l 21 MULTICOLUMN : hit RETURN until cursor is in last line of text * You have now created a rectangular block of text - the last set of RETURNs served to pad all of the lines to exactly 21 characters each. HOME POINT : move cursor to last line COPY * the rectangular region is now in the text buffer HOME EOL SET l 21 FORMAT y n * we have created a second, identical column - nothing special so far. TOP INSERT FORMAT y n * the new column has been INSERTED between the other two. TOP FORMAT y y * the new third column has been DELETED (if nothing else, it's fun to watch!) With appropriate use of the FORMAT command and the various modes, it is possible to change a single column of material into 2 or more columns, and vice versa (SHIFTLEFT is useful here to wipe away the left-hand column, and FORMAT with the delete option to wipe away the right-hand column). Configuring Ded Configuring Ded for your system and preferences takes two steps. The first step is that of configuring it to generate the appropriate terminal control sequences for your terminal or computer. This is normally only done once. The process is described in the writeup for the CONFIG program, which is also used to similarly configure other programs written using the Draco terminal independent CRT routines. In summary, perform the following steps: 1) Have files CONFIG.COM, CONFIG.DAT and DED.SET on your default drive. Enter config ded 2) Issue the CONFIG command 'L' and find your terminal on the list of terminals. If it isn't there, use the information provided with your terminal to create a new entry in the database using the 'C' command. 3) Issue the CONFIG command 'S' and select your terminal type. 4) Issue the CONFIG command 'P' to configure Ded. 5) Issue the CONFIG command 'Q' to return to CP/M. 6) Enter ren ded.cnf=ded.com The second configuration step is used to assign keystroke sequences to the various Ded commands. This can be done as many times as desired until you are happy with your assignment. Ded allows keystroke sequences to be any of the following: a single control character (other than CR, also known as CONTROL-M). a single character in the range (hex) 0x80 - 0xff a common escape character (usually ESC, CONTROL-[) followed by any single character the common escape character followed by one of a set of 'second escape characters', followed by any single character During the configuration process, you must inform the configuration program (DCONFIG.COM) of the common escape character and any 'second escape characters' (up to 5). To perform the keystroke configuration, make sure files DED.CNF (created by the other configuration process) and DCONFIG.COM are on your default drive. Enter dconfig The program will read in a copy of Ded from DED.CNF and present you with a menu of 4 choices. Choice 1) allows you to examine the current set of keystroke assignments in file DED.CNF. Choice 2) allows you to define your own keystoke assignment. You will have to enter your common escape character, any 'second escape characters' and your keystroke choices for the various Ded commands. When entering keystroke choices, the program will display the current value. You can keep this value by pressing RETURN, or replace it by typing the chosen keys. The program will not allow any duplicate sequences or invalid keystrokes. The keys you type will not be echoed in any way, so it is a good idea to examine the assignments (using choice 1) when you are done. Choice 3) writes the current settings out to a new file called DED.COM, along with all of the code for Ded. The only difference between DED.CNF and DED.COM is the selected keystroke sequences, thus you can rename an existing DED.COM as DED.CNF and configure from it. Choice 4) returns you to CP/M. Ded should now be ready to run.