CP/M/CPM_CDROM.iso/cpm/draco/draco-1.ark/DED.DOC

Text File | 1986-11-12 | 26KB | 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.