239 lines
6.6 KiB
Forth
Executable file
239 lines
6.6 KiB
Forth
Executable file
#!/usr/bin/env retro
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# retro-edit
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Copyright (c) 2021, Charles Childers
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This is a little line oriented editor.
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It's simple, not efficient, and probably will be difficult to use
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for most. But it's simple, only requires Retro, and has no dependencies
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on an addressable character display. You could use this with a serial
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line printing terminal, or a trivial 1-4 line character LCD. It's also
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useful if you're on a slow connection to a remote system.
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The editor is intentionally simple. Each line in a file is read into
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an array of lines, and input is typed at the terminal. Each command is
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a single character, followed by any needed parameters.
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An editing session (sans output) might look like:
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,
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a5
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i5,enter some text on line 5
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r0,10
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x8
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r15,30
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X20,22
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,
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W
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q
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Look further in the source for a table of commands.
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## Configuration
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The editor needs a max line length and max number of lines per
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file.
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~~~
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#140 'cfg:MAX-LINE-LENGTH const
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#2000 'cfg:MAX-LINES const
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~~~
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## The File Contents
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The file gets read into an array of lines. This is in the `File`
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structure. `Lines` holds the number of lines in the file.
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A word, `ed:to-line` takes a line number and returns the address
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of the actual line contents.
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Of note here: these account for adding in a NULL terminator for
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each line.
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~~~
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'File d:create
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cfg:MAX-LINES cfg:MAX-LINE-LENGTH *
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cfg:MAX-LINES + allot
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'Lines var
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:ed:constrain (n-m) #0 @Lines n:limit ;
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:ed:to-line (n-a) cfg:MAX-LINE-LENGTH over * + &File + ;
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~~~
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## Display A Line
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Line display is trivial in this. I optionally support line numbers,
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controlled by setting `ShowLineNumbers` to `TRUE`.
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~~~
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TRUE 'ShowLineNumbers var-n
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:ed:show-line-number (-)
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@ShowLineNumbers [ dup n:put ':___ s:put ] if ;
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:ed:display-line (n)
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ed:constrain ed:show-line-number ed:to-line s:put nl ;
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~~~
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## Command Processor
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Commands are single characters. I reserve an array of pointers
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(`Commands`), with the ASCII value of the character being an
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index into this. If the final pointer is non-zero, this will
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call the command handler.
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`ed:register-command` is used to add a handler to the table,
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and `ed:deregister-command` is used to remove one.
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~~~
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'Commands d:create #255 allot
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:ed:register-command (ac) &Commands + store ;
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:ed:deregister-command (c) &Commands + v:off ;
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:ed:process-command (c) fetch &Commands + fetch 0; call ;
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~~~
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## Some Editing Functions
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~~~
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:ed:blank-line (n) ed:to-line s:empty swap s:copy ;
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:ed:delete-line (n)
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&Lines v:dec
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@Lines over - [ [ ed:blank-line ]
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[ dup n:inc swap [ ed:to-line ] bi@ s:copy ]
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[ n:inc ] tri ] times drop ;
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:ed:copy-line (mn) [ ed:to-line ] bi@ s:copy ;
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{{
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:shift-line dup n:dec swap ed:copy-line ;
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---reveal---
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:ed:insert-line (n)
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[ @Lines [ [ shift-line ] sip n:dec dup-pair eq? ] until drop
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&Lines v:inc ] sip ed:blank-line ;
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}}
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~~~
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## Input
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Input is read by `ed:get-input`. This returns the first character as
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a value and stores the rest, with the pointer being kept in `Input`.
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~~~
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'Input var
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:ed:get-input (-c) s:get dup n:inc s:keep !Input ;
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~~~
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## Editor Loop
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The editor loop is thus simple. Get input, process the command, and
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repeat. I run this in a simple `Heap` preserving loop, so command
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handlers can allocate space at `here` without worrying about cleanup
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afterwards. I also reset the stack.
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~~~
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:edit
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repeat &Heap [
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reset ed:get-input ed:process-command
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] v:preserve again ;
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~~~
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## The Commands
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In general, each command is intended to do a single task.
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| a | line | add a line at line number, shifting lines down |
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| A | line,count | add lines at line number, shifting lines down |
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| d | line | erase contents of a line |
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| i | line,text | replace contents of line with text |
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| n | line | indent line |
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| N | line | unindent line |
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| p | line | display a single line |
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| q | | quit retro-edit |
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| r | first,last | display a range of lines |
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| W | | save file |
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| x | line | remove line |
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| X | first,last | remove lines first through last, inclusive |
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| , | | display all lines in the file |
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| # | | toggle display of line numbers |
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| / | | search for text; display matching lines |
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~~~
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{{
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:valid? @Input $, s:contains-char? ;
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:get-limits @Input $, s:tokenize [ s:to-number ed:constrain ] a:for-each ;
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:display-range over - n:inc [ dup ed:display-line n:inc ] times drop ;
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---reveal---
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:cmd:p @Input s:to-number ed:display-line ;
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:cmd:r valid? [ get-limits display-range ] if ;
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:cmd:A valid? [ get-limits [ dup ed:insert-line ] times drop ] if ;
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}}
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{{
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:match? I ed:to-line @Input s:contains-string? ;
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---reveal---
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:cmd:/ @Lines [ match? [ I ed:display-line ] if ] indexed-times ;
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}}
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:cmd:# @ShowLineNumbers not !ShowLineNumbers ;
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:cmd:i @Input $, s:split s:to-number ed:to-line [ n:inc ] dip s:copy ;
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:cmd:d @Input s:to-number ed:blank-line ;
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:cmd:q nl bye ;
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:cmd:x @Input s:to-number ed:delete-line ;
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:cmd:a @Input s:to-number ed:insert-line ;
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{{
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:valid? @Input $, s:contains-char? ;
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:get-limits @Input $, s:tokenize [ s:to-number ed:constrain ] a:for-each ;
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:delete-lines [ dup ed:delete-line n:dec dup-pair lteq? ] while drop-pair ;
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---reveal---
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:cmd:X valid? [ get-limits delete-lines ] if ;
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}}
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:cmd:, #0 @Lines [ dup ed:display-line n:inc ] times drop ;
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:cmd:n @Input s:to-number ed:to-line dup '__ s:prepend swap s:copy ;
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:cmd:N @Input s:to-number ed:to-line dup #2 + swap s:copy ;
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{{
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:filename #0 script:get-argument ;
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:with-file filename file:open-for-writing [ swap call ] sip file:close ;
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:write-line I ed:to-line [ over file:write ] s:for-each ;
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:nl ASCII:LF over file:write ;
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---reveal---
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:cmd:W [ @Lines [ write-line nl ] indexed-times ] with-file ;
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}}
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~~~
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## Register The Commands
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~~~
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&cmd:p $p ed:register-command
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&cmd:r $r ed:register-command
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&cmd:/ $/ ed:register-command
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&cmd:# $# ed:register-command
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&cmd:d $d ed:register-command
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&cmd:i $i ed:register-command
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&cmd:q $q ed:register-command
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&cmd:a $a ed:register-command
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&cmd:A $A ed:register-command
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&cmd:x $x ed:register-command
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&cmd:X $X ed:register-command
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&cmd:, $, ed:register-command
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&cmd:W $W ed:register-command
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&cmd:n $n ed:register-command
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&cmd:N $N ed:register-command
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~~~
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~~~
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(import_file)
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#0 #0 script:get-argument [ over ed:to-line s:copy n:inc ] file:for-each-line
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!Lines
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edit
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~~~
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