ueforth/ueforth/site/common.html

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<h5>Null Terminated Strings</h5>
<p>
As null terminated strings are used throughout C interfaces,
their use is supported in Forth by way of several non-standard
words with the convention of using Z/z to refer to such strings
in names and stack comments.
</p>
<pre>
Z" ( "string" -- z ) Creates a null terminated string on the heap
Z&gt;S ( z -- a n ) Convert a null terminated string to a counted string
S&gt;Z ( a n -- z ) Conver a counted string string to null terminated (copies string to heap)
</pre>

<h5>Raw Strings</h5>
<p>
Raw strings are provided better support using a string
for the duration of the current command, without consuming heap memory.
</p>
<pre>
R" ( "string" -- a n ) Creates a temporary counted string
R| ( string| -- a n ) Creates a temporary counted string ending with |
</pre>

<h5>Utilities</h5>
<pre>
DUMP ( a n -- ) Dump a memory region
SEE ( "name" -- ) Attempt to decompile a word
VARIABLE ECHO -- Determines if commands are echoed
</pre>

<h5>Vocabularies</h5>
<p>
{{FORTH}} uses a hybrid of Forth-79 and Forth-83 style vocabularies.
By default vocabularies chain to the vocabulary in which they were defined,
as in Forth-79. However, like Forth-83, <code>ALSO</code>
can be used to add vocabularies to a vocabulary stack of which
<code>CONTEXT @</code> is the first item.
The word <code>ONLY</code> clears the vocabulary stack, but as there is
no separate ONLY vocabulary, it also sets <code>CONTEXT</code>
to the <code>FORTH</code> vocabulary.
The word <code>SEALED</code> modifies the most recently defined vocabulary
such that it does not chain. Note, this must be done before words are added to it.
</p>
<pre>
VOCABULARY ( "name" ) Create a vocabulary with the current vocabulary as parent
FORTH ( -- ) Make the FORTH vocabulary the context vocabulary
DEFINITIONS ( -- ) Make the context vocabulary the current vocabulary
VLIST ( -- ) List the words in the context vocabulary (not chains)
WORDS ( -- ) List the words in the context vocabulary (including chains)
TRANSFER ( "name" ) Move a word from its current dictionary to the current vocabulary
                    Useful for "hiding" built-in words
TRANSFER{ ..words.. }TRANSFER ( -- ) Transfer multiple words to the current vocabulary
ALSO ( -- ) Duplicate the vocabulary at the top of the vocabulary stack
ONLY ( -- ) Reset context stack to one item, the FORTH dictionary
            Non-standard, as there's no distinct ONLY vocabulary
ORDER ( -- ) Print the vocabulary search order
SEALED ( -- ) Alter the last vocabulary defined so it doesn't chain
</pre>

<h5>Interpret Time Conditions</h5>
<p>
<code>[I]F</code>, <code>[ELSE]</code>, and <code>[THEN]</code> can be used
to selectively compile. Used in tandem with <code>DEFINED?</code> they can
be used to handle the absence of modules gracefully.
Nesting is supported.
</p>
<pre>
DEFINED? ( "name" -- xt|0 ) Check if a word exists (works at compile time too).
[IF] ( f -- ) Conditionally interpret the text the follows.
[ELSE] ( -- ) Interpret time ELSE.
[THEN] ( -- ) Interpret time THEN.
</pre>

<h5>Blocks</h5>
<pre>
USE ( "name" -- ) Use "name" as the blockfile, e.g. USE /spiffs/foo
OPEN-BLOCKS ( a n -- ) Open a file as the block file
LOAD ( n -- ) Evaluate a block
THRU ( a b -- ) Load blocks a thru b
LIST ( n -- ) List a block
BLOCK ( n -- a ) Get a 1024 byte block
BUFFER ( n -- a ) Get a 1024 byte block without regard to old contents
UPDATE ( -- ) Mark the last block modified
FLUSH ( -- ) Save and empty all buffers
EMPTY-BUFFERS ( -- ) Empty all buffers
SAVE-BUFFERS ( -- ) Save all buffers
SCR ( -- a ) Pointer to last listed block
</pre>

<h5>Block Editor</h5>
These words are available inside the <code>EDITOR</code> vocabulary.
Note the block editor places newlines in the 63rd column of each line
to make the block file readable in a text editor.
<pre>
WIPE ( -- ) Blank out the current block
L ( -- ) List the current block
D ( n -- ) Delete a line in the current block
E ( n -- ) Clear a line in the current block
R ( n "text" -- ) Replace a line in the current block
A ( n "text" -- ) Add (insert) a line in the current block
P ( -- ) Move to the previous block
N ( -- ) Move to the next block
</pre>

<h5>Utilities</h5>
<pre>
SEE ( "name" -- ) Attempt to decompile a word
ECHO ( -- a ) -- Address of flag that determines if commands are echoed
</pre>

<h5 id="dictimages">Dictionary Images and Startup</h5>

<p>
<b>WARNING: Danger ahead.</b><br/>
Snapshotting the dictionary may not be stable across reinstallations of the C build of Forth.
</p>

<p>
A collection of non-standard words is provided that allow snapshotting
the dictionary and restoring it at startup, with a start word.
</p>

<pre>
SAVE ( "name" -- ) Saves a snapshot of the current dictionary to a file.
RESTORE ( "name" -- ) Restore a snapshot from a file.
REMEMBER ( -- ) Save a snapshot to the default file
                (./myforth or /spiffs/myforth on ESP32).
STARTUP: ( "name" -- ) Save a snapshot to the default file arranging for
                       "name" to be run on startup.
REVIVE ( -- ) Restore the default filename.
RESET ( -- ) Delete the default filename.
</pre>

<p>
Here's an example usage:
</p>

<pre>
: welcome ." Hello!" cr 100 0 do i . loop cr ;
startup: welcome
bye

( Next boot will run a custom startup message )

reset

( Reset removes the custom message )
</pre>

<p>
The <code>INTERNALS</code> vocabulary has some additional words
for more control.
</p>

<pre>
SAVE-NAME ( a n -- ) Save a snapshot if the current vocabulary to a file.
RESTORE-NAME ( a n -- ) Restore a snapshot from a file.
'COLD ( -- a ) Address of the word that will be run on startup.
REMEMBER-FILENAME ( -- a n ) Deferred word specifying the platform specific
                             default snapshot filename.
</pre>