retroforth/doc/html/chapters/internals/calling-retro-from-c.html

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<p><span class="h1">Calling Retro from C</span>
<br/><br/>
The C implementation of Retro provides several functions for
interacting with code written in Retro.
<br/><br/>
<span class="h2">Dictionary</span>
<br/><br/>
The dictionary is a linked list, with a pointer to the most
recent entry stored in address 2.
<br/><br/>
You can access the fields for each entry using:
<br/><br/>
<tt class='indentedcode'>d_link</tt>
<tt class='indentedcode'>d_xt</tt>
<tt class='indentedcode'>d_class</tt>
<tt class='indentedcode'>d_name</tt>
<br/><br/>
Each takes a dictionary header address (the "dictionary token")
and returns a pointer to the Retro address for the desired data.
<br/><br/>
To find a dictionary token, use <span class="tt">d_lookup</span>. This takes the address
of the dictionary to search (<span class="tt">memory[2]</span> in most cases) and the
name of the word to find.
<br/><br/>
There is also <span class="tt">d_xt_for()</span> which takes a name and a dictionary
pointer and returns the execution token for the specified word.
<br/><br/>
<span class="h2">Strings</span>
<br/><br/>
Like C, Retro uses NUL terminated strings. But, since all
addressing is 32-bit (or 64-bit, depending on your configuration),
some conversion is needed.
<br/><br/>
To get a C version of a string, use <span class="tt">string_extract()</span>. This takes
a Retro address and returns a pointer to a C string.
<br/><br/>
Example:
<br/><br/>
<tt class='indentedcode'>//&nbsp;Get&nbsp;the&nbsp;name&nbsp;of&nbsp;the&nbsp;most&nbsp;recently&nbsp;defined&nbsp;word</tt>
<tt class='indentedcode'>string_extract(d_name(memory[2]));</tt>
<br/><br/>
To push a C string into Retro memory, use <span class="tt">string_inject()</span>. This
takes a C string and a Retro address.
<br/><br/>
<tt class='indentedcode'>//&nbsp;Copy&nbsp;a&nbsp;string&nbsp;to&nbsp;the&nbsp;TIB&nbsp;buffer</tt>
<tt class='indentedcode'>string_inject("hello",&nbsp;1024);</tt>
<br/><br/>
<span class="h2">Stack</span>
<br/><br/>
You can push values to the stack with <span class="tt">stack_push()</span> and pop them
off with <span class="tt">stack_pop()</span>.
<br/><br/>
<span class="h2">Interacting</span>
<br/><br/>
If you have a word named <span class="tt">hello</span> that you wish to run:
<br/><br/>
<tt class='indentedcode'>execute(d_xt_for("hello",&nbsp;memory[2]));</tt>
<br/><br/>
If you want to evaluate a token as if it was typed into a Retro
listener:
<br/><br/>
<tt class='indentedcode'>string_inject("token",&nbsp;1024);</tt>
<tt class='indentedcode'>stack_push(1024);</tt>
<tt class='indentedcode'>execute("interpret",&nbsp;memory[2]);</tt>
<br/><br/>
The <span class="tt">interpret</span> word handles things like sigils, so this is
needed if you want to run something that needs those.
</p>
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