Forth

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Forth on RPi

sudo apt-get install wget
wget http://www.fourmilab.ch/atlast/download/1.2/atlast-1.2.tar.gz
tar -xzvf atlast-1.2.tar.gz
cd atlast-1.2/
make

Start the Forth interpreter with ./atlast and exit with Ctrl-D

atlast.html and atlast.pdf is included and an is an extensive atlast-forth manual. Read it online [1] and read about Forth itself here [2]

Adding new words

It is easy to add your own words, just add a "define GERTBOARD" to atlast.c around line 64. In my case I will add some words for controlling my Gertboard. I will leave it as a skeleton until I've done the implementation myself. If you can't wait there is a detailed description on how to do this in the atlast-forth manual. And you can copy much of the word implementations from the gertboard_sw directory if you have downloaded the gertboard demo files.

#define STRING			      /* String functions */
#define SYSTEM			      /* System command function */
#define GERTBOARD			   /* Gertboard command function */

Then add your own word definitions at the end of the section with word definitions, around line 2700 in atlast.c

#ifdef GERTBOARD

prim P_gert_setport() // channel state ---
{ // Set a digital io port to a specified state
   Sl(2); // Make sure there is at least two params on the stack
	// Your code goes here
}

prim P_gert_getport() // channel  ---
{ // Get the state of a digital port
   Sl(1); // Make sure there is at least one param on the stack
	// Your code goes here
}

#endif /* GERTBOARD */

And finally, add the actual words to the list of defined words right after #endif /* EVALUATE */ at line 3050 or so.

#ifdef EVALUATE
    {"0EVALUATE", P_evaluate},
#endif /* EVALUATE */

#ifdef GERTBOARD
	 {"0SETIO", P_gert_setport},	
	 {"0GETIO", P_gert_getport},		
#endif /* GERTBOARD */

Now, save and run "make" again to recompile atlast.c.