Difference between revisions of "Colibri Forth"
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= Interactivity = | = Interactivity = | ||
Forth is an interactive language, which is awesome for embedded development. One can simply hook up a serial terminal and do development on the target itself. One can interactively work with the MCU registers and peripherals to figure out the proper configuration/operation without doing a full erase+write cycle to the flash memory. We can execute code directly from RAM and not commit it to Flash until we have worked out the details. | Forth is an interactive language, which is awesome for embedded development. One can simply hook up a serial terminal and do development on the target itself. One can interactively work with the MCU registers and peripherals to figure out the proper configuration/operation without doing a full erase+write cycle to the flash memory. We can execute code directly from RAM and not commit it to Flash until we have worked out the details. | ||
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| + | = Cookbook = | ||
| + | We are going to assemble useful snippets and words that will be useful, but not common enough to be included in the standard vocabulary. We call this the [[Colibri Forth Cookbook]] and will be a slowly growing document of Forth for the Colibri family. | ||
Revision as of 13:19, 20 July 2023
Colibri Forth is built upon MECRISP (https://mecrisp.sourceforge.net, written by Matthias Koch), the Stellaris variant, an advanced Forth, that compiles to machine code on the target itself, for optimal performance. Additional work/inspiration has been source from Peter Schmid's Mecrisp-Cube project (https://github.com/spyren/Mecrisp-Cube).
Architecture
Forth is a stack-oriented language that has 2 stacks, one for data and one call stack for with return addresses. It has very simple syntactic rules;
1. Everything is a "word" which must be surrounded by whitespace. All non-whitespace bytes are allowed in word. 1. Backslash is start of comment, and everything will be filtered out until parser reaches new line. 1. Everything between a pair of parentheses " ( xyz ) " is a comment. They can be stretching multiple lines. Nested parentheses are not supported. 1. Thereafter, try to locate word in dictionary. If found, "use" (depends on whether compiling or executing) it. 1. If word is not found in dictionary, try to parse it as a number. If successful, push number on stack. 1. All words operate on the stacks. Typically manipulating the Top-Of-Stack (TOS), by popping value(s) off the top and pushing the result back on top.
Colon ":" is the word to define other words, and the definition ends with semicolon ";". Example
: add4 4 + ; \ adds 4 to the value on TOS.
It is common to put the stack manipulation info as a comment after the defined word. Example
: add4 ( n -- n+4 ) 4 + ;
It is the same thing, just human-readable comment to hint at what the word does.
The Full Documentation of Mecrisp is written by Terry Porter and published at https://mecrisp-stellaris-folkdoc.sourceforge.io/
Interactivity
Forth is an interactive language, which is awesome for embedded development. One can simply hook up a serial terminal and do development on the target itself. One can interactively work with the MCU registers and peripherals to figure out the proper configuration/operation without doing a full erase+write cycle to the flash memory. We can execute code directly from RAM and not commit it to Flash until we have worked out the details.
Cookbook
We are going to assemble useful snippets and words that will be useful, but not common enough to be included in the standard vocabulary. We call this the Colibri Forth Cookbook and will be a slowly growing document of Forth for the Colibri family.