Intro

Let's try to take ST's C sources (well, the .h files anyway) and turn them into Forth.

Previously I had been downloading various STM32Cube zip files and pulling the .h files out of these. This is awkward and some of the zip files were quite large.

ST has recently decided to modularize their code. Now it is possible to download (much smaller) archives of the .h and .s startup files separately from the C library files. Everything is on GitHub now, and the Makefile will download and untar the appropriate files.

How to use it

You will need a relatively recent copy of Lua. Version 5.3 or later is required.

Lua is super easy to build. I like to install it in my $HOME directory.

Once you have Lua installed, just do this:

make download
make

to download ST's source files from GitHub and then process them into (hopefully useful) muforth source files.

You can also do make install to copy the generated .mu4 files into a local muforth tree; just set the INSTALL_DIR variable in the Makefile.

Right now the Makefile by default only processes a small subset of the files; approximately corresponding to a handful of the Discovery boards. If you have a chip that is not in the list, just add its .h file to the HFILES variable; the corresponding .mu4 file will be made automagically.

I have recently turned off generation of the bitfields. Right now only the interrupt vectors and I/O register addresses are generated. Once I figure out how I want to deal with the bitfields I will turn that code back on. Feel free to play around with it, if you like!

Mistakes?

ST used nested typedefs in a few places (CAN_TypeDef, in particular), and used them in such a way that the resulting register names had no relation to the names in the reference manual, or in the bit field definitions that follow the typedefs in the .h file. This seems really stupid. The nested typedefs are also harder to parse.

My solution? Using sed, of course! I have a sed script - provocatively called destupidify.sed - that flattens the nested (and broken) typedefs, using the register names from the reference manual. This is an improvement for C programmers too!

The Makefile will process the .h file from one of the cmsis_device_*-master directories, remove the \r characters, destupidify it, and create a fixed version of the file in the root directory. These are the inputs to c2forth.lua, which then generates the corresponding .mu4 file.

It seems like the comments (with offsets) for the OB typedef in the F103 are wrong. But the offsets (that I calculated from the types in the typedef) match several of the other parts! Go figure.

TODO

• Print the register bit fields directly after the register that they apply to? This is tricky, and it also clutters up the display of the register addresses.
• The HRTIM definitions are still broken and need to be fixed. If we are ever interested in the STM32F334, that is.