piBareMetalLisp

piBareMetalLisp(Raspberry pi Bare metal Lisp) is a toy lisp interpreter based on Circle,circle-stdlib and microlisp:now it's only use circle-stdlib's IO function as the lisp REPL.The effect on my rpi4b-notebook:

Build

You have to make circle and circle-stdlib well(you can test the samples,especially circle-stdlib sample2 02-stdio-hello).If everything is fine,copy or clone the project under the circle-stdlib's sample folder(to use the makefile and environment) ,first you may need make clean to delete useless files(like kernel8-rpi4.map,kernel.d,main.d),then make.The kernel8-rpi4.img is the result(I think you can use the kernel8-rpi4.img of the project already build directly,you may rename it to kernel8.img)

It seems rpi4 need kernel's name is kernel8.img.You may edit circle or circle-stdlib's makefile let the kernel file's name is kernel8.img which I have not do this.So you may need change kernel img's name from kernel8-rpi4.img to kernel8.img.(Maybe you can try set

kernel=kernel8-rpi4.img

in config.txt,I tryed but there is no effort )

Makefile include the Rules.mk:

include $(CIRCLEHOME)/Rules.mk

I have edit it,change

else ifeq ($(strip $(RASPPI)),4)
ARCHCPU	?= -mcpu=cortex-a72 -mlittle-endian
ARCH	+= -DAARCH=64 $(ARCHCPU)
TARGET	?= kernel8-rpi4

to

TARGET	?= kernel8

but it's not necessary to do this

I can't put erverythin under project's root folder.To compiler the files under folder game,I add this to Rules.mk

%.d: game/TicTacToe/%.cpp
	@$(CPP) $(CPPFLAGS) -M -MG -MT $*.o -MT $@ -MF $@ $<

Install

I have only run the img under rpi4b.I don't know if it can run on other rpi model(if it can,the img file name should be change)

1 copy the img file and other files

you should replace the img file of rpi4 of your sd card.I found these ways:

1. Make an sd card using rust-rpi-os's install guide:

https://github.com/rust-embedded/rust-raspberrypi-OS-tutorials/tree/master/05_drivers_gpio_uart#rpi-4

this method seems need fewer file to start rpi4b with kernel8.img

2. Make an sd card using circle's install guide:

https://github.com/rsta2/circle?tab=readme-ov-file#installation

3. Using a offical rpi4's os sd card,then replace (backup the orginal first) the img file

2 prepare the config.txt and cmdline.txt file

copy(or edit the options) the config.txt and cmdline.txt on the sd card's top floder(you can also use them under this project's configFile folder).

Be carefull ! :

the config.txt option are seperated line by line:

https://www.raspberrypi.com/documentation/computers/config_txt.html

but cmdline.txt option are seperated by space:

https://raspberrytips.com/raspberry-pi-cmdline-txt/

you maybe want to use the US keymap,then add the option

keymap=US

is in cmdline.txt(the default keymap of circle and circle-stdlib seems is DE).There are six keymap options can set:

https://github.com/rsta2/circle/blob/master/sample/08-usbkeyboard/README

And it seems the option

width=640 height=480

make the text look bigger,I suggest to add this option

when rpi4 start,you can see some log on screen first(make it more like an 'OS'),if set the option

logdev=ttyS1

these info will not display,you will see the lisp repl first

IDE config

I use vscode and vscode wsl plugin to edit the code.If vscode report it can't find the .h file(It seems if clone circle-stdlib project use root,the vscode report no error,but if not root,vscode will report can't find .h file),you may need to edit the vscode c/c++ plugin's "Include path" option by enter "Ctrl+Shift+p"(change ... to your absolute path):

/.../circle-stdlib/include
/.../circle-stdlib/libs/circle-newlib/newlib/libc/include
/.../circle-stdlib/libs/circle/include
/.../circle-stdlib/libs/circle/addon
/.../circle/circle-stdlib/libs/circle/addon
/.../circle/circle-stdlib/install/aarch64-none-circle/include/sys
/.../circle/circle-stdlib/libs/circle-newlib/newlib/libc/sys

Changes I make to let microlisp run on rpi4b bare metal with circle-stdlib

There is two edition of microlisp:scheme and scheme-gc,I just copy the scheme code(it seems easier) to circle-stdlib kernel.cpp,fix some error that vscode (with WSL's vscode plugin) report:

1. the microlisp defined macro TRUE and FALSE,but circle&circle-stdlib defined them too in types.h,so I rename them to TRUEE and FALSEE

2. microlisp use c and circle&circle-stdlib use c++,so I add casting of every malloc

3. add function my_strdup replace the use of strdup in function make_symbol in kernel.cpp,it seems vscode can't find the right strdup function

4. in this lisp on rpi4,some microlisp's buildin function like exit() obvious can't use now (I need to change function exit to poweroff later)

5. copy microlisp's code in main function to circle-stdlib app's main routine:

   CStdlibApp::TShutdownMode CKernel::Run (void)

man can decide if or not load lib.scm by command line option in microlisp,but I force to load it

bing! it worked(lucky)

TODO list

Here is the plan of future:

• try to create some file-system function,like (ls) (try to wrap the circle-stdlib's file opreation function)

I have support (ls),(mkdir "dirName"),(cd "folderName"),(unlink "fileOrFolderName"):

• now the interpreter can eval the single line expression.it can eval multi line function defination too,but it's better store the defination in a file.so there need a smallest editor that can edit the lisp code.A better editor should look like the classic QBasic's IDE

Now I have port some kilo's code,you can use it by (edit "fileName").You have to give a fileName.If file not exist,it will been created,or it will be open:

the code is from kilo,and for easy to debug,I only copy&test some of it's code:but enought to edit(create,edit,insert char,inster new line,delete char...) step by step(the code before ch6).

it's hard to merge kilo's code then merge microlisp's code:in rpi bare metel,there's no termios lib,I use these func to switch between cook and raw mode:

    void setRaw(){
		mConsole.SetOptions(0);
	}

	void restoreMode()
	{
		mConsole.SetOptions(CONSOLE_OPTION_ICANON|CONSOLE_OPTION_ECHO);
	}

and some of detail is different between the kilo's code,like:circle's key enter's code is /n in raw mode,where kilo use /r,and ARROW_LEFT = 1000 in kilo can't work,I change it to ARROW_LEFT = 1(I don't know why),and some ESCAPE SEQUENCES is same in circle and kilo,some are not (I clear the screen use ESCAPE SEQUENCES in /doc/screen.txt).If set keymap=US width=640 in cmdline.txt,the row is 25 and col is 80 each screen,I write it direct in code

• fix the microlisp's bug,and make it faster:

Now microlisp seems lake of error handle:the expression

(map (lambda(x)(+ x 1)) '(1 2 3))

works,but if missing the bracket:

(map (lambda(x)(+ x 1) '(1 2 3))

there is no error report on screen(in original microlisp either)

some tiny lisp interpreter like Mal's c edition can show the error message

and the microlisp seems read the expression from stdin every single char,better to make it faster

• The lisp interpreter itself can manage the memery,need to learn the detail,and let the lisp's memery manage way to be the OS's memery manage way

• It's better be a chess and a go game,start it using (chess) and (go)

I have port gnugo1.2,you can use (go) to play.But it played too low.so it's only "seems can play"(details can find in game/README.md):

You can use (ttt) to play TicTacToe

• There is other rpi4b function,like opengl,may be can try them.

Errors and unsloved problems:

1. c and c++'s string are not compatible,merge microlisp's c code and circle/circle-stdlib's c++ code got lots of

ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]

warning.add -Wno-write-strings to ingore it now

Acknowledgments

Circle

circle-stdlib

microlisp

kilo

lupos