README

Prereq

• Install arm-none-eabi-gcc
• Download from https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads or use homebrew
• Create adapter-speed.cfg to make the binary transfer at 10MHz (default 100KHz). This is used by .vscode/launch.json -> configFiles

$ cat ${HOMEBREW_PREFIX}/Cellar/open-ocd/0.12.0/share/openocd/scripts/interface/adapter-speed.cfg
adapter_khz 10000

How to build

cd build
make

How to run

• clone sokoide branch from a for at https://github.com/sokoide/rp2040js/tree/sokoide

git clone https://github.com/sokoide/rp2040js.git
cd rp2040js
git checkout -b sokoide origin/sokoide
npm install

• cd build and update rp2040js path in Makefile
• run it by make run
• log

initial task started.
hello
usermain started...
hello
usermain started...
TASK_STACK_UPPER_LIMIT: 0x20036F00
MAIN_TASK_STACK_BASE: 0x2003FF00
MAIN_TASK SP: 0x2003F2D0
TASK_STACK_BASE_N[00]: 0x2003EF00
TASK_STACK_BASE_N[01]: 0x2003EB00
TASK_STACK_BASE_N[02]: 0x2003E700
TASK_STACK_BASE_N[03]: 0x2003E300
TASK_STACK_BASE_N[04]: 0x2003DF00
TASK_STACK_BASE_N[05]: 0x2003DB00
TASK_STACK_BASE_N[06]: 0x2003D700
TASK_STACK_BASE_N[07]: 0x2003D300
...
(ctrl-c to quit)

• when you make a change in your rpi OS, run make reset to reload the new code

How to make a fat12 FS

brew install mtools
make fat12


hexdump -C koidos.fat
00000000  eb 3c 90 4d 54 4f 4f 34  30 34 33 00 02 02 01 00  |.<.MTOO4043.....|
00000010  02 70 00 a0 05 f9 03 00  09 00 02 00 00 00 00 00  |.p..............|
00000020  00 00 00 00 00 00 29 0d  15 11 23 4b 4f 49 46 31  |......)...#KOIF1|
...

Project Directories

• build: build directory
• boot: boot files
  • reset_handler, dispatch_entry, systimer_handler are in vector_table.c
• kernel: kernel
  • kernel functions
• application: application dir
  • usermain called by main called by reset_handler after initialization

Task Management

• task_manager.c has a ready_queue per priority
  • TaskControlBlock* ready_queue[MAX_TASK_PRI]
• It has a wait_queue which is not per priority
• When a task is started by sk_task_start, the task control block will be added to a tail of an appropriate reqdy_queue
• systimer_handler is called every TIMER_PERIOD (10ms by default) and does the followings
  • checks tasks in wait_queue and move them into ready_queue if the task's wait_time already passed
  • removes the current task from the top of ready_queue and add it to the tail
  • calls scheduler

Shell

• Very limited commands are supported
• Take a look at shell.c
• Example commands to dump the filesystem at 0x1010000 for 32 bytes
• Notice that that's the contents of koidos.fat above

# user is always 'root'
> whoami
root

# os version
> version
sokoide os ver: 0.0.1

# read memory at 0x10100000 for 32 bytes
> memread 10100000 32
0x10100000: EBCE3C03 54F54FF4
0x10100008: 30433433 02200210
0x10100010: 02007007 0590F93F
0x10100018: 09000020 00000000

> memread 10100e00 32
0x10100E00: 485445C4 4F042002
0x10100E08: 54855845 180100A0
0x10100E10: E26E5625 000000A0
0x10100E18: E26E5625 0C000000

# ls root directory
> ls
V KOIF12
F HELLO.TXT 12
F HELLOJ.TXT 12
F PAGE.TXT 14
D DIR1
D DIR2

# ls sub directory
> ls dir1
D .
D ..
D SUBDIR1

> ls dir1/subdir1
D .
D ..
F HOGE.TXT 11


# cat files
> cat page.txt
You are page.

> cat /dir1/subdir1/hoge.txt
I am hoge.

# show fat info
> fat
bytesPerSector: 512
sectorsPerCluster: 2
reservedSectorCount: 1
tableCount: 2
rootEntryCount: 112
root dir sector count: 7
total_sectors: 1440
tableSize16: 3
* fat start_sector 1
* fat sectors 6
* root_dir start_sector 7
* root_dir sectors 7
* data start_sector 14
- relative jump (eb3c) + nop (90)
- OEM Name
- bytes per sector
- sectors per cluster
- FAT table's 1st sector (reserved sectors)
- FAT table count
- Max entries in root table
- Total sector count
- Media type
- sectors per FAT table
- sectors per track
- head count
eb 3c 90 4d 54 4f 4f 34 30 34 33 00 02 02 01 00 **< **M T O O 4 0 4 3 **********
02 70 00 a0 05 f9 03 00 09 00 02 00 00 00 00 00 **p ****************************

File System

• Contents of koidos.fat is converted into koidos.o during a link phase in Makefile and mapped at 0x10100000 address of the Flash

Memory Map

• 0x10000000-0x10FFFFFF: 1st half of the flash. OS code is here.
• 0x10100000-0x101FFFFF: 2nd half of the flash. Contents of 720KB koidos.fat is here in FAT12 format.
• 0x20000000- (264KB): SRAM

Refefrence

• μT-Kernel 3.0