flipperzero-firmware/wiki/fw/FURI.md
coreglitch 1759787334
Furi (#24)
* furiac start and thread create implementation"

* create and kill task

* rename debug, add header

* remove write.c

* kill itself

* furi exit/switch

* success switch and exit

* WIP furi records

* add furi record interface

* rename furi app control file

* record implementation in progress

* wip furi implementation

* add automatic tests for FURI AC

* differ build tests

* small changes

* FURI record tests description

* change furi statuses

* FURI record test blank

* exit after all application ends

* delay: print then wait

* fix FURI implementatnion building

* pipe record test

* concurrent access

* uncomplete mute-test

* update FURI documentation
2020-08-24 18:31:22 +03:00

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Markdown

Flipper Universal Registry Implementation or FURI is important part of Flipper firmware. It is used to:
* application control (start, exit, switch between active)
* data exchange between application (create/open channel, subscribe and push messages or read/write values)
* non-volatile data storage for application (create/open value and read/write)
# Application registry and control (FURIAC)
### Start and change application wrokflow
**`FuriApp* furiac_start(void(app*)(void*), char* name, void* param)`**
simply starts application. It call `app` entrypoint with `param` passed as argument. Useful for daemon applications and pop-up.
**`FuriApp furiac_switch(void(app*)(void*), char* name, void* param)`**
swtich to other application. FURI **stop current app**, call `app` entrypoint with `param` passed as argument and save current application entrypoint to `prev` field in current application registry. Useful for UI or "active" application.
### Exit application
**`void furiac_exit(void* param)`**
stop current application (stop thread and clear application's stack), start application from `prev` entry in current application registry, cleanup current application registry.
**`bool furiac_kill(FuriApp app)`**
stop specified `app` without returning to `prev` application.
# Data exchange
**`bool furi_create(char* name, void* value, size_t size)`**
creates named FURI record. Returns NULL if registry have not enough memory for creating. If value is NULL, create FURI Pipe (only callbacks management, no data/mutex).
**`FuriRecordHandler furi_open(char* name, bool solo, bool no_mute, void(*FlipperRecordCallback)(const void*, size_t), void(*FlipperRecordStateCallback)(FlipperRecordState))`**
opens existing FURI record by name. Returns NULL if record does not exist. If `solo` is true **another applications handlers set into "muted" state**. When appication has exited or record has closed, all handlers is unmuted. It may be useful for concurrently acces to resources like framebuffer or beeper. If `no_mute` is true, another applications cannot mute this handler.
**`bool furi_close(FuriRecordHandler* record)`**
close handler and unmute anothers.
**`bool furi_read(FuriRecordHandler* record, void* data, size_t size)`**
read message from record. Returns true if success, false otherwise.
**`bool furi_write(FuriRecordHandler* record, const void* data, size_t size)`**
write message to record. Returns true if success, false otherwise (handler gone or muted).
**`void* furi_take(FuriRecordHandler* record)` works as `furi_read`**
lock value mutex. It can be useful if records contain pointer to buffer which you want to change. You must call `furi_give` after operation on data and you cannot block executing between `take` and `give` calls
**`bool furi_give(FuriRecordHandler* record)`**
unlock value mutex works as `furi_wrte` but unlock global mutex.
# Usage example
_Diagram below describes furi states_
![FURI states](https://github.com/Flipper-Zero/wiki/raw/master/images/furi_states.png)
* After start, init code run some applications: in this example there is status bar, a background task and Home screen
* Status bar open access to framebuffer by opening "/ui/fb" FURI record
* "Home screen" call "Menu" application by `furiac_switch`. "Home screen" application stops and then "Menu" application starts.
* "Menu" application call "Your cool app" the same way. It also get access to framebuffer by open "/ui/fb" FURI record
* If "Your cool app" needs some backend app, it call this by `furiac_start` and then kill by `furiac_kill`
* If background task needs to show popup message (for example "Low battery") it can call new app or simply open "/ui/fb" record.
* When "/ui/fb" record is opened by popup message, FURI mute framebuffer handle in "Your cool app". This prevent to overwrite popup message by application drawing.
* "Status bar" framebuffer handle not is muted, beacuse open framebuffer with no_mute=true.
* After popup message is closed by `furiac_exit` or closing "/ui/fb", FURI unmute previous muted "Your cool app" framebuffer handle.