Example ipc (#60)

* add blank example

* add ipc example code, need to change FURI API

* add ipc example code, need to change FURI API

* change core API, add context

* check handler at take

* fix important bugs in furi

* drawing example

* add posix mq

* fix unsigned demo counter

* create at open

* working local demo

* russian version of IPC example

* english version

* add gif

applications/examples/ipc.c

@@ -0,0 +1,158 @@
+#include "flipper.h"
+#include <string.h>
+
+#define FB_WIDTH 10
+#define FB_HEIGHT 3
+#define FB_SIZE (FB_WIDTH * FB_HEIGHT)
+
+// context structure used for pass some object from app thread to callback
+typedef struct {
+    SemaphoreHandle_t events; // queue to pass events from callback to app thread
+    FuriRecordSubscriber* log; // app logger
+} IpcCtx;
+
+static void handle_fb_change(const void* fb, size_t fb_size, void* raw_ctx) {
+    IpcCtx* ctx = (IpcCtx*)raw_ctx; // make right type
+
+    fuprintf(ctx->log, "[cb] framebuffer updated\n");
+
+    // send event to app thread
+    xSemaphoreGive(ctx->events);
+
+    // Attention! Please, do not make blocking operation like IO and waits inside callback
+    // Remember that callback execute in calling thread/context
+}
+
+static void print_fb(char* fb, FuriRecordSubscriber* log) {
+    if(fb == NULL) return;
+    
+    /* draw framebuffer like this:
+    +==========+
+    |          |
+    |          |
+    |          |
+    +==========+
+    */
+
+    char row_buffer[FB_WIDTH + 1];
+    row_buffer[FB_WIDTH] = '\0';
+
+    // FB layout is hardcoded here
+    fuprintf(log, "+==========+\n");
+    for(uint8_t i = 0; i < FB_HEIGHT; i++) {
+        strncpy(row_buffer, &fb[FB_WIDTH * i], FB_WIDTH);
+        fuprintf(log, "|%s|\n", row_buffer);
+    }
+    fuprintf(log, "+==========+\n");
+}
+
+void application_ipc_display(void* p) {
+    // get logger
+    FuriRecordSubscriber* log = get_default_log();
+
+    // create ASCII "framebuffer"
+    // FB_WIDTH x FB_HEIGHT char buffer
+    char _framebuffer[FB_SIZE];
+
+    // init framebuffer by spaces
+    for(size_t i = 0; i < FB_SIZE; i++) {
+        _framebuffer[i] = ' ';
+    }
+
+    // create record
+    if(!furi_create("test_fb", (void*)_framebuffer, FB_SIZE)) {
+        fuprintf(log, "[display] cannot create fb record\n");
+        furiac_exit(NULL);
+    }
+
+    StaticSemaphore_t event_descriptor;
+    // create stack-based counting semaphore
+    SemaphoreHandle_t events = xSemaphoreCreateCountingStatic(255, 0, &event_descriptor);
+
+    if(events == NULL) {
+        fuprintf(log, "[display] cannot create event semaphore\n");
+        furiac_exit(NULL);
+    }
+
+    // save log and event queue in context structure
+    IpcCtx ctx = {.events = events, .log = log};
+
+    // subscribe to record. ctx will be passed to handle_fb_change
+    FuriRecordSubscriber* fb_record = furi_open(
+        "test_fb", false, false, handle_fb_change, NULL, &ctx
+    );
+
+    if(fb_record == NULL) {
+        fuprintf(log, "[display] cannot open fb record\n");
+        furiac_exit(NULL);
+    }
+
+    #ifdef HW_DISPLAY
+    // on Flipper target -- open screen
+
+    // draw border
+
+    #else
+    // on Local target -- print "blank screen"
+    {
+        void* fb = furi_take(fb_record);
+        print_fb((char*)fb, log);
+        furi_give(fb_record);
+    }
+    #endif
+
+    while(1) {
+        // wait for event
+        if(xSemaphoreTake(events, portMAX_DELAY) == pdTRUE) {
+            fuprintf(log, "[display] get fb update\n\n");
+
+            #ifdef HW_DISPLAY
+            // on Flipper target draw the screen
+            #else
+            // on local target just print
+            {
+                void* fb = furi_take(fb_record);
+                print_fb((char*)fb, log);
+                furi_give(fb_record);
+            }
+            #endif
+        }
+    }
+}
+
+
+// Widget application
+void application_ipc_widget(void* p) {
+    FuriRecordSubscriber* log = get_default_log();
+
+    // open record
+    FuriRecordSubscriber* fb_record = furi_open(
+        "test_fb", false, false, NULL, NULL, NULL
+    );
+
+    if(fb_record == NULL) {
+        fuprintf(log, "[widget] cannot create fb record\n");
+        furiac_exit(NULL);
+    }
+
+    uint8_t counter = 0;
+
+    while(1) {
+        delay(120);
+
+        // write some ascii demo here: '#'' symbol run on overall screen
+        char* fb = (char*)furi_take(fb_record);
+
+        if(fb == NULL) furiac_exit(NULL);
+
+        for(size_t i = 0; i < FB_SIZE; i++) {
+            fb[i] = ' ';
+        }
+
+        fb[counter % FB_SIZE] = '#';
+
+        furi_commit(fb_record);
+
+        counter++;
+    }
+}