smooth refresh with aggregated changes

hello_usb.cpp

@@ -108,8 +108,10 @@ void init_epaper_display() {
 
 /**
  * Add an entry to the display list and send update to core 1
+ * @param entry The text to display
+ * @param finish_line If true, commits the line (moves to next line). If false, updates current line.
  */
-void send_display_update(const char *entry) {
+void send_display_update(const char *entry, bool finish_line) {
     if (!g_display_ready) return;  // Don't send if display isn't ready
     
     // Check if list is at capacity
@@ -120,10 +122,9 @@ void send_display_update(const char *entry) {
         g_force_full_refresh = true;
     }
     
-    // Add entry to global list
+    // Update the current entry (at g_entry_list.count)
     strncpy(g_entry_list.entries[g_entry_list.count], entry, ENTRY_LENGTH - 1);
     g_entry_list.entries[g_entry_list.count][ENTRY_LENGTH - 1] = '\0';
-    g_entry_list.count++;
     
     // Allocate message structure
     DisplayMessage *msg = (DisplayMessage *)malloc(sizeof(DisplayMessage));
@@ -134,6 +135,8 @@ void send_display_update(const char *entry) {
     
     // Copy entry list to message
     msg->entries = g_entry_list;
+    // We want to show the current line being edited, so we treat count as count + 1 for display purposes
+    msg->entries.count = g_entry_list.count + 1;
     
     // Decide whether to use partial or full refresh
     msg->use_partial = !g_force_full_refresh;
@@ -149,11 +152,18 @@ void send_display_update(const char *entry) {
     msg->xend = 800;       // Full width
     msg->yend = 480;       // Full height from header onwards
     
-    // Send message pointer to core 1
+    // Send message pointer to core 1 if FIFO has space
+    if (multicore_fifo_wready()) {
         multicore_fifo_push_blocking((uint32_t)msg);
+    } else {
+        printf("[Core 0] FIFO full, skipping display update\n");
+        free(msg);
+    }
     
-    // Wait for core 1 to complete the update
+    // If finishing the line, increment count for next time
-    multicore_fifo_pop_blocking();
+    if (finish_line) {
+        g_entry_list.count++;
+    }
 }
 
 /**
@@ -176,6 +186,14 @@ void core1_display_init() {
             uint32_t msg_addr = multicore_fifo_pop_blocking();
             DisplayMessage *msg = (DisplayMessage *)msg_addr;
 
+            // Drain FIFO to get the latest message
+            while (multicore_fifo_rvalid()) {
+                 printf("[Core 1] Skipping intermediate update\n");
+                 free(msg); // Free the stale message
+                 msg_addr = multicore_fifo_pop_blocking();
+                 msg = (DisplayMessage *)msg_addr;
+            }
+            
             printf("[Core 1] Updating display with %d entries\n", msg->entries.count);
             
             // Update the e-Paper display
@@ -199,8 +217,8 @@ void core1_display_init() {
                 
                 // Draw all entries starting below header
                 UWORD y_pos = 0;
-                // paint only the last 3 entries
+                // paint only the last 10 entries
-                int start_index = msg->entries.count > 2 ? msg->entries.count - 2 : 0;
+                int start_index = msg->entries.count > 10 ? msg->entries.count - 10 : 0;
                 for (int i = start_index; i < msg->entries.count; i++) {
                     if (y_pos + 25 < 480) {  //Don't draw beyond screen
                         Paint_DrawString_EN(20, i*25, msg->entries.entries[i], &Font16, WHITE, BLACK);
@@ -216,9 +234,6 @@ void core1_display_init() {
             
             // Free the message (it was allocated by core 0)
             free(msg);
-            
-            // Signal back to core 0 that update is complete
-            multicore_fifo_push_blocking(1);
         }
         
         sleep_ms(10);
@@ -359,49 +374,55 @@ static void process_kbd_report(hid_keyboard_report_t const *report) {
                 uint8_t ch = keycode2ascii[report->keycode[i]][is_shift ? 1 : 0];
                 
                 if (ch) {
-                    printf("%c", ch);
+                    bool is_enter = (ch == '\r' || ch == '\n');
+                    bool is_backspace = (ch == '\b' || ch == 127);
+                    bool is_printable = !is_enter && !is_backspace; // Includes space
 
-                    if (ch == '\r' || ch == '\n') {
+                    if (is_backspace) {
-                        printf("\n");
+                        if (g_buffer_index > 0) {
-                        // Process command
+                            printf("\b \b");
+                            g_buffer_index--;
                             g_input_buffer[g_buffer_index] = '\0';
                             
-                        // Echo logic
+                            // Update OLED
-                        echo_and_reset(g_input_buffer, &g_buffer_index);
+                            if (g_display_manager) g_display_manager->refresh(g_input_buffer, g_last_echo);
                             
-                        // Save last echoed (all caps) for display
+                            // Update e-Paper (in-place)
-                        size_t k = 0;
+                            send_display_update(g_input_buffer, false);
-                        for (; g_input_buffer[k] != '\0' && k < sizeof(g_last_echo) - 1; ++k) {
-                            g_last_echo[k] = g_input_buffer[k];
                         }
-                        g_last_echo[k] = '\0';
+                    } else if (is_enter) {
+                        printf("\n");
                         
-                        // Update displays
+                        // Update e-Paper (commit line)
+                        send_display_update(g_input_buffer, true);
+                        
+                        // Save to last echo
+                        strncpy(g_last_echo, g_input_buffer, sizeof(g_last_echo) - 1);
+                        g_last_echo[sizeof(g_last_echo) - 1] = '\0';
+                        
+                        // Clear buffer
+                        g_buffer_index = 0;
+                        g_input_buffer[0] = '\0';
+                        
+                        // Update OLED
                         if (g_display_manager) {
                             g_display_manager->set_last_echo(g_last_echo);
                             g_display_manager->refresh("", g_last_echo);
                         }
-                        send_display_update(g_last_echo);
+                    } else if (is_printable) {
-                        
+                        printf("%c", ch);
-                        // Reset buffer
+                        if (g_buffer_index < MAX_INPUT_LEN - 1) {
-                        g_buffer_index = 0;
+                            g_input_buffer[g_buffer_index++] = ch;
-                        g_input_buffer[0] = '\0';
-                        
-                    } else if (ch == '\b' || ch == 127) {
-                        if (g_buffer_index > 0) {
-                            g_buffer_index--;
                             g_input_buffer[g_buffer_index] = '\0';
-                            if (g_display_manager) {
+                            
-                                g_display_manager->refresh(g_input_buffer, g_last_echo);
+                            // Update OLED
+                            if (g_display_manager) g_display_manager->refresh(g_input_buffer, g_last_echo);
+                            
+                            // Update e-Paper ONLY if space (per user request)
+                            if (ch == ' ') {
+                                send_display_update(g_input_buffer, false);
                             }
                         }
-                    } else if (g_buffer_index < MAX_INPUT_LEN - 1) {
-                        g_input_buffer[g_buffer_index] = ch;
-                        g_buffer_index++;
-                        g_input_buffer[g_buffer_index] = '\0';
-                        if (g_display_manager) {
-                            g_display_manager->refresh(g_input_buffer, g_last_echo);
-                        }
                     }
                 }
             }