Add a method to read the OLED display buffer from user space

docs/feature_oled_driver.md

@@ -238,6 +238,10 @@ void oled_write_P(const char *data, bool invert);
 // Remapped to call 'void oled_write_ln(const char *data, bool invert);' on ARM
 void oled_write_ln_P(const char *data, bool invert);
 
+// Returns a pointer to the requested start index in the buffer plus remaining
+// buffer length as struct
+oled_buffer_reader_t oled_read_raw(uint16_t start_index);
+
 // Writes a string to the buffer at current cursor position
 void oled_write_raw(const char *data, uint16_t size);
 

drivers/oled/oled_driver.c

@@ -446,6 +446,14 @@ void oled_pan(bool left) {
     oled_dirty = ~((OLED_BLOCK_TYPE)0);
 }
 
+oled_buffer_reader_t oled_read_raw(uint16_t start_index) {
+    if (start_index > OLED_MATRIX_SIZE) start_index = OLED_MATRIX_SIZE;
+    oled_buffer_reader_t ret_reader;
+    ret_reader.current_element = &oled_buffer[start_index];
+    ret_reader.remaining_element_count = OLED_MATRIX_SIZE - start_index;
+    return ret_reader;
+}
+
 void oled_write_raw_byte(const char data, uint16_t index) {
     if (index > OLED_MATRIX_SIZE) index = OLED_MATRIX_SIZE;
     if (oled_buffer[index] == data) return;

drivers/oled/oled_driver.h

@@ -150,6 +150,13 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #    endif
 #endif
 
+
+typedef struct _oled_buffer_reader_t {
+    uint8_t     *current_element;
+    uint16_t    remaining_element_count;
+} oled_buffer_reader_t;
+
+
 // OLED Rotation enum values are flags
 typedef enum {
     OLED_ROTATION_0   = 0,
@@ -203,6 +210,10 @@ void oled_write_ln(const char *data, bool invert);
 // Pans the buffer to the right (or left by passing true) by moving contents of the buffer
 void oled_pan(bool left);
 
+// Returns a pointer to the requested start index in the buffer plus remaining
+// buffer length as struct
+oled_buffer_reader_t oled_read_raw(uint16_t start_index);
+
 void oled_write_raw(const char *data, uint16_t size);
 void oled_write_raw_byte(const char data, uint16_t index);