Add a method to read the OLED display buffer from user space (#8777)

* Adding extern and declaration

* Change to mediated buffer read

* Adding raw byte read

* Restore write raw... D'Oh

* Working struct return

* Pack that struct

* Remove conditional packing and add example to docs

* Cleanup tab/spaces

* Update docs/feature_oled_driver.md

Prettify formatting

* Update drivers/oled/oled_driver.h

Prettify formatting

2 files changed, 17 insertions, 0 deletions

diff --git a/drivers/oled/oled_driver.c b/drivers/oled/oled_driver.c
index f1990567f7..bbf010a090 100644
--- a/drivers/oled/oled_driver.c
+++ b/drivers/oled/oled_driver.c
@@ -444,6 +444,14 @@ 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;
diff --git a/drivers/oled/oled_driver.h b/drivers/oled/oled_driver.h
index 5c21c0cc8e..7ec00d66a3 100644
--- a/drivers/oled/oled_driver.h
+++ b/drivers/oled/oled_driver.h
@@ -154,6 +154,11 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #    define OLED_I2C_TIMEOUT 100
 #endif
 
+typedef struct __attribute__((__packed__)) {
+    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,
@@ -207,6 +212,10 @@ 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);