add document presence detection request to gt6816

backend/gt68xx_devices.c

@@ -86,7 +86,8 @@ static GT68xx_Command_Set mustek_gt6816_command_set = {
   gt68xx_generic_set_afe,
   gt68xx_generic_set_exposure_time,
   gt68xx_generic_get_id,
-  /* gt68xx_generic_move_paper */ NULL
+  /* gt68xx_generic_move_paper */ NULL,
+  /* gt6816_document_present */ NULL
 };
 
 static GT68xx_Command_Set mustek_gt6816_sheetfed_command_set = {
@@ -126,7 +127,8 @@ static GT68xx_Command_Set mustek_gt6816_sheetfed_command_set = {
   gt68xx_generic_set_afe,
   gt68xx_generic_set_exposure_time,
   gt68xx_generic_get_id,
-  gt68xx_generic_move_paper
+  gt68xx_generic_move_paper,
+  gt6816_document_present
 };
 
 static GT68xx_Command_Set mustek_gt6801_command_set = {
@@ -167,7 +169,8 @@ static GT68xx_Command_Set mustek_gt6801_command_set = {
   gt68xx_generic_set_afe,
   gt68xx_generic_set_exposure_time,
   gt68xx_generic_get_id,
-  /* gt68xx_generic_move_paper */ NULL
+  /* gt68xx_generic_move_paper */ NULL,
+  /* gt6816_document_present */ NULL
 };
 
 static GT68xx_Command_Set plustek_gt6801_command_set = {
@@ -207,7 +210,8 @@ static GT68xx_Command_Set plustek_gt6801_command_set = {
   gt68xx_generic_set_afe,
   /* set_exposure_time */ NULL,
   gt68xx_generic_get_id,
-  /* gt68xx_generic_move_paper */ NULL
+  /* gt68xx_generic_move_paper */ NULL,
+  /* gt6816_document_present */ NULL
 };
 
 static GT68xx_Model unknown_model = {

backend/gt68xx_gt6816.c

@@ -236,3 +236,28 @@ gt6816_stop_scan (GT68xx_Device * dev)
 
   return gt68xx_device_small_req (dev, req, req);
 }
+
+SANE_Status
+gt6816_document_present (GT68xx_Device * dev, SANE_Bool * present)
+{
+  SANE_Status status;
+  GT68xx_Packet req;
+
+  memset (req, 0, sizeof (req));
+  req[0] = 0x59;
+  req[1] = 0x01;
+
+  RIE (gt68xx_device_req (dev, req, req));
+
+  if (req[0] == 0x00 && req[1] == 0x59)
+    {
+      if (req[2] == 0)
+	*present = SANE_FALSE;
+      else
+	*present = SANE_TRUE;
+    }
+  else
+    return SANE_STATUS_IO_ERROR;
+
+  return SANE_STATUS_GOOD;
+}

backend/gt68xx_gt6816.h

@@ -67,4 +67,6 @@ static SANE_Status gt6816_carriage_home (GT68xx_Device * dev);
 
 static SANE_Status gt6816_stop_scan (GT68xx_Device * dev);
 
+static SANE_Status gt6816_document_present (GT68xx_Device * dev, SANE_Bool * present);
+
 #endif /* not GT68XX_GT6816_H */

backend/gt68xx_low.h

@@ -399,6 +399,14 @@ struct GT68xx_Command_Set
    */
     SANE_Status (*move_paper) (GT68xx_Device * dev,
 			       GT68xx_Scan_Request * request);
+
+  /** Detect if a document is inserted in the feeder
+   *
+   * @param dev Device object.
+   * @param present 
+   */
+    SANE_Status (*document_present) (GT68xx_Device * dev,
+			             SANE_Bool *present);
   /*@} */
 };