(2/5) Tweak AVT shading control functions

This patch tweaks the shading control functions for AVT cameras:

 - The read arguments to dc1394_avt_get_shading() and
   dc1394_avt_get_shading_memctrl() are now optional, pass NULL if you aren't
   interested in certain fields
 - Added the compute field to dc1394_avt_get_shading(), this was only present
   in the _set_shading variant.
 - Added the show field to dc1394_avt_get_shading() and dc1394_avt_set_shading()
 - dc1394_avt_set_shading_mem_ctrl() was writing to the wrong register
 - Fixed up prototypes for the above functions in the header file

Some of this is based on code from libavt1394

Index: libdc1394-2.0.0-rc3/dc1394/vendor/avt.c
===================================================================
--- libdc1394-2.0.0-rc3.orig/dc1394/vendor/avt.c
+++ libdc1394-2.0.0-rc3/dc1394/vendor/avt.c
@@ -191,7 +191,8 @@ dc1394_avt_print_advanced_feature(dc1394
 /************************************************************************/
 dc1394error_t
 dc1394_avt_get_shading(dc1394camera_t *camera, 
-		       dc1394bool_t *on_off, uint32_t *frame_nb)
+		       dc1394bool_t *on_off, dc1394bool_t *compute,
+		       dc1394bool_t *show, uint32_t *frame_nb)
 {
   dc1394error_t err;
   uint32_t value;
@@ -201,10 +202,20 @@ dc1394_avt_get_shading(dc1394camera_t *c
   DC1394_ERR_RTN(err,"Could not get AVT shading control reg");
 
   /* Shading ON / OFF : Bit 6 */
-  *on_off = (uint32_t)((value & 0x2000000UL) >> 25); 
-  
+  if (on_off)
+    *on_off = (uint32_t)((value & 0x2000000UL) >> 25);
+
+  /* Compute : Bit 5 */
+  if (compute)
+    *compute = (uint32_t)((value & 0x4000000UL) >> 26);
+
+  /* Show image : Bit 4 */
+  if (show)
+    *show = (uint32_t)((value & 0x8000000UL) >> 27);
+
   /* Number of images for auto computing of the shading reference: Bits 24..31 */
-  *frame_nb =(uint32_t)((value & 0xFFUL));      
+  if (frame_nb)
+    *frame_nb =(uint32_t)((value & 0xFFUL));
 
   return DC1394_SUCCESS;
   
@@ -216,7 +227,8 @@ dc1394_avt_get_shading(dc1394camera_t *c
 /************************************************************************/
 dc1394error_t
 dc1394_avt_set_shading(dc1394camera_t *camera,
-		       dc1394bool_t on_off,dc1394bool_t compute, uint32_t frame_nb)
+		       dc1394bool_t on_off, dc1394bool_t compute,
+		       dc1394bool_t show, uint32_t frame_nb)
 {
   dc1394error_t err;
   uint32_t curval;
@@ -230,7 +242,10 @@ dc1394_avt_set_shading(dc1394camera_t *c
   
   /* Compute : Bit 5 */
   curval = (curval & 0xFBFFFFFFUL) | ((compute ) << 26); 
-  
+
+  /* Show Image : Bit 4 */
+  curval = (curval & 0xF7FFFFFFUL) | ((show ) << 27);
+
   /* Number of images : Bits 24..31 */
   curval = (curval & 0xFFFFFF00UL) | ((frame_nb & 0xFFUL ));   
   
@@ -258,13 +273,16 @@ dc1394_avt_get_shading_mem_ctrl(dc1394ca
   DC1394_ERR_RTN(err,"Could not get AVT shading memory control");
   
   /* Enable write access : Bit 5 */
-  *en_write = (uint32_t)((value & 0x4000000UL) >> 26); 
+  if (en_write)
+    *en_write = (uint32_t)((value & 0x4000000UL) >> 26);
   
   /* Enable read access : Bit 6 */
-  *en_read = (uint32_t)((value & 0x2000000UL) >> 25); 
+  if (en_read)
+    *en_read = (uint32_t)((value & 0x2000000UL) >> 25);
   
   /* addroffset in byte : Bits 8..31 */
-  *addroffset =(uint32_t)((value & 0xFFFFFFUL));
+  if (addroffset)
+    *addroffset =(uint32_t)((value & 0xFFFFFFUL));
   
   return DC1394_SUCCESS;
 }
@@ -294,7 +312,7 @@ dc1394_avt_set_shading_mem_ctrl(dc1394ca
   curval = (curval & 0xFF000000UL) | ((addroffset & 0xFFFFFFUL ));   
   
   /* Set new parameters */ 
-  err=SetCameraAdvControlRegister(camera,REG_CAMERA_AVT_LUT_MEM_CTRL, curval);
+  err=SetCameraAdvControlRegister(camera,REG_CAMERA_AVT_SHDG_MEM_CTRL, curval);
   DC1394_ERR_RTN(err,"Could not get AVT LUT memory control");
   
   return DC1394_SUCCESS;
Index: libdc1394-2.0.0-rc3/dc1394/vendor/avt.h
===================================================================
--- libdc1394-2.0.0-rc3.orig/dc1394/vendor/avt.h
+++ libdc1394-2.0.0-rc3/dc1394/vendor/avt.h
@@ -90,8 +90,10 @@ dc1394error_t dc1394_avt_print_advanced_
 /* Retrieve if shading is on and the number of frames used to compute 	*/	 
 /* The shading reference frame						*/
 /************************************************************************/
-int dc1394_avt_get_shading(dc1394camera_t *camera, 
-			   dc1394bool_t *on_off, uint32_t *frame_nb);
+dc1394error_t dc1394_avt_get_shading(dc1394camera_t *camera,
+				     dc1394bool_t *on_off,
+				     dc1394bool_t *compute,
+				     dc1394bool_t *show, uint32_t *frame_nb);
 
 
 /************************************************************************/
@@ -100,9 +102,9 @@ int dc1394_avt_get_shading(dc1394camera_
 /* Set the shading to on/off and the number of frames used to compute 	*/	 
 /* The shading reference frame						*/
 /************************************************************************/
-int dc1394_avt_set_shading(dc1394camera_t *camera,
-			   dc1394bool_t on_off, dc1394bool_t compute,
-			   uint32_t frame_nb);
+dc1394error_t dc1394_avt_set_shading(dc1394camera_t *camera,
+				     dc1394bool_t on_off, dc1394bool_t compute,
+				     dc1394bool_t show, uint32_t frame_nb);