(3/5) Add functions to access AVT shading buffer

 - Add code to read from and write to AVT GPData buffer
 - Remove pdata access stubs, no point having empty functions like this, and 
   maybe they were intended to read the GPData anyway?
 - Add functions to read shading image into a user-supplied buffer, and write
   shading image from user-supplied buffer.

Some of this is based on code from avt1394.

Index: libdc1394/dc1394/vendor/avt.c
===================================================================
--- libdc1394.orig/dc1394/vendor/avt.c
+++ libdc1394/dc1394/vendor/avt.c
@@ -1252,22 +1252,198 @@ dc1394_avt_get_gpdata_info(dc1394camera_
 
 
 /************************************************************************/
-/* Get pdata_buffer : experimental, does not work			*/
+/* Common code for GPData register access computation			*/
+/************************************************************************/
+static void gpdata_io_common(uint32_t *buf_local, uint32_t gpdata_numquads,
+			     uint32_t *nextIndex, uint32_t index, uint32_t size,
+			     uint32_t *newBufferSize, uint32_t *nQuadWriteSize,
+			     dc1394bool_t *finish)
+{
+  /* clear buffer */
+  memset(buf_local, 0, gpdata_numquads * sizeof(uint32_t));
+
+  /* calculate the index after writing the next block */
+  *nextIndex = index + (gpdata_numquads * 4);
+  /* if the next index lies behind the allocated memory -> align */
+  if (size < *nextIndex) {
+    *newBufferSize = (gpdata_numquads * 4) - (*nextIndex - size);
+    /* if the reduced write-buffer size (buffer-size - 'overhang') is dividable by 4 */
+    *nQuadWriteSize = *newBufferSize / 4;
+    if ((*newBufferSize % 4) != 0)
+      *nQuadWriteSize = *nQuadWriteSize + 1;
+
+    *finish = DC1394_TRUE; /* ...because it's the last block */
+  }
+  else
+    *nQuadWriteSize = gpdata_numquads;
+
+  if (*nextIndex == size)
+    *finish = DC1394_TRUE;
+}
+
+
+/************************************************************************/
+/* Read size number of bytes from GPData buffer				*/
 /************************************************************************/
 dc1394error_t
-dc1394_avt_get_pdata_buffer(dc1394camera_t *camera, uint32_t *buff)
+dc1394_avt_read_gpdata(dc1394camera_t *camera, unsigned char *buf, uint32_t size)
 {
-  return DC1394_FAILURE ;       
+  uint32_t gpdata_numquads, gpdata_bufsize;
+  uint32_t nQuadReadSize, newBufferSize;
+  uint32_t i, index = 0, nextIndex;
+  uint32_t *buf_local;
+  dc1394bool_t finish = DC1394_FALSE;
+  dc1394error_t err;
+
+  /* determine gpdata_bufsize (as read-block-size) */
+  err = dc1394_avt_get_gpdata_info(camera, &gpdata_bufsize);
+  DC1394_ERR_RTN(err,"Could not get AVT GPData info");
+
+  /* calculate the number of quadlets in the gpdata buffer */
+  gpdata_numquads = gpdata_bufsize / 4;
+  if ((gpdata_bufsize % 4) != 0)
+    gpdata_numquads++;
+
+  /* allocate memory for the 'read-buffer' */
+  buf_local = malloc(gpdata_numquads * sizeof(uint32_t));
+  if (buf_local == NULL)
+    return DC1394_FAILURE;
+
+  do {
+    gpdata_io_common(buf_local, gpdata_numquads, &nextIndex, index, size, &newBufferSize, &nQuadReadSize, &finish);
+
+    /* read block */
+    err = GetCameraAdvControlRegisters(camera, REG_CAMERA_AVT_GPDATA_BUFFER,
+		     buf_local, nQuadReadSize);
+    if (err != DC1394_SUCCESS) {
+  	  free(buf_local);
+      return DC1394_FAILURE;
+    }
+
+    /* copy block-contents to user buf */
+    for (i = 0; i < nQuadReadSize; i++)
+      memcpy(buf + index + (i * 4), &buf_local[i], sizeof(uint32_t));
+
+    index += (nQuadReadSize * 4);
+
+    /* loop until all bytes are read */
+  } while (!finish);
+
+  free(buf_local);
+  return DC1394_SUCCESS;
 }
 
 
 /************************************************************************/
-/* Set pdata_buffer	experimental, does not work			*/
+/* Write size number of bytes to GPData buffer				*/
 /************************************************************************/
 dc1394error_t
-dc1394_avt_set_pdata_buffer(dc1394camera_t *camera, uint32_t buff)
+dc1394_avt_write_gpdata(dc1394camera_t *camera, unsigned char *buf, uint32_t size)
 {
-  return DC1394_FAILURE;
+  uint32_t gpdata_bufsize, gpdata_numquads;
+  uint32_t nQuadWriteSize, newBufferSize;
+  uint32_t i, index = 0, nextIndex;
+  uint32_t *buf_local;
+  dc1394bool_t finish = DC1394_FALSE;
+  dc1394error_t err;
+
+  /* determine gpdata_bufsize */
+  err = dc1394_avt_get_gpdata_info(camera, &gpdata_bufsize);
+  DC1394_ERR_RTN(err,"Could not get AVT GPData info");
+
+  /* calculate the number of quadlets in the gpdata buffer */
+  gpdata_numquads = gpdata_bufsize / 4;
+  if ((gpdata_bufsize % 4) != 0)
+    gpdata_numquads++;
+
+  /* allocate memory for the write buffer */
+  buf_local = malloc(gpdata_numquads * sizeof(uint32_t));
+  if (buf_local == NULL)
+    return DC1394_FAILURE;
+
+  do {
+    gpdata_io_common(buf_local, gpdata_numquads, &nextIndex, index, size, &newBufferSize, &nQuadWriteSize, &finish);
+
+    /* copy block-contents to buf_local */
+    for (i = 0; i < nQuadWriteSize; i++)
+      memcpy(&buf_local[i], buf + index + (i * 4), sizeof(uint32_t));
+
+    /* write block */
+    err = SetCameraAdvControlRegisters(camera, REG_CAMERA_AVT_GPDATA_BUFFER,
+                                       buf_local, nQuadWriteSize);
+    if (err != DC1394_SUCCESS) {
+      free(buf_local);
+      return DC1394_FAILURE;
+    }
+
+    index += (nQuadWriteSize * 4);
+
+    /* loop until all bytes are read */
+  } while (!finish);
+
+  free(buf_local);
+  return DC1394_SUCCESS;
 }
 
 
+/************************************************************************/
+/* Read shading image from camera into buffer       			*/
+/************************************************************************/
+dc1394error_t
+dc1394_avt_read_shading_img(dc1394camera_t *camera, unsigned char *buf,
+			    uint32_t size)
+{
+  dc1394error_t err;
+  dc1394bool_t en_write;
+  uint32_t addr;
+
+  /* Enable read at address 0 */
+  err = dc1394_avt_get_shading_mem_ctrl(camera, &en_write, NULL, NULL);
+  DC1394_ERR_RTN(err,"Could not read AVT shading mem ctrl");
+  err = dc1394_avt_set_shading_mem_ctrl(camera, en_write, DC1394_TRUE, 0);
+  DC1394_ERR_RTN(err,"Could not write AVT shading mem ctrl");
+
+  /* Read data */
+  err = dc1394_avt_read_gpdata(camera, buf, size);
+  DC1394_ERR_RTN(err,"Could not read AVT gpdata");
+
+  /* Disable read */
+  err = dc1394_avt_get_shading_mem_ctrl(camera, &en_write, NULL, &addr);
+  DC1394_ERR_RTN(err,"Could not read AVT shading mem ctrl");
+  err = dc1394_avt_set_shading_mem_ctrl(camera, en_write, DC1394_FALSE, addr);
+  DC1394_ERR_RTN(err,"Could not write AVT shading mem ctrl");
+
+  return DC1394_SUCCESS;
+}
+
+
+/************************************************************************/
+/* Write shading image from buffer to camera				*/
+/************************************************************************/
+dc1394error_t
+dc1394_avt_write_shading_img(dc1394camera_t *camera, unsigned char *buf,
+			     uint32_t size)
+{
+  dc1394error_t err;
+  dc1394bool_t en_read;
+  uint32_t addr;
+
+  /* Enable write at address 0 */
+  err = dc1394_avt_get_shading_mem_ctrl(camera, NULL, &en_read, NULL);
+  DC1394_ERR_RTN(err,"Could not read AVT shading mem ctrl");
+  err = dc1394_avt_set_shading_mem_ctrl(camera, DC1394_TRUE, en_read, 0);
+  DC1394_ERR_RTN(err,"Could not write AVT shading mem ctrl");
+
+  /* Write data */
+  err = dc1394_avt_write_gpdata(camera, buf, size);
+  DC1394_ERR_RTN(err,"Could not write AVT gpdata");
+
+  /* Disable write */
+  err = dc1394_avt_get_shading_mem_ctrl(camera, NULL, &en_read, &addr);
+  DC1394_ERR_RTN(err,"Could not read AVT shading mem ctrl");
+  err = dc1394_avt_set_shading_mem_ctrl(camera, DC1394_FALSE, en_read, addr);
+  DC1394_ERR_RTN(err,"Could not write AVT shading mem ctrl");
+
+  return DC1394_SUCCESS;
+}
+
Index: libdc1394/dc1394/vendor/avt.h
===================================================================
--- libdc1394.orig/dc1394/vendor/avt.h
+++ libdc1394/dc1394/vendor/avt.h
@@ -515,23 +515,32 @@ dc1394error_t dc1394_avt_set_deferred_tr
 					    dc1394bool_t SendImage );
 
 
+/************************************************************************/
+/* Read size number of bytes from GPData buffer				*/
+/************************************************************************/
+dc1394error_t dc1394_avt_read_gpdata(dc1394camera_t *camera, unsigned char *buf,
+				     uint32_t size);
+
+
+/************************************************************************/
+/* Write size number of bytes to GPData buffer				*/
+/************************************************************************/
+dc1394error_t dc1394_avt_write_gpdata(dc1394camera_t *camera,
+				      unsigned char *buf, uint32_t size);
+
 
 /************************************************************************/
-/* Get pdata_buffer : DOESNT WORK					*/
-/*----------------------------------------------------------------------*/
-/* will Get the  buffer	...						*/
+/* Read shading image from camera into buffer       			*/
 /************************************************************************/
-dc1394error_t dc1394_avt_get_pdata_buffer(dc1394camera_t *camera, 
-					  uint32_t *buff);
+dc1394error_t dc1394_avt_read_shading_img(dc1394camera_t *camera,
+					  unsigned char *buf, uint32_t size);
 
 
 /************************************************************************/
-/* Set pdata_buffer : DOESNT WORK					*/
-/*----------------------------------------------------------------------*/
-/* will Set the  buffer	...						*/
+/* Write shading image from buffer to camera				*/
 /************************************************************************/
-dc1394error_t dc1394_avt_set_pdata_buffer(dc1394camera_t *camera, 
-					  uint32_t buff);
+dc1394error_t dc1394_avt_write_shading_img(dc1394camera_t *camera,
+					   unsigned char *buf, uint32_t size);
 
 
 #ifdef __cplusplus