From 50106abe04f943dd37865e9454942aaa02e4b023 Mon Sep 17 00:00:00 2001
From: jpr <jpr>
Date: Thu, 29 Jun 2006 13:27:28 +0000
Subject: [PATCH] Add comments on the use od Rescale Slope / Intercept

---
 src/gdcmFileHelper.cxx | 157 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 155 insertions(+), 2 deletions(-)

diff --git a/src/gdcmFileHelper.cxx b/src/gdcmFileHelper.cxx
index 62c03740..40d1a83c 100644
--- a/src/gdcmFileHelper.cxx
+++ b/src/gdcmFileHelper.cxx
@@ -4,8 +4,8 @@
   Module:    $RCSfile: gdcmFileHelper.cxx,v $
   Language:  C++
 
-  Date:      $Date: 2006/05/30 08:14:50 $
-  Version:   $Revision: 1.104 $
+  Date:      $Date: 2006/06/29 13:27:28 $
+  Version:   $Revision: 1.105 $
                                                                                 
   Copyright (c) CREATIS (Centre de Recherche et d'Applications en Traitement de
   l'Image). All rights reserved. See Doc/License.txt or
@@ -283,6 +283,7 @@ DataEntry *FileHelper::InsertEntryString(std::string const &content,
  * @param   lgth new value length
  * @param   group   Group number of the Entry 
  * @param   elem  Element number of the Entry
+ * @param   vr  Value Represenation of the DataElement to be inserted 
  * \return  pointer to the modified/created DataEntry (NULL when creation
  *          failed).
  */
@@ -1934,3 +1935,155 @@ void FileHelper::Print(std::ostream &os, std::string const &)
 
 //-----------------------------------------------------------------------------
 } // end namespace gdcm
+
+
+/* Probabely something to be added to use Rescale Slope/Intercept
+Have a look ,at ITK code !
+
+// Internal function to rescale pixel according to Rescale Slope/Intercept
+template<class TBuffer, class TSource>
+void RescaleFunction(TBuffer* buffer, TSource *source,
+                     double slope, double intercept, size_t size)
+{
+  size /= sizeof(TSource);
+
+  if (slope != 1.0 && intercept != 0.0)
+    {
+    // Duff's device.  Instead of this code:
+    //
+    //   for(unsigned int i=0; i<size; i++)
+    //    {
+    //    buffer[i] = (TBuffer)(source[i]*slope + intercept);
+    //    }
+    //
+    // use Duff's device which exploits "fall through"
+    register size_t n = (size + 7) / 8;
+    switch ( size % 8)
+      {
+      case 0: do { *buffer++ = (TBuffer)((*source++)*slope + intercept);
+      case 7:      *buffer++ = (TBuffer)((*source++)*slope + intercept);
+      case 6:      *buffer++ = (TBuffer)((*source++)*slope + intercept);
+      case 5:      *buffer++ = (TBuffer)((*source++)*slope + intercept);
+      case 4:      *buffer++ = (TBuffer)((*source++)*slope + intercept);
+      case 3:      *buffer++ = (TBuffer)((*source++)*slope + intercept);
+      case 2:      *buffer++ = (TBuffer)((*source++)*slope + intercept);
+      case 1:      *buffer++ = (TBuffer)((*source++)*slope + intercept);
+                 }  while (--n > 0);
+      }
+    }
+  else if (slope == 1.0 && intercept != 0.0)
+    {
+    // Duff's device.  Instead of this code:
+    //
+    //   for(unsigned int i=0; i<size; i++)
+    //    {
+    //    buffer[i] = (TBuffer)(source[i] + intercept);
+    //    }
+    //
+    // use Duff's device which exploits "fall through"
+    register size_t n = (size + 7) / 8;
+    switch ( size % 8)
+      {
+      case 0: do { *buffer++ = (TBuffer)(*source++ + intercept);
+      case 7:      *buffer++ = (TBuffer)(*source++ + intercept);
+      case 6:      *buffer++ = (TBuffer)(*source++ + intercept);
+      case 5:      *buffer++ = (TBuffer)(*source++ + intercept);
+      case 4:      *buffer++ = (TBuffer)(*source++ + intercept);
+      case 3:      *buffer++ = (TBuffer)(*source++ + intercept);
+      case 2:      *buffer++ = (TBuffer)(*source++ + intercept);
+      case 1:      *buffer++ = (TBuffer)(*source++ + intercept);
+                 }  while (--n > 0);
+      }
+    }
+  else if (slope != 1.0 && intercept == 0.0)
+    {
+    // Duff's device.  Instead of this code:
+    //
+    //   for(unsigned int i=0; i<size; i++)
+    //    {
+    //    buffer[i] = (TBuffer)(source[i]*slope);
+    //    }
+    //
+    // use Duff's device which exploits "fall through"
+    register size_t n = (size + 7) / 8;
+    switch ( size % 8)
+      {
+      case 0: do { *buffer++ = (TBuffer)((*source++)*slope);
+      case 7:      *buffer++ = (TBuffer)((*source++)*slope);
+      case 6:      *buffer++ = (TBuffer)((*source++)*slope);
+      case 5:      *buffer++ = (TBuffer)((*source++)*slope);
+      case 4:      *buffer++ = (TBuffer)((*source++)*slope);
+      case 3:      *buffer++ = (TBuffer)((*source++)*slope);
+      case 2:      *buffer++ = (TBuffer)((*source++)*slope);
+      case 1:      *buffer++ = (TBuffer)((*source++)*slope);
+                 }  while (--n > 0);
+      }
+    }
+  else
+    {
+    // Duff's device.  Instead of this code:
+    //
+    //   for(unsigned int i=0; i<size; i++)
+    //    {
+    //    buffer[i] = (TBuffer)(source[i]);
+    //    }
+    //
+    // use Duff's device which exploits "fall through"
+    register size_t n = (size + 7) / 8;
+    switch ( size % 8)
+      {
+      case 0: do { *buffer++ = (TBuffer)(*source++);
+      case 7:      *buffer++ = (TBuffer)(*source++);
+      case 6:      *buffer++ = (TBuffer)(*source++);
+      case 5:      *buffer++ = (TBuffer)(*source++);
+      case 4:      *buffer++ = (TBuffer)(*source++);
+      case 3:      *buffer++ = (TBuffer)(*source++);
+      case 2:      *buffer++ = (TBuffer)(*source++);
+      case 1:      *buffer++ = (TBuffer)(*source++);
+                 }  while (--n > 0);
+      }
+    }
+    
+    
+}
+
+
+template<class TSource>
+void RescaleFunction(ImageIOBase::IOComponentType bufferType,
+                     void* buffer, TSource *source,
+                     double slope, double intercept, size_t size)
+{
+  switch (bufferType)
+    {
+    case ImageIOBase::UCHAR:
+      RescaleFunction( (unsigned char *)buffer, source, slope, intercept, size);
+      break;
+    case ImageIOBase::CHAR:
+      RescaleFunction( (char *)buffer, source, slope, intercept, size);
+      break;
+    case ImageIOBase::USHORT:
+      RescaleFunction( (unsigned short *)buffer, source, slope, intercept,size);
+      break;
+    case ImageIOBase::SHORT:
+      RescaleFunction( (short *)buffer, source, slope, intercept, size);
+      break;
+    case ImageIOBase::UINT:
+      RescaleFunction( (unsigned int *)buffer, source, slope, intercept, size);
+      break;
+    case ImageIOBase::INT:
+      RescaleFunction( (int *)buffer, source, slope, intercept, size);
+      break;
+    case ImageIOBase::FLOAT:
+      RescaleFunction( (float *)buffer, source, slope, intercept, size);
+      break;
+    case ImageIOBase::DOUBLE:
+      RescaleFunction( (double *)buffer, source, slope, intercept, size);
+      break;
+    default:
+      ::itk::OStringStream message;
+      message << "itk::ERROR: GDCMImageIO: Unknown component type : " << bufferType;
+      ::itk::ExceptionObject e(__FILE__, __LINE__, message.str().c_str(),ITK_LOCATION);
+      throw e;
+    }
+}
+*/
-- 
2.48.1