Further enhanced computation of buffer size when using partial read a…

…ccess

to pixel data. Now also some rare cases of BitsAllocated are supported.

CHANGES.355

@@ -1,6 +1,12 @@
 
 Changes between releases are documented here.
 
+**** Changes from 2010.04.16 (riesmeier)
+
+- Further enhanced computation of buffer size when using partial read access
+  to pixel data. Now also some rare cases of BitsAllocated are supported.
+  Affects: dcmimgle/include/dcmtk/dcmimgle/diinpxt.h
+
 **** Changes from 2010.04.15 (riesmeier)
 
 - Fixed possibly wrong computation of a buffer size when using partial read

dcmimgle/include/dcmtk/dcmimgle/diinpxt.h

@@ -22,8 +22,8 @@
  *  Purpose: DicomInputPixelTemplate (Header)
  *
  *  Last Update:      $Author: joergr $
- *  Update Date:      $Date: 2010-04-15 14:18:36 $
- *  CVS/RCS Revision: $Revision: 1.39 $
+ *  Update Date:      $Date: 2010-04-16 12:56:46 $
+ *  CVS/RCS Revision: $Revision: 1.40 $
  *  Status:           $State: Exp $
  *
  *  CVS/RCS Log at end of file
@@ -377,13 +377,12 @@ class DiInputPixelTemplate
         if ((document->getFlags() & CIF_UsePartialAccessToPixelData) && (PixelCount > 0) &&
             (!uncompressed || !pixelData->valueLoaded()) && (bitsAllocated % 8 == 0))
         {
-            /* Bits Allocated is always a multiple of 8 (see above) */
-            const Uint32 byteFactor = (bitsAllocated / 8);
-            /* need to split the calculation in order to avoid integer overflow for large pixel data */
-            const Uint32 count_B1 = bitsof_T1 / bitsAllocated;
-            const Uint32 count_T1 = (count_B1 > 0) ? PixelCount / count_B1 : PixelCount * (bitsAllocated / bitsof_T1);
+            /* Bits Allocated is always a multiple of 8 (see above), same for bits of T1 */
+            const Uint32 byteFactor = bitsAllocated / 8;
+            const Uint32 bytes_T1 = bitsof_T1 / 8;
+            const Uint32 count_T1 = (byteFactor == bytes_T1) ? PixelCount : (PixelCount * byteFactor + bytes_T1 - 1) / bytes_T1;
 #ifdef DEBUG
-            DCMIMGLE_TRACE("PixelCount: " << PixelCount << ", byteFactor: " << byteFactor << ", count_B1: " << count_B1 << ", count_T1: " << count_T1);
+            DCMIMGLE_TRACE("PixelCount: " << PixelCount << ", byteFactor: " << byteFactor << ", bytes_T1: " << bytes_T1 << ", count_T1: " << count_T1);
 #endif
             /* allocate temporary buffer */
             pixel = new T1[count_T1];
@@ -643,6 +642,10 @@ class DiInputPixelTemplate
  *
  * CVS/RCS Log:
  * $Log: diinpxt.h,v $
+ * Revision 1.40  2010-04-16 12:56:46  joergr
+ * Further enhanced computation of buffer size when using partial read access
+ * to pixel data. Now also some rare cases of BitsAllocated are supported.
+ *
  * Revision 1.39  2010-04-15 14:18:36  joergr
  * Fixed possibly wrong computation of a buffer size when using partial read
  * access to pixel data. This could lead to a crash under certain conditions.