Re: Oct Files Help -- mkoctfile

[John W. Eaton]

On 10-Jan-2008, gOS wrote:

| to figure out if I am calling mxCalcSingleSubscript incorrectly for your mex
| compiler. It does not throw an error, but it returns an incorrect index
| which does not move beyond the first row of the file I'm trying to turn into
| a Cell Array.
| 
| Here is a code sample if it helps:
| 
| [...]

I checked in the following change to cvs head and the 3.0 branch.  I
think mxCalcSingleSubscript should work correctly with this patch.

jwe


src/ChangeLog:

2008-01-10  John W. Eaton  <address@hidden>

        * mex.cc (calc_single_subscript_internal): New static function.
        (mxArray_octave_value::calc_single_subscript): Use it.
        (mxArray_matlab::calc_single_subscript): Use it.


Index: src/mex.cc
===================================================================
RCS file: /cvs/octave/src/mex.cc,v
retrieving revision 1.36
diff -u -u -r1.36 mex.cc
--- src/mex.cc  28 Dec 2007 20:56:57 -0000      1.36
+++ src/mex.cc  10 Jan 2008 19:27:17 -0000
@@ -271,6 +271,38 @@
   }
 };
 
+static mwIndex
+calc_single_subscript_internal (mwSize ndims, const mwSize *dims,
+                               mwSize nsubs, const mwIndex *subs)
+{
+  mwIndex retval = 0;
+
+  switch (nsubs)
+    {
+    case 0:
+      break;
+
+    case 1:
+      retval = subs[0];
+      break;
+
+    default:
+      {
+       // Both nsubs and ndims should be at least 2 here.
+
+       mwSize n = nsubs <= ndims ? nsubs : ndims;
+
+       retval = subs[--n];
+
+       while (--n >= 0)
+         retval = dims[n] * retval + subs[n];
+      }
+      break;
+    }
+
+  return retval;
+}
+
 // The object that handles values pass to MEX files from Octave.  Some
 // methods in this class may set mutate_flag to TRUE to tell the
 // mxArray class to convert to the Matlab-style representation and
@@ -605,17 +637,10 @@
 
   mwIndex calc_single_subscript (mwSize nsubs, mwIndex *subs) const
   {
-    mwIndex retval = 0;
-
     // Force ndims, dims to be cached.
     get_dimensions ();
 
-    mwIndex n = nsubs <= ndims ? nsubs : ndims;
-
-    while (--n > 0)
-      retval = retval * dims[n] + subs[n];
-
-    return retval;
+    return calc_single_subscript_internal (ndims, dims, nsubs, subs);
   }
 
   size_t get_element_size (void) const
@@ -996,14 +1021,7 @@
 
   mwIndex calc_single_subscript (mwSize nsubs, mwIndex *subs) const
   {
-    mwIndex retval = 0;
-
-    mwSize n = nsubs <= ndims ? nsubs : ndims;
-
-    while (--n > 0)
-      retval = retval * dims[n] + subs[n];
-
-    return retval;
+    return calc_single_subscript_internal (ndims, dims, nsubs, subs);
   }
 
   size_t get_element_size (void) const