add RowChan type

gridder_cxx.h

@@ -245,6 +245,11 @@ size_t get_supp(double epsilon)
   throw runtime_error("requested epsilon too small - minimum is 2e-13");
   }
 
+struct RowChan
+  {
+  size_t row, chan;
+  };
+
 template<typename T> class EC_Kernel
   {
   protected:
@@ -332,14 +337,17 @@ template<typename T> class Baselines
         coord[i] = UVW<T>(coord_(i,0), coord_(i,1), coord_(i,2));
       }
 
-    UVW<T> effectiveCoord(uint32_t index) const
+    RowChan getRowChan(uint32_t index) const
       {
       size_t irow = index/nchan;
       size_t ichan = index-nchan*irow;
-      return coord[irow]*f_over_c[ichan];
+      return RowChan{irow, ichan};
       }
-    UVW<T> effectiveCoord(size_t irow, size_t ichan) const
-      { return coord[irow]*f_over_c[ichan]; }
+
+    UVW<T> effectiveCoord(const RowChan &rc) const
+      { return coord[rc.row]*f_over_c[rc.chan]; }
+    UVW<T> effectiveCoord(uint32_t index) const
+      { return effectiveCoord(getRowChan(index)); }
     size_t Nrows() const { return nrows; }
     size_t Nchannels() const { return nchan; }
 
@@ -367,10 +375,8 @@ template<typename T> class Baselines
 #pragma omp parallel for num_threads(nthreads)
       for (size_t i=0; i<nvis; ++i)
         {
-        auto t = idx(i);
-        auto row = t/nchan;
-        auto chan = t-row*nchan;
-        vis[i] = ms(row, chan);
+        auto rc = getRowChan(idx(i));
+        vis[i] = ms(rc.row, rc.chan);
         }
       }
 
@@ -384,10 +390,8 @@ template<typename T> class Baselines
 #pragma omp parallel for num_threads(nthreads)
       for (size_t i=0; i<nvis; ++i)
         {
-        auto t = idx(i);
-        auto row = t/nchan;
-        auto chan = t-row*nchan;
-        ms(row, chan) += vis(i);
+        auto rc = getRowChan(idx(i));
+        ms(rc.row, rc.chan) += vis(i);
         }
       }
   };
@@ -724,15 +728,13 @@ template<typename T> void ms2grid_c
 #pragma omp for schedule(guided,100)
   for (size_t ipart=0; ipart<nvis; ++ipart)
     {
-    auto tidx = idx(ipart);
-    auto row = tidx/nchan;
-    auto chan = tidx-row*nchan;
-    UVW<T> coord = baselines.effectiveCoord(tidx);
+    auto rc = baselines.getRowChan(idx(ipart));
+    UVW<T> coord = baselines.effectiveCoord(rc);
     hlp.prep(coord.u, coord.v);
     auto * ptr = hlp.p0w;
-    auto v(ms(row,chan)*emb);
+    auto v(ms(rc.row,rc.chan)*emb);
     if (have_wgt)
-      v*=wgt(row,chan);
+      v*=wgt(rc.row,rc.chan);
     for (size_t cu=0; cu<supp; ++cu)
       {
       complex<T> tmp(v*ku[cu]);
@@ -820,10 +822,8 @@ template<typename T> void grid2ms_c
 #pragma omp for schedule(guided,100)
   for (size_t ipart=0; ipart<nvis; ++ipart)
     {
-    auto tidx = idx(ipart);
-    auto row = tidx/nchan;
-    auto chan = tidx-row*nchan;
-    UVW<T> coord = baselines.effectiveCoord(tidx);
+    auto rc = baselines.getRowChan(idx(ipart));
+    UVW<T> coord = baselines.effectiveCoord(rc);
     hlp.prep(coord.u, coord.v);
     complex<T> r = 0;
     const auto * ptr = hlp.p0r;
@@ -835,8 +835,8 @@ template<typename T> void grid2ms_c
       r += tmp*ku[cu];
       ptr += jump;
       }
-    if (have_wgt) r*=wgt(row,chan);
-    ms(row,chan) = r*emb;
+    if (have_wgt) r*=wgt(rc.row,rc.chan);
+    ms(rc.row,rc.chan) = r*emb;
     }
 }
   }

nifty_gridder.cc

@@ -649,7 +649,7 @@ template<typename T> pyarr<uint32_t> getIndices(const PyBaselines<T> &baselines,
     for (int ichan=chbegin; ichan<chend; ++ichan)
       if (!flags[irow*nchan+ichan])
         {
-        auto uvw = baselines.effectiveCoord(irow, ichan);
+        auto uvw = baselines.effectiveCoord(RowChan{irow,size_t(ichan)});
         if ((uvw.w>=wmin) && (uvw.w<wmax))
           {
           T u, v;
@@ -673,7 +673,7 @@ template<typename T> pyarr<uint32_t> getIndices(const PyBaselines<T> &baselines,
     for (int ichan=chbegin; ichan<chend; ++ichan)
       if (!flags[irow*nchan+ichan])
         {
-        auto uvw = baselines.effectiveCoord(irow, ichan);
+        auto uvw = baselines.effectiveCoord(RowChan{irow,size_t(ichan)});
         if ((uvw.w>=wmin) && (uvw.w<wmax))
           iout[acc[tmp[idx++]]++] = irow*nchan+ichan;
         }