Revert "Standardize rescale"

poly_grid_partition appears to depend on integer calculation for large
scaling

This reverts commit eef16fe717.

libs/kimath/CMakeLists.txt

@@ -17,6 +17,9 @@ set( KIMATH_SRCS
     src/geometry/shape_rect.cpp
     src/geometry/shape_compound.cpp
     src/geometry/shape_segment.cpp
+
+
+    src/math/util.cpp
 )
 
 # Include the other smaller math libraries in this one for convenience

libs/kimath/include/math/util.h

@@ -1,7 +1,6 @@
 /*
  * This program source code file is part of KICAD, a free EDA CAD application.
  *
- * Copyright (C) 2021 KiCad Developers, see AUTHORS.txt for contributors.
  * Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
  * Copyright (C) CERN
  * @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
@@ -31,7 +30,6 @@
 #include <cstdint>
 #include <limits>
 #include <typeinfo>
-#include <type_traits>
 #include <wx/debug.h>
 #include <wx/log.h>
 
@@ -93,26 +91,10 @@ constexpr ret_type KiROUND( fp_type v )
  * Scales a number (value) by rational (numerator/denominator). Numerator must be <= denominator.
  */
 
-template <typename T>
-T rescale( T aNumerator, T aValue, T aDenominator, std::false_type )
-{
-    /// Rescales for floating point, casting up to double
-    return static_cast<double>( aNumerator ) * static_cast<double>( aValue )
-                    / static_cast<double>( aDenominator );
-}
-
-template <typename T>
-T rescale( T aNumerator, T aValue, T aDenominator, std::true_type )
-{
-    /// Rescales for integers casting to double and handling rounding to nearest
-    return KiROUND( static_cast<double>( aNumerator ) * static_cast<double>( aValue )
-                    / static_cast<double>( aDenominator ) );
-}
-
 template <typename T>
 T rescale( T aNumerator, T aValue, T aDenominator )
 {
-    return rescale( aNumerator, aValue, aDenominator, std::is_integral<T>() );
+    return aNumerator * aValue / aDenominator;
 }
 
 template <typename T>
@@ -121,4 +103,11 @@ int sign( T val )
     return ( T( 0 ) < val) - ( val < T( 0 ) );
 }
 
+// explicit specializations for integer types, taking care of overflow.
+template <>
+int rescale( int aNumerator, int aValue, int aDenominator );
+
+template <>
+int64_t rescale( int64_t aNumerator, int64_t aValue, int64_t aDenominator );
+
 #endif // UTIL_H

libs/kimath/src/math/util.cpp

@@ -0,0 +1,91 @@
+/*
+ * This program source code file is part of KICAD, a free EDA CAD application.
+ *
+ * Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
+ * Copyright (C) CERN
+ * @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#include <cmath>
+#include <cstdlib>
+#include <climits>
+#include <math/util.h>
+
+template<>
+int rescale( int aNumerator, int aValue, int aDenominator )
+{
+    return (int) ( (int64_t) aNumerator * (int64_t) aValue / (int64_t) aDenominator );
+}
+
+
+template<>
+int64_t rescale( int64_t aNumerator, int64_t aValue, int64_t aDenominator )
+{
+#ifdef __x86_64__
+    return ( (__int128_t) aNumerator * (__int128_t) aValue ) / aDenominator;
+#else
+    int64_t r = 0;
+    int64_t sign = ( ( aNumerator < 0 ) ? -1 : 1 ) * ( aDenominator < 0 ? -1 : 1 ) *
+                                                     ( aValue < 0 ? -1 : 1 );
+
+    int64_t a = std::abs( aNumerator );
+    int64_t b = std::abs( aValue );
+    int64_t c = std::abs( aDenominator );
+
+    r = c / 2;
+
+    if( b <= INT_MAX && c <= INT_MAX )
+    {
+        if( a <= INT_MAX )
+            return sign * ( ( a * b + r ) / c );
+        else
+            return sign * ( a / c * b + ( a % c * b + r ) / c);
+    }
+    else
+    {
+        uint64_t a0 = a & 0xFFFFFFFF;
+        uint64_t a1 = a >> 32;
+        uint64_t b0 = b & 0xFFFFFFFF;
+        uint64_t b1 = b >> 32;
+        uint64_t t1 = a0 * b1 + a1 * b0;
+        uint64_t t1a = t1 << 32;
+        int i;
+
+        a0 = a0 * b0 + t1a;
+        a1 = a1 * b1 + ( t1 >> 32 ) + ( a0 < t1a );
+        a0 += r;
+        a1 += a0 < (uint64_t)r;
+
+        for( i = 63; i >= 0; i-- )
+        {
+            a1  += a1 + ( ( a0 >> i ) & 1 );
+            t1  += t1;
+
+            if( (uint64_t) c <= a1 )
+            {
+                a1 -= c;
+                t1++;
+            }
+        }
+
+        return t1 * sign;
+    }
+#endif
+}