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diff --git a/xBRZ/src/xbrz_tools.h b/xBRZ/src/xbrz_tools.h
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+++ b/xBRZ/src/xbrz_tools.h
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+// ****************************************************************************
+// * This file is part of the xBRZ project. It is distributed under           *
+// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0         *
+// * Copyright (C) Zenju (zenju AT gmx DOT de) - All Rights Reserved          *
+// *                                                                          *
+// * Additionally and as a special exception, the author gives permission     *
+// * to link the code of this program with the following libraries            *
+// * (or with modified versions that use the same licenses), and distribute   *
+// * linked combinations including the two: MAME, FreeFileSync, Snes9x, ePSXe *
+// * You must obey the GNU General Public License in all respects for all of  *
+// * the code used other than MAME, FreeFileSync, Snes9x, ePSXe.              *
+// * If you modify this file, you may extend this exception to your version   *
+// * of the file, but you are not obligated to do so. If you do not wish to   *
+// * do so, delete this exception statement from your version.                *
+// ****************************************************************************
+
+#ifndef XBRZ_TOOLS_H_825480175091875
+#define XBRZ_TOOLS_H_825480175091875
+
+#include <cassert>
+#include <algorithm>
+#include <type_traits>
+
+
+namespace xbrz
+{
+template <uint32_t N> inline
+unsigned char getByte(uint32_t val) { return static_cast<unsigned char>((val >> (8 * N)) & 0xff); }
+
+inline unsigned char getAlpha(uint32_t pix) { return getByte<3>(pix); }
+inline unsigned char getRed  (uint32_t pix) { return getByte<2>(pix); }
+inline unsigned char getGreen(uint32_t pix) { return getByte<1>(pix); }
+inline unsigned char getBlue (uint32_t pix) { return getByte<0>(pix); }
+
+inline uint32_t makePixel(unsigned char a, unsigned char r, unsigned char g, unsigned char b) { return (a << 24) | (r << 16) | (g << 8) | b; }
+inline uint32_t makePixel(                 unsigned char r, unsigned char g, unsigned char b) { return             (r << 16) | (g << 8) | b; }
+
+inline uint32_t rgb555to888(uint16_t pix) { return ((pix & 0x7C00) << 9) | ((pix & 0x03E0) << 6) | ((pix & 0x001F) << 3); }
+inline uint32_t rgb565to888(uint16_t pix) { return ((pix & 0xF800) << 8) | ((pix & 0x07E0) << 5) | ((pix & 0x001F) << 3); }
+
+inline uint16_t rgb888to555(uint32_t pix) { return static_cast<uint16_t>(((pix & 0xF80000) >> 9) | ((pix & 0x00F800) >> 6) | ((pix & 0x0000F8) >> 3)); }
+inline uint16_t rgb888to565(uint32_t pix) { return static_cast<uint16_t>(((pix & 0xF80000) >> 8) | ((pix & 0x00FC00) >> 5) | ((pix & 0x0000F8) >> 3)); }
+
+
+template <class Pix> inline
+Pix* byteAdvance(Pix* ptr, int bytes)
+{
+    using PixNonConst = typename std::remove_cv<Pix>::type;
+    using PixByte     = typename std::conditional<std::is_same<Pix, PixNonConst>::value, char, const char>::type;
+
+    static_assert(std::is_integral<PixNonConst>::value, "Pix* is expected to be cast-able to char*");
+
+    return reinterpret_cast<Pix*>(reinterpret_cast<PixByte*>(ptr) + bytes);
+}
+
+
+//fill block  with the given color
+template <class Pix> inline
+void fillBlock(Pix* trg, int pitch, Pix col, int blockWidth, int blockHeight)
+{
+    //for (int y = 0; y < blockHeight; ++y, trg = byteAdvance(trg, pitch))
+    //    std::fill(trg, trg + blockWidth, col);
+
+    for (int y = 0; y < blockHeight; ++y, trg = byteAdvance(trg, pitch))
+        for (int x = 0; x < blockWidth; ++x)
+            trg[x] = col;
+}
+
+
+//nearest-neighbor (going over target image - slow for upscaling, since source is read multiple times missing out on cache! Fast for similar image sizes!)
+template <class PixSrc, class PixTrg, class PixConverter>
+void nearestNeighborScale(const PixSrc* src, int srcWidth, int srcHeight, int srcPitch,
+                          /**/  PixTrg* trg, int trgWidth, int trgHeight, int trgPitch,
+                          int yFirst, int yLast, PixConverter pixCvrt /*convert PixSrc to PixTrg*/)
+{
+    static_assert(std::is_integral<PixSrc>::value, "PixSrc* is expected to be cast-able to char*");
+    static_assert(std::is_integral<PixTrg>::value, "PixTrg* is expected to be cast-able to char*");
+
+    static_assert(std::is_same<decltype(pixCvrt(PixSrc())), PixTrg>::value, "PixConverter returning wrong pixel format");
+
+    if (srcPitch < srcWidth * static_cast<int>(sizeof(PixSrc))  ||
+        trgPitch < trgWidth * static_cast<int>(sizeof(PixTrg)))
+    {
+        assert(false);
+        return;
+    }
+
+    yFirst = std::max(yFirst, 0);
+    yLast  = std::min(yLast, trgHeight);
+    if (yFirst >= yLast || srcHeight <= 0 || srcWidth <= 0) return;
+
+    for (int y = yFirst; y < yLast; ++y)
+    {
+        const int ySrc = srcHeight * y / trgHeight;
+        const PixSrc* const srcLine = byteAdvance(src, ySrc * srcPitch);
+        PixTrg*       const trgLine = byteAdvance(trg, y    * trgPitch);
+
+        for (int x = 0; x < trgWidth; ++x)
+        {
+            const int xSrc = srcWidth * x / trgWidth;
+            trgLine[x] = pixCvrt(srcLine[xSrc]);
+        }
+    }
+}
+
+
+//nearest-neighbor (going over source image - fast for upscaling, since source is read only once
+template <class PixSrc, class PixTrg, class PixConverter>
+void nearestNeighborScaleOverSource(const PixSrc* src, int srcWidth, int srcHeight, int srcPitch,
+                                    /**/  PixTrg* trg, int trgWidth, int trgHeight, int trgPitch,
+                                    int yFirst, int yLast, PixConverter pixCvrt /*convert PixSrc to PixTrg*/)
+{
+    static_assert(std::is_integral<PixSrc>::value, "PixSrc* is expected to be cast-able to char*");
+    static_assert(std::is_integral<PixTrg>::value, "PixTrg* is expected to be cast-able to char*");
+
+    static_assert(std::is_same<decltype(pixCvrt(PixSrc())), PixTrg>::value, "PixConverter returning wrong pixel format");
+
+    if (srcPitch < srcWidth * static_cast<int>(sizeof(PixSrc))  ||
+        trgPitch < trgWidth * static_cast<int>(sizeof(PixTrg)))
+    {
+        assert(false);
+        return;
+    }
+
+    yFirst = std::max(yFirst, 0);
+    yLast  = std::min(yLast, srcHeight);
+    if (yFirst >= yLast || trgWidth <= 0 || trgHeight <= 0) return;
+
+    for (int y = yFirst; y < yLast; ++y)
+    {
+        //mathematically: ySrc = floor(srcHeight * yTrg / trgHeight)
+        // => search for integers in: [ySrc, ySrc + 1) * trgHeight / srcHeight
+
+        //keep within for loop to support MT input slices!
+        const int yTrgFirst = ( y      * trgHeight + srcHeight - 1) / srcHeight; //=ceil(y * trgHeight / srcHeight)
+        const int yTrgLast  = ((y + 1) * trgHeight + srcHeight - 1) / srcHeight; //=ceil(((y + 1) * trgHeight) / srcHeight)
+        const int blockHeight = yTrgLast - yTrgFirst;
+
+        if (blockHeight > 0)
+        {
+            const PixSrc* srcLine = byteAdvance(src, y         * srcPitch);
+            /**/  PixTrg* trgLine = byteAdvance(trg, yTrgFirst * trgPitch);
+            int xTrgFirst = 0;
+
+            for (int x = 0; x < srcWidth; ++x)
+            {
+                const int xTrgLast = ((x + 1) * trgWidth + srcWidth - 1) / srcWidth;
+                const int blockWidth = xTrgLast - xTrgFirst;
+                if (blockWidth > 0)
+                {
+                    xTrgFirst = xTrgLast;
+
+                    const auto trgPix = pixCvrt(srcLine[x]);
+                    fillBlock(trgLine, trgPitch, trgPix, blockWidth, blockHeight);
+                    trgLine += blockWidth;
+                }
+            }
+        }
+    }
+}
+
+
+template <class PixTrg, class PixConverter>
+void bilinearScale(const uint32_t* src, int srcWidth, int srcHeight, int srcPitch,
+                   /**/    PixTrg* trg, int trgWidth, int trgHeight, int trgPitch,
+                   int yFirst, int yLast, PixConverter pixCvrt /*convert uint32_t to PixTrg*/)
+{
+    static_assert(std::is_integral<PixTrg>::value,                            "PixTrg* is expected to be cast-able to char*");
+    static_assert(std::is_same<decltype(pixCvrt(uint32_t())), PixTrg>::value, "PixConverter returning wrong pixel format");
+
+    if (srcPitch < srcWidth * static_cast<int>(sizeof(uint32_t)) ||
+        trgPitch < trgWidth * static_cast<int>(sizeof(PixTrg)))
+    {
+        assert(false);
+        return;
+    }
+
+    yFirst = std::max(yFirst, 0);
+    yLast  = std::min(yLast, trgHeight);
+    if (yFirst >= yLast || srcHeight <= 0 || srcWidth <= 0) return;
+
+    const double scaleX = static_cast<double>(trgWidth ) / srcWidth;
+    const double scaleY = static_cast<double>(trgHeight) / srcHeight;
+
+    //perf notes:
+    //    -> double-based calculation is (slightly) faster than float
+    //    -> precalculation gives significant boost; std::vector<> memory allocation is negligible!
+    struct CoeffsX
+    {
+        int     x1 = 0;
+        int     x2 = 0;
+        double xx1 = 0;
+        double x2x = 0;
+    };
+    std::vector<CoeffsX> buf(trgWidth);
+    for (int x = 0; x < trgWidth; ++x)
+    {
+        const int x1 = srcWidth * x / trgWidth;
+        int x2 = x1 + 1;
+        if (x2 == srcWidth) --x2;
+
+        const double xx1 = x / scaleX - x1;
+        const double x2x = 1 - xx1;
+
+        buf[x] = { x1, x2, xx1, x2x };
+    }
+
+    for (int y = yFirst; y < yLast; ++y)
+    {
+        const int y1 = srcHeight * y / trgHeight;
+        int y2 = y1 + 1;
+        if (y2 == srcHeight) --y2;
+
+        const double yy1 = y / scaleY - y1;
+        const double y2y = 1 - yy1;
+
+        const uint32_t* const srcLine     = byteAdvance(src, y1 * srcPitch);
+        const uint32_t* const srcLineNext = byteAdvance(src, y2 * srcPitch);
+        PixTrg*         const trgLine     = byteAdvance(trg, y  * trgPitch);
+
+        for (int x = 0; x < trgWidth; ++x)
+        {
+            //perf: do NOT "simplify" the variable layout without measurement!
+            const int     x1 = buf[x].x1;
+            const int     x2 = buf[x].x2;
+            const double xx1 = buf[x].xx1;
+            const double x2x = buf[x].x2x;
+
+            const double x2xy2y = x2x * y2y;
+            const double xx1y2y = xx1 * y2y;
+            const double x2xyy1 = x2x * yy1;
+            const double xx1yy1 = xx1 * yy1;
+
+            auto interpolate = [=](int offset)
+            {
+                /*
+                    https://en.wikipedia.org/wiki/Bilinear_interpolation
+                    (c11(x2 - x) + c21(x - x1)) * (y2 - y ) +
+                    (c12(x2 - x) + c22(x - x1)) * (y  - y1)
+                */
+                const auto c11 = (srcLine    [x1] >> (8 * offset)) & 0xff;
+                const auto c21 = (srcLine    [x2] >> (8 * offset)) & 0xff;
+                const auto c12 = (srcLineNext[x1] >> (8 * offset)) & 0xff;
+                const auto c22 = (srcLineNext[x2] >> (8 * offset)) & 0xff;
+
+                return c11 * x2xy2y + c21 * xx1y2y +
+                       c12 * x2xyy1 + c22 * xx1yy1;
+            };
+
+            const double bi = interpolate(0);
+            const double gi = interpolate(1);
+            const double ri = interpolate(2);
+            const double ai = interpolate(3);
+
+            const auto b = static_cast<uint32_t>(bi + 0.5);
+            const auto g = static_cast<uint32_t>(gi + 0.5);
+            const auto r = static_cast<uint32_t>(ri + 0.5);
+            const auto a = static_cast<uint32_t>(ai + 0.5);
+
+            const uint32_t trgPix = (a << 24) | (r << 16) | (g << 8) | b;
+
+            trgLine[x] = pixCvrt(trgPix);
+        }
+    }
+}
+}
+
+#endif //XBRZ_TOOLS_H_825480175091875