From 8209042cdbf47c28b8b31153d2ffd406ef5e8cea Mon Sep 17 00:00:00 2001
From: Isaac Plunkett <isplunke@microsoft.com>
Date: Thu, 19 Sep 2024 17:27:30 -0700
Subject: [PATCH] use extractBits

---
 DirectXTex/DirectXTexSwizzle.cpp | 151 +++++++++++++++++++++++--------
 1 file changed, 114 insertions(+), 37 deletions(-)

diff --git a/DirectXTex/DirectXTexSwizzle.cpp b/DirectXTex/DirectXTexSwizzle.cpp
index b310919e..14e2d881 100644
--- a/DirectXTex/DirectXTexSwizzle.cpp
+++ b/DirectXTex/DirectXTexSwizzle.cpp
@@ -19,6 +19,7 @@ namespace
 {
 #ifdef __AVX2__
 #define deposit_bits(v,m) _pdep_u32(v,m)
+#define extract_bits(v,m) _pext_u32(v,m)
 #else
     // N3864 - A constexpr bitwise operations library for C++
     // https://github.com/fmatthew5876/stdcxx-bitops
@@ -35,6 +36,19 @@ namespace
         }
         return res;
     }
+    uint32_t extract_bits(uint32_t val, uint32_t mask)
+    {
+        uint32_t res = 0;
+        for (uint32_t bb = 1; mask !=0; bb += bb)
+        {
+            if (val & mask & -mask)
+            {
+                res |= bb;
+            }
+            mask &= (mask - 1);
+        }
+        return res;
+    }
 #endif
 }
 
@@ -68,20 +82,37 @@ HRESULT DirectX::StandardSwizzle(const Image& srcImage, bool toSwizzle, ScratchI
     size_t height = IsCompressed(srcImage.format) ? (srcImage.height + 3) / 4 : srcImage.height;
     size_t width  = IsCompressed(srcImage.format) ? (srcImage.width  + 3) / 4 : srcImage.width;
 
-    for (size_t y = 0; y < height; y++)
+    if (toSwizzle)
     {
-        for (size_t x = 0; x < width; x++)
+        size_t rowPitch = srcImage.rowPitch;
+        for (size_t y = 0; y < height; y++)
         {
-            uint32_t swizzleIndex = deposit_bits(x, xBytesMask) + deposit_bits(y, yBytesMask);
-            size_t swizzleOffset = swizzleIndex * bytesPerPixel;
+            for (size_t x = 0; x < width; x++)
+            {
+                uint32_t swizzleIndex = deposit_bits(x, xBytesMask) + deposit_bits(y, yBytesMask);
+                size_t swizzleOffset = swizzleIndex * bytesPerPixel;
 
-            size_t rowMajorOffset = y * srcImage.rowPitch + x * bytesPerPixel;
+                size_t rowMajorOffset = y * rowPitch + x * bytesPerPixel;
 
-            size_t sourceOffset = toSwizzle ? rowMajorOffset : swizzleOffset;
-            size_t destOffset   = toSwizzle ? swizzleOffset  : rowMajorOffset;
+                const uint8_t* sourcePixelPointer = sptr + rowMajorOffset;
+                uint8_t* destPixelPointer = dptr + swizzleOffset;
+                memcpy(destPixelPointer, sourcePixelPointer, bytesPerPixel);
+            }
+        }
+    }
+    else
+    {
+        size_t rowPitch = result.GetImages()[0].rowPitch;
+        for (size_t swizzleIndex = 0; swizzleIndex < (width * height); swizzleIndex++)
+        {
+            size_t swizzleOffset = swizzleIndex * bytesPerPixel;
 
-            const uint8_t* sourcePixelPointer = sptr + sourceOffset;
-            uint8_t* destPixelPointer = dptr + destOffset;
+            uint32_t destX = extract_bits(swizzleIndex, xBytesMask);
+            uint32_t destY = extract_bits(swizzleIndex, yBytesMask);
+            size_t rowMajorOffset = destY * rowPitch + destX * bytesPerPixel;
+
+            const uint8_t* sourcePixelPointer = sptr + swizzleOffset;
+            uint8_t* destPixelPointer = dptr + rowMajorOffset;
             memcpy(destPixelPointer, sourcePixelPointer, bytesPerPixel);
         }
     }
@@ -124,20 +155,37 @@ HRESULT DirectX::StandardSwizzle(const Image* srcImages, size_t nimages, const T
         uint32_t xBytesMask = 0b1010101010101010;
         uint32_t yBytesMask = 0b0101010101010101;
 
-        for (size_t y = 0; y <height; y++)
+        if (toSwizzle)
         {
-            for (size_t x = 0; x < width; x++)
+            size_t rowPitch = srcImages[imageIndex].rowPitch;
+            for (size_t y = 0; y < height; y++)
             {
-                uint32_t swizzleIndex = deposit_bits(x, xBytesMask) + deposit_bits(y, yBytesMask);
-                size_t swizzleOffset = swizzleIndex * bytesPerPixel;
+                for (size_t x = 0; x < width; x++)
+                {
+                    uint32_t swizzleIndex = deposit_bits(x, xBytesMask) + deposit_bits(y, yBytesMask);
+                    size_t swizzleOffset = swizzleIndex * bytesPerPixel;
 
-                size_t rowMajorOffset = y * srcImages[0].rowPitch + x * bytesPerPixel;
+                    size_t rowMajorOffset = y * rowPitch + x * bytesPerPixel;
 
-                size_t sourceOffset = toSwizzle ? rowMajorOffset : swizzleOffset;
-                size_t destOffset = toSwizzle ? swizzleOffset : rowMajorOffset;
+                    const uint8_t* sourcePixelPointer = sptr + rowMajorOffset;
+                    uint8_t* destPixelPointer = dptr + swizzleOffset;
+                    memcpy(destPixelPointer, sourcePixelPointer, bytesPerPixel);
+                }
+            }
+        }
+        else
+        {
+            size_t rowPitch = result.GetImages()[imageIndex].rowPitch;
+            for (size_t swizzleIndex = 0; swizzleIndex < (width * height); swizzleIndex++)
+            {
+                size_t swizzleOffset = swizzleIndex * bytesPerPixel;
 
-                const uint8_t* sourcePixelPointer = sptr + sourceOffset;
-                uint8_t* destPixelPointer = dptr + destOffset;
+                uint32_t destX = extract_bits(swizzleIndex, xBytesMask);
+                uint32_t destY = extract_bits(swizzleIndex, yBytesMask);
+                size_t rowMajorOffset = destY * rowPitch + destX * bytesPerPixel;
+
+                const uint8_t* sourcePixelPointer = sptr + swizzleOffset;
+                uint8_t* destPixelPointer = dptr + rowMajorOffset;
                 memcpy(destPixelPointer, sourcePixelPointer, bytesPerPixel);
             }
         }
@@ -171,34 +219,63 @@ HRESULT DirectX::StandardSwizzle3D(const Image* srcImages, size_t depth, const T
     uint32_t yBytesMask = 0b0100100100100100;
     uint32_t zBytesMask = 0b0010010010010010;
 
-    for (size_t z = 0; z < depth; z++)
+    if (toSwizzle)
     {
-        for (size_t y = 0; y < height; y++)
+        const Image* destImages = result.GetImages();
+        for (size_t z = 0; z < depth; z++)
         {
-            for (size_t x = 0; x < width; x++)
+            size_t rowPitch = srcImages[z].rowPitch;
+            const uint8_t* sptr = srcImages[z].pixels;
+            if (!sptr)
+                return E_POINTER;
+            for (size_t y = 0; y < height; y++)
             {
-                uint32_t swizzle3Dindex = deposit_bits(x, xBytesMask) + deposit_bits(y, yBytesMask) + deposit_bits(z, zBytesMask);
-                uint32_t swizzle2Dindex = swizzle3Dindex % (metadata.width * metadata.height);
-                uint32_t swizzleSlice   = swizzle3Dindex / (metadata.width * metadata.height);
-                size_t swizzleOffset = swizzle2Dindex * bytesPerPixel;
-
-                size_t rowMajorOffset = y * srcImages[0].rowPitch + x * bytesPerPixel;
+                for (size_t x = 0; x < width; x++)
+                {
+                    uint32_t swizzle3Dindex = deposit_bits(x, xBytesMask) + deposit_bits(y, yBytesMask) + deposit_bits(z, zBytesMask);
+                    uint32_t swizzle2Dindex = swizzle3Dindex % (metadata.width * metadata.height);
+                    uint32_t swizzleSlice   = swizzle3Dindex / (metadata.width * metadata.height);
+                    size_t swizzleOffset = swizzle2Dindex * bytesPerPixel;
+
+                    size_t rowMajorOffset = y * rowPitch + x * bytesPerPixel;
+
+                    uint8_t* dptr = destImages[swizzleSlice].pixels;
+                    if (!dptr)
+                        return E_POINTER;
+
+                    const uint8_t* sourcePixelPointer = sptr + rowMajorOffset;
+                    uint8_t* destPixelPointer = dptr + swizzleOffset;
+                    memcpy(destPixelPointer, sourcePixelPointer, bytesPerPixel);
+                }
+            }
+        }
+    }
+    else
+    {
+        const Image* destImages = result.GetImages();
+        for (size_t z = 0; z < depth; z++)
+        {
+            const uint8_t* sptr = srcImages[z].pixels;
+            if (!sptr)
+                return E_POINTER;
 
-                size_t sourceOffset = toSwizzle ? rowMajorOffset : swizzleOffset;
-                uint32_t sourceSlice = toSwizzle ? z : swizzleSlice;
+            for (size_t swizzleIndex = 0; swizzleIndex < (width * height); swizzleIndex++)
+            {
+                size_t swizzleOffset = swizzleIndex * bytesPerPixel;
+                const uint8_t* sourcePixelPointer = sptr + swizzleOffset;
 
-                size_t destOffset = toSwizzle ? swizzleOffset : rowMajorOffset;
-                uint32_t destSlice = toSwizzle ? swizzleSlice : z;
+                size_t index3D = z * width * height + swizzleIndex;
+                uint32_t destX = extract_bits(index3D, xBytesMask);
+                uint32_t destY = extract_bits(index3D, yBytesMask);
+                uint32_t destZ = extract_bits(index3D, zBytesMask);
+                size_t rowPitch = destImages[z].rowPitch;
+                size_t rowMajorOffset = destY * rowPitch + destX * bytesPerPixel;
 
-                const uint8_t* sptr = srcImages[sourceSlice].pixels;
-                if (!sptr)
-                    return E_POINTER;
-                uint8_t* dptr = result.GetImages()[destSlice].pixels;
+                uint8_t* dptr = destImages[destZ].pixels;
                 if (!dptr)
                     return E_POINTER;
+                uint8_t* destPixelPointer = dptr + rowMajorOffset;
 
-                const uint8_t* sourcePixelPointer = sptr + sourceOffset;
-                uint8_t* destPixelPointer = dptr + destOffset;
                 memcpy(destPixelPointer, sourcePixelPointer, bytesPerPixel);
             }
         }