Merge branch 'master' into bp/webpalpha

Author: brianpopow

src/ImageSharp/Formats/Jpeg/Components/Block8x8F.cs

@@ -280,7 +280,7 @@ public void AddInPlace(float value)
         }
 
         /// <summary>
-        /// Quantize input block, apply zig-zag ordering and store result as 16bit integers.
+        /// Quantize input block, transpose, apply zig-zag ordering and store as <see cref="Block8x8"/>.
         /// </summary>
         /// <param name="block">Source block.</param>
         /// <param name="dest">Destination block.</param>
@@ -291,19 +291,19 @@ public static void Quantize(ref Block8x8F block, ref Block8x8 dest, ref Block8x8
             if (Avx2.IsSupported)
             {
                 MultiplyIntoInt16_Avx2(ref block, ref qt, ref dest);
-                ZigZag.ApplyZigZagOrderingAvx2(ref dest);
+                ZigZag.ApplyTransposingZigZagOrderingAvx2(ref dest);
             }
             else if (Ssse3.IsSupported)
             {
                 MultiplyIntoInt16_Sse2(ref block, ref qt, ref dest);
-                ZigZag.ApplyZigZagOrderingSsse3(ref dest);
+                ZigZag.ApplyTransposingZigZagOrderingSsse3(ref dest);
             }
             else
 #endif
             {
                 for (int i = 0; i < Size; i++)
                 {
-                    int idx = ZigZag.ZigZagOrder[i];
+                    int idx = ZigZag.TransposingOrder[i];
                     float quantizedVal = block[idx] * qt[idx];
                     quantizedVal += quantizedVal < 0 ? -0.5f : 0.5f;
                     dest[i] = (short)quantizedVal;

src/ImageSharp/Formats/Jpeg/Components/FastFloatingPointDCT.Intrinsic.cs

@@ -29,11 +29,10 @@ private static void FDCT8x8_Avx(ref Block8x8F block)
         {
             DebugGuard.IsTrue(Avx.IsSupported, "Avx support is required to execute this operation.");
 
-            // First pass - process rows
-            block.TransposeInplace();
+            // First pass - process columns
             FDCT8x8_1D_Avx(ref block);
 
-            // Second pass - process columns
+            // Second pass - process rows
             block.TransposeInplace();
             FDCT8x8_1D_Avx(ref block);
 

src/ImageSharp/Formats/Jpeg/Components/FastFloatingPointDCT.cs

@@ -92,6 +92,11 @@ public static void AdjustToFDCT(ref Block8x8F quantTable)
                 tableRef = 0.125f / (tableRef * Unsafe.Add(ref multipliersRef, i));
                 tableRef = ref Unsafe.Add(ref tableRef, 1);
             }
+
+            // Spectral macroblocks are not transposed before quantization
+            // Transpose is done after quantization at zig-zag stage
+            // so we must transpose quantization table
+            quantTable.TransposeInplace();
         }
 
         /// <summary>
@@ -133,14 +138,9 @@ public static void TransformFDCT(ref Block8x8F block)
             }
             else
 #endif
-            if (Vector.IsHardwareAccelerated)
             {
                 FDCT_Vector4(ref block);
             }
-            else
-            {
-                FDCT_Scalar(ref block);
-            }
         }
 
         /// <summary>
@@ -217,136 +217,17 @@ static void IDCT8x4_Vector4(ref Vector4 vecRef)
             }
         }
 
-        /// <summary>
-        /// Apply 2D floating point FDCT inplace using scalar operations.
-        /// </summary>
-        /// <remarks>
-        /// Ported from libjpeg-turbo https://github.com/libjpeg-turbo/libjpeg-turbo/blob/main/jfdctflt.c.
-        /// </remarks>
-        /// <param name="block">Input block.</param>
-        private static void FDCT_Scalar(ref Block8x8F block)
-        {
-            const int dctSize = 8;
-
-            float tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
-            float tmp10, tmp11, tmp12, tmp13;
-            float z1, z2, z3, z4, z5, z11, z13;
-
-            // First pass - process rows
-            ref float blockRef = ref Unsafe.As<Block8x8F, float>(ref block);
-            for (int ctr = 7; ctr >= 0; ctr--)
-            {
-                tmp0 = Unsafe.Add(ref blockRef, 0) + Unsafe.Add(ref blockRef, 7);
-                tmp7 = Unsafe.Add(ref blockRef, 0) - Unsafe.Add(ref blockRef, 7);
-                tmp1 = Unsafe.Add(ref blockRef, 1) + Unsafe.Add(ref blockRef, 6);
-                tmp6 = Unsafe.Add(ref blockRef, 1) - Unsafe.Add(ref blockRef, 6);
-                tmp2 = Unsafe.Add(ref blockRef, 2) + Unsafe.Add(ref blockRef, 5);
-                tmp5 = Unsafe.Add(ref blockRef, 2) - Unsafe.Add(ref blockRef, 5);
-                tmp3 = Unsafe.Add(ref blockRef, 3) + Unsafe.Add(ref blockRef, 4);
-                tmp4 = Unsafe.Add(ref blockRef, 3) - Unsafe.Add(ref blockRef, 4);
-
-                // Even part
-                tmp10 = tmp0 + tmp3;
-                tmp13 = tmp0 - tmp3;
-                tmp11 = tmp1 + tmp2;
-                tmp12 = tmp1 - tmp2;
-
-                Unsafe.Add(ref blockRef, 0) = tmp10 + tmp11;
-                Unsafe.Add(ref blockRef, 4) = tmp10 - tmp11;
-
-                z1 = (tmp12 + tmp13) * 0.707106781f;
-                Unsafe.Add(ref blockRef, 2) = tmp13 + z1;
-                Unsafe.Add(ref blockRef, 6) = tmp13 - z1;
-
-                // Odd part
-                tmp10 = tmp4 + tmp5;
-                tmp11 = tmp5 + tmp6;
-                tmp12 = tmp6 + tmp7;
-
-                z5 = (tmp10 - tmp12) * 0.382683433f;
-                z2 = (0.541196100f * tmp10) + z5;
-                z4 = (1.306562965f * tmp12) + z5;
-                z3 = tmp11 * 0.707106781f;
-
-                z11 = tmp7 + z3;
-                z13 = tmp7 - z3;
-
-                Unsafe.Add(ref blockRef, 5) = z13 + z2;
-                Unsafe.Add(ref blockRef, 3) = z13 - z2;
-                Unsafe.Add(ref blockRef, 1) = z11 + z4;
-                Unsafe.Add(ref blockRef, 7) = z11 - z4;
-
-                blockRef = ref Unsafe.Add(ref blockRef, dctSize);
-            }
-
-            // Second pass - process columns
-            blockRef = ref Unsafe.As<Block8x8F, float>(ref block);
-            for (int ctr = 7; ctr >= 0; ctr--)
-            {
-                tmp0 = Unsafe.Add(ref blockRef, dctSize * 0) + Unsafe.Add(ref blockRef, dctSize * 7);
-                tmp7 = Unsafe.Add(ref blockRef, dctSize * 0) - Unsafe.Add(ref blockRef, dctSize * 7);
-                tmp1 = Unsafe.Add(ref blockRef, dctSize * 1) + Unsafe.Add(ref blockRef, dctSize * 6);
-                tmp6 = Unsafe.Add(ref blockRef, dctSize * 1) - Unsafe.Add(ref blockRef, dctSize * 6);
-                tmp2 = Unsafe.Add(ref blockRef, dctSize * 2) + Unsafe.Add(ref blockRef, dctSize * 5);
-                tmp5 = Unsafe.Add(ref blockRef, dctSize * 2) - Unsafe.Add(ref blockRef, dctSize * 5);
-                tmp3 = Unsafe.Add(ref blockRef, dctSize * 3) + Unsafe.Add(ref blockRef, dctSize * 4);
-                tmp4 = Unsafe.Add(ref blockRef, dctSize * 3) - Unsafe.Add(ref blockRef, dctSize * 4);
-
-                // Even part
-                tmp10 = tmp0 + tmp3;
-                tmp13 = tmp0 - tmp3;
-                tmp11 = tmp1 + tmp2;
-                tmp12 = tmp1 - tmp2;
-
-                Unsafe.Add(ref blockRef, dctSize * 0) = tmp10 + tmp11;
-                Unsafe.Add(ref blockRef, dctSize * 4) = tmp10 - tmp11;
-
-                z1 = (tmp12 + tmp13) * 0.707106781f;
-                Unsafe.Add(ref blockRef, dctSize * 2) = tmp13 + z1;
-                Unsafe.Add(ref blockRef, dctSize * 6) = tmp13 - z1;
-
-                // Odd part
-                tmp10 = tmp4 + tmp5;
-                tmp11 = tmp5 + tmp6;
-                tmp12 = tmp6 + tmp7;
-
-                z5 = (tmp10 - tmp12) * 0.382683433f;
-                z2 = (0.541196100f * tmp10) + z5;
-                z4 = (1.306562965f * tmp12) + z5;
-                z3 = tmp11 * 0.707106781f;
-
-                z11 = tmp7 + z3;
-                z13 = tmp7 - z3;
-
-                Unsafe.Add(ref blockRef, dctSize * 5) = z13 + z2;
-                Unsafe.Add(ref blockRef, dctSize * 3) = z13 - z2;
-                Unsafe.Add(ref blockRef, dctSize * 1) = z11 + z4;
-                Unsafe.Add(ref blockRef, dctSize * 7) = z11 - z4;
-
-                blockRef = ref Unsafe.Add(ref blockRef, 1);
-            }
-        }
-
         /// <summary>
         /// Apply floating point FDCT inplace using <see cref="Vector4"/> API.
         /// </summary>
-        /// <remarks>
-        /// This implementation must be called only if hardware supports 4
-        /// floating point numbers vector. Otherwise explicit scalar
-        /// implementation <see cref="FDCT_Scalar"/> is faster
-        /// because it does not rely on block transposition.
-        /// </remarks>
         /// <param name="block">Input block.</param>
         public static void FDCT_Vector4(ref Block8x8F block)
         {
-            DebugGuard.IsTrue(Vector.IsHardwareAccelerated, "Scalar implementation should be called for non-accelerated hardware.");
-
-            // First pass - process rows
-            block.TransposeInplace();
+            // First pass - process columns
             FDCT8x4_Vector4(ref block.V0L);
             FDCT8x4_Vector4(ref block.V0R);
 
-            // Second pass - process columns
+            // Second pass - process rows
             block.TransposeInplace();
             FDCT8x4_Vector4(ref block.V0L);
             FDCT8x4_Vector4(ref block.V0R);