📷 A modern, cross-platform, 2D Graphics library for .NET
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using System;
using System.Buffers;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
// ReSharper disable InconsistentNaming
namespace ImageSharp.Formats
{
/// <summary>
/// DCT code Ported from https://github.com/norishigefukushima/dct_simd
/// </summary>
internal partial struct Block8x8F
{
public Vector4 V0L;
public Vector4 V0R;
public Vector4 V1L;
public Vector4 V1R;
public Vector4 V2L;
public Vector4 V2R;
public Vector4 V3L;
public Vector4 V3R;
public Vector4 V4L;
public Vector4 V4R;
public Vector4 V5L;
public Vector4 V5R;
public Vector4 V6L;
public Vector4 V6R;
public Vector4 V7L;
public Vector4 V7R;
public const int VectorCount = 16;
public const int ScalarCount = VectorCount*4;
private static readonly ArrayPool<float> ScalarArrayPool = ArrayPool<float>.Create(ScalarCount, 50);
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public unsafe void LoadFrom(MutableSpan<float> source)
{
fixed (Vector4* ptr = &V0L)
{
Marshal.Copy(source.Data, source.Offset, (IntPtr) ptr, ScalarCount);
//float* fp = (float*)ptr;
//for (int i = 0; i < ScalarCount; i++)
//{
// fp[i] = source[i];
//}
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public unsafe void CopyTo(MutableSpan<float> dest)
{
fixed (Vector4* ptr = &V0L)
{
Marshal.Copy((IntPtr) ptr, dest.Data, dest.Offset, ScalarCount);
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public unsafe void CopyTo(float[] dest)
{
fixed (Vector4* ptr = &V0L)
{
Marshal.Copy((IntPtr) ptr, dest, 0, ScalarCount);
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static unsafe void LoadFrom(Block8x8F* blockPtr, MutableSpan<float> source)
{
Marshal.Copy(source.Data, source.Offset, (IntPtr) blockPtr, ScalarCount);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static unsafe void CopyTo(Block8x8F* blockPtr, MutableSpan<float> dest)
{
Marshal.Copy((IntPtr) blockPtr, dest.Data, dest.Offset, ScalarCount);
}
internal unsafe void LoadFrom(MutableSpan<int> source)
{
fixed (Vector4* ptr = &V0L)
{
float* fp = (float*) ptr;
for (int i = 0; i < ScalarCount; i++)
{
fp[i] = source[i];
}
}
}
internal unsafe void CopyTo(MutableSpan<int> dest)
{
fixed (Vector4* ptr = &V0L)
{
float* fp = (float*) ptr;
for (int i = 0; i < ScalarCount; i++)
{
dest[i] = (int) fp[i];
}
}
}
public unsafe void TransposeInplace()
{
fixed (Vector4* ptr = &V0L)
{
float* data = (float*) ptr;
for (int i = 1; i < 8; i++)
{
int i8 = i*8;
for (int j = 0; j < i; j++)
{
float tmp = data[i8 + j];
data[i8 + j] = data[j*8 + i];
data[j*8 + i] = tmp;
}
}
}
}
/// <summary>
/// Reference implementation we can benchmark against
/// </summary>
internal unsafe void TransposeInto_PinningImpl(ref Block8x8F destination)
{
fixed (Vector4* sPtr = &V0L)
{
float* src = (float*) sPtr;
fixed (Vector4* dPtr = &destination.V0L)
{
float* dest = (float*) dPtr;
for (int i = 0; i < 8; i++)
{
int i8 = i*8;
for (int j = 0; j < 8; j++)
{
dest[j*8 + i] = src[i8 + j];
}
}
}
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static unsafe void TransposeInto(Block8x8F* sourcePtr, Block8x8F* destPtr)
{
float* src = (float*) sourcePtr;
float* dest = (float*) destPtr;
for (int i = 0; i < 8; i++)
{
int i8 = i*8;
for (int j = 0; j < 8; j++)
{
dest[j*8 + i] = src[i8 + j];
}
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void MultiplyAllInplace(Vector4 s)
{
V0L *= s;
V0R *= s;
V1L *= s;
V1R *= s;
V2L *= s;
V2R *= s;
V3L *= s;
V3R *= s;
V4L *= s;
V4R *= s;
V5L *= s;
V5R *= s;
V6L *= s;
V6R *= s;
V7L *= s;
V7R *= s;
}
// ReSharper disable once InconsistentNaming
public void IDCTInto(ref Block8x8F dest, ref Block8x8F temp)
{
TransposeInto(ref temp);
temp.iDCT2D8x4_LeftPart(ref dest);
temp.iDCT2D8x4_RightPart(ref dest);
dest.TransposeInto(ref temp);
temp.iDCT2D8x4_LeftPart(ref dest);
temp.iDCT2D8x4_RightPart(ref dest);
dest.MultiplyAllInplace(_0_125);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void IDCTInplace()
{
Block8x8F result = new Block8x8F();
Block8x8F temp = new Block8x8F();
IDCTInto(ref result, ref temp);
this = result;
}
private static readonly Vector4 _1_175876 = new Vector4(1.175876f);
private static readonly Vector4 _1_961571 = new Vector4(-1.961571f);
private static readonly Vector4 _0_390181 = new Vector4(-0.390181f);
private static readonly Vector4 _0_899976 = new Vector4(-0.899976f);
private static readonly Vector4 _2_562915 = new Vector4(-2.562915f);
private static readonly Vector4 _0_298631 = new Vector4(0.298631f);
private static readonly Vector4 _2_053120 = new Vector4(2.053120f);
private static readonly Vector4 _3_072711 = new Vector4(3.072711f);
private static readonly Vector4 _1_501321 = new Vector4(1.501321f);
private static readonly Vector4 _0_541196 = new Vector4(0.541196f);
private static readonly Vector4 _1_847759 = new Vector4(-1.847759f);
private static readonly Vector4 _0_765367 = new Vector4(0.765367f);
private static readonly Vector4 _0_125 = new Vector4(0.1250f);
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal void iDCT2D8x4_LeftPart(ref Block8x8F d)
{
/*
float a0,a1,a2,a3,b0,b1,b2,b3; float z0,z1,z2,z3,z4; float r[8]; int i;
for(i = 0;i < 8;i++){ r[i] = (float)(cos((double)i / 16.0 * M_PI) * M_SQRT2); }
*/
/*
0: 1.414214
1: 1.387040
2: 1.306563
3:
4: 1.000000
5: 0.785695
6:
7: 0.275899
*/
Vector4 my1 = V1L;
Vector4 my7 = V7L;
Vector4 mz0 = my1 + my7;
Vector4 my3 = V3L;
Vector4 mz2 = my3 + my7;
Vector4 my5 = V5L;
Vector4 mz1 = my3 + my5;
Vector4 mz3 = my1 + my5;
Vector4 mz4 = ((mz0 + mz1)*_1_175876);
//z0 = y[1] + y[7]; z1 = y[3] + y[5]; z2 = y[3] + y[7]; z3 = y[1] + y[5];
//z4 = (z0 + z1) * r[3];
mz2 = mz2*_1_961571 + mz4;
mz3 = mz3*_0_390181 + mz4;
mz0 = mz0*_0_899976;
mz1 = mz1*_2_562915;
/*
-0.899976
-2.562915
-1.961571
-0.390181
z0 = z0 * (-r[3] + r[7]);
z1 = z1 * (-r[3] - r[1]);
z2 = z2 * (-r[3] - r[5]) + z4;
z3 = z3 * (-r[3] + r[5]) + z4;*/
Vector4 mb3 = my7*_0_298631 + mz0 + mz2;
Vector4 mb2 = my5*_2_053120 + mz1 + mz3;
Vector4 mb1 = my3*_3_072711 + mz1 + mz2;
Vector4 mb0 = my1*_1_501321 + mz0 + mz3;
/*
0.298631
2.053120
3.072711
1.501321
b3 = y[7] * (-r[1] + r[3] + r[5] - r[7]) + z0 + z2;
b2 = y[5] * ( r[1] + r[3] - r[5] + r[7]) + z1 + z3;
b1 = y[3] * ( r[1] + r[3] + r[5] - r[7]) + z1 + z2;
b0 = y[1] * ( r[1] + r[3] - r[5] - r[7]) + z0 + z3;
*/
Vector4 my2 = V2L;
Vector4 my6 = V6L;
mz4 = (my2 + my6)*_0_541196;
Vector4 my0 = V0L;
Vector4 my4 = V4L;
mz0 = my0 + my4;
mz1 = my0 - my4;
mz2 = mz4 + my6*_1_847759;
mz3 = mz4 + my2*_0_765367;
my0 = mz0 + mz3;
my3 = mz0 - mz3;
my1 = mz1 + mz2;
my2 = mz1 - mz2;
/*
1.847759
0.765367
z4 = (y[2] + y[6]) * r[6];
z0 = y[0] + y[4]; z1 = y[0] - y[4];
z2 = z4 - y[6] * (r[2] + r[6]);
z3 = z4 + y[2] * (r[2] - r[6]);
a0 = z0 + z3; a3 = z0 - z3;
a1 = z1 + z2; a2 = z1 - z2;
*/
d.V0L = my0 + mb0;
d.V7L = my0 - mb0;
d.V1L = my1 + mb1;
d.V6L = my1 - mb1;
d.V2L = my2 + mb2;
d.V5L = my2 - mb2;
d.V3L = my3 + mb3;
d.V4L = my3 - mb3;
/*
x[0] = a0 + b0; x[7] = a0 - b0;
x[1] = a1 + b1; x[6] = a1 - b1;
x[2] = a2 + b2; x[5] = a2 - b2;
x[3] = a3 + b3; x[4] = a3 - b3;
for(i = 0;i < 8;i++){ x[i] *= 0.353554f; }
*/
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal void iDCT2D8x4_RightPart(ref Block8x8F d)
{
/*
float a0,a1,a2,a3,b0,b1,b2,b3; float z0,z1,z2,z3,z4; float r[8]; int i;
for(i = 0;i < 8;i++){ r[i] = (float)(cos((double)i / 16.0 * M_PI) * M_SQRT2); }
*/
/*
0: 1.414214
1: 1.387040
2: 1.306563
3:
4: 1.000000
5: 0.785695
6:
7: 0.275899
*/
Vector4 my1 = V1R;
Vector4 my7 = V7R;
Vector4 mz0 = my1 + my7;
Vector4 my3 = V3R;
Vector4 mz2 = my3 + my7;
Vector4 my5 = V5R;
Vector4 mz1 = my3 + my5;
Vector4 mz3 = my1 + my5;
Vector4 mz4 = ((mz0 + mz1)*_1_175876);
//z0 = y[1] + y[7]; z1 = y[3] + y[5]; z2 = y[3] + y[7]; z3 = y[1] + y[5];
//z4 = (z0 + z1) * r[3];
mz2 = mz2*_1_961571 + mz4;
mz3 = mz3*_0_390181 + mz4;
mz0 = mz0*_0_899976;
mz1 = mz1*_2_562915;
/*
-0.899976
-2.562915
-1.961571
-0.390181
z0 = z0 * (-r[3] + r[7]);
z1 = z1 * (-r[3] - r[1]);
z2 = z2 * (-r[3] - r[5]) + z4;
z3 = z3 * (-r[3] + r[5]) + z4;*/
Vector4 mb3 = my7*_0_298631 + mz0 + mz2;
Vector4 mb2 = my5*_2_053120 + mz1 + mz3;
Vector4 mb1 = my3*_3_072711 + mz1 + mz2;
Vector4 mb0 = my1*_1_501321 + mz0 + mz3;
/*
0.298631
2.053120
3.072711
1.501321
b3 = y[7] * (-r[1] + r[3] + r[5] - r[7]) + z0 + z2;
b2 = y[5] * ( r[1] + r[3] - r[5] + r[7]) + z1 + z3;
b1 = y[3] * ( r[1] + r[3] + r[5] - r[7]) + z1 + z2;
b0 = y[1] * ( r[1] + r[3] - r[5] - r[7]) + z0 + z3;
*/
Vector4 my2 = V2R;
Vector4 my6 = V6R;
mz4 = (my2 + my6)*_0_541196;
Vector4 my0 = V0R;
Vector4 my4 = V4R;
mz0 = my0 + my4;
mz1 = my0 - my4;
mz2 = mz4 + my6*_1_847759;
mz3 = mz4 + my2*_0_765367;
my0 = mz0 + mz3;
my3 = mz0 - mz3;
my1 = mz1 + mz2;
my2 = mz1 - mz2;
/*
1.847759
0.765367
z4 = (y[2] + y[6]) * r[6];
z0 = y[0] + y[4]; z1 = y[0] - y[4];
z2 = z4 - y[6] * (r[2] + r[6]);
z3 = z4 + y[2] * (r[2] - r[6]);
a0 = z0 + z3; a3 = z0 - z3;
a1 = z1 + z2; a2 = z1 - z2;
*/
d.V0R = my0 + mb0;
d.V7R = my0 - mb0;
d.V1R = my1 + mb1;
d.V6R = my1 - mb1;
d.V2R = my2 + mb2;
d.V5R = my2 - mb2;
d.V3R = my3 + mb3;
d.V4R = my3 - mb3;
/*
x[0] = a0 + b0; x[7] = a0 - b0;
x[1] = a1 + b1; x[6] = a1 - b1;
x[2] = a2 + b2; x[5] = a2 - b2;
x[3] = a3 + b3; x[4] = a3 - b3;
for(i = 0;i < 8;i++){ x[i] *= 0.353554f; }
*/
}
internal static void SuchIDCT(ref Block block)
{
Block8x8F source = new Block8x8F();
source.LoadFrom(block.Data);
Block8x8F dest = new Block8x8F();
Block8x8F temp = new Block8x8F();
source.IDCTInto(ref dest, ref temp);
dest.CopyTo(block.Data);
}
internal static void SuchIDCT(ref BlockF block)
{
Block8x8F source = new Block8x8F();
source.LoadFrom(block.Data);
Block8x8F dest = new Block8x8F();
Block8x8F temp = new Block8x8F();
source.IDCTInto(ref dest, ref temp);
dest.CopyTo(block.Data);
}
public unsafe float this[int idx]
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
get
{
fixed (Block8x8F* p = &this)
{
float* fp = (float*) p;
return fp[idx];
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
set
{
fixed (Block8x8F* p = &this)
{
float* fp = (float*) p;
fp[idx] = value;
}
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static unsafe void UnZig(Block8x8F* block, Block8x8F* qt, int* unzigPtr)
{
float* b = (float*) block;
float* qtp = (float*) qt;
for (int zig = 0; zig < BlockF.BlockSize; zig++)
{
float* unzigPos = b + unzigPtr[zig];
float val = *unzigPos;
val *= qtp[zig];
*unzigPos = val;
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static unsafe float GetScalarAt(Block8x8F* blockPtr, int idx)
{
float* fp = (float*) blockPtr;
return fp[idx];
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static unsafe void SetScalarAt(Block8x8F* blockPtr, int idx, float value)
{
float* fp = (float*) blockPtr;
fp[idx] = value;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal void Clear()
{
this = new Block8x8F(); // LOL C# Plz!
}
internal void LoadFrom(ref BlockF legacyBlock)
{
LoadFrom(legacyBlock.Data);
}
internal void CopyTo(ref BlockF legacyBlock)
{
CopyTo(legacyBlock.Data);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static byte ToColorByte(float c)
{
if (c < -128)
{
return 0;
}
else if (c > 127)
{
return 255;
}
else
{
c += 128;
return (byte) c;
}
}
internal unsafe void CopyColorsTo(MutableSpan<byte> buffer, int stride)
{
fixed (Block8x8F* p = &this)
{
float* b = (float*) p;
for (int y = 0; y < 8; y++)
{
int y8 = y*8;
int yStride = y*stride;
for (int x = 0; x < 8; x++)
{
float c = b[y8 + x];
if (c < -128)
{
c = 0;
}
else if (c > 127)
{
c = 255;
}
else
{
c += 128;
}
buffer[yStride + x] = (byte) c;
}
}
}
}
private static readonly Vector4 CMin4 = new Vector4(-128f);
private static readonly Vector4 CMax4 = new Vector4(127f);
private static readonly Vector4 COff4 = new Vector4(128f);
/// <summary>
/// Level shift by +128, clip to [0, 255], and write to buffer.
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal unsafe void CopyColorsTo(
MutableSpan<byte> buffer,
int stride,
Block8x8F* temp)
{
ColorifyInto(ref *temp);
float* src = (float*) temp;
for (int i = 0; i < 8; i++)
{
buffer[0] = (byte) src[0];
buffer[1] = (byte) src[1];
buffer[2] = (byte) src[2];
buffer[3] = (byte) src[3];
buffer[4] = (byte) src[4];
buffer[5] = (byte) src[5];
buffer[6] = (byte) src[6];
buffer[7] = (byte) src[7];
buffer.AddOffset(stride);
src += 8;
}
}
}
}