From b22b710d2b6efd5453707b023ad512e867b48bf1 Mon Sep 17 00:00:00 2001
From: tpietzsch <tobias.pietzsch@gmail.com>
Date: Sun, 10 Mar 2024 10:55:28 +0100
Subject: [PATCH] AFFINE-BLK, WIP: Add SubArrayCopy prototype

---
 .../java/net/imglib2/blocks/SubArrayCopy.java | 151 ++++++++++++++++++
 1 file changed, 151 insertions(+)
 create mode 100644 src/main/java/net/imglib2/blocks/SubArrayCopy.java

diff --git a/src/main/java/net/imglib2/blocks/SubArrayCopy.java b/src/main/java/net/imglib2/blocks/SubArrayCopy.java
new file mode 100644
index 000000000..69c680799
--- /dev/null
+++ b/src/main/java/net/imglib2/blocks/SubArrayCopy.java
@@ -0,0 +1,151 @@
+package net.imglib2.blocks;
+
+import net.imglib2.type.PrimitiveType;
+import net.imglib2.type.numeric.integer.IntType;
+
+public interface SubArrayCopy
+{
+	// TODO: Can we inline everything and make it work for arbitrary
+	//       dimensionality? (get rid of steps arrays and pass everything as
+	//       arguments to the recursive run() call).
+	static SubArrayCopy create( final int n, final PrimitiveType primitiveType )
+	{
+		return new SubArrayCopyImpl<>( n, MemCopy.forPrimitiveType( primitiveType ) );
+	}
+
+	/**
+	 * @param src
+	 * 		flat src array
+	 * @param o_src
+	 * 		origin in src
+	 * @param size_src
+	 * 		dimensions of src
+	 * @param dst
+	 * 		flat dst array
+	 * @param o_dst
+	 * 		origin in dst
+	 * @param size_dst
+	 * 		dimensions of dst
+	 * @param size
+	 * 		size of the region to copy
+	 */
+	void copy(
+			final Object src, final int[] o_src, final int[] size_src,
+			final Object dst, final int[] o_dst, final int[] size_dst,
+			final int[] size );
+
+	public static void main( String[] args )
+	{
+		int[] data_src = new int[] {
+				11, 12, 13, 14, 15,
+				21, 22, 23, 24, 25,
+				31, 32, 33, 34, 35,
+				41, 42, 43, 44, 45,
+		};
+
+		int[] data_dst = new int[ 10 * 10 ];
+
+		SubArrayCopy c = SubArrayCopy.create( 2, new IntType().getNativeTypeFactory().getPrimitiveType() );
+		c.copy(
+				data_src, new int[] { 1, 2 }, new int[] { 5, 4 },
+				data_dst, new int[] { 3, 7 }, new int[] { 10, 10 },
+				new int[] { 2, 2 } );
+		print( data_dst, 10 );
+	}
+
+	static void print( final int[] data, final int w )
+	{
+		for ( int i = 0; i < data.length; ++i )
+		{
+			System.out.print( data[ i ] );
+			if ( i % w == w - 1 )
+				System.out.println();
+			else
+				System.out.print( ", " );
+		}
+	}
+}
+
+class SubArrayCopyImpl< S, T > implements SubArrayCopy
+{
+	private final int[] steps_src;
+
+	private final int[] steps_dst;
+
+	private final MemCopy< S, T > memCopy;
+
+	private S src;
+
+	private T dst;
+
+	private int[] size;
+
+	SubArrayCopyImpl( final int n, MemCopy< S, T > memCopy )
+	{
+		steps_src = new int[ n ];
+		steps_dst = new int[ n ];
+		this.memCopy = memCopy;
+	}
+
+	/**
+	 * @param src
+	 * 		flat src array
+	 * @param o_src
+	 * 		origin in src
+	 * @param size_src
+	 * 		dimensions of src
+	 * @param dst
+	 * 		flat dst array
+	 * @param o_dst
+	 * 		origin in dst
+	 * @param size_dst
+	 * 		dimensions of dst
+	 * @param size
+	 * 		size of the region to copy
+	 */
+	@Override
+	public void copy(
+			final Object src, final int[] o_src, final int[] size_src,
+			final Object dst, final int[] o_dst, final int[] size_dst,
+			final int[] size )
+	{
+		this.src = ( S ) src;
+		this.dst = ( T ) dst;
+		this.size = size;
+
+		steps_src[ 0 ] = 1;
+		steps_dst[ 0 ] = 1;
+		final int n = steps_src.length;
+		for ( int d = 0; d < n - 1; ++d )
+		{
+			steps_src[ d + 1 ] = steps_src[ d ] * size_src[ d ];
+			steps_dst[ d + 1 ] = steps_dst[ d ] * size_dst[ d ];
+		}
+
+		int origin_offset_src = o_src[ 0 ];
+		int origin_offset_dst = o_dst[ 0 ];
+		for ( int d = 0; d < n - 1; ++d )
+		{
+			origin_offset_src += o_src[ d + 1 ] * steps_src[ d + 1 ];
+			origin_offset_dst += o_dst[ d + 1 ] * steps_dst[ d + 1 ];
+		}
+
+		run( n - 1, origin_offset_src, origin_offset_dst );
+	}
+
+	private void run( final int d, final int offset_src, final int offset_dst )
+	{
+		final int len = size[ d ];
+		if ( d > 0 )
+		{
+			final int stride_src = steps_src[ d ];
+			final int stride_dst = steps_dst[ d ];
+			for ( int i = 0; i < len; ++i )
+				run( d - 1, offset_src + i * stride_src, offset_dst + i * stride_dst );
+		}
+		else
+		{
+			memCopy.copyForward( src, offset_src, dst, offset_dst, len );
+		}
+	}
+}