ircd::simd: Add scatter template.

include/ircd/simd/scatter.h

@@ -0,0 +1,60 @@
+// The Construct
+//
+// Copyright (C) The Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2020 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_SIMD_SCATTER_H
+
+namespace ircd::simd
+{
+	template<int scale = 1,
+	         class value,
+	         class index_vector,
+	         class value_vector>
+	void scatter(value *, const index_vector, const u64, const value_vector) noexcept;
+}
+
+/// Scatter values to memory locations from the argument vector.
+///
+/// Each lane in the index vector corresponds to each lane in the operand vector.
+/// Each bit in the mask corresponds to each lane as well.
+///
+template<int scale,
+         class value,
+         class index_vector,
+         class value_vector>
+inline void
+ircd::simd::scatter(value *const __restrict__ base,
+                    const index_vector index,
+                    const u64 mask,
+                    const value_vector val)
+noexcept
+{
+	static_assert
+	(
+		lanes<index_vector>() == lanes<value_vector>()
+	);
+
+	const auto *const in
+	{
+		reinterpret_cast<const lane_type<value_vector> *>(&val)
+	};
+
+	const auto *const idx
+	{
+		reinterpret_cast<const lane_type<index_vector> *>(&index)
+	};
+
+	#if defined(__AVX512F__)
+	#pragma clang loop unroll(disable)
+	#endif
+	for(size_t i(0); i < lanes<index_vector>(); ++i)
+		if(mask & (1UL << i))
+			base[idx[i] * scale] = in[i];
+}

include/ircd/simd/simd.h

@@ -21,6 +21,7 @@
 #include "upper.h"
 #include "mask.h"
 #include "gather.h"
+#include "scatter.h"
 #include "shl.h"
 #include "shr.h"
 #include "rol.h"