From a5b30247499ba7ef048f51cd0ecf78c35b5eea0a Mon Sep 17 00:00:00 2001
From: Bernhard Manfred Gruber <bernhardmgruber@gmail.com>
Date: Wed, 10 Jan 2024 16:43:14 +0100
Subject: [PATCH] Use std::span for n-body

---
 examples/nbody/CMakeLists.txt |  2 +-
 examples/nbody/nbody.cpp      | 11 ++++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/examples/nbody/CMakeLists.txt b/examples/nbody/CMakeLists.txt
index 89d261bd89..f1a2a0a467 100644
--- a/examples/nbody/CMakeLists.txt
+++ b/examples/nbody/CMakeLists.txt
@@ -16,7 +16,7 @@ if (NOT TARGET llama::llama)
 endif()
 
 add_executable(${PROJECT_NAME} nbody.cpp ../common/Stopwatch.hpp)
-target_compile_features(${PROJECT_NAME} PRIVATE cxx_std_17)
+target_compile_features(${PROJECT_NAME} PRIVATE cxx_std_20)
 target_link_libraries(${PROJECT_NAME} PRIVATE llama::llama fmt::fmt)
 if (LLAMA_NBODY_OPENMP)
 	target_link_libraries(${PROJECT_NAME} PRIVATE OpenMP::OpenMP_CXX)
diff --git a/examples/nbody/nbody.cpp b/examples/nbody/nbody.cpp
index 9f09632496..2e7ed2a75b 100644
--- a/examples/nbody/nbody.cpp
+++ b/examples/nbody/nbody.cpp
@@ -11,6 +11,7 @@
 #include <iostream>
 #include <llama/llama.hpp>
 #include <random>
+#include <span>
 #include <thread>
 #include <utility>
 #include <vector>
@@ -482,7 +483,7 @@ namespace manualAoS
                 update(particles.data());
                 statsUpdate(watch.printAndReset("update", '\t'));
             }
-            move(particles.data());
+            manualAoS::move(particles.data());
             statsMove(watch.printAndReset("move"));
         }
         plotFile << std::quoted(title) << "\t" << statsUpdate.mean() << "\t" << statsUpdate.sem() << '\t'
@@ -1339,7 +1340,7 @@ namespace manualAoSSIMD
     }
 
     template<typename Simd>
-    void update(Particle* particles)
+    void update(std::span<Particle> particles)
     {
         PARALLEL_FOR
         for(std::ptrdiff_t i = 0; i < problemSize; i += Simd::size)
@@ -1370,7 +1371,7 @@ namespace manualAoSSIMD
     }
 
     template<typename Simd>
-    void move(Particle* particles)
+    void move(std::span<Particle> particles)
     {
         PARALLEL_FOR
         for(std::ptrdiff_t i = 0; i < problemSize; i += Simd::size)
@@ -1412,10 +1413,10 @@ namespace manualAoSSIMD
         {
             if constexpr(runUpdate)
             {
-                update<Simd>(particles.data());
+                update<Simd>(particles);
                 statsUpdate(watch.printAndReset("update", '\t'));
             }
-            move<Simd>(particles.data());
+            manualAoSSIMD::move<Simd>(particles);
             statsMove(watch.printAndReset("move"));
         }
         plotFile << std::quoted(title) << "\t" << statsUpdate.mean() << "\t" << statsUpdate.sem() << '\t'