From 381fa26aac478dcb1da4ea53b8f6de4bb9531be9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Max=20L=C3=BCbke?= <mluebke@uni-potsdam.de>
Date: Mon, 2 Oct 2023 12:58:45 +0200
Subject: [PATCH] add hashfunction for checksum calculation

---
 CMakeLists.txt |  5 +++++
 matrix.hpp     | 11 ++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4a68522..9610a75 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,8 +1,13 @@
 cmake_minimum_required(VERSION 3.25)
 
+set(CMAKE_CXX_STANDARD 17)
+
 project(sycl_example)
 
 find_package(AdaptiveCpp REQUIRED)
 
+find_library(LIB_XXHASH xxhash)
+
 add_executable(sycl_comp sycl_comp.cpp)
 add_sycl_to_target(TARGET sycl_comp)
+target_link_libraries(sycl_comp PRIVATE ${LIB_XXHASH})
diff --git a/matrix.hpp b/matrix.hpp
index 3887d4b..d0d321a 100644
--- a/matrix.hpp
+++ b/matrix.hpp
@@ -7,6 +7,8 @@
 #include <numeric>
 #include <vector>
 
+#include <xxhash.h>
+
 template <class T> struct Matrix {
   std::uint32_t rows;
   std::uint32_t cols;
@@ -40,6 +42,10 @@ template <class T> struct Matrix {
     return data[row_i * cols + col_j];
   }
 
+  const T &operator()(std::uint32_t row_i, std::uint32_t col_j) const {
+    return data[row_i * cols + col_j];
+  }
+
   Matrix<T> &operator=(const Matrix<T> &mat) {
     this->rows = mat.rows;
     this->cols = mat.cols;
@@ -58,7 +64,10 @@ template <class T> struct Matrix {
     return transposed;
   }
 
-  T sum() const { return std::accumulate(data.begin(), data.end(), 0); }
+  XXH32_hash_t chksum() const {
+    constexpr XXH32_hash_t HASH_SEED = 42;
+    return XXH32(this->data.data(), data.size(), HASH_SEED);
+  }
 };
 
 template <class T> std::ostream &operator<<(std::ostream &os, Matrix<T> &mat) {