From 44c814e3340151b36343e218ceead1790661b8b5 Mon Sep 17 00:00:00 2001
From: Rostislav Vasilikhin <savuor@gmail.com>
Date: Tue, 23 Jul 2024 07:06:15 +0200
Subject: [PATCH] Merge pull request #25936 from savuor:rv/hal_dot

HAL for dot product added #25936

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake
---
 modules/core/src/hal_replacement.hpp | 21 +++++++++++++++++++++
 modules/core/src/matmul.dispatch.cpp | 11 ++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/modules/core/src/hal_replacement.hpp b/modules/core/src/hal_replacement.hpp
index f78608dbad..67f3ac7141 100644
--- a/modules/core/src/hal_replacement.hpp
+++ b/modules/core/src/hal_replacement.hpp
@@ -899,6 +899,27 @@ inline int hal_ni_meanStdDev(const uchar* src_data, size_t src_step, int width,
 #define cv_hal_meanStdDev hal_ni_meanStdDev
 //! @endcond
 
+/**
+ * @brief calculates dot product of two vectors (represented as 2d images)
+ *
+ * @param a_data Pointer to 1st 2nd image data
+ * @param a_step Stride of 1st 2nd image
+ * @param b_data Pointer to 1st 2nd image data
+ * @param b_step Stride of 1st 2nd image
+ * @param width Width of both images
+ * @param height Height of both images
+ * @param type Data type of both images, for example CV_8U or CV_32F
+ * @param dot_val Pointer to resulting dot product value
+ * @return int
+ */
+inline int hal_ni_dotProduct(const uchar* a_data, size_t a_step, const uchar* b_data, size_t b_step, int width, int height,
+                             int type, double *dot_val)
+{ return CV_HAL_ERROR_NOT_IMPLEMENTED; }
+
+//! @cond IGNORED
+#define cv_hal_dotProduct hal_ni_dotProduct
+//! @endcond
+
 /**
    @brief hal_flip
    @param src_type source and destination image type
diff --git a/modules/core/src/matmul.dispatch.cpp b/modules/core/src/matmul.dispatch.cpp
index 81953265d7..35b7ad54c4 100644
--- a/modules/core/src/matmul.dispatch.cpp
+++ b/modules/core/src/matmul.dispatch.cpp
@@ -995,9 +995,18 @@ double Mat::dot(InputArray _mat) const
     CV_INSTRUMENT_REGION();
 
     Mat mat = _mat.getMat();
+    CV_Assert_N( mat.type() == type(), mat.size == size);
+
     int cn = channels();
+    if (this->dims <= 2)
+    {
+        double product = 0;
+        CALL_HAL_RET(dotProduct, cv_hal_dotProduct, product, this->data, this->step, mat.data, mat.step,
+                     this->cols * cn, this->rows, this->depth());
+    }
+
     DotProdFunc func = getDotProdFunc(depth());
-    CV_Assert_N( mat.type() == type(), mat.size == size, func != 0 );
+    CV_Assert(func != 0 );
 
     if( isContinuous() && mat.isContinuous() )
     {