From 12e2cc9502bc51bb01ed3fdd2f39ce1533c8236e Mon Sep 17 00:00:00 2001
From: Rostislav Vasilikhin <savuor@gmail.com>
Date: Sat, 27 Apr 2024 13:38:44 +0200
Subject: [PATCH] Merge pull request #25491 from savuor:rv/hal_norm_hamming

HAL for Hamming norm added #25491

fixes #25474

### 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
- [x] There is a reference to the original bug report and related work
- [x] 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 | 30 ++++++++++++++++++++++++++++
 modules/core/src/norm.cpp            |  6 ++++++
 2 files changed, 36 insertions(+)

diff --git a/modules/core/src/hal_replacement.hpp b/modules/core/src/hal_replacement.hpp
index 046b0678a4..15149453c7 100644
--- a/modules/core/src/hal_replacement.hpp
+++ b/modules/core/src/hal_replacement.hpp
@@ -214,6 +214,36 @@ inline int hal_ni_not8u(const uchar *src_data, size_t src_step, uchar *dst_data,
 #define cv_hal_not8u hal_ni_not8u
 //! @endcond
 
+/**
+Hamming norm of a vector
+@param a pointer to vector data
+@param n length of a vector
+@param cellSize how many bits of the vector will be added and treated as a single bit, can be 1 (standard Hamming distance), 2 or 4
+@param result pointer to result output
+*/
+//! @addtogroup core_hal_interface_hamming Hamming distance
+//! @{
+inline int hal_ni_normHamming8u(const uchar* a, int n, int cellSize, int* result) { return CV_HAL_ERROR_NOT_IMPLEMENTED; }
+//! @}
+
+/**
+Hamming distance between two vectors
+@param a pointer to first vector data
+@param b pointer to second vector data
+@param n length of vectors
+@param cellSize how many bits of the vectors will be added and treated as a single bit, can be 1 (standard Hamming distance), 2 or 4
+@param result pointer to result output
+*/
+//! @addtogroup core_hal_interface_hamming Hamming distance
+//! @{
+inline int hal_ni_normHammingDiff8u(const uchar* a, const uchar* b, int n, int cellSize, int* result) { return CV_HAL_ERROR_NOT_IMPLEMENTED; }
+//! @}
+
+//! @cond IGNORED
+#define cv_hal_normHamming8u hal_ni_normHamming8u
+#define cv_hal_normHammingDiff8u hal_ni_normHammingDiff8u
+//! @endcond
+
 /**
 Compare: _dst[i] = src1[i] op src2[i]_
 @param src1_data first source image data
diff --git a/modules/core/src/norm.cpp b/modules/core/src/norm.cpp
index 49d781fcb0..f2f84c35b8 100644
--- a/modules/core/src/norm.cpp
+++ b/modules/core/src/norm.cpp
@@ -52,6 +52,9 @@ static const uchar popCountTable4[] =
 
 int normHamming(const uchar* a, int n, int cellSize)
 {
+    int output;
+    CALL_HAL_RET(normHamming8u, cv_hal_normHamming8u, output, a, n, cellSize);
+
     if( cellSize == 1 )
         return normHamming(a, n);
     const uchar* tab = 0;
@@ -98,6 +101,9 @@ int normHamming(const uchar* a, int n, int cellSize)
 
 int normHamming(const uchar* a, const uchar* b, int n, int cellSize)
 {
+    int output;
+    CALL_HAL_RET(normHammingDiff8u, cv_hal_normHammingDiff8u, output, a, b, n, cellSize);
+
     if( cellSize == 1 )
         return normHamming(a, b, n);
     const uchar* tab = 0;