Merge pull request #26789 from amane-ame:minmax_hal_rvv

Add RISC-V HAL implementation for minMaxIdx #26789

On the RISC-V platform, `minMaxIdx` cannot benefit from Universal Intrinsics because the UI-optimized `minMaxIdx` only supports `CV_SIMD128` (and does not accept `CV_SIMD_SCALABLE` for RVV).

https://github.com/opencv/opencv/blob/1d701d1690b8cc9aa6b86744bffd5d9841ac6fd3/modules/core/src/minmax.cpp#L209-L214

This patch implements `minMaxIdx` function in RVV_HAL using native intrinsic, optimizing the performance for all data types with one channel.

Tested on MUSE-PI for both gcc 14.2 and clang 20.0.

```
$ opencv_test_core --gtest_filter="*MinMaxLoc*"
$ opencv_perf_core --gtest_filter="*minMaxLoc*"
```
<img width="1122" alt="Untitled" src="https://github.com/user-attachments/assets/6a246852-87af-42c5-a50b-c349c2765f3f" />

### 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
- [ ] 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.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/core/src/hal_replacement.hpp

@@ -911,8 +911,26 @@ inline int hal_ni_gemm64fc(const double* src1, size_t src1_step, const double* s
 inline int hal_ni_minMaxIdx(const uchar* src_data, size_t src_step, int width, int height, int depth, double* minVal, double* maxVal,
                             int* minIdx, int* maxIdx, uchar* mask) { return CV_HAL_ERROR_NOT_IMPLEMENTED; }
 
+/**
+   @brief Finds the global minimum and maximum in an array.
+   @param src_data Source image
+   @param src_step Source image
+   @param width Source image dimensions
+   @param height Source image dimensions
+   @param depth Depth of source image
+   @param minVal Pointer to the returned global minimum and maximum in an array.
+   @param maxVal Pointer to the returned global minimum and maximum in an array.
+   @param minIdx Pointer to the returned minimum and maximum location.
+   @param maxIdx Pointer to the returned minimum and maximum location.
+   @param mask Specified array region.
+   @param mask_step Mask array step.
+*/
+inline int hal_ni_minMaxIdxMaskStep(const uchar* src_data, size_t src_step, int width, int height, int depth, double* minVal, double* maxVal,
+                                    int* minIdx, int* maxIdx, uchar* mask, size_t mask_step) { return CV_HAL_ERROR_NOT_IMPLEMENTED; }
+
 //! @cond IGNORED
 #define cv_hal_minMaxIdx hal_ni_minMaxIdx
+#define cv_hal_minMaxIdxMaskStep hal_ni_minMaxIdxMaskStep
 //! @endcond
 
 /**

modules/core/src/minmax.cpp

@@ -1514,10 +1514,19 @@ void cv::minMaxIdx(InputArray _src, double* minVal,
 
     if (src.dims <= 2)
     {
-        CALL_HAL(minMaxIdx, cv_hal_minMaxIdx, src.data, src.step, src.cols*cn, src.rows,
-                 src.depth(), minVal, maxVal, minIdx, maxIdx, mask.data);
+        if ((size_t)src.step == (size_t)mask.step)
+        {
+            CALL_HAL(minMaxIdx, cv_hal_minMaxIdx, src.data, src.step, src.cols*cn, src.rows,
+                     src.depth(), minVal, maxVal, minIdx, maxIdx, mask.data);
+        }
+        else
+        {
+            CALL_HAL(minMaxIdxMaskStep, cv_hal_minMaxIdxMaskStep, src.data, src.step, src.cols*cn, src.rows,
+                     src.depth(), minVal, maxVal, minIdx, maxIdx, mask.data, mask.step);
+        }
+
     }
-    else if (src.isContinuous())
+    else if (src.isContinuous() && mask.isContinuous())
     {
         int res = cv_hal_minMaxIdx(src.data, 0, (int)src.total()*cn, 1, src.depth(),
                                    minVal, maxVal, minIdx, maxIdx, mask.data);