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Zhang JinhanandSHS
39fbe07189
Add an RVV HAL implementation for CV_32F to CV_16S conversion.
The RISC-V convertScale HAL already handles several source/destination
depth combinations, but CV_32F to CV_16S currently returns
CV_HAL_ERROR_NOT_IMPLEMENTED and falls back to the generic core path.
Implement the missing conversion using native RVV intrinsics. The
identity-scale case skips the multiply-add, while scaled conversions
apply alpha and beta before narrowing to signed 16-bit output.
The implementation is VLEN-agnostic and uses vsetvl for tail handling.
Functional test:
```text
./build-rvv/bin/opencv_test_core \
--gtest_filter='*ConvertScale*'
```
Performance was measured with opencv_perf_core on SpacemiT K3
(RVV 1.0, VLEN=256), comparing against an unmodified 5.x baseline.
CV_32F -> CV_16S median time:
```text
1920x1080 C1, alpha=1:
26.16 ms -> 1.46 ms (17.92x)
1920x1080 C1, alpha=1/255:
24.10 ms -> 1.45 ms (16.62x)
1920x1080 C4, alpha=1:
103.76 ms -> 6.06 ms (17.12x)
1920x1080 C4, alpha=1/255:
96.03 ms -> 5.68 ms (16.91x)
```
All four corresponding opencv_perf_core cases pass.
Co-authored-by: Yang Wang [yangwang@iscas.ac.cn](mailto:yangwang@iscas.ac.cn)
Co-authored-by: Yuansheng [yuansheng@iscas.ac.cn](mailto:yuansheng@iscas.ac.cn)