src/cuda/hough_circles.cu

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#if !defined CUDA_DISABLER

#include "opencv2/core/cuda/common.hpp"
#include "opencv2/core/cuda/emulation.hpp"
#include "opencv2/core/cuda/dynamic_smem.hpp"

#include "opencv2/opencv_modules.hpp"

#ifdef HAVE_OPENCV_CUDAFILTERS

namespace cv { namespace cuda { namespace device
{
    namespace hough_circles
    {
        __device__ int g_counter;

        ////////////////////////////////////////////////////////////////////////
        // circlesAccumCenters

        __global__ void circlesAccumCenters(const unsigned int* list, const int count, const PtrStepi dx, const PtrStepi dy,
                                            PtrStepi accum, const int width, const int height, const int minRadius, const int maxRadius, const float idp)
        {
            const int SHIFT = 10;
            const int ONE = 1 << SHIFT;

            const int tid = blockIdx.x * blockDim.x + threadIdx.x;

            if (tid >= count)
                return;

            const unsigned int val = list[tid];

            const int x = (val & 0xFFFF);
            const int y = (val >> 16) & 0xFFFF;

            const int vx = dx(y, x);
            const int vy = dy(y, x);

            if (vx == 0 && vy == 0)
                return;

            const float mag = ::sqrtf(vx * vx + vy * vy);

            const int x0 = __float2int_rn((x * idp) * ONE);
            const int y0 = __float2int_rn((y * idp) * ONE);

            int sx = __float2int_rn((vx * idp) * ONE / mag);
            int sy = __float2int_rn((vy * idp) * ONE / mag);

            // Step from minRadius to maxRadius in both directions of the gradient
            for (int k1 = 0; k1 < 2; ++k1)
            {
                int x1 = x0 + minRadius * sx;
                int y1 = y0 + minRadius * sy;

                for (int r = minRadius; r <= maxRadius; x1 += sx, y1 += sy, ++r)
                {
                    const int x2 = x1 >> SHIFT;
                    const int y2 = y1 >> SHIFT;

                    if (x2 < 0 || x2 >= width || y2 < 0 || y2 >= height)
                        break;

                    ::atomicAdd(accum.ptr(y2 + 1) + x2 + 1, 1);
                }

                sx = -sx;
                sy = -sy;
            }
        }

        void circlesAccumCenters_gpu(const unsigned int* list, int count, PtrStepi dx, PtrStepi dy, PtrStepSzi accum, int minRadius, int maxRadius, float idp)
        {
            const dim3 block(256);
            const dim3 grid(divUp(count, block.x));

            cudaSafeCall( cudaFuncSetCacheConfig(circlesAccumCenters, cudaFuncCachePreferL1) );

            circlesAccumCenters<<<grid, block>>>(list, count, dx, dy, accum, accum.cols - 2, accum.rows - 2, minRadius, maxRadius, idp);
            cudaSafeCall( cudaGetLastError() );

            cudaSafeCall( cudaDeviceSynchronize() );
        }

        ////////////////////////////////////////////////////////////////////////
        // buildCentersList

        __global__ void buildCentersList(const PtrStepSzi accum, unsigned int* centers, const int threshold)
        {
            const int x = blockIdx.x * blockDim.x + threadIdx.x;
            const int y = blockIdx.y * blockDim.y + threadIdx.y;

            if (x < accum.cols - 2 && y < accum.rows - 2)
            {
                const int top = accum(y, x + 1);

                const int left = accum(y + 1, x);
                const int cur = accum(y + 1, x + 1);
                const int right = accum(y + 1, x + 2);

                const int bottom = accum(y + 2, x + 1);

                if (cur > threshold && cur > top && cur >= bottom && cur >  left && cur >= right)
                {
                    const unsigned int val = (y << 16) | x;
                    const int idx = ::atomicAdd(&g_counter, 1);
                    centers[idx] = val;
                }
            }
        }

        int buildCentersList_gpu(PtrStepSzi accum, unsigned int* centers, int threshold)
        {
            void* counterPtr;
            cudaSafeCall( cudaGetSymbolAddress(&counterPtr, g_counter) );

            cudaSafeCall( cudaMemset(counterPtr, 0, sizeof(int)) );

            const dim3 block(32, 8);
            const dim3 grid(divUp(accum.cols - 2, block.x), divUp(accum.rows - 2, block.y));

            cudaSafeCall( cudaFuncSetCacheConfig(buildCentersList, cudaFuncCachePreferL1) );

            buildCentersList<<<grid, block>>>(accum, centers, threshold);
            cudaSafeCall( cudaGetLastError() );

            cudaSafeCall( cudaDeviceSynchronize() );

            int totalCount;
            cudaSafeCall( cudaMemcpy(&totalCount, counterPtr, sizeof(int), cudaMemcpyDeviceToHost) );

            return totalCount;
        }

        ////////////////////////////////////////////////////////////////////////
        // circlesAccumRadius

        __global__ void circlesAccumRadius(const unsigned int* centers, const unsigned int* list, const int count,
                                           float3* circles, const int maxCircles, const float dp,
                                           const int minRadius, const int maxRadius, const int histSize, const int threshold)
        {
            int* smem = DynamicSharedMem<int>();

            for (int i = threadIdx.x; i < histSize + 2; i += blockDim.x)
                smem[i] = 0;
            __syncthreads();

            unsigned int val = centers[blockIdx.x];

            float cx = (val & 0xFFFF);
            float cy = (val >> 16) & 0xFFFF;

            cx = (cx + 0.5f) * dp;
            cy = (cy + 0.5f) * dp;

            for (int i = threadIdx.x; i < count; i += blockDim.x)
            {
                val = list[i];

                const int x = (val & 0xFFFF);
                const int y = (val >> 16) & 0xFFFF;

                const float rad = ::sqrtf((cx - x) * (cx - x) + (cy - y) * (cy - y));
                if (rad >= minRadius && rad <= maxRadius)
                {
                    const int r = __float2int_rn(rad - minRadius);

                    Emulation::smem::atomicAdd(&smem[r + 1], 1);
                }
            }

            __syncthreads();

            for (int i = threadIdx.x; i < histSize; i += blockDim.x)
            {
                const int curVotes = smem[i + 1];

                if (curVotes >= threshold && curVotes > smem[i] && curVotes >= smem[i + 2])
                {
                    const int ind = ::atomicAdd(&g_counter, 1);
                    if (ind < maxCircles)
                        circles[ind] = make_float3(cx, cy, i + minRadius);
                }
            }
        }

        int circlesAccumRadius_gpu(const unsigned int* centers, int centersCount, const unsigned int* list, int count,
                                   float3* circles, int maxCircles, float dp, int minRadius, int maxRadius, int threshold, bool has20)
        {
            void* counterPtr;
            cudaSafeCall( cudaGetSymbolAddress(&counterPtr, g_counter) );

            cudaSafeCall( cudaMemset(counterPtr, 0, sizeof(int)) );

            const dim3 block(has20 ? 1024 : 512);
            const dim3 grid(centersCount);

            const int histSize = maxRadius - minRadius + 1;
            size_t smemSize = (histSize + 2) * sizeof(int);

            circlesAccumRadius<<<grid, block, smemSize>>>(centers, list, count, circles, maxCircles, dp, minRadius, maxRadius, histSize, threshold);
            cudaSafeCall( cudaGetLastError() );

            cudaSafeCall( cudaDeviceSynchronize() );

            int totalCount;
            cudaSafeCall( cudaMemcpy(&totalCount, counterPtr, sizeof(int), cudaMemcpyDeviceToHost) );

            totalCount = ::min(totalCount, maxCircles);

            return totalCount;
        }
    }
}}}

#endif // HAVE_OPENCV_CUDAFILTERS

#endif /* CUDA_DISABLER */