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/** @file   reduce_sum.cu
 *  @author Thomas Müller, NVIDIA
 *  @brief  Wrapper around thrust's sum reduction to provide warning-free compilation.
 */

#include <tiny-cuda-nn/reduce_sum.h>

namespace tcnn {

__global__ void block_reduce1(
	const uint32_t n_elements,
	float* __restrict__ inout
) {
	const uint32_t i = threadIdx.x + blockIdx.x * blockDim.x;

	extern __shared__ float sdata[];
	sdata[threadIdx.x] = i < n_elements ? inout[i] : 0;

	__syncthreads();

	for (unsigned int s = blockDim.x / 2; s > 32; s >>= 1) {
		if (threadIdx.x < s) {
			sdata[threadIdx.x] += sdata[threadIdx.x + s];
		}

		__syncthreads();
	}

	if (threadIdx.x < 32) {
		float val = sdata[threadIdx.x];
		val = warp_reduce(val);

		if (threadIdx.x == 0) {
			inout[blockIdx.x] = val;
		}
	}
}

uint32_t reduce_sum_workspace_size(uint32_t n_elements) {
	return n_blocks_linear(n_elements);
}

}