Segmented Scan - Nvidia

Intra-block Scan using Intra-warp Scan
__device__ int block_scan(int* p) {
int prefix = scan_warp(p);
__syncthreads();
if (lane == warpSize - 1) p[warp] = prefix + x;
__syncthreads();
if (warp == 0) p[i] = scan_warp(p);
__syncthreads();
return prefix + p[warp];
}