1 files changed, 48 insertions, 0 deletions
diff --git a/nerv/lib/matrix/generic/cukernel.cu b/nerv/lib/matrix/generic/cukernel.cu
index 8fbe05d..51e3b6a 100644
--- a/nerv/lib/matrix/generic/cukernel.cu
+++ b/nerv/lib/matrix/generic/cukernel.cu
@@ -383,6 +383,20 @@ __global__ void cudak_(copy_rows_by_colidx)(const MATRIX_ELEM *a, MATRIX_ELEM *b
     b[j + i * stride] = a[j + k * stride];
 }
 
+__global__ void cudak_(prefixsum_row_reduce)(const MATRIX_ELEM *a, MATRIX_ELEM *b,
+                        int nrow, int ncol, int stride_a, int stride_b, int offset) {
+    int j = blockIdx.x * blockDim.x + threadIdx.x;
+    int i = blockIdx.y * blockDim.y + threadIdx.y;
+    long idx_a, idx_b;
+    if (i >= nrow || j >= ncol) return;
+    idx_b = j + i * stride_b;
+    idx_a = j + i * stride_a;
+    //b[idx] = 1.0 / (1.0 + exp(-a[idx]));
+    if (j >= offset) 
+        b[idx_b] = a[idx_a] + a[idx_a - offset];
+    else
+        b[idx_b] = a[idx_a];
+}
 
 extern "C" {
 #include "../cukernel.h"
@@ -745,6 +759,40 @@ extern "C" {
         cudaStreamSynchronize(0);
     }
 
+    void cudak_(cuda_prefixsum_row)(const Matrix *a, Matrix *b) {
+        dim3 threadsPerBlock(CUDA_THREADS_N, CUDA_THREADS_N);
+        dim3 numBlocks(CEIL_DIV(b->ncol, threadsPerBlock.x),
+                CEIL_DIV(b->nrow, threadsPerBlock.y));
+        
+        MATRIX_ELEM *tmp[2];
+        size_t tmp_stride[2];
+        cudaMallocPitch(tmp, tmp_stride + 0, a->ncol * sizeof(MATRIX_ELEM), a->nrow);
+        cudaMallocPitch(tmp + 1, tmp_stride + 1, a->ncol * sizeof(MATRIX_ELEM), a->nrow);
+        
+        int offset = 1;
+        cudak_(prefixsum_row_reduce)<<<numBlocks, threadsPerBlock>>> \
+            (MATRIX_ELEM_PTR(a), tmp[0], b->nrow, b->ncol,
+            a->stride / sizeof(MATRIX_ELEM), tmp_stride[0] / sizeof(MATRIX_ELEM), offset);
+        int pin = 0, pout = 1;
+
+        for (offset = 2;offset <= a->ncol / 2;offset *= 2) {
+            cudak_(prefixsum_row_reduce)<<<numBlocks, threadsPerBlock>>> \
+                (tmp[pin], tmp[pout], b->nrow, b->ncol,
+                tmp_stride[pin] / sizeof(MATRIX_ELEM), tmp_stride[pout] / sizeof(MATRIX_ELEM), offset);
+            pin = 1 - pin; 
+            pout = 1 - pout;
+        }
+
+        cudak_(prefixsum_row_reduce)<<<numBlocks, threadsPerBlock>>> \
+            (tmp[pin], MATRIX_ELEM_PTR(b), b->nrow, b->ncol,
+            tmp_stride[pin] / sizeof(MATRIX_ELEM), b->stride / sizeof(MATRIX_ELEM), offset);
+        
+        cudaFree(tmp[0]);
+        cudaFree(tmp[1]);
+        
+        cudaStreamSynchronize(0);
+    }
+
     void cudak_(cuda_decompress)(const Matrix *a, Matrix *b) {
         dim3 threadsPerBlock(1, CUDA_THREADS_NN);
         dim3 numBlocks(1, CEIL_DIV(a->nrow, threadsPerBlock.y));