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Diffstat (limited to 'examples/quickcl/histogram/histogram.cl')
-rw-r--r-- | examples/quickcl/histogram/histogram.cl | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/examples/quickcl/histogram/histogram.cl b/examples/quickcl/histogram/histogram.cl new file mode 100644 index 0000000..de97c2d --- /dev/null +++ b/examples/quickcl/histogram/histogram.cl @@ -0,0 +1,57 @@ +// Based on https://code.google.com/p/opencl-book-samples/source/browse/trunk/src/Chapter_14/histogram + +#pragma OPENCL EXTENSION cl_khr_local_int32_base_atomics : enable + +constant sampler_t sampler = CLK_NORMALIZED_COORDS_FALSE | CLK_ADDRESS_CLAMP_TO_EDGE | CLK_FILTER_NEAREST; + +kernel void histogram(image2d_t img, int num_pixels_per_workitem, global uint *buf) +{ + int local_size = get_local_size(0) * get_local_size(1); + int item_offset = get_local_id(0) + get_local_id(1) * get_local_size(0); + local uint tmp[256]; + + int i = 0, j = 256; + do { + if (item_offset < j) + tmp[item_offset + i] = 0; + j -= local_size; + i += local_size; + } while (j > 0); + + barrier(CLK_LOCAL_MEM_FENCE); + + int x, image_width = get_image_width(img), image_height = get_image_height(img); + for (i = 0, x = get_global_id(0); i < num_pixels_per_workitem; ++i, x += get_global_size(0)) { + if (x < image_width && get_global_id(1) < image_height) { + float4 clr = read_imagef(img, sampler, (int2)(x, get_global_id(1))); + if (clr.w > 0.99f) { + float v = (clr.x + clr.y + clr.z) / 3.0f; + atom_inc(&tmp[convert_ushort_sat(min(v, 1.0f) * 255.0f)]); + } + } + } + + barrier(CLK_LOCAL_MEM_FENCE); + + int group_offset = (get_group_id(0) + get_group_id(1) * get_num_groups(0)) * 256; + i = 0; + j = 256; + do { + if (item_offset < j) + buf[group_offset + item_offset + i] = tmp[item_offset + i]; + j -= local_size; + i += local_size; + } while (j > 0); +} + +kernel void sum_histogram(global uint *buf, int num_groups, global uint *result) +{ + int idx = get_global_id(0) + get_group_id(0); + uint v = 0; + int group_offset = 0, n = num_groups; + while (--n >= 0) { + v += buf[group_offset + idx]; + group_offset += 256; + } + result[idx] = v; +} |