All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Pages
scan.hpp
Go to the documentation of this file.
#ifndef VIENNACL_LINALG_OPENCL_KERNELS_SCAN_HPP
#define VIENNACL_LINALG_OPENCL_KERNELS_SCAN_HPP
/* =========================================================================
Copyright (c) 2010-2016, Institute for Microelectronics,
Institute for Analysis and Scientific Computing,
TU Wien.
Portions of this software are copyright by UChicago Argonne, LLC.
-----------------
ViennaCL - The Vienna Computing Library
-----------------
Project Head: Karl Rupp rupp@iue.tuwien.ac.at
(A list of authors and contributors can be found in the manual)
License: MIT (X11), see file LICENSE in the base directory
============================================================================= */
#include "viennacl/tools/tools.hpp"
#include "viennacl/ocl/kernel.hpp"
#include "viennacl/ocl/platform.hpp"
#include "viennacl/ocl/utils.hpp"
namespace viennacl
{
namespace linalg
{
namespace opencl
{
namespace kernels
{
template <typename StringType>
void generate_scan_kernel_1(StringType & source, std::string const & numeric_string)
{
source.append("__kernel void scan_1(__global "); source.append(numeric_string); source.append("* X, \n");
source.append(" unsigned int startX, \n");
source.append(" unsigned int incX, \n");
source.append(" unsigned int sizeX, \n");
source.append(" __global "); source.append(numeric_string); source.append("* Y, \n");
source.append(" unsigned int startY, \n");
source.append(" unsigned int incY, \n");
source.append(" unsigned int scan_offset, \n"); // 0 for inclusive scan, 1 for exclusive scan
source.append(" __global "); source.append(numeric_string); source.append("* carries) { \n");
source.append(" __local "); source.append(numeric_string); source.append(" shared_buffer[256]; \n");
source.append(" "); source.append(numeric_string); source.append(" my_value; \n");
source.append(" unsigned int work_per_thread = (sizeX - 1) / get_global_size(0) + 1; \n");
source.append(" unsigned int block_start = work_per_thread * get_local_size(0) * get_group_id(0); \n");
source.append(" unsigned int block_stop = work_per_thread * get_local_size(0) * (get_group_id(0) + 1); \n");
source.append(" unsigned int block_offset = 0; \n");
// run scan on each section:
source.append(" for (unsigned int i = block_start + get_local_id(0); i < block_stop; i += get_local_size(0)) { \n");
// load data
source.append(" my_value = (i < sizeX) ? X[i * incX + startX] : 0; \n");
// inclusive scan in shared buffer:
source.append(" for(unsigned int stride = 1; stride < get_local_size(0); stride *= 2) { \n");
source.append(" barrier(CLK_LOCAL_MEM_FENCE); \n");
source.append(" shared_buffer[get_local_id(0)] = my_value; \n");
source.append(" barrier(CLK_LOCAL_MEM_FENCE); \n");
source.append(" if (get_local_id(0) >= stride) \n");
source.append(" my_value += shared_buffer[get_local_id(0) - stride]; \n");
source.append(" } \n");
source.append(" barrier(CLK_LOCAL_MEM_FENCE); \n");
source.append(" shared_buffer[get_local_id(0)] = my_value; \n");
source.append(" barrier(CLK_LOCAL_MEM_FENCE); \n");
// write to output array:
source.append(" if (scan_offset > 0) \n");
source.append(" my_value = (get_local_id(0) > 0) ? shared_buffer[get_local_id(0) - 1] : 0; \n");
source.append(" if (i < sizeX) \n");
source.append(" Y[i * incY + startY] = block_offset + my_value; \n");
source.append(" block_offset += shared_buffer[get_local_size(0)-1]; \n");
source.append(" } \n");
// write carry:
source.append(" if (get_local_id(0) == 0) carries[get_group_id(0)] = block_offset; \n");
source.append("} \n");
}
template <typename StringType>
void generate_scan_kernel_2(StringType & source, std::string const & numeric_string)
{
source.append("__kernel void scan_2(__global "); source.append(numeric_string); source.append("* carries) { \n");
source.append(" __local "); source.append(numeric_string); source.append(" shared_buffer[256]; \n"); //section size
// load data
source.append(" "); source.append(numeric_string); source.append(" my_carry = carries[get_local_id(0)]; \n");
// scan in shared buffer:
source.append(" for(unsigned int stride = 1; stride < get_local_size(0); stride *= 2) { \n");
source.append(" barrier(CLK_LOCAL_MEM_FENCE); \n");
source.append(" shared_buffer[get_local_id(0)] = my_carry; \n");
source.append(" barrier(CLK_LOCAL_MEM_FENCE); \n");
source.append(" if (get_local_id(0) >= stride) \n");
source.append(" my_carry += shared_buffer[get_local_id(0) - stride]; \n");
source.append(" } \n");
source.append(" barrier(CLK_LOCAL_MEM_FENCE); \n");
source.append(" shared_buffer[get_local_id(0)] = my_carry; \n");
source.append(" barrier(CLK_LOCAL_MEM_FENCE); \n");
// write to output array:
source.append(" carries[get_local_id(0)] = (get_local_id(0) > 0) ? shared_buffer[get_local_id(0) - 1] : 0; \n");
source.append("} \n");
}
template <typename StringType>
void generate_scan_kernel_3(StringType & source, std::string const & numeric_string)
{
source.append("__kernel void scan_3(__global "); source.append(numeric_string); source.append(" * Y, \n");
source.append(" unsigned int startY, \n");
source.append(" unsigned int incY, \n");
source.append(" unsigned int sizeY, \n");
source.append(" __global "); source.append(numeric_string); source.append("* carries) { \n");
source.append(" unsigned int work_per_thread = (sizeY - 1) / get_global_size(0) + 1; \n");
source.append(" unsigned int block_start = work_per_thread * get_local_size(0) * get_group_id(0); \n");
source.append(" unsigned int block_stop = work_per_thread * get_local_size(0) * (get_group_id(0) + 1); \n");
source.append(" __local "); source.append(numeric_string); source.append(" shared_offset; \n");
source.append(" if (get_local_id(0) == 0) shared_offset = carries[get_group_id(0)]; \n");
source.append(" barrier(CLK_LOCAL_MEM_FENCE); \n");
source.append(" for (unsigned int i = block_start + get_local_id(0); i < block_stop; i += get_local_size(0)) \n");
source.append(" if (i < sizeY) \n");
source.append(" Y[i * incY + startY] += shared_offset; \n");
source.append("} \n");
}
// main kernel class
template<typename NumericT>
struct scan
{
static std::string program_name()
{
return viennacl::ocl::type_to_string<NumericT>::apply() + "_scan";
}
static void init(viennacl::ocl::context & ctx)
{
static std::map<cl_context, bool> init_done;
if (!init_done[ctx.handle().get()])
{
viennacl::ocl::DOUBLE_PRECISION_CHECKER<NumericT>::apply(ctx);
std::string numeric_string = viennacl::ocl::type_to_string<NumericT>::apply();
std::string source;
source.reserve(1024);
viennacl::ocl::append_double_precision_pragma<NumericT>(ctx, source);
generate_scan_kernel_1(source, numeric_string);
generate_scan_kernel_2(source, numeric_string);
generate_scan_kernel_3(source, numeric_string);
std::string prog_name = program_name();
#ifdef VIENNACL_BUILD_INFO
std::cout << "Creating program " << prog_name << std::endl;
#endif
ctx.add_program(source, prog_name);
init_done[ctx.handle().get()] = true;
} //if
} //init
};
} // namespace kernels
} // namespace opencl
} // namespace linalg
} // namespace viennacl
#endif
platform.hpp
Implements a OpenCL platform within ViennaCL.
viennacl::linalg::opencl::kernels::generate_scan_kernel_3
void generate_scan_kernel_3(StringType &source, std::string const &numeric_string)
Definition: scan.hpp:124
tools.hpp
Various little tools used here and there in ViennaCL.
viennacl::ocl::context
Manages an OpenCL context and provides the respective convenience functions for creating buffers...
Definition: context.hpp:55
utils.hpp
Provides OpenCL-related utilities.
viennacl::linalg::opencl::kernels::scan::init
static void init(viennacl::ocl::context &ctx)
Definition: scan.hpp:162
viennacl::linalg::opencl::kernels::scan
Main kernel class for generating OpenCL kernels for singular value decomposition of dense matrices...
Definition: scan.hpp:155
viennacl::ocl::context::handle
const viennacl::ocl::handle< cl_context > & handle() const
Returns the context handle.
Definition: context.hpp:611
viennacl::ocl::DOUBLE_PRECISION_CHECKER::apply
static void apply(viennacl::ocl::context const &)
Definition: utils.hpp:40
viennacl::ocl::handle::get
const OCL_TYPE & get() const
Definition: handle.hpp:191
viennacl::linalg::opencl::kernels::scan::program_name
static std::string program_name()
Definition: scan.hpp:157
kernel.hpp
Representation of an OpenCL kernel in ViennaCL.
viennacl::linalg::opencl::kernels::generate_scan_kernel_1
void generate_scan_kernel_1(StringType &source, std::string const &numeric_string)
Definition: scan.hpp:39
viennacl::linalg::opencl::kernels::generate_scan_kernel_2
void generate_scan_kernel_2(StringType &source, std::string const &numeric_string)
Definition: scan.hpp:96
viennacl::ocl::type_to_string
Helper class for converting a type to its string representation.
Definition: utils.hpp:57