/opencl/oclfft

//

// File:       fft_internal.h

//

// Version:    <1.0>

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////////////////////////////////////////////////////////////////////////////////////////////////////

#ifndef __CLFFT_INTERNAL_H

#define __CLFFT_INTERNAL_H

#include "clFFT.h"

#include <sstream>

using namespace std;

typedef enum kernel_dir_t

{

	cl_fft_kernel_x,

	cl_fft_kernel_y,

	cl_fft_kernel_z

}cl_fft_kernel_dir;

typedef struct kernel_info_t

{

	cl_kernel kernel;

	char *kernel_name;

	size_t lmem_size;

	size_t num_workgroups;

    size_t num_xforms_per_workgroup;

	size_t num_workitems_per_workgroup;

	cl_fft_kernel_dir dir;

	int in_place_possible;

	kernel_info_t *next;

}cl_fft_kernel_info;

typedef struct 

{

	// context in which fft resources are created and kernels are executed

	cl_context              context;

	// size of signal

	clFFT_Dim3              n;

	// dimension of transform ... must be either 1D, 2D or 3D

	clFFT_Dimension			dim;

	// data format ... must be either interleaved or plannar

	clFFT_DataFormat		format;

	// string containing kernel source. Generated at runtime based on

	// n, dim, format and other parameters

	string                  *kernel_string;

	// CL program containing source and kernel this particular 

	// n, dim, data format

	cl_program				program;

	// linked list of kernels which needs to be executed for this fft

	cl_fft_kernel_info		*kernel_info;

	// number of kernels

	int                     num_kernels;

	// twist kernel for virtualizing fft of very large sizes that do not

	// fit in GPU global memory

	cl_kernel				twist_kernel;

	// flag indicating if temporary intermediate buffer is needed or not.

	// this depends on fft kernels being executed and if transform is 

	// in-place or out-of-place. e.g. Local memory fft (say 1D 1024 ... 

	// one that does not require global transpose do not need temporary buffer)

	// 2D 1024x1024 out-of-place fft however do require intermediate buffer.

	// If temp buffer is needed, its allocation is lazy i.e. its not allocated

	// until its needed

	cl_int                  temp_buffer_needed;

	// Batch size is runtime parameter and size of temporary buffer (if needed)

	// depends on batch size. Allocation of temporary buffer is lazy i.e. its

	// only created when needed. Once its created at first call of clFFT_Executexxx

	// it is not allocated next time if next time clFFT_Executexxx is called with 

	// batch size different than the first call. last_batch_size caches the last

	// batch size with which this plan is used so that we dont keep allocating/deallocating

	// temp buffer if same batch size is used again and again.

	size_t                  last_batch_size;

	// temporary buffer for interleaved plan

	cl_mem   				tempmemobj;

	// temporary buffer for planner plan. Only one of tempmemobj or 

	// (tempmemobj_real, tempmemobj_imag) pair is valid (allocated) depending 

	// data format of plan (plannar or interleaved)

	cl_mem                  tempmemobj_real, tempmemobj_imag;

	// Maximum size of signal for which local memory transposed based

	// fft is sufficient i.e. no global mem transpose (communication)

	// is needed

	size_t					max_localmem_fft_size;

	// Maximum work items per work group allowed. This, along with max_radix below controls 

	// maximum local memory being used by fft kernels of this plan. Set to 256 by default

	size_t                  max_work_item_per_workgroup;

	// Maximum base radix for local memory fft ... this controls the maximum register 

	// space used by work items. Currently defaults to 16

	size_t                  max_radix;

	// Device depended parameter that tells how many work-items need to be read consecutive

	// values to make sure global memory access by work-items of a work-group result in 

	// coalesced memory access to utilize full bandwidth e.g. on NVidia tesla, this is 16

	size_t                  min_mem_coalesce_width;

	// Number of local memory banks. This is used to geneate kernel with local memory 

	// transposes with appropriate padding to avoid bank conflicts to local memory

	// e.g. on NVidia it is 16.

	size_t                  num_local_mem_banks;

}cl_fft_plan;

void FFT1D(cl_fft_plan *plan, cl_fft_kernel_dir dir);

#endif