clfft 0.3.3

Bindings for clFFT, a FFT library for OpenCL.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

/* ************************************************************************
 * Copyright 2013 Advanced Micro Devices, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ************************************************************************/

#include <stdio.h>
#include <stdlib.h>

/* No need to explicitely include the OpenCL headers */
#include <clFFT.h>

int main( void )
{
    cl_int err;
    cl_platform_id platform = 0;
    cl_device_id device = 0;
    cl_context_properties props[3] = { CL_CONTEXT_PLATFORM, 0, 0 };
    cl_context ctx = 0;
    cl_command_queue queue = 0;
    cl_mem bufX;
    float *X;
    cl_event event = NULL;
    int ret = 0;
    size_t N = 16;
    char platform_name[128];
    char device_name[128];

    /* FFT library realted declarations */
    clfftPlanHandle planHandle;
    clfftDim dim = CLFFT_1D;
    size_t clLengths[1] = {N};

    /* Setup OpenCL environment. */
    err = clGetPlatformIDs( 1, &platform, NULL );

    size_t ret_param_size = 0;
    err = clGetPlatformInfo(platform, CL_PLATFORM_NAME,
            sizeof(platform_name), platform_name,
            &ret_param_size);
    printf("Platform found: %s\n", platform_name);

    err = clGetDeviceIDs( platform, CL_DEVICE_TYPE_DEFAULT, 1, &device, NULL );

    err = clGetDeviceInfo(device, CL_DEVICE_NAME,
            sizeof(device_name), device_name,
            &ret_param_size);
    printf("Device found on the above platform: %s\n", device_name);

    props[1] = (cl_context_properties)platform;
    ctx = clCreateContext( props, 1, &device, NULL, NULL, &err );
    queue = clCreateCommandQueue( ctx, device, 0, &err );

    /* Setup clFFT. */
    clfftSetupData fftSetup;
    err = clfftInitSetupData(&fftSetup);
    err = clfftSetup(&fftSetup);

    /* Allocate host & initialize data. */
    /* Only allocation shown for simplicity. */
    X = (float *)malloc(N * 2 * sizeof(*X));

    /* print input array */
    printf("\nPerforming fft on an one dimensional array of size N = %lu\n", (unsigned long)N);
    int print_iter = 0;
    while(print_iter<N) {
        float x = (float)print_iter;
        float y = (float)print_iter*3;
        X[2*print_iter  ] = x;
        X[2*print_iter+1] = y;
        printf("(%f, %f) ", x, y);
        print_iter++;
    }
    printf("\n\nfft result: \n");

    /* Prepare OpenCL memory objects and place data inside them. */
    bufX = clCreateBuffer( ctx, CL_MEM_READ_WRITE, N * 2 * sizeof(*X), NULL, &err );

    err = clEnqueueWriteBuffer( queue, bufX, CL_TRUE, 0,
            N * 2 * sizeof( *X ), X, 0, NULL, NULL );

    /* Create a default plan for a complex FFT. */
    err = clfftCreateDefaultPlan(&planHandle, ctx, dim, clLengths);

    /* Set plan parameters. */
    err = clfftSetPlanPrecision(planHandle, CLFFT_SINGLE);
    err = clfftSetLayout(planHandle, CLFFT_COMPLEX_INTERLEAVED, CLFFT_COMPLEX_INTERLEAVED);
    err = clfftSetResultLocation(planHandle, CLFFT_INPLACE);

    /* Bake the plan. */
    err = clfftBakePlan(planHandle, 1, &queue, NULL, NULL);

    /* Execute the plan. */
    err = clfftEnqueueTransform(planHandle, CLFFT_FORWARD, 1, &queue, 0, NULL, NULL, &bufX, NULL, NULL);

    /* Wait for calculations to be finished. */
    err = clFinish(queue);

    /* Fetch results of calculations. */
    err = clEnqueueReadBuffer( queue, bufX, CL_TRUE, 0, N * 2 * sizeof( *X ), X, 0, NULL, NULL );

    /* print output array */
    print_iter = 0;
    while(print_iter<N) {
        printf("(%f, %f) ", X[2*print_iter], X[2*print_iter+1]);
        print_iter++;
    }
    printf("\n");

    /* Release OpenCL memory objects. */
    clReleaseMemObject( bufX );

    free(X);

    /* Release the plan. */
    err = clfftDestroyPlan( &planHandle );

    /* Release clFFT library. */
    clfftTeardown( );

    /* Release OpenCL working objects. */
    clReleaseCommandQueue( queue );
    clReleaseContext( ctx );

    return ret;
}