1/* Copyright (c) 2013 Julien Pommier ( pommier@modartt.com )
2
3 Based on original fortran 77 code from FFTPACKv4 from NETLIB,
4 authored by Dr Paul Swarztrauber of NCAR, in 1985.
5
6 As confirmed by the NCAR fftpack software curators, the following
7 FFTPACKv5 license applies to FFTPACKv4 sources. My changes are
8 released under the same terms.
9
10 FFTPACK license:
11
12 http://www.cisl.ucar.edu/css/software/fftpack5/ftpk.html
13
14 Copyright (c) 2004 the University Corporation for Atmospheric
15 Research ("UCAR"). All rights reserved. Developed by NCAR's
16 Computational and Information Systems Laboratory, UCAR,
17 www.cisl.ucar.edu.
18
19 Redistribution and use of the Software in source and binary forms,
20 with or without modification, is permitted provided that the
21 following conditions are met:
22
23 - Neither the names of NCAR's Computational and Information Systems
24 Laboratory, the University Corporation for Atmospheric Research,
25 nor the names of its sponsors or contributors may be used to
26 endorse or promote products derived from this Software without
27 specific prior written permission.
28
29 - Redistributions of source code must retain the above copyright
30 notices, this list of conditions, and the disclaimer below.
31
32 - Redistributions in binary form must reproduce the above copyright
33 notice, this list of conditions, and the disclaimer below in the
34 documentation and/or other materials provided with the
35 distribution.
36
37 THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
38 EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO THE WARRANTIES OF
39 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
40 NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT
41 HOLDERS BE LIABLE FOR ANY CLAIM, INDIRECT, INCIDENTAL, SPECIAL,
42 EXEMPLARY, OR CONSEQUENTIAL DAMAGES OR OTHER LIABILITY, WHETHER IN AN
43 ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
44 CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
45 SOFTWARE.
46*/
47
48/*
49 PFFFT : a Pretty Fast FFT.
50
51 This is basically an adaptation of the single precision fftpack
52 (v4) as found on netlib taking advantage of SIMD instruction found
53 on cpus such as intel x86 (SSE1), powerpc (Altivec), and arm (NEON).
54
55 For architectures where no SIMD instruction is available, the code
56 falls back to a scalar version.
57
58 Restrictions:
59
60 - 1D transforms only, with 32-bit single precision.
61
62 - supports only transforms for inputs of length N of the form
63 N=(2^a)*(3^b)*(5^c), a >= 5, b >=0, c >= 0 (32, 48, 64, 96, 128,
64 144, 160, etc are all acceptable lengths). Performance is best for
65 128<=N<=8192.
66
67 - all (float*) pointers in the functions below are expected to
68 have an "simd-compatible" alignment, that is 16 bytes on x86 and
69 powerpc CPUs.
70
71 You can allocate such buffers with the functions
72 pffft_aligned_malloc / pffft_aligned_free (or with stuff like
73 posix_memalign..)
74
75*/
76
77#ifndef PFFFT_H
78#define PFFFT_H
79
80#include <stddef.h> // for size_t
81
82#ifdef __cplusplus
83extern "C" {
84#endif
85
86 /* opaque struct holding internal stuff (precomputed twiddle factors)
87 this struct can be shared by many threads as it contains only
88 read-only data.
89 */
90 typedef struct PFFFT_Setup PFFFT_Setup;
91
92 /* direction of the transform */
93 typedef enum { PFFFT_FORWARD, PFFFT_BACKWARD } pffft_direction_t;
94
95 /* type of transform */
96 typedef enum { PFFFT_REAL, PFFFT_COMPLEX } pffft_transform_t;
97
98 /*
99 prepare for performing transforms of size N -- the returned
100 PFFFT_Setup structure is read-only so it can safely be shared by
101 multiple concurrent threads.
102 */
103 PFFFT_Setup *pffft_new_setup(int N, pffft_transform_t transform);
104 void pffft_destroy_setup(PFFFT_Setup *);
105 /*
106 Perform a Fourier transform , The z-domain data is stored in the
107 most efficient order for transforming it back, or using it for
108 convolution. If you need to have its content sorted in the
109 "usual" way, that is as an array of interleaved complex numbers,
110 either use pffft_transform_ordered , or call pffft_zreorder after
111 the forward fft, and before the backward fft.
112
113 Transforms are not scaled: PFFFT_BACKWARD(PFFFT_FORWARD(x)) = N*x.
114 Typically you will want to scale the backward transform by 1/N.
115
116 The 'work' pointer should point to an area of N (2*N for complex
117 fft) floats, properly aligned. If 'work' is NULL, then stack will
118 be used instead (this is probably the best strategy for small
119 FFTs, say for N < 16384).
120
121 input and output may alias.
122 */
123 void pffft_transform(PFFFT_Setup *setup, const float *input, float *output, float *work, pffft_direction_t direction);
124
125 /*
126 Similar to pffft_transform, but makes sure that the output is
127 ordered as expected (interleaved complex numbers). This is
128 similar to calling pffft_transform and then pffft_zreorder.
129
130 input and output may alias.
131 */
132 void pffft_transform_ordered(PFFFT_Setup *setup, const float *input, float *output, float *work, pffft_direction_t direction);
133
134 /*
135 call pffft_zreorder(.., PFFFT_FORWARD) after pffft_transform(...,
136 PFFFT_FORWARD) if you want to have the frequency components in
137 the correct "canonical" order, as interleaved complex numbers.
138
139 (for real transforms, both 0-frequency and half frequency
140 components, which are real, are assembled in the first entry as
141 F(0)+i*F(n/2+1). Note that the original fftpack did place
142 F(n/2+1) at the end of the arrays).
143
144 input and output should not alias.
145 */
146 void pffft_zreorder(PFFFT_Setup *setup, const float *input, float *output, pffft_direction_t direction);
147
148 /*
149 Perform a multiplication of the frequency components of dft_a and
150 dft_b and accumulate them into dft_ab. The arrays should have
151 been obtained with pffft_transform(.., PFFFT_FORWARD) and should
152 *not* have been reordered with pffft_zreorder (otherwise just
153 perform the operation yourself as the dft coefs are stored as
154 interleaved complex numbers).
155
156 the operation performed is: dft_ab += (dft_a * fdt_b)*scaling
157
158 The dft_a, dft_b and dft_ab pointers may alias.
159 */
160 void pffft_zconvolve_accumulate(PFFFT_Setup *setup, const float *dft_a, const float *dft_b, float *dft_ab, float scaling);
161
162 /*
163 the float buffers must have the correct alignment (16-byte boundary
164 on intel and powerpc). This function may be used to obtain such
165 correctly aligned buffers.
166 */
167 void *pffft_aligned_malloc(size_t nb_bytes);
168 void pffft_aligned_free(void *);
169
170 /* return 4 or 1 wether support SSE/Altivec instructions was enable when building pffft.c */
171 int pffft_simd_size(void);
172
173#ifdef __cplusplus
174}
175#endif
176
177#endif // PFFFT_H
178

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source code of qtmultimedia/src/3rdparty/pffft/pffft.h