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 /**
87 Opaque struct holding internal stuff (precomputed twiddle factors)
88 this struct can be shared by many threads as it contains only
89 read-only data.
90 */
91 typedef struct PFFFT_Setup PFFFT_Setup;
92
93 /** Direction of the transform */
94 typedef enum { PFFFT_FORWARD, PFFFT_BACKWARD } pffft_direction_t;
95
96 /** Type of transform */
97 typedef enum { PFFFT_REAL, PFFFT_COMPLEX } pffft_transform_t;
98
99 /**
100 Prepare for performing transforms of size N -- the returned
101 PFFFT_Setup structure is read-only so it can safely be shared by
102 multiple concurrent threads.
103
104 Will return NULL if N is not suitable (too large / no decomposable with simple integer
105 factors..)
106 */
107 PFFFT_Setup *pffft_new_setup(int N, pffft_transform_t transform);
108 void pffft_destroy_setup(PFFFT_Setup *);
109 /**
110 Perform a Fourier transform , The z-domain data is stored in the
111 most efficient order for transforming it back, or using it for
112 convolution. If you need to have its content sorted in the
113 "usual" way, that is as an array of interleaved complex numbers,
114 either use pffft_transform_ordered , or call pffft_zreorder after
115 the forward fft, and before the backward fft.
116
117 Transforms are not scaled: PFFFT_BACKWARD(PFFFT_FORWARD(x)) = N*x.
118 Typically you will want to scale the backward transform by 1/N.
119
120 The 'work' pointer should point to an area of N (2*N for complex
121 fft) floats, properly aligned. If 'work' is NULL, then stack will
122 be used instead (this is probably the best strategy for small
123 FFTs, say for N < 16384).
124
125 input and output may alias.
126 */
127 void pffft_transform(PFFFT_Setup *setup, const float *input, float *output, float *work, pffft_direction_t direction);
128
129 /**
130 Similar to pffft_transform, but makes sure that the output is
131 ordered as expected (interleaved complex numbers). This is
132 similar to calling pffft_transform and then pffft_zreorder.
133
134 input and output may alias.
135 */
136 void pffft_transform_ordered(PFFFT_Setup *setup, const float *input, float *output, float *work, pffft_direction_t direction);
137
138 /**
139 call pffft_zreorder(.., PFFFT_FORWARD) after pffft_transform(...,
140 PFFFT_FORWARD) if you want to have the frequency components in
141 the correct "canonical" order, as interleaved complex numbers.
142
143 (for real transforms, both 0-frequency and half frequency
144 components, which are real, are assembled in the first entry as
145 F(0)+i*F(n/2+1). Note that the original fftpack did place
146 F(n/2+1) at the end of the arrays).
147
148 input and output should not alias.
149 */
150 void pffft_zreorder(PFFFT_Setup *setup, const float *input, float *output, pffft_direction_t direction);
151
152 /**
153 Perform a multiplication of the frequency components of dft_a and
154 dft_b and accumulate them into dft_ab. The arrays should have
155 been obtained with pffft_transform(.., PFFFT_FORWARD) and should
156 *not* have been reordered with pffft_zreorder (otherwise just
157 perform the operation yourself as the dft coefs are stored as
158 interleaved complex numbers).
159
160 the operation performed is: dft_ab += (dft_a * fdt_b)*scaling
161
162 The dft_a, dft_b and dft_ab pointers may alias.
163 */
164 void pffft_zconvolve_accumulate(PFFFT_Setup *setup, const float *dft_a, const float *dft_b, float *dft_ab, float scaling);
165
166 /**
167 the float buffers must have the correct alignment (16-byte boundary
168 on intel and powerpc). This function may be used to obtain such
169 correctly aligned buffers.
170 */
171 void *pffft_aligned_malloc(size_t nb_bytes);
172 void pffft_aligned_free(void *);
173
174 /** return 4 or 1 wether support SSE/Altivec instructions was enable when building pffft.c */
175 int pffft_simd_size(void);
176
177#ifdef __cplusplus
178}
179#endif
180
181#endif // PFFFT_H
182

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