r8brain-free-src
High-quality pro audio sample rate converter library
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pffft.h
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#include <stdint.h>
82
83#ifdef __cplusplus
84extern "C" {
85#endif
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#ifndef PFFFT_COMMON_ENUMS
94#define PFFFT_COMMON_ENUMS
95
96 /* direction of the transform */
97 typedef enum { PFFFT_FORWARD, PFFFT_BACKWARD } pffft_direction_t;
98
99 /* type of transform */
100 typedef enum { PFFFT_REAL, PFFFT_COMPLEX } pffft_transform_t;
101
102#endif
103
104 /*
105 prepare for performing transforms of size N -- the returned
106 PFFFT_Setup structure is read-only so it can safely be shared by
107 multiple concurrent threads.
108 */
109 PFFFT_Setup *pffft_new_setup(int N, pffft_transform_t transform);
110 void pffft_destroy_setup(PFFFT_Setup *);
111 /*
112 Perform a Fourier transform , The z-domain data is stored in the
113 most efficient order for transforming it back, or using it for
114 convolution. If you need to have its content sorted in the
115 "usual" way, that is as an array of interleaved complex numbers,
116 either use pffft_transform_ordered , or call pffft_zreorder after
117 the forward fft, and before the backward fft.
118
119 Transforms are not scaled: PFFFT_BACKWARD(PFFFT_FORWARD(x)) = N*x.
120 Typically you will want to scale the backward transform by 1/N.
121
122 The 'work' pointer should point to an area of N (2*N for complex
123 fft) floats, properly aligned. If 'work' is NULL, then stack will
124 be used instead (this is probably the best strategy for small
125 FFTs, say for N < 16384).
126
127 input and output may alias.
128 */
129 void pffft_transform(PFFFT_Setup *setup, const float *input, float *output, float *work, pffft_direction_t direction);
130
131 /*
132 Similar to pffft_transform, but makes sure that the output is
133 ordered as expected (interleaved complex numbers). This is
134 similar to calling pffft_transform and then pffft_zreorder.
135
136 input and output may alias.
137 */
138 void pffft_transform_ordered(PFFFT_Setup *setup, const float *input, float *output, float *work, pffft_direction_t direction);
139
140 /*
141 call pffft_zreorder(.., PFFFT_FORWARD) after pffft_transform(...,
142 PFFFT_FORWARD) if you want to have the frequency components in
143 the correct "canonical" order, as interleaved complex numbers.
144
145 (for real transforms, both 0-frequency and half frequency
146 components, which are real, are assembled in the first entry as
147 F(0)+i*F(n/2+1). Note that the original fftpack did place
148 F(n/2+1) at the end of the arrays).
149
150 input and output should not alias.
151 */
152 void pffft_zreorder(PFFFT_Setup *setup, const float *input, float *output, pffft_direction_t direction);
153
154 /*
155 Perform a multiplication of the frequency components of dft_a and
156 dft_b and accumulate them into dft_ab. The arrays should have
157 been obtained with pffft_transform(.., PFFFT_FORWARD) and should
158 *not* have been reordered with pffft_zreorder (otherwise just
159 perform the operation yourself as the dft coefs are stored as
160 interleaved complex numbers).
161
162 the operation performed is: dft_ab += (dft_a * fdt_b)*scaling
163
164 The dft_a, dft_b and dft_ab pointers may alias.
165 */
166 void pffft_zconvolve_accumulate(PFFFT_Setup *setup, const float *dft_a, const float *dft_b, float *dft_ab, float scaling);
167
168 /*
169 the float buffers must have the correct alignment (16-byte boundary
170 on intel and powerpc). This function may be used to obtain such
171 correctly aligned buffers.
172 */
173 void *pffft_aligned_malloc(size_t nb_bytes);
174 void pffft_aligned_free(void *);
175
176 /* return 4 or 1 wether support SSE/Altivec instructions was enable when building pffft.c */
177 int pffft_simd_size();
178
179#ifdef __cplusplus
180}
181#endif
182
183#endif // PFFFT_H
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