/* Copyright (c) 2013 Julien Pommier ( [email protected] ) Based on original fortran 77 code from FFTPACKv4 from NETLIB, authored by Dr Paul Swarztrauber of NCAR, in 1985. As confirmed by the NCAR fftpack software curators, the following FFTPACKv5 license applies to FFTPACKv4 sources. My changes are released under the same terms. FFTPACK license: http://www.cisl.ucar.edu/css/software/fftpack5/ftpk.html Copyright (c) 2004 the University Corporation for Atmospheric Research ("UCAR"). All rights reserved. Developed by NCAR's Computational and Information Systems Laboratory, UCAR, www.cisl.ucar.edu. Redistribution and use of the Software in source and binary forms, with or without modification, is permitted provided that the following conditions are met: - Neither the names of NCAR's Computational and Information Systems Laboratory, the University Corporation for Atmospheric Research, nor the names of its sponsors or contributors may be used to endorse or promote products derived from this Software without specific prior written permission. - Redistributions of source code must retain the above copyright notices, this list of conditions, and the disclaimer below. - Redistributions in binary form must reproduce the above copyright notice, this list of conditions, and the disclaimer below in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE SOFTWARE. */ /* PFFFT : a Pretty Fast FFT. This is basically an adaptation of the single precision fftpack (v4) as found on netlib taking advantage of SIMD instruction found on cpus such as intel x86 (SSE1), powerpc (Altivec), and arm (NEON). For architectures where no SIMD instruction is available, the code falls back to a scalar version. Restrictions: - 1D transforms only, with 32-bit single precision. - supports only transforms for inputs of length N of the form N=(2^a)*(3^b)*(5^c), a >= 5, b >=0, c >= 0 (32, 48, 64, 96, 128, 144, 160, etc are all acceptable lengths). Performance is best for 128<=N<=8192. - all (float*) pointers in the functions below are expected to have an "simd-compatible" alignment, that is 16 bytes on x86 and powerpc CPUs. You can allocate such buffers with the functions pffft_aligned_malloc / pffft_aligned_free (or with stuff like posix_memalign..) */ #ifndef PFFFT_H #define PFFFT_H #include <stddef.h> // for size_t #ifdef __cplusplus extern "C" { #endif #ifndef PFFFT_SIMD_DISABLE // Detects compiler bugs with respect to simd instruction. void validate_pffft_simd(); #endif /* opaque struct holding internal stuff (precomputed twiddle factors) this struct can be shared by many threads as it contains only read-only data. */ PFFFT_Setup; /* direction of the transform */ pffft_direction_t; /* type of transform */ pffft_transform_t; /* prepare for performing transforms of size N -- the returned PFFFT_Setup structure is read-only so it can safely be shared by multiple concurrent threads. */ PFFFT_Setup* pffft_new_setup(int N, pffft_transform_t transform); void pffft_destroy_setup(PFFFT_Setup*); /* Perform a Fourier transform , The z-domain data is stored in the most efficient order for transforming it back, or using it for convolution. If you need to have its content sorted in the "usual" way, that is as an array of interleaved complex numbers, either use pffft_transform_ordered , or call pffft_zreorder after the forward fft, and before the backward fft. Transforms are not scaled: PFFFT_BACKWARD(PFFFT_FORWARD(x)) = N*x. Typically you will want to scale the backward transform by 1/N. The 'work' pointer should point to an area of N (2*N for complex fft) floats, properly aligned. If 'work' is NULL, then stack will be used instead (this is probably the best strategy for small FFTs, say for N < 16384). input and output may alias. */ void pffft_transform(PFFFT_Setup* setup, const float* input, float* output, float* work, pffft_direction_t direction); /* Similar to pffft_transform, but makes sure that the output is ordered as expected (interleaved complex numbers). This is similar to calling pffft_transform and then pffft_zreorder. input and output may alias. */ void pffft_transform_ordered(PFFFT_Setup* setup, const float* input, float* output, float* work, pffft_direction_t direction); /* call pffft_zreorder(.., PFFFT_FORWARD) after pffft_transform(..., PFFFT_FORWARD) if you want to have the frequency components in the correct "canonical" order, as interleaved complex numbers. (for real transforms, both 0-frequency and half frequency components, which are real, are assembled in the first entry as F(0)+i*F(n/2+1). Note that the original fftpack did place F(n/2+1) at the end of the arrays). input and output should not alias. */ void pffft_zreorder(PFFFT_Setup* setup, const float* input, float* output, pffft_direction_t direction); /* Perform a multiplication of the frequency components of dft_a and dft_b and accumulate them into dft_ab. The arrays should have been obtained with pffft_transform(.., PFFFT_FORWARD) and should *not* have been reordered with pffft_zreorder (otherwise just perform the operation yourself as the dft coefs are stored as interleaved complex numbers). the operation performed is: dft_ab += (dft_a * fdt_b)*scaling The dft_a, dft_b and dft_ab pointers may alias. */ void pffft_zconvolve_accumulate(PFFFT_Setup* setup, const float* dft_a, const float* dft_b, float* dft_ab, float scaling); /* the float buffers must have the correct alignment (16-byte boundary on intel and powerpc). This function may be used to obtain such correctly aligned buffers. */ void* pffft_aligned_malloc(size_t nb_bytes); void pffft_aligned_free(void*); /* return 4 or 1 wether support SSE/Altivec instructions was enable when * building pffft.c */ int pffft_simd_size(); #ifdef __cplusplus } #endif #endif // PFFFT_H
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