third_party/pffft/src/pffft.h - chromium/src - Git at Google

 /* Copyright (c) 2013  Julien Pommier ( pommier@modartt.com )

    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.
 */
 typedef struct PFFFT_Setup PFFFT_Setup;

 /* direction of the transform */
 typedef enum { PFFFT_FORWARD, PFFFT_BACKWARD } pffft_direction_t;

 /* type of transform */
 typedef enum { PFFFT_REAL, PFFFT_COMPLEX } 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
	/* Copyright (c) 2013 Julien Pommier ( pommier@modartt.com )

	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.
	*/
	typedef struct PFFFT_Setup PFFFT_Setup;

	/* direction of the transform */
	typedef enum { PFFFT_FORWARD, PFFFT_BACKWARD } pffft_direction_t;

	/* type of transform */
	typedef enum { PFFFT_REAL, PFFFT_COMPLEX } 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