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45 #include "gromacs/fft/fft.h"
46 #include "gromacs/legacyheaders/types/simple.h"
47 #include "gmx_fatal.h"
49 #include "external/fftpack/fftpack.h"
53 * Contents of the FFTPACK fft datatype.
55 * Note that this is one of several possible implementations of gmx_fft_t.
57 * FFTPACK only does 1d transforms, so we use a pointers to another fft for
58 * the transform in the next dimension.
59 * Thus, a 3d-structure contains a pointer to a 2d one, which in turns contains
60 * a pointer to a 1d. The 1d structure has next==NULL.
63 struct gmx_fft_fftpack
68 int ndim; /**< Dimensions, including our subdimensions. */
69 int n; /**< Number of points in this dimension. */
70 int ifac[15]; /**< 15 bytes needed for cfft and rfft */
71 struct gmx_fft *next; /**< Pointer to next dimension, or NULL. */
72 real * work; /**< 1st 4n reserved for cfft, 1st 2n for rfft */
80 gmx_fft_init_1d(gmx_fft_t * pfft,
88 gmx_fatal(FARGS, "Invalid FFT opaque type pointer.");
93 if ( (fft = (struct gmx_fft *)malloc(sizeof(struct gmx_fft))) == NULL)
101 /* Need 4*n storage for 1D complex FFT */
102 if ( (fft->work = (real *)malloc(sizeof(real)*(4*nx))) == NULL)
110 fftpack_cffti1(nx, fft->work, fft->ifac);
120 gmx_fft_init_1d_real(gmx_fft_t * pfft,
122 int gmx_unused flags)
128 gmx_fatal(FARGS, "Invalid FFT opaque type pointer.");
133 if ( (fft = (struct gmx_fft *)malloc(sizeof(struct gmx_fft))) == NULL)
141 /* Need 2*n storage for 1D real FFT */
142 if ((fft->work = (real *)malloc(sizeof(real)*(2*nx))) == NULL)
150 fftpack_rffti1(nx, fft->work, fft->ifac);
158 gmx_fft_init_2d_real(gmx_fft_t * pfft,
164 int nyc = (ny/2 + 1);
169 gmx_fatal(FARGS, "Invalid FFT opaque type pointer.");
174 /* Create the X transform */
175 if ( (fft = (struct gmx_fft *)malloc(sizeof(struct gmx_fft))) == NULL)
182 /* Need 4*nx storage for 1D complex FFT, and another
183 * 2*nx*nyc elements for complex-to-real storage in our high-level routine.
185 if ( (fft->work = (real *)malloc(sizeof(real)*(4*nx+2*nx*nyc))) == NULL)
190 fftpack_cffti1(nx, fft->work, fft->ifac);
192 /* Create real Y transform as a link from X */
193 if ( (rc = gmx_fft_init_1d_real(&(fft->next), ny, flags)) != 0)
205 gmx_fft_1d (gmx_fft_t fft,
206 enum gmx_fft_direction dir,
218 p1 = (real *)in_data;
219 p2 = (real *)out_data;
224 /* FFTPACK only does in-place transforms, so emulate out-of-place
225 * by copying data to the output array first.
227 if (in_data != out_data)
229 p1 = (real *)in_data;
230 p2 = (real *)out_data;
232 /* n complex = 2*n real elements */
233 for (i = 0; i < 2*n; i++)
239 /* Elements 0 .. 2*n-1 in work are used for ffac values,
240 * Elements 2*n .. 4*n-1 are internal FFTPACK work space.
243 if (dir == GMX_FFT_FORWARD)
245 fftpack_cfftf1(n, (real *)out_data, fft->work+2*n, fft->work, fft->ifac, -1);
247 else if (dir == GMX_FFT_BACKWARD)
249 fftpack_cfftf1(n, (real *)out_data, fft->work+2*n, fft->work, fft->ifac, 1);
253 gmx_fatal(FARGS, "FFT plan mismatch - bad plan or direction.");
263 gmx_fft_1d_real (gmx_fft_t fft,
264 enum gmx_fft_direction dir,
276 p1 = (real *)in_data;
277 p2 = (real *)out_data;
279 if (dir == GMX_FFT_REAL_TO_COMPLEX)
285 if (dir == GMX_FFT_REAL_TO_COMPLEX)
287 /* FFTPACK only does in-place transforms, so emulate out-of-place
288 * by copying data to the output array first. This works fine, since
289 * the complex array must be larger than the real.
291 if (in_data != out_data)
293 p1 = (real *)in_data;
294 p2 = (real *)out_data;
296 for (i = 0; i < 2*(n/2+1); i++)
302 /* Elements 0 .. n-1 in work are used for ffac values,
303 * Elements n .. 2*n-1 are internal FFTPACK work space.
305 fftpack_rfftf1(n, (real *)out_data, fft->work+n, fft->work, fft->ifac);
308 * FFTPACK has a slightly more compact storage than we, time to
309 * convert it: ove most of the array one step up to make room for
310 * zero imaginary parts.
312 p2 = (real *)out_data;
313 for (i = n-1; i > 0; i--)
317 /* imaginary zero freq. */
327 else if (dir == GMX_FFT_COMPLEX_TO_REAL)
329 /* FFTPACK only does in-place transforms, and we cannot just copy
330 * input to output first here since our real array is smaller than
331 * the complex one. However, since the FFTPACK complex storage format
332 * is more compact than ours (2 reals) it will fit, so compact it
333 * and copy on-the-fly to the output array.
335 p1 = (real *) in_data;
336 p2 = (real *)out_data;
339 for (i = 1; i < n; i++)
343 fftpack_rfftb1(n, (real *)out_data, fft->work+n, fft->work, fft->ifac);
347 gmx_fatal(FARGS, "FFT plan mismatch - bad plan or direction.");
356 gmx_fft_2d_real (gmx_fft_t fft,
357 enum gmx_fft_direction dir,
361 int i, j, nx, ny, nyc;
369 /* Number of complex elements in y direction */
372 work = fft->work+4*nx;
374 if (dir == GMX_FFT_REAL_TO_COMPLEX)
376 /* If we are doing an in-place transform the 2D array is already
377 * properly padded by the user, and we are all set.
379 * For out-of-place there is no array padding, but FFTPACK only
380 * does in-place FFTs internally, so we need to start by copying
381 * data from the input to the padded (larger) output array.
383 if (in_data != out_data)
385 p1 = (real *)in_data;
386 p2 = (real *)out_data;
388 for (i = 0; i < nx; i++)
390 for (j = 0; j < ny; j++)
392 p2[i*nyc*2+j] = p1[i*ny+j];
396 data = (t_complex *)out_data;
398 /* y real-to-complex FFTs */
399 for (i = 0; i < nx; i++)
401 gmx_fft_1d_real(fft->next, GMX_FFT_REAL_TO_COMPLEX, data+i*nyc, data+i*nyc);
404 /* Transform to get X data in place */
405 gmx_fft_transpose_2d(data, data, nx, nyc);
407 /* Complex-to-complex X FFTs */
408 for (i = 0; i < nyc; i++)
410 gmx_fft_1d(fft, GMX_FFT_FORWARD, data+i*nx, data+i*nx);
414 gmx_fft_transpose_2d(data, data, nyc, nx);
417 else if (dir == GMX_FFT_COMPLEX_TO_REAL)
419 /* An in-place complex-to-real transform is straightforward,
420 * since the output array must be large enough for the padding to fit.
422 * For out-of-place complex-to-real transforms we cannot just copy
423 * data to the output array, since it is smaller than the input.
424 * In this case there's nothing to do but employing temporary work data,
425 * starting at work+4*nx and using nx*nyc*2 elements.
427 if (in_data != out_data)
429 memcpy(work, in_data, sizeof(t_complex)*nx*nyc);
430 data = (t_complex *)work;
435 data = (t_complex *)out_data;
438 /* Transpose to get X arrays */
439 gmx_fft_transpose_2d(data, data, nx, nyc);
442 for (i = 0; i < nyc; i++)
444 gmx_fft_1d(fft, GMX_FFT_BACKWARD, data+i*nx, data+i*nx);
447 /* Transpose to get Y arrays */
448 gmx_fft_transpose_2d(data, data, nyc, nx);
451 for (i = 0; i < nx; i++)
453 gmx_fft_1d_real(fft->next, GMX_FFT_COMPLEX_TO_REAL, data+i*nyc, data+i*nyc);
456 if (in_data != out_data)
458 /* Output (pointed to by data) is now in padded format.
459 * Pack it into out_data if we were doing an out-of-place transform.
462 p2 = (real *)out_data;
464 for (i = 0; i < nx; i++)
466 for (j = 0; j < ny; j++)
468 p2[i*ny+j] = p1[i*nyc*2+j];
475 gmx_fatal(FARGS, "FFT plan mismatch - bad plan or direction.");
483 gmx_fft_destroy(gmx_fft_t fft)
488 if (fft->next != NULL)
490 gmx_fft_destroy(fft->next);
496 void gmx_fft_cleanup()
500 const char *gmx_fft_get_version_info()
502 return "fftpack (built-in)";