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38 #include "gromacs/fft/fft.h"
45 #include "gromacs/utility/fatalerror.h"
46 #include "gromacs/utility/real.h"
48 #include "external/fftpack/fftpack.h"
52 * Contents of the FFTPACK fft datatype.
54 * Note that this is one of several possible implementations of gmx_fft_t.
56 * FFTPACK only does 1d transforms, so we use a pointers to another fft for
57 * the transform in the next dimension.
58 * Thus, a 3d-structure contains a pointer to a 2d one, which in turns contains
59 * a pointer to a 1d. The 1d structure has next==NULL.
62 struct gmx_fft_fftpack
67 int ndim; /**< Dimensions, including our subdimensions. */
68 int n; /**< Number of points in this dimension. */
69 int ifac[15]; /**< 15 bytes needed for cfft and rfft */
70 struct gmx_fft *next; /**< Pointer to next dimension, or NULL. */
71 real * work; /**< 1st 4n reserved for cfft, 1st 2n for rfft */
79 gmx_fft_init_1d(gmx_fft_t * pfft,
87 gmx_fatal(FARGS, "Invalid FFT opaque type pointer.");
92 if ( (fft = (struct gmx_fft *)malloc(sizeof(struct gmx_fft))) == NULL)
100 /* Need 4*n storage for 1D complex FFT */
101 if ( (fft->work = (real *)malloc(sizeof(real)*(4*nx))) == NULL)
109 fftpack_cffti1(nx, fft->work, fft->ifac);
119 gmx_fft_init_1d_real(gmx_fft_t * pfft,
121 int gmx_unused flags)
127 gmx_fatal(FARGS, "Invalid FFT opaque type pointer.");
132 if ( (fft = (struct gmx_fft *)malloc(sizeof(struct gmx_fft))) == NULL)
140 /* Need 2*n storage for 1D real FFT */
141 if ((fft->work = (real *)malloc(sizeof(real)*(2*nx))) == NULL)
149 fftpack_rffti1(nx, fft->work, fft->ifac);
157 gmx_fft_init_2d_real(gmx_fft_t * pfft,
163 int nyc = (ny/2 + 1);
168 gmx_fatal(FARGS, "Invalid FFT opaque type pointer.");
173 /* Create the X transform */
174 if ( (fft = (struct gmx_fft *)malloc(sizeof(struct gmx_fft))) == NULL)
181 /* Need 4*nx storage for 1D complex FFT, and another
182 * 2*nx*nyc elements for complex-to-real storage in our high-level routine.
184 if ( (fft->work = (real *)malloc(sizeof(real)*(4*nx+2*nx*nyc))) == NULL)
189 fftpack_cffti1(nx, fft->work, fft->ifac);
191 /* Create real Y transform as a link from X */
192 if ( (rc = gmx_fft_init_1d_real(&(fft->next), ny, flags)) != 0)
204 gmx_fft_1d (gmx_fft_t fft,
205 enum gmx_fft_direction dir,
217 p1 = (real *)in_data;
218 p2 = (real *)out_data;
223 /* FFTPACK only does in-place transforms, so emulate out-of-place
224 * by copying data to the output array first.
226 if (in_data != out_data)
228 p1 = (real *)in_data;
229 p2 = (real *)out_data;
231 /* n complex = 2*n real elements */
232 for (i = 0; i < 2*n; i++)
238 /* Elements 0 .. 2*n-1 in work are used for ffac values,
239 * Elements 2*n .. 4*n-1 are internal FFTPACK work space.
242 if (dir == GMX_FFT_FORWARD)
244 fftpack_cfftf1(n, (real *)out_data, fft->work+2*n, fft->work, fft->ifac, -1);
246 else if (dir == GMX_FFT_BACKWARD)
248 fftpack_cfftf1(n, (real *)out_data, fft->work+2*n, fft->work, fft->ifac, 1);
252 gmx_fatal(FARGS, "FFT plan mismatch - bad plan or direction.");
262 gmx_fft_1d_real (gmx_fft_t fft,
263 enum gmx_fft_direction dir,
275 p1 = (real *)in_data;
276 p2 = (real *)out_data;
278 if (dir == GMX_FFT_REAL_TO_COMPLEX)
284 if (dir == GMX_FFT_REAL_TO_COMPLEX)
286 /* FFTPACK only does in-place transforms, so emulate out-of-place
287 * by copying data to the output array first. This works fine, since
288 * the complex array must be larger than the real.
290 if (in_data != out_data)
292 p1 = (real *)in_data;
293 p2 = (real *)out_data;
295 for (i = 0; i < 2*(n/2+1); i++)
301 /* Elements 0 .. n-1 in work are used for ffac values,
302 * Elements n .. 2*n-1 are internal FFTPACK work space.
304 fftpack_rfftf1(n, (real *)out_data, fft->work+n, fft->work, fft->ifac);
307 * FFTPACK has a slightly more compact storage than we, time to
308 * convert it: ove most of the array one step up to make room for
309 * zero imaginary parts.
311 p2 = (real *)out_data;
312 for (i = n-1; i > 0; i--)
316 /* imaginary zero freq. */
326 else if (dir == GMX_FFT_COMPLEX_TO_REAL)
328 /* FFTPACK only does in-place transforms, and we cannot just copy
329 * input to output first here since our real array is smaller than
330 * the complex one. However, since the FFTPACK complex storage format
331 * is more compact than ours (2 reals) it will fit, so compact it
332 * and copy on-the-fly to the output array.
334 p1 = (real *) in_data;
335 p2 = (real *)out_data;
338 for (i = 1; i < n; i++)
342 fftpack_rfftb1(n, (real *)out_data, fft->work+n, fft->work, fft->ifac);
346 gmx_fatal(FARGS, "FFT plan mismatch - bad plan or direction.");
355 gmx_fft_2d_real (gmx_fft_t fft,
356 enum gmx_fft_direction dir,
360 int i, j, nx, ny, nyc;
368 /* Number of complex elements in y direction */
371 work = fft->work+4*nx;
373 if (dir == GMX_FFT_REAL_TO_COMPLEX)
375 /* If we are doing an in-place transform the 2D array is already
376 * properly padded by the user, and we are all set.
378 * For out-of-place there is no array padding, but FFTPACK only
379 * does in-place FFTs internally, so we need to start by copying
380 * data from the input to the padded (larger) output array.
382 if (in_data != out_data)
384 p1 = (real *)in_data;
385 p2 = (real *)out_data;
387 for (i = 0; i < nx; i++)
389 for (j = 0; j < ny; j++)
391 p2[i*nyc*2+j] = p1[i*ny+j];
395 data = (t_complex *)out_data;
397 /* y real-to-complex FFTs */
398 for (i = 0; i < nx; i++)
400 gmx_fft_1d_real(fft->next, GMX_FFT_REAL_TO_COMPLEX, data+i*nyc, data+i*nyc);
403 /* Transform to get X data in place */
404 gmx_fft_transpose_2d(data, data, nx, nyc);
406 /* Complex-to-complex X FFTs */
407 for (i = 0; i < nyc; i++)
409 gmx_fft_1d(fft, GMX_FFT_FORWARD, data+i*nx, data+i*nx);
413 gmx_fft_transpose_2d(data, data, nyc, nx);
416 else if (dir == GMX_FFT_COMPLEX_TO_REAL)
418 /* An in-place complex-to-real transform is straightforward,
419 * since the output array must be large enough for the padding to fit.
421 * For out-of-place complex-to-real transforms we cannot just copy
422 * data to the output array, since it is smaller than the input.
423 * In this case there's nothing to do but employing temporary work data,
424 * starting at work+4*nx and using nx*nyc*2 elements.
426 if (in_data != out_data)
428 memcpy(work, in_data, sizeof(t_complex)*nx*nyc);
429 data = (t_complex *)work;
434 data = (t_complex *)out_data;
437 /* Transpose to get X arrays */
438 gmx_fft_transpose_2d(data, data, nx, nyc);
441 for (i = 0; i < nyc; i++)
443 gmx_fft_1d(fft, GMX_FFT_BACKWARD, data+i*nx, data+i*nx);
446 /* Transpose to get Y arrays */
447 gmx_fft_transpose_2d(data, data, nyc, nx);
450 for (i = 0; i < nx; i++)
452 gmx_fft_1d_real(fft->next, GMX_FFT_COMPLEX_TO_REAL, data+i*nyc, data+i*nyc);
455 if (in_data != out_data)
457 /* Output (pointed to by data) is now in padded format.
458 * Pack it into out_data if we were doing an out-of-place transform.
461 p2 = (real *)out_data;
463 for (i = 0; i < nx; i++)
465 for (j = 0; j < ny; j++)
467 p2[i*ny+j] = p1[i*nyc*2+j];
474 gmx_fatal(FARGS, "FFT plan mismatch - bad plan or direction.");
482 gmx_fft_destroy(gmx_fft_t fft)
487 if (fft->next != NULL)
489 gmx_fft_destroy(fft->next);
495 void gmx_fft_cleanup()
499 const char *gmx_fft_get_version_info()
501 return "fftpack (built-in)";