finufft_low.c

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/*
 Copyright (C) 2026 Octopus developers
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2, or (at your option)
 any later version.
 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 02110-1301, USA.
 
*/
 
#include <config.h>
 
#ifdef HAVE_NFFT
 
#include <limits.h>
#include <stdlib.h>
 
#include <finufft.h>
 
static int oct_finufft_nthreads(void) {
  const char *env = getenv("FINUFFT_NUM_THREADS");
  if (env == NULL || *env == '\0') {
    return 0;
  }
 
  char *end = NULL;
  long value = strtol(env, &end, 10);
  if (*end != '\0' || value < 0 || value > INT_MAX) {
    return 0;
  }
 
  return (int)value;
}
 
void *oct_finufft_opts_init(int nthreads) {
  finufft_opts *opts = malloc(sizeof(*opts));
 
  if (opts == NULL) {
    return NULL;
  }
 
  finufft_default_opts(opts);
  if (nthreads > 0) {
    opts->nthreads = nthreads;
  } else {
    opts->nthreads = oct_finufft_nthreads();
  }
 
  return opts;
}
 
void oct_finufft_opts_end(void *opts) { free(opts); }
 
#endif