view xthresh.c @ 392:78fed0d4c108 api-inversion

Include some necessary information in struct adb.

Now the struct adb contains a database fd, the flags used to open that
fd (so that we can later tell if it was for write or not) and a database
header pointer.

audiodb_open() is now responsible for filling in all of that
information.  To do that, it needs to take an open(2) flag; that's good,
because it means that the call to open(2) is no longer invoking
undefined behaviour.  (Also, the previous version of audiodb_open()
leaked an fd).  Unfortunately, that means we have broken ABI and API
compatibility.  (Fortunately, we have fewer than 12 users).

Use audiodb_open() in audioDB::initDBHeader().

We've temporarily(?) put acquire_lock(int, bool) in the API header; that
means we need to include <stdbool.h> and compile C files with -std=c99.
Do so.

Make audiodb_close() free resources allocated by audiodb_open().

Include a struct adb * field in the audioDB C++ object...
... which lets us actually implement memory-correctness, by
audiodb_close()ing the database in audioDB::cleanup().

[ The lock is, I think, correctly disposed of; man fcntl(2) on Linux
  says that the locks are released once any file descriptor relating to
  the file is closed, and we close the fd in audiodb_close(). ]

#include <gsl/gsl_sf.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(int argc, char *argv[]) {
  if(argc != 4) {
    fprintf(stderr, "Wrong number of arguments: %d\n", argc);
    exit(1);
  }

  long int meanN = strtol(argv[1], NULL, 10);

  double d = strtod(argv[2], NULL);
  double sigma2 = strtod(argv[3], NULL);

  double logw = (2 / d) * gsl_sf_log(-gsl_sf_log(0.99));
  double logxthresh = gsl_sf_log(sigma2) + logw
    - (2 / d) * gsl_sf_log(meanN)
    - gsl_sf_log(d/2)
    - (2 / d) * gsl_sf_log(2 / d)
    + (2 / d) * gsl_sf_lngamma(d / 2);

  printf("w: %f\n", exp(logw));
  printf("x_thresh: %f\n", exp(logxthresh));
  exit(0);
}