view l2norm.cpp @ 401:a8a5f2ca5380 api-inversion

Invert audioDB::l2norm / audiodb_l2norm()

We now have some functions that shouldn't be exported to the user of the
library, but are used in more than one source file; case in point:
audiodb_sync_header().  Make a new audioDB-internals.h file for them,
and while we're at it put the scary mmap()-related macros in there too.

We can't delete audioDB::unitNormAndInsertL2() quite yet, because it's
used in insertion too, but we can delete the non-append branches.
That's not very much code to lose, but every little helps.

#include "audioDB.h"
extern "C" {
#include "audioDB_API.h"
#include "audioDB-internals.h"
}

static int audiodb_l2norm_existing(adb_t *adb) {
  double *data_buffer, *l2norm_buffer;
  double *dp, *lp;
  adb_header_t *header = adb->header;
  size_t data_buffer_size = ALIGN_PAGE_UP(header->length);
  size_t nvectors = header->length / (sizeof(double) * header->dim);
  /* FIXME: this map of the vector data will lose if we ever turn the
   * l2norm flag on when we have already inserted a large number of
   * vectors, as the mmap() will fail.  "Don't do that, then" is one
   * possible answer. */
  mmap_or_goto_error(double *, data_buffer, header->dataOffset, data_buffer_size);
  l2norm_buffer = (double *) malloc(nvectors * sizeof(double));
  if(!l2norm_buffer) {
    goto error;
  }

  dp = data_buffer;
  lp = l2norm_buffer;
  for(size_t i = 0; i < nvectors; i++) {
    *lp = 0;
    for(unsigned int k = 0; k < header->dim; k++) {
      *lp += (*dp)*(*dp);
      dp++;
    }
    lp++;
  }

  if(lseek(adb->fd, adb->header->l2normTableOffset, SEEK_SET) == (off_t) -1) {
    goto error;
  }
  if(write(adb->fd, l2norm_buffer, nvectors * sizeof(double)) != (ssize_t) (nvectors * sizeof(double))) {
    goto error;
  }

  munmap(data_buffer, data_buffer_size);
  free(l2norm_buffer);

  return 0;

 error:
  maybe_munmap(data_buffer, data_buffer_size);
  if(l2norm_buffer) {
    free(l2norm_buffer);
  }
  return 1;
}

int audiodb_l2norm(adb_t *adb) {
  adb_header_t *header = adb->header;
  if(header->flags & O2_FLAG_L2NORM) {
    /* non-error code for forthcoming backwards-compatibility
     * reasons */
    return 0;
  }
  if((!(header->flags & O2_FLAG_LARGE_ADB)) && (header->length > 0)) {
    if(audiodb_l2norm_existing(adb)) {
      goto error;
    }
  }
  adb->header->flags |= O2_FLAG_L2NORM;
  return audiodb_sync_header(adb);

 error:
  return 1;
}