annotate liszt.cpp @ 580:633614461994

API for retrieving a track's data.

A new function, audiodb_retrieve_datum() fills a provided adb_datum_t
structure with the data corresponding to a given database key; the
companion audiodb_free_datum() function frees the data in a given datum
appropriately.

Just in case, I continue to require passing in the adb_t * as the first
argument to audiodb_free_datum(), even though it's not currently used:
I couldn't convince myself that _all_ possible implementations could
free a datum without reference to the adb_t.

This meant rewriting the internal code to use a new internal
audiodb_really_free_datum() function, which audiodb_free_datum() also
calls.

Sanity-checked by implementing a binding in sb-alien to this function,
lightly-tested.

All this fixes ticket:20 in Trac.

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

adb_liszt_results_t *audiodb_liszt(adb_t *adb) {
  uint32_t nfiles = adb->header->numFiles;
  adb_liszt_results_t *results;
  results = (adb_liszt_results_t *) calloc(sizeof(adb_liszt_results_t),1);
  results->nresults = nfiles;
  if(nfiles > 0) {
    results->entries = (adb_track_entry_t *) malloc(nfiles * sizeof(adb_track_entry_t));
  }
  for(uint32_t k = 0; k < nfiles; k++) {
    results->entries[k].nvectors = (*adb->track_lengths)[k];
    results->entries[k].key = audiodb_index_key(adb, k);
  }
  return results;
}

int audiodb_liszt_free_results(adb_t *adb, adb_liszt_results_t *results) {
  free(results->entries);
  free(results);
  return 0;
}