mop3/kernel/id/id_alloc.c

#include <id/id_alloc.h>
#include <libk/bm.h>
#include <libk/std.h>
#include <mm/malloc.h>
#include <status.h>
#include <sync/spin_lock.h>
#include <sys/debug.h>

bool id_alloc_init (struct id_alloc* ida, size_t nbits) {
  size_t buffer_size = (nbits + 7) / 8;

  uint8_t* buffer = malloc (buffer_size);

  if (buffer == NULL)
    return false;

  bm_init (&ida->bm, buffer, nbits);
  ida->lock = SPIN_LOCK_INIT;

  return true;
}

void id_alloc_fini (struct id_alloc* ida) {
  free (ida->bm.base);
  ida->bm.base = NULL;
  ida->bm.nbits = 0;
}

int id_alloc (struct id_alloc* ida) {
  uint64_t fid;

  spin_lock (&ida->lock, &fid);

  size_t start = ida->next_id;
  size_t current = start;
  do {
    if (!bm_test (&ida->bm, current)) {
      bm_set (&ida->bm, current);

      ida->next_id = (current + 1) % ida->bm.nbits;

      spin_unlock (&ida->lock, fid);
      return (int)current;
    }

    current = (current + 1) % ida->bm.nbits;
  } while (current != start);

  spin_unlock (&ida->lock, fid);
  return -ST_OOM_ERROR;
}

void id_free (struct id_alloc* ida, int id) {
  uint64_t fid;

  if (id < 0)
    return;

  spin_lock (&ida->lock, &fid);
  bm_clear (&ida->bm, (size_t)id);
  spin_unlock (&ida->lock, fid);
}