event_gen_alloc.c

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/*
** Copyright (C) 2005 by Kevin L. Mitchell <klmitch@mit.edu>
**
** 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 of the License, 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**
** @(#)$Id: event_gen_alloc.c,v 1.3 2005/10/26 12:53:59 klmitch Exp $
*/
#include "event_int.h"

#include <stdlib.h>

RCSTAG("@(#)$Id: event_gen_alloc.c,v 1.3 2005/10/26 12:53:59 klmitch Exp $");

ev_err_t
event_gen_alloc(ev_ctx_t *ctx, unsigned int gentype, void *gen)
{
  ev_err_t err;
  ev_gendesc_t *gd;
  ev_genhdr_t *hdr;

  ev_init(); /* make sure library is initialized... */

  if (!ec_verify(ctx) || !gentype || !gen) /* sanity-check arguments */
    ev_return(EINVAL);

  /* OK, first, let's look up the descriptor for the generator... */
  if ((err = _ev_gen_lookup(ctx, gentype, &gd)))
    ev_return(err);

  /* Next, let's pop one off the free list if possible... */
  if ((hdr = gd->gd_free.gl_list)) {
    if (hdr->eg_next) /* clip it out of the list... */
      hdr->eg_next->eg_prev = hdr->eg_prev;
    ev_assert(!hdr->eg_prev);
    gd->gd_free.gl_list = hdr->eg_next; /* move the list up... */
    gd->gd_free.gl_count--; /* and update the count */
  } else {
    ev_assert(!gd->gd_free.gl_count);
    if (!(hdr = (ev_genhdr_t *)malloc(gd->gd_size))) /* allocate some memory */
      ev_return(ENOMEM);
  }

  /* OK, now we have a genhdr structure.  Let's initialize it... */
  ev_gen_init(ctx, hdr, gd);

  /* now link it into the active list... */
  hdr->eg_next = gd->gd_active.gl_list;
  if (hdr->eg_next)
    hdr->eg_next->eg_prev = hdr;
  gd->gd_active.gl_list = hdr;

  gd->gd_active.gl_count++; /* and increment the active list count */

  *((void **)gen) = hdr; /* return the initialized structure... */

  ev_return(0); /* all done! */
}

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