/* Copyright (C) 2001-2006 artofcode LLC.
   All Rights Reserved.
  
  This file is part of GNU ghostscript

  GNU ghostscript is free software; you can redistribute it and/or
  modify it under the terms of the version 2 of the GNU General Public
  License as published by the Free Software Foundation.

  GNU ghostscript 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
  ghostscript; see the file COPYING. If not, write to the Free Software Foundation,
  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

*/

/* $Id: gxsync.c,v 1.6 2007/08/01 14:26:29 jemarch Exp $ */
/* Interface to platform-based synchronization primitives */

/* Initial version 2/1/98 by John Desrosiers (soho@crl.com) */

#include "memory_.h"
#include "gx.h"
#include "gserrors.h"
#include "gsmemory.h"
#include "gxsync.h"

/* This module abstracts the platform-specific synchronization primitives. */
/* Since these routines will see heavy use, performance is important. */


/* ----- Semaphore interface ----- */
/* These have the usual queued, counting semaphore semantics: at init time, */
/* the event count is set to 0 ('wait' will wait until 1st signal). */

/* Allocate & initialize a semaphore */
gx_semaphore_t *		/* returns a new semaphore, 0 if error */
gx_semaphore_alloc(
		      gs_memory_t * memory	/* memory allocator to use */
)
{
    gx_semaphore_t *sema;

    /* sizeof decl'd sema struct, minus semaphore placeholder's size, + actual semaphore size */
    unsigned semaSizeof
    = sizeof(*sema) - sizeof(sema->native) + gp_semaphore_sizeof();

    if (gp_semaphore_open(0) == 0)	/* see if gp_semaphores are movable */
	/* movable */
	sema = (gx_semaphore_t *) gs_alloc_bytes(memory, semaSizeof,
						 "gx_semaphore (create)");
    else
	/* unmovable */
	sema = (gx_semaphore_t *) gs_alloc_bytes_immovable(memory, semaSizeof,
						   "gx_semaphore (create)");
    if (sema == 0)
	return 0;

    /* Make sema remember which allocator was used to allocate it */
    sema->memory = memory;

    if (gp_semaphore_open(&sema->native) < 0) {
	gs_free_object(memory, sema, "gx_semaphore (alloc)");
	return 0;
    }
    return sema;
}

/* Deinit & free a semaphore */
void
gx_semaphore_free(
		     gx_semaphore_t * sema	/* semaphore to delete */
)
{
    if (sema) {
	gp_semaphore_close(&sema->native);
	gs_free_object(sema->memory, sema, "gx_semaphore (free)");
    }
}

/* Macros defined in gxsync.h, but redefined here so compiler chex consistency */
#define gx_semaphore_wait(sema)  gp_semaphore_wait(&(sema)->native)
#define gx_semaphore_signal(sema)  gp_semaphore_signal(&(sema)->native)


/* ----- Monitor interface ----- */
/* These have the usual monitor semantics: at init time, */
/* the event count is set to 1 (1st 'enter' succeeds immediately). */

/* Allocate & Init a monitor */
gx_monitor_t *			/* returns a new monitor, 0 if error */
gx_monitor_alloc(
		    gs_memory_t * memory	/* memory allocator to use */
)
{
    gx_monitor_t *mon;

    /* sizeof decl'd mon struct, minus monitor placeholder's size, + actual monitor size */
    unsigned monSizeof
    = sizeof(*mon) - sizeof(mon->native) + gp_monitor_sizeof();

    if (gp_monitor_open(0) == 0)	/* see if gp_monitors are movable */
	/* movable */
	mon = (gx_monitor_t *) gs_alloc_bytes(memory, monSizeof,
					      "gx_monitor (create)");
    else
	/* unmovable */
	mon = (gx_monitor_t *) gs_alloc_bytes_immovable(memory, monSizeof,
						     "gx_monitor (create)");
    if (mon == 0)
	return 0;

    /* Make monitor remember which allocator was used to allocate it */
    mon->memory = memory;

    if (gp_monitor_open(&mon->native) < 0) {
	gs_free_object(memory, mon, "gx_monitor (alloc)");
	return 0;
    }
    return mon;
}

/* Dnit & free a monitor */
void
gx_monitor_free(
		   gx_monitor_t * mon	/* monitor to delete */
)
{
    if (mon) {
	gp_monitor_close(&mon->native);
	gs_free_object(mon->memory, mon, "gx_monitor (free)");
    }
}

/* Macros defined in gxsync.h, but redefined here so compiler chex consistency */
#define gx_monitor_enter(sema)  gp_monitor_enter(&(sema)->native)
#define gx_monitor_leave(sema)  gp_monitor_leave(&(sema)->native)
