/* Copyright (C) 1998 Aladdin Enterprises.  All rights reserved.
  
  This file is part of GNU Ghostscript.
  
  GNU Ghostscript is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility
  to anyone for the consequences of using it or for whether it serves any
  particular purpose or works at all, unless he says so in writing.  Refer
  to the GNU General Public License for full details.
  
  Everyone is granted permission to copy, modify and redistribute GNU
  Ghostscript, but only under the conditions described in the GNU General
  Public License.  A copy of this license is supposed to have been given
  to you along with GNU Ghostscript so you can know your rights and
  responsibilities.  It should be in a file named COPYING.  Among other
  things, the copyright notice and this notice must be preserved on all
  copies.
*/

/*$RCSfile: gxsync.c,v $ $Revision: 1.2.2.1 $ */
/* 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)
