1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
/* ring.h: RING INTERFACE
 *
 * $Id: //info.ravenbrook.com/project/mps/custom/cet/main/code/ring.h#5 $
 * Copyright (c) 2001-2014 Ravenbrook Limited.  See end of file for license.
 * Portions copyright (C) 2001 Global Graphics Software.
 */


#ifndef ring_h
#define ring_h

#include "check.h"
#include "mpmtypes.h"


/* RingStruct -- double-ended queue structure
 *
 * .ring: The ring structure is used as a field in other structures
 * in order to link them together into "rings".  See <code/ring.c>.
 */

typedef struct RingStruct *Ring;
typedef struct RingStruct {     /* double-ended queue structure */
  Ring next, prev;              /* links to next and prev element */
} RingStruct;


#define RingNONE ((Ring)0)

extern Bool RingCheck(Ring ring);
extern Bool RingCheckSingle(Ring ring);
extern Bool RingIsSingle(Ring ring);
extern Count RingLength(Ring ring);

/* .ring.init: See <design/ring/#init> */
extern void (RingInit)(Ring ring);
#define RingInit(ring) \
  BEGIN \
    Ring _ring = (ring); \
    AVER(_ring != NULL); \
    _ring->next = _ring; \
    _ring->prev = _ring; \
    AVER(RingCheck(_ring)); \
  END

/* .ring.finish: See <design/ring/#finish> */
extern void (RingFinish)(Ring ring);
#define RingFinish(ring) \
  BEGIN \
    Ring _ring = (ring); \
    AVER(RingCheckSingle(_ring)); \
    _ring->next = RingNONE; \
    _ring->prev = RingNONE; \
  END

/* .ring.append: See <design/ring/#append> */
extern void (RingAppend)(Ring ring, Ring new);
#define RingAppend(ring, new) \
  BEGIN \
    Ring _ring = (ring), _new = (new); \
    AVER(RingCheck(_ring)); \
    AVER(RingCheckSingle(_new)); \
    _new->prev = _ring->prev; \
    _new->next = _ring; \
    _ring->prev->next = _new; \
    _ring->prev = _new; \
  END

/* .ring.insert: */
extern void (RingInsert)(Ring ring, Ring new);
#define RingInsert(ring, new) \
  BEGIN \
    Ring _ring = (ring), _new = (new); \
    AVER(RingCheck(_ring)); \
    AVER(RingCheckSingle(_new)); \
    _new->prev = _ring; \
    _new->next = _ring->next; \
    _ring->next->prev = _new; \
    _ring->next = _new; \
  END

/* .ring.remove: See <design/ring/#remove> */
extern void (RingRemove)(Ring old);
#define RingRemove(old) \
  BEGIN \
    Ring _old = (old); \
    AVER(RingCheck(_old)); \
    AVER(!RingIsSingle(_old)); \
    _old->next->prev = _old->prev; \
    _old->prev->next = _old->next; \
    _old->next = _old; \
    _old->prev = _old; \
  END

/* .ring.next: See <design/ring/#next> */
extern Ring (RingNext)(Ring ring);
#define RingNext(ring)  ((ring)->next)

/* .ring.prev: See <design/ring/#prev> */
extern Ring (RingPrev)(Ring ring);
#define RingPrev(ring)  ((ring)->prev)

/* .ring.elt: See <design/ring/#elt> */
#define RING_ELT(type, field, node) \
  PARENT(type ## Struct, field, node)

/* .ring.for: See <design/ring/#for> */
#define RING_FOR(node, ring, next) \
  for(node = RingNext(ring), next = RingNext(node); \
      node != (ring); \
      node = (next), next = RingNext(node))


#endif /* ring_h */


/* C. COPYRIGHT AND LICENSE
 *
 * Copyright (C) 2001-2014 Ravenbrook Limited <http://www.ravenbrook.com/>.
 * All rights reserved.  This is an open source license.  Contact
 * Ravenbrook for commercial licensing options.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * 3. Redistributions in any form must be accompanied by information on how
 * to obtain complete source code for this software and any accompanying
 * software that uses this software.  The source code must either be
 * included in the distribution or be available for no more than the cost
 * of distribution plus a nominal fee, and must be freely redistributable
 * under reasonable conditions.  For an executable file, complete source
 * code means the source code for all modules it contains. It does not
 * include source code for modules or files that typically accompany the
 * major components of the operating system on which the executable file
 * runs.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */