| 1 | //
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| 2 | // Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo
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| 3 | //
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| 4 | // The contents of this file are covered under the licence agreement in the
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| 5 | // file "LICENCE" distributed with Cforall.
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| 6 | //
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| 7 | // list -- lets a user-defined stuct form intrusive linked lists
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| 8 | //
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| 9 | // Author : Michael Brooks
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| 10 | // Created On : Wed Apr 22 18:00:00 2020
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| 11 | // Last Modified By : Michael Brooks
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| 12 | // Last Modified On : Wed Apr 22 18:00:00 2020
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| 13 | // Update Count : 1
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| 14 | //
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| 15 |
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| 16 | #pragma once
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| 17 |
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| 18 | #include <assert.h>
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| 19 |
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| 20 | forall( Decorator &, T & )
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| 21 | struct tytagref {
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| 22 | inline T &;
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| 23 | };
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| 24 |
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| 25 | trait embedded( tOuter &, tMid &, tInner & ) {
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| 26 | tytagref( tMid, tInner ) ?`inner( tOuter & );
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| 27 | };
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| 28 |
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| 29 | // embedded is reflexive, with no info (void) as the type tag
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| 30 | forall (T &)
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| 31 | static inline tytagref(void, T) ?`inner ( T & this ) { tytagref( void, T ) ret = {this}; return ret; }
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| 32 |
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| 33 | // use this on every case of plan-9 inheritance, to make embedded a closure of plan-9 inheritance
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| 34 | #define P9_EMBEDDED( derived, immedBase ) \
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| 35 | forall( Tbase &, TdiscardPath & | { tytagref( TdiscardPath, Tbase ) ?`inner( immedBase & ); } ) \
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| 36 | static inline tytagref(immedBase, Tbase) ?`inner( derived & this ) { \
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| 37 | immedBase & ib = this; \
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| 38 | Tbase & b = ib`inner; \
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| 39 | tytagref(immedBase, Tbase) result = { b }; \
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| 40 | return result; \
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| 41 | }
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| 42 |
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| 43 | #define EMBEDDED_VIA( OUTER, MID, INNER ) \
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| 44 | (struct { tytagref(MID, INNER) ( * ?`inner ) ( OUTER & ); }){ ?`inner }
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| 45 |
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| 46 | #define DLINK_VIA( TE, TLINK ) \
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| 47 | EMBEDDED_VIA( TE, TLINK, dlink(TE) )
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| 48 |
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| 49 |
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| 50 | // The origin is the position encountered at the start of iteration,
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| 51 | // signifying, "need to advance to the first element," and at the end
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| 52 | // of iteration, signifying, "no more elements." Normal comsumption of
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| 53 | // an iterator runs ?`moveNext as the first step, and uses the return
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| 54 | // of ?`moveNext as a guard, before dereferencing the iterator. So
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| 55 | // normal consumption of an iterator does not dereference an iterator
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| 56 | // in origin position. The value of a pointer (underlying a refence)
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| 57 | // that is exposed publicly as an iteraor, and also a pointer stored
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| 58 | // internally in a link field, is tagged, to indicate "is the origin"
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| 59 | // (internally, is the list-head sentinel node), or untagged, to indicate
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| 60 | // "is a regular node." Intent is to help a user who dereferences an
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| 61 | // iterator in origin position (which would be an API-use error on their
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| 62 | // part), by failing fast.
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| 63 |
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| 64 | #if defined( __x86_64 )
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| 65 | // Preferred case: tag in the most-significant bit. Dereference
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| 66 | // has been shown to segfault consistently. Maintenance should
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| 67 | // list more architectures as "ok" here, to let them use the
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| 68 | // preferred case, when valid.
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| 69 | #define ORIGIN_TAG_BITNO ( 8 * sizeof( size_t ) - 1 )
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| 70 | #else
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| 71 | // Fallback case: tag in the least-significant bit. Dereference
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| 72 | // will often give an alignment error, but may not, e.g. if
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| 73 | // accessing a char-typed member. 32-bit x86 uses the most-
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| 74 | // significant bit for real room on the heap.
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| 75 | #define ORIGIN_TAG_BITNO 0
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| 76 | #endif
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| 77 | #define ORIGIN_TAG_MASK (((size_t)1) << ORIGIN_TAG_BITNO)
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| 78 |
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| 79 | #define ORIGIN_TAG_SET(p) ((p) | ORIGIN_TAG_MASK)
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| 80 | #define ORIGIN_TAG_CLEAR(p) ((p) & ~ORIGIN_TAG_MASK)
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| 81 | #define ORIGIN_TAG_QUERY(p) ((p) & ORIGIN_TAG_MASK)
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| 82 |
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| 83 |
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| 84 | forall( tE & ) {
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| 85 |
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| 86 | struct dlink{
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| 87 | tE *next;
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| 88 | tE *prev;
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| 89 | };
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| 90 |
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| 91 | static inline void ?{}( dlink(tE) & this ) {
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| 92 | this.next = 0p;
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| 93 | this.prev = 0p;
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| 94 | }
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| 95 |
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| 96 | forall( tLinks & = dlink(tE) )
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| 97 | struct dlist {
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| 98 | inline dlink(tE);
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| 99 | };
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| 100 |
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| 101 | forall( tLinks & | embedded( tE, tLinks, dlink(tE) ) ) {
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| 102 | static inline tE * $get_list_origin_addr( dlist(tE, tLinks) & lst ) {
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| 103 | dlink(tE) & link_from_null = ( * (tE *) 0p )`inner;
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| 104 | ptrdiff_t link_offset = (ptrdiff_t) & link_from_null;
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| 105 | size_t origin_addr = ((size_t) & lst) - link_offset;
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| 106 | size_t preResult = ORIGIN_TAG_SET( origin_addr );
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| 107 | return (tE *)preResult;
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| 108 | }
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| 109 |
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| 110 | static inline void ?{}( dlist(tE, tLinks) & this ) {
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| 111 | tE * listOrigin = $get_list_origin_addr( this );
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| 112 | ( ( dlink(tE) & ) this ){ listOrigin, listOrigin } ;
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| 113 | }
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| 114 | }
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| 115 |
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| 116 | }
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| 117 |
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| 118 |
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| 119 | forall( tE &, tLinks & | embedded( tE, tLinks, dlink(tE) ) ) {
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| 120 |
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| 121 | static inline void insert_after(tE & list_pos, tE &to_insert) {
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| 122 | verify (&list_pos != 0p);
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| 123 | verify (&to_insert != 0p);
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| 124 | dlink(tE) & linkToInsert = to_insert`inner;
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| 125 | verify(linkToInsert.prev == 0p);
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| 126 | verify(linkToInsert.next == 0p);
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| 127 | tE & list_pos_elem = * (tE *) ORIGIN_TAG_CLEAR( (size_t) & list_pos );
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| 128 | dlink(tE) & list_pos_links = list_pos_elem`inner;
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| 129 | asm( "" : : : "memory" );
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| 130 | tE & after_raw = * list_pos_links.next;
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| 131 | tE & after_elem = * (tE *) ORIGIN_TAG_CLEAR( (size_t) & after_raw );
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| 132 | linkToInsert.prev = & list_pos;
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| 133 | linkToInsert.next = & after_raw;
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| 134 | dlink(tE) & afterLinks = after_elem`inner;
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| 135 | afterLinks.prev = &to_insert;
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| 136 | list_pos_links.next = &to_insert;
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| 137 | asm( "" : : : "memory" );
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| 138 | }
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| 139 |
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| 140 | static inline void insert_before(tE & list_pos, tE &to_insert) {
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| 141 | verify (&list_pos != 0p);
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| 142 | verify (&to_insert != 0p);
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| 143 | dlink(tE) & linkToInsert = to_insert`inner;
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| 144 | verify(linkToInsert.next == 0p);
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| 145 | verify(linkToInsert.prev == 0p);
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| 146 | tE & list_pos_elem = * (tE *) ORIGIN_TAG_CLEAR( (size_t) & list_pos );
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| 147 | dlink(tE) & list_pos_links = list_pos_elem`inner;
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| 148 | asm( "" : : : "memory" );
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| 149 | tE & before_raw = * (list_pos_links).prev;
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| 150 | tE & before_elem = * (tE *) ORIGIN_TAG_CLEAR( (size_t) & before_raw );
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| 151 | linkToInsert.next = & list_pos;
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| 152 | linkToInsert.prev = & before_raw;
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| 153 | dlink(tE) & beforeLinks = before_elem`inner;
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| 154 | beforeLinks.next = &to_insert;
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| 155 | (list_pos_links).prev = &to_insert;
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| 156 | asm( "" : : : "memory" );
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| 157 | }
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| 158 |
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| 159 | static inline tE & remove(tE & list_pos) {
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| 160 | verify (&list_pos != 0p);
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| 161 | verify( ! ORIGIN_TAG_QUERY((size_t) & list_pos) );
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| 162 | dlink(tE) & list_pos_links = list_pos`inner;
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| 163 | tE & before_raw = * list_pos_links.prev;
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| 164 | tE & before_elem = * (tE *) ORIGIN_TAG_CLEAR( (size_t) & before_raw );
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| 165 | dlink(tE) & before_links = before_elem`inner;
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| 166 | tE & after_raw = * list_pos_links.next;
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| 167 | tE & after_elem = * (tE *) ORIGIN_TAG_CLEAR( (size_t) & after_raw );
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| 168 | dlink(tE) & after_links = after_elem`inner;
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| 169 | before_links.next = &after_raw;
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| 170 | after_links.prev = &before_raw;
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| 171 | asm( "" : : : "memory" );
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| 172 | list_pos_links.prev = 0p;
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| 173 | list_pos_links.next = 0p;
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| 174 | asm( "" : : : "memory" );
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| 175 | return list_pos;
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| 176 | }
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| 177 |
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| 178 | static inline tE & ?`first( dlist(tE, tLinks) &lst ) {
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| 179 | tE * firstPtr = lst.next;
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| 180 | if (ORIGIN_TAG_QUERY((size_t)firstPtr)) firstPtr = 0p;
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| 181 | return *firstPtr;
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| 182 | }
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| 183 | static inline tE & ?`last ( dlist(tE, tLinks) &lst ) {
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| 184 | tE * lastPtr = lst.prev;
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| 185 | if (ORIGIN_TAG_QUERY((size_t)lastPtr)) lastPtr = 0p;
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| 186 | return *lastPtr;
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| 187 | }
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| 188 |
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| 189 | static inline bool ?`isEmpty( dlist(tE, tLinks) & lst ) {
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| 190 | tE * firstPtr = lst.next;
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| 191 | if (ORIGIN_TAG_QUERY((size_t)firstPtr)) firstPtr = 0p;
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| 192 | return firstPtr == 0p;
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| 193 | }
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| 194 |
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| 195 | static inline bool ?`isListed( tE & e ) {
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| 196 | verify (&e != 0p);
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| 197 | dlink(tE) & e_links = e`inner;
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| 198 | return (e_links.prev != 0p) || (e_links.next != 0p);
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| 199 | }
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| 200 |
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| 201 | static inline tE & ?`elems( dlist(tE, tLinks) & lst ) {
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| 202 | tE * origin = $get_list_origin_addr( lst );
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| 203 | return *origin;
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| 204 | }
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| 205 |
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| 206 | static inline bool ?`moveNext( tE && refx ) {
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| 207 | tE && ref_inner = refx;
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| 208 | tE & oldReferent = * (tE*) ORIGIN_TAG_CLEAR( (size_t) & ref_inner );
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| 209 | &ref_inner = oldReferent`inner.next;
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| 210 | return &ref_inner != 0p &&
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| 211 | ! ORIGIN_TAG_QUERY( (size_t) & ref_inner );
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| 212 | }
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| 213 |
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| 214 | static inline bool ?`movePrev( tE && refx ) {
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| 215 | tE && ref_inner = refx;
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| 216 | tE & oldReferent = * (tE*) ORIGIN_TAG_CLEAR( (size_t) & ref_inner );
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| 217 | &ref_inner = oldReferent`inner.prev;
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| 218 | return &ref_inner != 0p &&
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| 219 | ! ORIGIN_TAG_QUERY( (size_t) & ref_inner );
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| 220 | }
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| 221 |
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| 222 | static inline bool ?`hasNext( tE & e ) {
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| 223 | return e`moveNext;
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| 224 | }
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| 225 |
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| 226 | static inline bool ?`hasPrev( tE & e ) {
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| 227 | return e`movePrev;
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| 228 | }
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| 229 |
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| 230 | static inline tE & ?`next( tE & e ) {
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| 231 | if( e`moveNext ) return e;
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| 232 | return * 0p;
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| 233 | }
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| 234 |
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| 235 | static inline tE & ?`prev( tE & e ) {
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| 236 | if( e`movePrev ) return e;
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| 237 | return * 0p;
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| 238 | }
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| 239 |
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| 240 | static inline void insert_first( dlist(tE, tLinks) &lst, tE & e ) {
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| 241 | insert_after(lst`elems, e);
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| 242 | }
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| 243 |
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| 244 | static inline void insert_last( dlist(tE, tLinks) &lst, tE & e ) {
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| 245 | insert_before(lst`elems, e);
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| 246 | }
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| 247 |
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| 248 | static inline tE & try_pop_front( dlist(tE, tLinks) &lst ) {
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| 249 | tE & first_inlist = lst`first;
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| 250 | tE & first_item = first_inlist;
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| 251 | if (&first_item) remove(first_inlist);
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| 252 | return first_item;
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| 253 | }
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| 254 |
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| 255 | static inline tE & try_pop_back( dlist(tE, tLinks) &lst ) {
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| 256 | tE & last_inlist = lst`last;
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| 257 | tE & last_item = last_inlist;
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| 258 | if (&last_item) remove(last_inlist);
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| 259 | return last_item;
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| 260 | }
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| 261 |
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| 262 |
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| 263 | #if !defined(NDEBUG) && (defined(__CFA_DEBUG__) || defined(__CFA_VERIFY__))
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| 264 | static bool $validate_fwd( dlist(tE, tLinks) & this ) {
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| 265 | if ( ! & this`first ) return ( (& this`last) == 0p);
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| 266 |
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| 267 | tE & lagElem = *0p;
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| 268 |
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| 269 | while ( tE & it = this`elems; it`moveNext ) {
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| 270 | if (& lagElem == 0p && &it != & this`first ) return false;
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| 271 | & lagElem = & it;
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| 272 | }
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| 273 |
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| 274 | if (& lagElem != & this`last) return false;
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| 275 |
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| 276 | // TODO: verify that it is back at this`elems;
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| 277 | return true;
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| 278 | }
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| 279 | static bool $validate_rev( dlist(tE, tLinks) & this ) {
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| 280 | if ( ! & this`last ) return ( (& this`first) == 0p);
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| 281 |
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| 282 | tE & lagElem = *0p;
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| 283 |
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| 284 | while ( tE & it = this`elems; it`movePrev ) {
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| 285 | if (& lagElem == 0p && &it != & this`last ) return false;
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| 286 | & lagElem = & it;
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| 287 | }
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| 288 |
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| 289 | if (& lagElem != & this`first) return false;
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| 290 |
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| 291 | // TODO: verify that it is back at this`elems;
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| 292 | return true;
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| 293 | }
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| 294 | static bool validate( dlist(tE, tLinks) & this ) {
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| 295 | return $validate_fwd(this) && $validate_rev(this);
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| 296 | }
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| 297 | #endif
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| 298 |
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| 299 | }
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| 300 |
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