libobjc/objc/sarray.h

   1 /* Sparse Arrays for Objective C dispatch tables
   2    Copyright (C) 1993, 1995, 1996 Free Software Foundation, Inc.
   3    Contributed by Kresten Krab Thorup.
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 /* As a special exception, if you link this library with files
  23    compiled with GCC to produce an executable, this does not cause
  24    the resulting executable to be covered by the GNU General Public License.
  25    This exception does not however invalidate any other reasons why
  26    the executable file might be covered by the GNU General Public License.  */
  27
  28 #ifndef __sarray_INCLUDE_GNU
  29 #define __sarray_INCLUDE_GNU
  30
  31 #define OBJC_SPARSE2            /* 2-level sparse array */
  32 /* #define OBJC_SPARSE3 */      /* 3-level sparse array */
  33
  34 #ifdef OBJC_SPARSE2
  35 extern const char* __objc_sparse2_id;
  36 #endif
  37
  38 #ifdef OBJC_SPARSE3
  39 extern const char* __objc_sparse3_id;
  40 #endif
  41
  42 #include <stddef.h>
  43
  44 #include "objc/thr.h"
  45
  46 extern int nbuckets;            /* for stats */
  47 extern int nindices;
  48 extern int narrays;
  49 extern int idxsize;
  50
  51 #include <assert.h>
  52
  53 /* An unsigned integer of same size as a pointer */
  54 #define SIZET_BITS (sizeof(size_t)*8)
  55
  56 #if defined(__sparc__) || defined(OBJC_SPARSE2)
  57 #define PRECOMPUTE_SELECTORS
  58 #endif
  59
  60 #ifdef OBJC_SPARSE3
  61
  62 /* Buckets are 8 words each */
  63 #define BUCKET_BITS 3
  64 #define BUCKET_SIZE (1<<BUCKET_BITS)
  65 #define BUCKET_MASK (BUCKET_SIZE-1)
  66
  67 /* Indices are 16 words each */
  68 #define INDEX_BITS 4
  69 #define INDEX_SIZE (1<<INDEX_BITS)
  70 #define INDEX_MASK (INDEX_SIZE-1)
  71
  72 #define INDEX_CAPACITY (BUCKET_SIZE*INDEX_SIZE)
  73
  74 #else /* OBJC_SPARSE2 */
  75
  76 /* Buckets are 32 words each */
  77 #define BUCKET_BITS 5
  78 #define BUCKET_SIZE (1<<BUCKET_BITS)
  79 #define BUCKET_MASK (BUCKET_SIZE-1)
  80
  81 #endif /* OBJC_SPARSE2 */
  82
  83 typedef size_t sidx;
  84
  85 #ifdef PRECOMPUTE_SELECTORS
  86
  87 struct soffset {
  88 #ifdef OBJC_SPARSE3
  89   unsigned int unused : SIZET_BITS/4;
  90   unsigned int eoffset : SIZET_BITS/4;
  91   unsigned int boffset : SIZET_BITS/4;
  92   unsigned int ioffset : SIZET_BITS/4;
  93 #else /* OBJC_SPARSE2 */
  94 #ifdef __sparc__
  95   unsigned long boffset : (SIZET_BITS - 2) - BUCKET_BITS;
  96   unsigned int eoffset : BUCKET_BITS;
  97   unsigned int unused  : 2;
  98 #else
  99   unsigned int boffset : SIZET_BITS/2;
 100   unsigned int eoffset : SIZET_BITS/2;
 101 #endif
 102 #endif /* OBJC_SPARSE2 */
 103 };
 104
 105 union sofftype {
 106   struct soffset off;
 107   sidx idx;
 108 };
 109
 110 #endif /* not PRECOMPUTE_SELECTORS */
 111
 112 union sversion {
 113   int   version;
 114   void *next_free;
 115 };
 116
 117 struct sbucket {
 118   void* elems[BUCKET_SIZE];     /* elements stored in array */
 119   union sversion        version;                /* used for copy-on-write */
 120 };
 121
 122 #ifdef OBJC_SPARSE3
 123
 124 struct sindex {
 125   struct sbucket* buckets[INDEX_SIZE];
 126   union sversion        version;                /* used for copy-on-write */
 127 };
 128
 129 #endif /* OBJC_SPARSE3 */
 130
 131 struct sarray {
 132 #ifdef OBJC_SPARSE3
 133   struct sindex** indices;
 134   struct sindex* empty_index;
 135 #else /* OBJC_SPARSE2 */
 136   struct sbucket** buckets;
 137 #endif  /* OBJC_SPARSE2 */
 138   struct sbucket* empty_bucket;
 139   union sversion        version;                /* used for copy-on-write */
 140   short ref_count;
 141   struct sarray* is_copy_of;
 142   size_t capacity;
 143 };
 144
 145 struct sarray* sarray_new(int, void* default_element);
 146 void sarray_free(struct sarray*);
 147 struct sarray* sarray_lazy_copy(struct sarray*);
 148 void sarray_realloc(struct sarray*, int new_size);
 149 void sarray_at_put(struct sarray*, sidx index, void* elem);
 150 void sarray_at_put_safe(struct sarray*, sidx index, void* elem);
 151
 152 struct sarray* sarray_hard_copy(struct sarray*); /* ... like the name? */
 153 void sarray_remove_garbage(void);
 154 \f
 155
 156 #ifdef PRECOMPUTE_SELECTORS
 157 /* Transform soffset values to ints and vica verca */
 158 static inline unsigned int
 159 soffset_decode(sidx index)
 160 {
 161   union sofftype x;
 162   x.idx = index;
 163 #ifdef OBJC_SPARSE3
 164   return x.off.eoffset
 165     + (x.off.boffset*BUCKET_SIZE)
 166       + (x.off.ioffset*INDEX_CAPACITY);
 167 #else /* OBJC_SPARSE2 */
 168   return x.off.eoffset + (x.off.boffset*BUCKET_SIZE);
 169 #endif /* OBJC_SPARSE2 */
 170 }
 171
 172 static inline sidx
 173 soffset_encode(size_t offset)
 174 {
 175   union sofftype x;
 176   x.off.eoffset = offset%BUCKET_SIZE;
 177 #ifdef OBJC_SPARSE3
 178   x.off.boffset = (offset/BUCKET_SIZE)%INDEX_SIZE;
 179   x.off.ioffset = offset/INDEX_CAPACITY;
 180 #else /* OBJC_SPARSE2 */
 181   x.off.boffset = offset/BUCKET_SIZE;
 182 #endif
 183   return (sidx)x.idx;
 184 }
 185
 186 #else /* not PRECOMPUTE_SELECTORS */
 187
 188 static inline size_t
 189 soffset_decode(sidx index)
 190 {
 191   return index;
 192 }
 193
 194 static inline sidx
 195 soffset_encode(size_t offset)
 196 {
 197   return offset;
 198 }
 199 #endif /* not PRECOMPUTE_SELECTORS */
 200
 201 /* Get element from the Sparse array `array' at offset `index' */
 202
 203 static inline void* sarray_get(struct sarray* array, sidx index)
 204 {
 205 #ifdef PRECOMPUTE_SELECTORS
 206   union sofftype x;
 207   x.idx = index;
 208 #ifdef OBJC_SPARSE3
 209   return
 210     array->
 211       indices[x.off.ioffset]->
 212         buckets[x.off.boffset]->
 213           elems[x.off.eoffset];
 214 #else /* OBJC_SPARSE2 */
 215   return array->buckets[x.off.boffset]->elems[x.off.eoffset];
 216 #endif /* OBJC_SPARSE2 */
 217 #else /* not PRECOMPUTE_SELECTORS */
 218 #ifdef OBJC_SPARSE3
 219   return array->
 220     indices[index/INDEX_CAPACITY]->
 221       buckets[(index/BUCKET_SIZE)%INDEX_SIZE]->
 222         elems[index%BUCKET_SIZE];
 223 #else /* OBJC_SPARSE2 */
 224   return array->buckets[index/BUCKET_SIZE]->elems[index%BUCKET_SIZE];
 225 #endif /* not OBJC_SPARSE3 */
 226 #endif /* not PRECOMPUTE_SELECTORS */
 227 }
 228
 229 static inline void* sarray_get_safe(struct sarray* array, sidx index)
 230 {
 231   if(soffset_decode(index) < array->capacity)
 232     return sarray_get(array, index);
 233   else
 234     return (array->empty_bucket->elems[0]);
 235 }
 236
 237 #endif /* __sarray_INCLUDE_GNU */