FD.io VPP  v20.01-48-g3e0dafb74
Vector Packet Processing
sparse_vec.h
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2015 Cisco and/or its affiliates.
3  * Licensed under the Apache License, Version 2.0 (the "License");
4  * you may not use this file except in compliance with the License.
5  * You may obtain a copy of the License at:
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software
10  * distributed under the License is distributed on an "AS IS" BASIS,
11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  * See the License for the specific language governing permissions and
13  * limitations under the License.
14  */
15 /*
16  Copyright (c) 2005 Eliot Dresselhaus
17 
18  Permission is hereby granted, free of charge, to any person obtaining
19  a copy of this software and associated documentation files (the
20  "Software"), to deal in the Software without restriction, including
21  without limitation the rights to use, copy, modify, merge, publish,
22  distribute, sublicense, and/or sell copies of the Software, and to
23  permit persons to whom the Software is furnished to do so, subject to
24  the following conditions:
25 
26  The above copyright notice and this permission notice shall be
27  included in all copies or substantial portions of the Software.
28 
29  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
30  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
31  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
32  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
33  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
34  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
35  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
36 */
37 
38 #ifndef included_sparse_vec_h
39 #define included_sparse_vec_h
40 
41 #include <vppinfra/vec.h>
42 #include <vppinfra/bitops.h>
43 
44 /* Sparsely indexed vectors. Basic idea taken from Hacker's delight.
45  Eliot added ranges. */
46 typedef struct
47 {
48  /* Bitmap one for each sparse index. */
50 
51  /* member_counts[i] = total number of members with j < i. */
53 
54 #define SPARSE_VEC_IS_RANGE (1 << 0)
55 #define SPARSE_VEC_IS_VALID_RANGE (1 << 1)
58 
61 {
62  return vec_header (v, sizeof (sparse_vec_header_t));
63 }
64 
65 /* Index 0 is always used to mark indices that are not valid in
66  sparse vector. For example, you look up V[0x1234] and 0x1234 is not
67  known you'll get 0 back as an index. */
68 #define SPARSE_VEC_INVALID_INDEX (0)
69 
70 always_inline void *
71 sparse_vec_new (uword elt_bytes, uword sparse_index_bits)
72 {
73  void *v;
75  word n;
76 
77  ASSERT (sparse_index_bits <= 16);
78 
79  v = _vec_resize ((void *) 0,
80  /* length increment */ 8,
81  /* data bytes */ 8 * elt_bytes,
82  /* header bytes */ sizeof (h[0]),
83  /* data align */ 0);
84 
85  /* Make space for invalid entry (entry 0). */
86  _vec_len (v) = 1;
87 
88  h = sparse_vec_header (v);
89 
90  n = sparse_index_bits - min_log2 (BITS (uword));
91  if (n < 0)
92  n = 0;
93  n = 1ULL << n;
95  vec_resize (h->member_counts, n);
96 
97  return v;
98 }
99 
102  uword sparse_index,
103  uword maybe_range, u32 * insert)
104 {
106  uword i, b, d, w;
107  u8 is_member;
108 
109  h = sparse_vec_header (v);
110  i = sparse_index / BITS (h->is_member_bitmap[0]);
111  b = sparse_index % BITS (h->is_member_bitmap[0]);
112 
113  ASSERT (i < vec_len (h->is_member_bitmap));
114  ASSERT (i < vec_len (h->member_counts));
115 
116  w = h->is_member_bitmap[i];
117 
118  /* count_trailing_zeros(0) == 0, take care of that case */
119  if (PREDICT_FALSE (maybe_range == 0 && insert == 0 && w == 0))
120  return 0;
121 
122  if (PREDICT_TRUE (maybe_range == 0 && insert == 0 &&
123  count_trailing_zeros (w) == b))
124  return h->member_counts[i] + 1;
125 
126  d = h->member_counts[i] + count_set_bits (w & ((1ULL << b) - 1));
127  is_member = (w & (1ULL << b)) != 0;
128 
129  if (maybe_range)
130  {
131  u8 r = h->range_flags[d];
132  u8 is_range, is_valid_range;
133 
134  is_range = maybe_range & (r & SPARSE_VEC_IS_RANGE);
135  is_valid_range = (r & SPARSE_VEC_IS_VALID_RANGE) != 0;
136 
137  is_member = is_range ? is_valid_range : is_member;
138  }
139 
140  if (insert)
141  {
142  *insert = !is_member;
143  if (!is_member)
144  {
145  uword j;
146  w |= 1ULL << b;
147  h->is_member_bitmap[i] = w;
148  for (j = i + 1; j < vec_len (h->member_counts); j++)
149  h->member_counts[j] += 1;
150  }
151 
152  return 1 + d;
153  }
154 
155  d = is_member ? d : 0;
156 
157  return is_member + d;
158 }
159 
161 sparse_vec_index (void *v, uword sparse_index)
162 {
163  return sparse_vec_index_internal (v, sparse_index,
164  /* maybe range */ 0,
165  /* insert? */ 0);
166 }
167 
168 always_inline void
170  u32 si0, u32 si1, u32 * i0_return, u32 * i1_return)
171 {
173  uword b0, b1, w0, w1, v0, v1;
174  u32 i0, i1, d0, d1;
175  u8 is_member0, is_member1;
176 
177  h = sparse_vec_header (v);
178 
179  i0 = si0 / BITS (h->is_member_bitmap[0]);
180  i1 = si1 / BITS (h->is_member_bitmap[0]);
181 
182  b0 = si0 % BITS (h->is_member_bitmap[0]);
183  b1 = si1 % BITS (h->is_member_bitmap[0]);
184 
185  ASSERT (i0 < vec_len (h->is_member_bitmap));
186  ASSERT (i1 < vec_len (h->is_member_bitmap));
187 
188  ASSERT (i0 < vec_len (h->member_counts));
189  ASSERT (i1 < vec_len (h->member_counts));
190 
191  w0 = h->is_member_bitmap[i0];
192  w1 = h->is_member_bitmap[i1];
193 
194  if (PREDICT_TRUE ((count_trailing_zeros (w0) == b0) +
195  (count_trailing_zeros (w1) == b1) == 2))
196  {
197  *i0_return = h->member_counts[i0] + 1;
198  *i1_return = h->member_counts[i1] + 1;
199  return;
200  }
201 
202  v0 = w0 & ((1ULL << b0) - 1);
203  v1 = w1 & ((1ULL << b1) - 1);
204 
205  /* Speculate that masks will have zero or one bits set. */
206  d0 = h->member_counts[i0] + (v0 != 0);
207  d1 = h->member_counts[i1] + (v1 != 0);
208 
209  /* Validate speculation. */
210  if (PREDICT_FALSE (!is_pow2 (v0) || !is_pow2 (v1)))
211  {
212  d0 += count_set_bits (v0) - (v0 != 0);
213  d1 += count_set_bits (v1) - (v1 != 0);
214  }
215 
216  is_member0 = (w0 & (1ULL << b0)) != 0;
217  is_member1 = (w1 & (1ULL << b1)) != 0;
218 
219  d0 = is_member0 ? d0 : 0;
220  d1 = is_member1 ? d1 : 0;
221 
222  *i0_return = is_member0 + d0;
223  *i1_return = is_member1 + d1;
224 }
225 
226 #define sparse_vec_free(v) vec_free(v)
227 
228 #define sparse_vec_elt_at_index(v,i) \
229  vec_elt_at_index ((v), sparse_vec_index ((v), (i)))
230 
231 #define sparse_vec_validate(v,i) \
232 ({ \
233  uword _i; \
234  u32 _insert; \
235  \
236  if (! (v)) \
237  (v) = sparse_vec_new (sizeof ((v)[0]), BITS (u16)); \
238  \
239  _i = sparse_vec_index_internal ((v), (i), \
240  /* maybe range */ 0, \
241  /* insert? */ &_insert); \
242  if (_insert) \
243  vec_insert_ha ((v), 1, _i, \
244  /* header size */ sizeof (sparse_vec_header_t), \
245  /* align */ 0); \
246  \
247  /* Invalid index is 0. */ \
248  ASSERT (_i > 0); \
249  \
250  (v) + _i; \
251 })
252 
253 #endif /* included_sparse_vec_h */
254 
255 /*
256  * fd.io coding-style-patch-verification: ON
257  *
258  * Local Variables:
259  * eval: (c-set-style "gnu")
260  * End:
261  */
#define SPARSE_VEC_IS_RANGE
Definition: sparse_vec.h:54
#define PREDICT_TRUE(x)
Definition: clib.h:112
int i
unsigned char u8
Definition: types.h:56
#define count_trailing_zeros(x)
Definition: clib.h:139
static uword min_log2(uword x)
Definition: clib.h:144
i64 word
Definition: types.h:111
#define vec_resize(V, N)
Resize a vector (no header, unspecified alignment) Add N elements to end of given vector V...
Definition: vec.h:243
unsigned int u32
Definition: types.h:88
static void sparse_vec_index2(void *v, u32 si0, u32 si1, u32 *i0_return, u32 *i1_return)
Definition: sparse_vec.h:169
unsigned short u16
Definition: types.h:57
#define PREDICT_FALSE(x)
Definition: clib.h:111
#define always_inline
Definition: ipsec.h:28
static sparse_vec_header_t * sparse_vec_header(void *v)
Definition: sparse_vec.h:60
static uword sparse_vec_index(void *v, uword sparse_index)
Definition: sparse_vec.h:161
#define ASSERT(truth)
static uword is_pow2(uword x)
Definition: clib.h:235
static uword sparse_vec_index_internal(void *v, uword sparse_index, uword maybe_range, u32 *insert)
Definition: sparse_vec.h:101
#define vec_len(v)
Number of elements in vector (rvalue-only, NULL tolerant)
u64 uword
Definition: types.h:112
#define SPARSE_VEC_IS_VALID_RANGE
Definition: sparse_vec.h:55
static void * vec_header(void *v, uword header_bytes)
Find a user vector header.
Definition: vec_bootstrap.h:93
static uword count_set_bits(uword x)
Definition: bitops.h:45
uword * is_member_bitmap
Definition: sparse_vec.h:49
static void * sparse_vec_new(uword elt_bytes, uword sparse_index_bits)
Definition: sparse_vec.h:71
#define BITS(x)
Definition: clib.h:61
CLIB vectors are ubiquitous dynamically resized arrays with by user defined "headers".