FD.io VPP  v17.04.2-2-ga8f93f8
Vector Packet Processing
fifo.c
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) 2001, 2002, 2003 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 #include <vppinfra/cache.h>
39 #include <vppinfra/fifo.h>
40 #include <vppinfra/error.h>
41 #include <vppinfra/string.h>
42 
43 /*
44  General first in/first out queues.
45  FIFOs can have arbitrary size and type.
46  Let T be any type (i.e. char, int, struct foo, etc.).
47 
48  A null fifo is initialized:
49 
50  T * f = 0;
51 
52  For example, typedef struct { int a, b; } T;
53 
54  Elements can be added in 3 ways.
55 
56  #1 1 element is added:
57  T x;
58  x.a = 10; x.b = 20;
59  fifo_add1 (f, x);
60 
61  #2 n elements are added
62  T buf[10];
63  initialize buf[0] .. buf[9];
64  fifo_add (f, buf, 10);
65 
66  #3 1 element is added, pointer is returned
67  T * x;
68  fifo_add2 (f, x);
69  x->a = 10;
70  x->b = 20;
71 
72  Elements are removed 1 at a time:
73  T x;
74  fifo_sub1 (f, x);
75 
76  fifo_free (f) frees fifo.
77 */
78 
79 void *
80 _clib_fifo_resize (void *v_old, uword n_new_elts, uword elt_bytes)
81 {
82  void *v_new, *end, *head;
83  uword n_old_elts, header_bytes;
84  uword n_copy_bytes, n_zero_bytes;
85  clib_fifo_header_t *f_new, *f_old;
86 
87  n_old_elts = clib_fifo_elts (v_old);
88  n_new_elts += n_old_elts;
89  if (n_new_elts < 32)
90  n_new_elts = 32;
91  else
92  n_new_elts = max_pow2 (n_new_elts);
93 
94  header_bytes = vec_header_bytes (sizeof (clib_fifo_header_t));
95 
96  v_new = clib_mem_alloc_no_fail (n_new_elts * elt_bytes + header_bytes);
97  v_new += header_bytes;
98 
99  f_new = clib_fifo_header (v_new);
100  f_new->head_index = 0;
101  f_new->tail_index = n_old_elts;
102  _vec_len (v_new) = n_new_elts;
103 
104  /* Copy old -> new. */
105  n_copy_bytes = n_old_elts * elt_bytes;
106  if (n_copy_bytes > 0)
107  {
108  f_old = clib_fifo_header (v_old);
109  end = v_old + _vec_len (v_old) * elt_bytes;
110  head = v_old + f_old->head_index * elt_bytes;
111 
112  if (head + n_copy_bytes >= end)
113  {
114  uword n = end - head;
115  clib_memcpy (v_new, head, n);
116  clib_memcpy (v_new + n, v_old, n_copy_bytes - n);
117  }
118  else
119  clib_memcpy (v_new, head, n_copy_bytes);
120  }
121 
122  /* Zero empty space. */
123  n_zero_bytes = (n_new_elts - n_old_elts) * elt_bytes;
124  memset (v_new + n_copy_bytes, 0, n_zero_bytes);
125 
126  clib_fifo_free (v_old);
127 
128  return v_new;
129 }
130 
131 /*
132  * fd.io coding-style-patch-verification: ON
133  *
134  * Local Variables:
135  * eval: (c-set-style "gnu")
136  * End:
137  */
static uword clib_fifo_elts(void *v)
Definition: fifo.h:66
static uword vec_header_bytes(uword header_bytes)
Definition: vec_bootstrap.h:79
#define clib_mem_alloc_no_fail(size)
Definition: mem.h:153
#define clib_memcpy(a, b, c)
Definition: string.h:69
static uword max_pow2(uword x)
Definition: clib.h:263
u32 head_index
Definition: fifo.h:48
#define clib_fifo_free(f)
Definition: fifo.h:257
u64 uword
Definition: types.h:112
u32 tail_index
Definition: fifo.h:51
static clib_fifo_header_t * clib_fifo_header(void *f)
Definition: fifo.h:55