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source: kBuild/vendor/grep/2.12/lib/i-ring.h

Last change on this file was 2595, checked in by bird, 12 years ago

gnu grep version 2.12 (grep-2.12.tar.xz, md5sum=8d2f0346d08b13c18afb81f0e8aa1e2f)

  • Property svn:eol-style set to native
File size: 1.6 KB
Line 
1/* definitions for a simple ring buffer
2 Copyright (C) 2006, 2009-2012 Free Software Foundation, Inc.
3
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
16
17#include <stdbool.h>
18#include "verify.h"
19
20enum { I_RING_SIZE = 4 };
21verify (1 <= I_RING_SIZE);
22
23/* When ir_empty is true, the ring is empty.
24 Otherwise, ir_data[B..F] are defined, where B..F is the contiguous
25 range of indices, modulo I_RING_SIZE, from back to front, inclusive.
26 Undefined elements of ir_data are always set to ir_default_val.
27 Popping from an empty ring aborts.
28 Pushing onto a full ring returns the displaced value.
29 An empty ring has F==B and ir_empty == true.
30 A ring with one entry still has F==B, but now ir_empty == false. */
31struct I_ring
32{
33 int ir_data[I_RING_SIZE];
34 int ir_default_val;
35 unsigned int ir_front;
36 unsigned int ir_back;
37 bool ir_empty;
38};
39typedef struct I_ring I_ring;
40
41void i_ring_init (I_ring *ir, int ir_default_val);
42int i_ring_push (I_ring *ir, int val);
43int i_ring_pop (I_ring *ir);
44bool i_ring_empty (I_ring const *ir) _GL_ATTRIBUTE_PURE;
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