1 /* definitions for a simple ring buffer
2 Copyright (C) 2006 Free Software Foundation, Inc.
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 2, or (at your option)
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.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
21 enum { I_RING_SIZE = 4 };
22 verify (1 <= I_RING_SIZE);
24 /* When ir_empty is true, the ring is empty.
25 Otherwise, ir_data[B..F] are defined, where B..F is the contiguous
26 range of indices, modulo I_RING_SIZE, from back to front, inclusive.
27 Undefined elements of ir_data are always set to ir_default_val.
28 Popping from an empty ring aborts.
29 Pushing onto a full ring returns the displaced value.
30 An empty ring has F==B and ir_empty == true.
31 A ring with one entry still has F==B, but now ir_empty == false. */
34 int ir_data[I_RING_SIZE];
36 unsigned int ir_front;
40 typedef struct I_ring I_ring;
42 void i_ring_init (I_ring *ir, int ir_default_val);
43 int i_ring_push (I_ring *ir, int val);
44 int i_ring_pop (I_ring *ir);
45 bool i_ring_empty (I_ring const *ir);