1 /* a simple ring buffer
2 Copyright (C) 2006, 2009-2011 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 3 of the License, or
7 (at your option) any later version.
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, see <http://www.gnu.org/licenses/>. */
17 /* written by Jim Meyering */
25 i_ring_init (I_ring *ir, int default_val)
31 for (i = 0; i < I_RING_SIZE; i++)
32 ir->ir_data[i] = default_val;
33 ir->ir_default_val = default_val;
37 i_ring_empty (I_ring const *ir)
43 i_ring_push (I_ring *ir, int val)
45 unsigned int dest_idx = (ir->ir_front + !ir->ir_empty) % I_RING_SIZE;
46 int old_val = ir->ir_data[dest_idx];
47 ir->ir_data[dest_idx] = val;
48 ir->ir_front = dest_idx;
49 if (dest_idx == ir->ir_back)
50 ir->ir_back = (ir->ir_back + !ir->ir_empty) % I_RING_SIZE;
56 i_ring_pop (I_ring *ir)
59 if (i_ring_empty (ir))
61 top_val = ir->ir_data[ir->ir_front];
62 ir->ir_data[ir->ir_front] = ir->ir_default_val;
63 if (ir->ir_front == ir->ir_back)
66 ir->ir_front = ((ir->ir_front + I_RING_SIZE - 1) % I_RING_SIZE);