Line data    Source code

       1             : /* a simple ring buffer
       2             :    Copyright (C) 2006 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             : /* written by Jim Meyering */
      18             : 
      19             : #include <config.h>
      20             : #include "i-ring.h"
      21             : 
      22             : #include <stdlib.h>
      23             : 
      24             : void
      25         176 : i_ring_init (I_ring *ir, int default_val)
      26             : {
      27             :   int i;
      28         176 :   ir->ir_empty = true;
      29         176 :   ir->ir_front = 0;
      30         176 :   ir->ir_back = 0;
      31         880 :   for (i = 0; i < I_RING_SIZE; i++)
      32         704 :     ir->ir_data[i] = default_val;
      33         176 :   ir->ir_default_val = default_val;
      34         176 : }
      35             : 
      36             : bool
      37      190391 : i_ring_empty (I_ring const *ir)
      38             : {
      39      190391 :   return ir->ir_empty;
      40             : }
      41             : 
      42             : int
      43      106278 : i_ring_push (I_ring *ir, int val)
      44             : {
      45      106278 :   unsigned int dest_idx = (ir->ir_front + !ir->ir_empty) % I_RING_SIZE;
      46      106278 :   int old_val = ir->ir_data[dest_idx];
      47      106278 :   ir->ir_data[dest_idx] = val;
      48      106278 :   ir->ir_front = dest_idx;
      49      106278 :   if (dest_idx == ir->ir_back)
      50       32065 :     ir->ir_back = (ir->ir_back + !ir->ir_empty) % I_RING_SIZE;
      51      106278 :   ir->ir_empty = false;
      52      106278 :   return old_val;
      53             : }
      54             : 
      55             : int
      56       83694 : i_ring_pop (I_ring *ir)
      57             : {
      58             :   int top_val;
      59       83694 :   if (i_ring_empty (ir))
      60           0 :     abort ();
      61       83694 :   top_val = ir->ir_data[ir->ir_front];
      62       83694 :   ir->ir_data[ir->ir_front] = ir->ir_default_val;
      63       83694 :   if (ir->ir_front == ir->ir_back)
      64        9481 :     ir->ir_empty = true;
      65             :   else
      66       74213 :     ir->ir_front = ((ir->ir_front + I_RING_SIZE - 1) % I_RING_SIZE);
      67       83694 :   return top_val;
      68             : }