1cf28ed85SJohn Marino /* a simple ring buffer 2*09d4459fSDaniel Fojt Copyright (C) 2006, 2009-2020 Free Software Foundation, Inc. 3cf28ed85SJohn Marino 4cf28ed85SJohn Marino This program is free software: you can redistribute it and/or modify 5cf28ed85SJohn Marino it under the terms of the GNU General Public License as published by 6cf28ed85SJohn Marino the Free Software Foundation; either version 3 of the License, or 7cf28ed85SJohn Marino (at your option) any later version. 8cf28ed85SJohn Marino 9cf28ed85SJohn Marino This program is distributed in the hope that it will be useful, 10cf28ed85SJohn Marino but WITHOUT ANY WARRANTY; without even the implied warranty of 11cf28ed85SJohn Marino MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12cf28ed85SJohn Marino GNU General Public License for more details. 13cf28ed85SJohn Marino 14cf28ed85SJohn Marino You should have received a copy of the GNU General Public License 15*09d4459fSDaniel Fojt along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16cf28ed85SJohn Marino 17cf28ed85SJohn Marino /* written by Jim Meyering */ 18cf28ed85SJohn Marino 19cf28ed85SJohn Marino #include <config.h> 20cf28ed85SJohn Marino #include "i-ring.h" 21cf28ed85SJohn Marino 22cf28ed85SJohn Marino #include <stdlib.h> 23cf28ed85SJohn Marino 24cf28ed85SJohn Marino void i_ring_init(I_ring * ir,int default_val)25cf28ed85SJohn Marinoi_ring_init (I_ring *ir, int default_val) 26cf28ed85SJohn Marino { 27cf28ed85SJohn Marino int i; 28cf28ed85SJohn Marino ir->ir_empty = true; 29cf28ed85SJohn Marino ir->ir_front = 0; 30cf28ed85SJohn Marino ir->ir_back = 0; 31cf28ed85SJohn Marino for (i = 0; i < I_RING_SIZE; i++) 32cf28ed85SJohn Marino ir->ir_data[i] = default_val; 33cf28ed85SJohn Marino ir->ir_default_val = default_val; 34cf28ed85SJohn Marino } 35cf28ed85SJohn Marino 36cf28ed85SJohn Marino bool i_ring_empty(I_ring const * ir)37cf28ed85SJohn Marinoi_ring_empty (I_ring const *ir) 38cf28ed85SJohn Marino { 39cf28ed85SJohn Marino return ir->ir_empty; 40cf28ed85SJohn Marino } 41cf28ed85SJohn Marino 42cf28ed85SJohn Marino int i_ring_push(I_ring * ir,int val)43cf28ed85SJohn Marinoi_ring_push (I_ring *ir, int val) 44cf28ed85SJohn Marino { 45cf28ed85SJohn Marino unsigned int dest_idx = (ir->ir_front + !ir->ir_empty) % I_RING_SIZE; 46cf28ed85SJohn Marino int old_val = ir->ir_data[dest_idx]; 47cf28ed85SJohn Marino ir->ir_data[dest_idx] = val; 48cf28ed85SJohn Marino ir->ir_front = dest_idx; 49cf28ed85SJohn Marino if (dest_idx == ir->ir_back) 50cf28ed85SJohn Marino ir->ir_back = (ir->ir_back + !ir->ir_empty) % I_RING_SIZE; 51cf28ed85SJohn Marino ir->ir_empty = false; 52cf28ed85SJohn Marino return old_val; 53cf28ed85SJohn Marino } 54cf28ed85SJohn Marino 55cf28ed85SJohn Marino int i_ring_pop(I_ring * ir)56cf28ed85SJohn Marinoi_ring_pop (I_ring *ir) 57cf28ed85SJohn Marino { 58cf28ed85SJohn Marino int top_val; 59cf28ed85SJohn Marino if (i_ring_empty (ir)) 60cf28ed85SJohn Marino abort (); 61cf28ed85SJohn Marino top_val = ir->ir_data[ir->ir_front]; 62cf28ed85SJohn Marino ir->ir_data[ir->ir_front] = ir->ir_default_val; 63cf28ed85SJohn Marino if (ir->ir_front == ir->ir_back) 64cf28ed85SJohn Marino ir->ir_empty = true; 65cf28ed85SJohn Marino else 66cf28ed85SJohn Marino ir->ir_front = ((ir->ir_front + I_RING_SIZE - 1) % I_RING_SIZE); 67cf28ed85SJohn Marino return top_val; 68cf28ed85SJohn Marino } 69