2 Copyright (C) 2000 Paul Davis & Benno Senoner
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 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, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 //#include <sys/mman.h>
32 RingBuffer (size_t sz) {
35 for (power_of_two = 1; 1U<<power_of_two < sz; power_of_two++);
37 size = 1<<power_of_two;
45 virtual ~RingBuffer() {
50 /* !!! NOT THREAD SAFE !!! */
51 g_atomic_int_set (&write_ptr, 0);
52 g_atomic_int_set (&read_ptr, 0);
55 void set (size_t r, size_t w) {
56 /* !!! NOT THREAD SAFE !!! */
57 g_atomic_int_set (&write_ptr, w);
58 g_atomic_int_set (&read_ptr, r);
61 size_t read (T *dest, size_t cnt);
62 size_t write (T *src, size_t cnt);
69 void get_read_vector (rw_vector *);
70 void get_write_vector (rw_vector *);
72 void decrement_read_ptr (size_t cnt) {
73 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) - cnt) & size_mask);
76 void increment_read_ptr (size_t cnt) {
77 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) + cnt) & size_mask);
80 void increment_write_ptr (size_t cnt) {
81 g_atomic_int_set (&write_ptr, (g_atomic_int_get(&write_ptr) + cnt) & size_mask);
84 size_t write_space () {
87 w = g_atomic_int_get (&write_ptr);
88 r = g_atomic_int_get (&read_ptr);
91 return ((r - w + size) & size_mask) - 1;
99 size_t read_space () {
102 w = g_atomic_int_get (&write_ptr);
103 r = g_atomic_int_get (&read_ptr);
108 return (w - r + size) & size_mask;
112 T *buffer () { return buf; }
113 size_t get_write_ptr () const { return g_atomic_int_get (&write_ptr); }
114 size_t get_read_ptr () const { return g_atomic_int_get (&read_ptr); }
115 size_t bufsize () const { return size; }
120 mutable gint write_ptr;
121 mutable gint read_ptr;
125 template<class T> size_t
126 RingBuffer<T>::read (T *dest, size_t cnt)
132 size_t priv_read_ptr;
134 priv_read_ptr=g_atomic_int_get(&read_ptr);
136 if ((free_cnt = read_space ()) == 0) {
140 to_read = cnt > free_cnt ? free_cnt : cnt;
142 cnt2 = priv_read_ptr + to_read;
145 n1 = size - priv_read_ptr;
146 n2 = cnt2 & size_mask;
152 memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
153 priv_read_ptr = (priv_read_ptr + n1) & size_mask;
156 memcpy (dest+n1, buf, n2 * sizeof (T));
160 g_atomic_int_set(&read_ptr, priv_read_ptr);
164 template<class T> size_t
165 RingBuffer<T>::write (T *src, size_t cnt)
172 size_t priv_write_ptr;
174 priv_write_ptr=g_atomic_int_get(&write_ptr);
176 if ((free_cnt = write_space ()) == 0) {
180 to_write = cnt > free_cnt ? free_cnt : cnt;
182 cnt2 = priv_write_ptr + to_write;
185 n1 = size - priv_write_ptr;
186 n2 = cnt2 & size_mask;
192 memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
193 priv_write_ptr = (priv_write_ptr + n1) & size_mask;
196 memcpy (buf, src+n1, n2 * sizeof (T));
200 g_atomic_int_set(&write_ptr, priv_write_ptr);
204 template<class T> void
205 RingBuffer<T>::get_read_vector (RingBuffer<T>::rw_vector *vec)
212 w = g_atomic_int_get (&write_ptr);
213 r = g_atomic_int_get (&read_ptr);
218 free_cnt = (w - r + size) & size_mask;
224 /* Two part vector: the rest of the buffer after the
225 current write ptr, plus some from the start of
229 vec->buf[0] = &buf[r];
230 vec->len[0] = size - r;
232 vec->len[1] = cnt2 & size_mask;
236 /* Single part vector: just the rest of the buffer */
238 vec->buf[0] = &buf[r];
239 vec->len[0] = free_cnt;
244 template<class T> void
245 RingBuffer<T>::get_write_vector (RingBuffer<T>::rw_vector *vec)
252 w = g_atomic_int_get (&write_ptr);
253 r = g_atomic_int_get (&read_ptr);
256 free_cnt = ((r - w + size) & size_mask) - 1;
258 free_cnt = (r - w) - 1;
267 /* Two part vector: the rest of the buffer after the
268 current write ptr, plus some from the start of
272 vec->buf[0] = &buf[w];
273 vec->len[0] = size - w;
275 vec->len[1] = cnt2 & size_mask;
277 vec->buf[0] = &buf[w];
278 vec->len[0] = free_cnt;
284 #endif /* __ringbuffer_h__ */