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.
20 #ifndef ringbuffer_npt_h
21 #define ringbuffer_npt_h
23 //#include <sys/mman.h>
27 /* ringbuffer class where the element size is not required to be a power of two */
33 RingBufferNPT (size_t sz) {
39 virtual ~RingBufferNPT () {
44 /* !!! NOT THREAD SAFE !!! */
45 g_atomic_int_set (&write_ptr, 0);
46 g_atomic_int_set (&read_ptr, 0);
49 void set (size_t r, size_t w) {
50 /* !!! NOT THREAD SAFE !!! */
51 g_atomic_int_set (&write_ptr, w);
52 g_atomic_int_set (&read_ptr, r);
55 size_t read (T *dest, size_t cnt);
56 size_t write (T *src, size_t cnt);
63 void get_read_vector (rw_vector *);
64 void get_write_vector (rw_vector *);
66 void decrement_read_ptr (size_t cnt) {
67 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) - cnt) % size);
70 void increment_read_ptr (size_t cnt) {
71 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) + cnt) % size);
74 void increment_write_ptr (size_t cnt) {
75 g_atomic_int_set (&write_ptr, (g_atomic_int_get(&write_ptr) + cnt) % size);
78 size_t write_space () {
81 w = g_atomic_int_get (&write_ptr);
82 r = g_atomic_int_get (&read_ptr);
85 return ((r - w + size) % size) - 1;
93 size_t read_space () {
96 w = g_atomic_int_get (&write_ptr);
97 r = g_atomic_int_get (&read_ptr);
102 return (w - r + size) % size;
106 T *buffer () { return buf; }
107 size_t get_write_ptr () const { return g_atomic_int_get (&write_ptr); }
108 size_t get_read_ptr () const { return g_atomic_int_get (&read_ptr); }
109 size_t bufsize () const { return size; }
114 mutable gint write_ptr;
115 mutable gint read_ptr;
118 template<class T> size_t
119 RingBufferNPT<T>::read (T *dest, size_t cnt)
125 size_t priv_read_ptr;
127 priv_read_ptr=g_atomic_int_get(&read_ptr);
129 if ((free_cnt = read_space ()) == 0) {
133 to_read = cnt > free_cnt ? free_cnt : cnt;
135 cnt2 = priv_read_ptr + to_read;
138 n1 = size - priv_read_ptr;
145 memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
146 priv_read_ptr = (priv_read_ptr + n1) % size;
149 memcpy (dest+n1, buf, n2 * sizeof (T));
153 g_atomic_int_set(&read_ptr, priv_read_ptr);
157 template<class T> size_t
158 RingBufferNPT<T>::write (T *src, size_t cnt)
164 size_t priv_write_ptr;
166 priv_write_ptr=g_atomic_int_get(&write_ptr);
168 if ((free_cnt = write_space ()) == 0) {
172 to_write = cnt > free_cnt ? free_cnt : cnt;
174 cnt2 = priv_write_ptr + to_write;
177 n1 = size - priv_write_ptr;
184 memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
185 priv_write_ptr = (priv_write_ptr + n1) % size;
188 memcpy (buf, src+n1, n2 * sizeof (T));
192 g_atomic_int_set(&write_ptr, priv_write_ptr);
196 template<class T> void
197 RingBufferNPT<T>::get_read_vector (RingBufferNPT<T>::rw_vector *vec)
203 w = g_atomic_int_get (&write_ptr);
204 r = g_atomic_int_get (&read_ptr);
209 free_cnt = (w - r + size) % size;
215 /* Two part vector: the rest of the buffer after the
216 current write ptr, plus some from the start of
220 vec->buf[0] = &buf[r];
221 vec->len[0] = size - r;
223 vec->len[1] = cnt2 % size;
227 /* Single part vector: just the rest of the buffer */
229 vec->buf[0] = &buf[r];
230 vec->len[0] = free_cnt;
235 template<class T> void
236 RingBufferNPT<T>::get_write_vector (RingBufferNPT<T>::rw_vector *vec)
242 w = g_atomic_int_get (&write_ptr);
243 r = g_atomic_int_get (&read_ptr);
246 free_cnt = ((r - w + size) % size) - 1;
248 free_cnt = (r - w) - 1;
257 /* Two part vector: the rest of the buffer after the
258 current write ptr, plus some from the start of
262 vec->buf[0] = &buf[w];
263 vec->len[0] = size - w;
265 vec->len[1] = cnt2 % size;
267 vec->buf[0] = &buf[w];
268 vec->len[0] = free_cnt;
273 #endif /* __ringbuffer_npt_h__ */