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>
28 #include "pbd/libpbd_visibility.h"
32 /* ringbuffer class where the element size is not required to be a power of two */
35 class /*LIBPBD_API*/ RingBufferNPT
38 RingBufferNPT (size_t sz) {
44 virtual ~RingBufferNPT () {
49 /* !!! NOT THREAD SAFE !!! */
50 g_atomic_int_set (&write_ptr, 0);
51 g_atomic_int_set (&read_ptr, 0);
54 void set (size_t r, size_t w) {
55 /* !!! NOT THREAD SAFE !!! */
56 g_atomic_int_set (&write_ptr, w);
57 g_atomic_int_set (&read_ptr, r);
60 size_t read (T *dest, size_t cnt);
61 size_t write (const T *src, size_t cnt);
68 void get_read_vector (rw_vector *);
69 void get_write_vector (rw_vector *);
71 void decrement_read_ptr (size_t cnt) {
72 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) - cnt) % size);
75 void increment_read_ptr (size_t cnt) {
76 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) + cnt) % size);
79 void increment_write_ptr (size_t cnt) {
80 g_atomic_int_set (&write_ptr, (g_atomic_int_get(&write_ptr) + cnt) % size);
83 size_t write_space () {
86 w = g_atomic_int_get (&write_ptr);
87 r = g_atomic_int_get (&read_ptr);
90 return ((r - w + size) % size) - 1;
98 size_t read_space () {
101 w = g_atomic_int_get (&write_ptr);
102 r = g_atomic_int_get (&read_ptr);
107 return (w - r + size) % size;
111 T *buffer () { return buf; }
112 size_t get_write_ptr () const { return g_atomic_int_get (&write_ptr); }
113 size_t get_read_ptr () const { return g_atomic_int_get (&read_ptr); }
114 size_t bufsize () const { return size; }
119 mutable gint write_ptr;
120 mutable gint read_ptr;
123 template<class T> /*LIBPBD_API*/ size_t
124 RingBufferNPT<T>::read (T *dest, size_t cnt)
130 size_t priv_read_ptr;
132 priv_read_ptr=g_atomic_int_get(&read_ptr);
134 if ((free_cnt = read_space ()) == 0) {
138 to_read = cnt > free_cnt ? free_cnt : cnt;
140 cnt2 = priv_read_ptr + to_read;
143 n1 = size - priv_read_ptr;
150 memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
151 priv_read_ptr = (priv_read_ptr + n1) % size;
154 memcpy (dest+n1, buf, n2 * sizeof (T));
158 g_atomic_int_set(&read_ptr, priv_read_ptr);
162 template<class T> /*LIBPBD_API*/ size_t
163 RingBufferNPT<T>::write (const T *src, size_t cnt)
169 size_t priv_write_ptr;
171 priv_write_ptr=g_atomic_int_get(&write_ptr);
173 if ((free_cnt = write_space ()) == 0) {
177 to_write = cnt > free_cnt ? free_cnt : cnt;
179 cnt2 = priv_write_ptr + to_write;
182 n1 = size - priv_write_ptr;
189 memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
190 priv_write_ptr = (priv_write_ptr + n1) % size;
193 memcpy (buf, src+n1, n2 * sizeof (T));
197 g_atomic_int_set(&write_ptr, priv_write_ptr);
201 template<class T> /*LIBPBD_API*/ void
202 RingBufferNPT<T>::get_read_vector (typename RingBufferNPT<T>::rw_vector *vec)
208 w = g_atomic_int_get (&write_ptr);
209 r = g_atomic_int_get (&read_ptr);
214 free_cnt = (w - r + size) % size;
220 /* Two part vector: the rest of the buffer after the
221 current write ptr, plus some from the start of
225 vec->buf[0] = &buf[r];
226 vec->len[0] = size - r;
228 vec->len[1] = cnt2 % size;
232 /* Single part vector: just the rest of the buffer */
234 vec->buf[0] = &buf[r];
235 vec->len[0] = free_cnt;
241 template<class T> /*LIBPBD_API*/ void
242 RingBufferNPT<T>::get_write_vector (typename RingBufferNPT<T>::rw_vector *vec)
248 w = g_atomic_int_get (&write_ptr);
249 r = g_atomic_int_get (&read_ptr);
252 free_cnt = ((r - w + size) % size) - 1;
254 free_cnt = (r - w) - 1;
263 /* Two part vector: the rest of the buffer after the
264 current write ptr, plus some from the start of
268 vec->buf[0] = &buf[w];
269 vec->len[0] = size - w;
271 vec->len[1] = cnt2 % size;
273 vec->buf[0] = &buf[w];
274 vec->len[0] = free_cnt;
281 #endif /* __ringbuffer_npt_h__ */