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);
62 size_t write_one (const T src);
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);
76 void increment_read_ptr (size_t cnt) {
77 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) + cnt) % size);
80 void increment_write_ptr (size_t cnt) {
81 g_atomic_int_set (&write_ptr, (g_atomic_int_get(&write_ptr) + cnt) % size);
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) - 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;
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;
124 template<class T> /*LIBPBD_API*/ size_t
125 RingBufferNPT<T>::read (T *dest, size_t cnt)
131 size_t priv_read_ptr;
133 priv_read_ptr=g_atomic_int_get(&read_ptr);
135 if ((free_cnt = read_space ()) == 0) {
139 to_read = cnt > free_cnt ? free_cnt : cnt;
141 cnt2 = priv_read_ptr + to_read;
144 n1 = size - priv_read_ptr;
151 memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
152 priv_read_ptr = (priv_read_ptr + n1) % size;
155 memcpy (dest+n1, buf, n2 * sizeof (T));
159 g_atomic_int_set(&read_ptr, priv_read_ptr);
163 template<class T> /*LIBPBD_API*/ size_t
164 RingBufferNPT<T>::write (const T *src, size_t cnt)
170 size_t priv_write_ptr;
172 priv_write_ptr=g_atomic_int_get(&write_ptr);
174 if ((free_cnt = write_space ()) == 0) {
178 to_write = cnt > free_cnt ? free_cnt : cnt;
180 cnt2 = priv_write_ptr + to_write;
183 n1 = size - priv_write_ptr;
190 memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
191 priv_write_ptr = (priv_write_ptr + n1) % size;
194 memcpy (buf, src+n1, n2 * sizeof (T));
198 g_atomic_int_set(&write_ptr, priv_write_ptr);
202 template<class T> /*LIBPBD_API*/ size_t
203 RingBufferNPT<T>::write_one (const T src)
205 return write (&src, 1);
208 template<class T> /*LIBPBD_API*/ void
209 RingBufferNPT<T>::get_read_vector (typename RingBufferNPT<T>::rw_vector *vec)
215 w = g_atomic_int_get (&write_ptr);
216 r = g_atomic_int_get (&read_ptr);
221 free_cnt = (w - r + size) % size;
227 /* Two part vector: the rest of the buffer after the
228 current write ptr, plus some from the start of
232 vec->buf[0] = &buf[r];
233 vec->len[0] = size - r;
235 vec->len[1] = cnt2 % size;
239 /* Single part vector: just the rest of the buffer */
241 vec->buf[0] = &buf[r];
242 vec->len[0] = free_cnt;
248 template<class T> /*LIBPBD_API*/ void
249 RingBufferNPT<T>::get_write_vector (typename RingBufferNPT<T>::rw_vector *vec)
255 w = g_atomic_int_get (&write_ptr);
256 r = g_atomic_int_get (&read_ptr);
259 free_cnt = ((r - w + size) % size) - 1;
261 free_cnt = (r - w) - 1;
270 /* Two part vector: the rest of the buffer after the
271 current write ptr, plus some from the start of
275 vec->buf[0] = &buf[w];
276 vec->len[0] = size - w;
278 vec->len[1] = cnt2 % size;
280 vec->buf[0] = &buf[w];
281 vec->len[0] = free_cnt;
288 #endif /* __ringbuffer_npt_h__ */