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.
21 #ifndef ringbuffer_npt_h
22 #define ringbuffer_npt_h
25 #include <pbd/atomic.h>
27 /** Ringbuffer class where the element size is not required to be a
34 RingBufferNPT (size_t sz) {
41 virtual ~RingBufferNPT() {
46 /* !!! NOT THREAD SAFE !!! */
47 atomic_set (&write_ptr, 0);
48 atomic_set (&read_ptr, 0);
51 void set (size_t r, size_t w) {
52 /* !!! NOT THREAD SAFE !!! */
53 atomic_set (&write_ptr, w);
54 atomic_set (&read_ptr, r);
57 size_t read (T *dest, size_t cnt);
58 size_t write (T *src, size_t cnt);
65 void get_read_vector (rw_vector *);
66 void get_write_vector (rw_vector *);
68 void decrement_read_ptr (size_t cnt) {
69 atomic_set (&read_ptr, (atomic_read(&read_ptr) - cnt) % size);
72 void increment_read_ptr (size_t cnt) {
73 atomic_set (&read_ptr, (atomic_read(&read_ptr) + cnt) % size);
76 void increment_write_ptr (size_t cnt) {
77 atomic_set (&write_ptr, (atomic_read(&write_ptr) + cnt) % size);
80 size_t write_space () {
83 w = atomic_read (&write_ptr);
84 r = atomic_read (&read_ptr);
87 return ((r - w + size) % size) - 1;
95 size_t read_space () {
98 w = atomic_read (&write_ptr);
99 r = atomic_read (&read_ptr);
104 return (w - r + size) % size;
108 T *buffer () { return buf; }
109 size_t get_write_ptr () const { return atomic_read (&write_ptr); }
110 size_t get_read_ptr () const { return atomic_read (&read_ptr); }
111 size_t bufsize () const { return size; }
116 mutable gint write_ptr;
117 mutable gint read_ptr;
120 template<class T> size_t
121 RingBufferNPT<T>::read (T *dest, size_t cnt)
127 size_t priv_read_ptr;
129 priv_read_ptr=atomic_read(&read_ptr);
131 if ((free_cnt = read_space ()) == 0) {
135 to_read = cnt > free_cnt ? free_cnt : cnt;
137 cnt2 = priv_read_ptr + to_read;
140 n1 = size - priv_read_ptr;
147 memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
148 priv_read_ptr = (priv_read_ptr + n1) % size;
151 memcpy (dest+n1, buf, n2 * sizeof (T));
155 atomic_set(&read_ptr, priv_read_ptr);
159 template<class T> size_t
160 RingBufferNPT<T>::write (T *src, size_t cnt)
166 size_t priv_write_ptr;
168 priv_write_ptr=atomic_read(&write_ptr);
170 if ((free_cnt = write_space ()) == 0) {
174 to_write = cnt > free_cnt ? free_cnt : cnt;
176 cnt2 = priv_write_ptr + to_write;
179 n1 = size - priv_write_ptr;
186 memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
187 priv_write_ptr = (priv_write_ptr + n1) % size;
190 memcpy (buf, src+n1, n2 * sizeof (T));
194 atomic_set(&write_ptr, priv_write_ptr);
198 template<class T> void
199 RingBufferNPT<T>::get_read_vector (RingBufferNPT<T>::rw_vector *vec)
205 w = atomic_read (&write_ptr);
206 r = atomic_read (&read_ptr);
211 free_cnt = (w - r + size) % size;
217 /* Two part vector: the rest of the buffer after the
218 current write ptr, plus some from the start of
222 vec->buf[0] = &buf[r];
223 vec->len[0] = size - r;
225 vec->len[1] = cnt2 % size;
229 /* Single part vector: just the rest of the buffer */
231 vec->buf[0] = &buf[r];
232 vec->len[0] = free_cnt;
237 template<class T> void
238 RingBufferNPT<T>::get_write_vector (RingBufferNPT<T>::rw_vector *vec)
244 w = atomic_read (&write_ptr);
245 r = atomic_read (&read_ptr);
248 free_cnt = ((r - w + size) % size) - 1;
250 free_cnt = (r - w) - 1;
259 /* Two part vector: the rest of the buffer after the
260 current write ptr, plus some from the start of
264 vec->buf[0] = &buf[w];
265 vec->len[0] = size - w;
267 vec->len[1] = cnt2 % size;
269 vec->buf[0] = &buf[w];
270 vec->len[0] = free_cnt;
275 #endif /* __ringbuffer_npt_h__ */