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) {
40 virtual ~RingBufferNPT() {
45 /* !!! NOT THREAD SAFE !!! */
46 g_atomic_int_set (&write_ptr, 0);
47 g_atomic_int_set (&read_ptr, 0);
50 void set (size_t r, size_t w) {
51 /* !!! NOT THREAD SAFE !!! */
52 g_atomic_int_set (&write_ptr, w);
53 g_atomic_int_set (&read_ptr, r);
56 size_t read (T *dest, size_t cnt);
57 size_t write (T *src, size_t cnt);
64 void get_read_vector (rw_vector *);
65 void get_write_vector (rw_vector *);
67 void decrement_read_ptr (size_t cnt) {
68 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) - cnt) % size);
71 void increment_read_ptr (size_t cnt) {
72 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) + cnt) % size);
75 void increment_write_ptr (size_t cnt) {
76 g_atomic_int_set (&write_ptr, (g_atomic_int_get(&write_ptr) + cnt) % size);
79 size_t write_space () {
82 w = g_atomic_int_get (&write_ptr);
83 r = g_atomic_int_get (&read_ptr);
86 return ((r - w + size) % size) - 1;
94 size_t read_space () {
97 w = g_atomic_int_get (&write_ptr);
98 r = g_atomic_int_get (&read_ptr);
103 return (w - r + size) % size;
107 T *buffer () { return buf; }
108 size_t get_write_ptr () const { return g_atomic_int_get (&write_ptr); }
109 size_t get_read_ptr () const { return g_atomic_int_get (&read_ptr); }
110 size_t bufsize () const { return size; }
115 mutable gint write_ptr;
116 mutable gint read_ptr;
119 template<class T> size_t
120 RingBufferNPT<T>::read (T *dest, size_t cnt)
126 size_t priv_read_ptr;
128 priv_read_ptr=g_atomic_int_get(&read_ptr);
130 if ((free_cnt = read_space ()) == 0) {
134 to_read = cnt > free_cnt ? free_cnt : cnt;
136 cnt2 = priv_read_ptr + to_read;
139 n1 = size - priv_read_ptr;
146 memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
147 priv_read_ptr = (priv_read_ptr + n1) % size;
150 memcpy (dest+n1, buf, n2 * sizeof (T));
154 g_atomic_int_set(&read_ptr, priv_read_ptr);
158 template<class T> size_t
159 RingBufferNPT<T>::write (T *src, size_t cnt)
165 size_t priv_write_ptr;
167 priv_write_ptr=g_atomic_int_get(&write_ptr);
169 if ((free_cnt = write_space ()) == 0) {
173 to_write = cnt > free_cnt ? free_cnt : cnt;
175 cnt2 = priv_write_ptr + to_write;
178 n1 = size - priv_write_ptr;
185 memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
186 priv_write_ptr = (priv_write_ptr + n1) % size;
189 memcpy (buf, src+n1, n2 * sizeof (T));
193 g_atomic_int_set(&write_ptr, priv_write_ptr);
197 template<class T> void
198 RingBufferNPT<T>::get_read_vector (RingBufferNPT<T>::rw_vector *vec)
204 w = g_atomic_int_get (&write_ptr);
205 r = g_atomic_int_get (&read_ptr);
210 free_cnt = (w - r + size) % size;
216 /* Two part vector: the rest of the buffer after the
217 current write ptr, plus some from the start of
221 vec->buf[0] = &buf[r];
222 vec->len[0] = size - r;
224 vec->len[1] = cnt2 % size;
228 /* Single part vector: just the rest of the buffer */
230 vec->buf[0] = &buf[r];
231 vec->len[0] = free_cnt;
236 template<class T> void
237 RingBufferNPT<T>::get_write_vector (RingBufferNPT<T>::rw_vector *vec)
243 w = g_atomic_int_get (&write_ptr);
244 r = g_atomic_int_get (&read_ptr);
247 free_cnt = ((r - w + size) % size) - 1;
249 free_cnt = (r - w) - 1;
258 /* Two part vector: the rest of the buffer after the
259 current write ptr, plus some from the start of
263 vec->buf[0] = &buf[w];
264 vec->len[0] = size - w;
266 vec->len[1] = cnt2 % size;
268 vec->buf[0] = &buf[w];
269 vec->len[0] = free_cnt;
274 #endif /* __ringbuffer_npt_h__ */