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>
30 /* ringbuffer class where the element size is not required to be a power of two */
36 RingBufferNPT (size_t sz) {
42 virtual ~RingBufferNPT () {
47 /* !!! NOT THREAD SAFE !!! */
48 g_atomic_int_set (&write_ptr, 0);
49 g_atomic_int_set (&read_ptr, 0);
52 void set (size_t r, size_t w) {
53 /* !!! NOT THREAD SAFE !!! */
54 g_atomic_int_set (&write_ptr, w);
55 g_atomic_int_set (&read_ptr, r);
58 size_t read (T *dest, size_t cnt);
59 size_t write (const T *src, size_t cnt);
66 void get_read_vector (rw_vector *);
67 void get_write_vector (rw_vector *);
69 void decrement_read_ptr (size_t cnt) {
70 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) - cnt) % size);
73 void increment_read_ptr (size_t cnt) {
74 g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) + cnt) % size);
77 void increment_write_ptr (size_t cnt) {
78 g_atomic_int_set (&write_ptr, (g_atomic_int_get(&write_ptr) + cnt) % size);
81 size_t write_space () {
84 w = g_atomic_int_get (&write_ptr);
85 r = g_atomic_int_get (&read_ptr);
88 return ((r - w + size) % size) - 1;
96 size_t read_space () {
99 w = g_atomic_int_get (&write_ptr);
100 r = g_atomic_int_get (&read_ptr);
105 return (w - r + size) % size;
109 T *buffer () { return buf; }
110 size_t get_write_ptr () const { return g_atomic_int_get (&write_ptr); }
111 size_t get_read_ptr () const { return g_atomic_int_get (&read_ptr); }
112 size_t bufsize () const { return size; }
117 mutable gint write_ptr;
118 mutable gint read_ptr;
121 template<class T> size_t
122 RingBufferNPT<T>::read (T *dest, size_t cnt)
128 size_t priv_read_ptr;
130 priv_read_ptr=g_atomic_int_get(&read_ptr);
132 if ((free_cnt = read_space ()) == 0) {
136 to_read = cnt > free_cnt ? free_cnt : cnt;
138 cnt2 = priv_read_ptr + to_read;
141 n1 = size - priv_read_ptr;
148 memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
149 priv_read_ptr = (priv_read_ptr + n1) % size;
152 memcpy (dest+n1, buf, n2 * sizeof (T));
156 g_atomic_int_set(&read_ptr, priv_read_ptr);
160 template<class T> size_t
161 RingBufferNPT<T>::write (const T *src, size_t cnt)
167 size_t priv_write_ptr;
169 priv_write_ptr=g_atomic_int_get(&write_ptr);
171 if ((free_cnt = write_space ()) == 0) {
175 to_write = cnt > free_cnt ? free_cnt : cnt;
177 cnt2 = priv_write_ptr + to_write;
180 n1 = size - priv_write_ptr;
187 memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
188 priv_write_ptr = (priv_write_ptr + n1) % size;
191 memcpy (buf, src+n1, n2 * sizeof (T));
195 g_atomic_int_set(&write_ptr, priv_write_ptr);
199 template<class T> void
200 RingBufferNPT<T>::get_read_vector (RingBufferNPT<T>::rw_vector *vec)
206 w = g_atomic_int_get (&write_ptr);
207 r = g_atomic_int_get (&read_ptr);
212 free_cnt = (w - r + size) % size;
218 /* Two part vector: the rest of the buffer after the
219 current write ptr, plus some from the start of
223 vec->buf[0] = &buf[r];
224 vec->len[0] = size - r;
226 vec->len[1] = cnt2 % size;
230 /* Single part vector: just the rest of the buffer */
232 vec->buf[0] = &buf[r];
233 vec->len[0] = free_cnt;
238 template<class T> void
239 RingBufferNPT<T>::get_write_vector (RingBufferNPT<T>::rw_vector *vec)
245 w = g_atomic_int_get (&write_ptr);
246 r = g_atomic_int_get (&read_ptr);
249 free_cnt = ((r - w + size) % size) - 1;
251 free_cnt = (r - w) - 1;
260 /* Two part vector: the rest of the buffer after the
261 current write ptr, plus some from the start of
265 vec->buf[0] = &buf[w];
266 vec->len[0] = size - w;
268 vec->len[1] = cnt2 % size;
270 vec->buf[0] = &buf[w];
271 vec->len[0] = free_cnt;
278 #endif /* __ringbuffer_npt_h__ */