285 lines
6.1 KiB
C++
285 lines
6.1 KiB
C++
/*
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Copyright (C) 2000 Paul Davis & Benno Senoner
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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$Id$
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*/
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#ifndef ringbuffer_h
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#define ringbuffer_h
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//#include <sys/mman.h>
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#include <glib.h>
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template<class T>
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class RingBuffer
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{
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public:
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RingBuffer (size_t sz) {
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size_t power_of_two;
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for (power_of_two = 1; 1U<<power_of_two < sz; power_of_two++);
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size = 1<<power_of_two;
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size_mask = size;
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size_mask -= 1;
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buf = new T[size];
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reset ();
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};
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virtual ~RingBuffer() {
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delete [] buf;
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}
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void reset () {
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/* !!! NOT THREAD SAFE !!! */
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g_atomic_int_set (&write_ptr, 0);
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g_atomic_int_set (&read_ptr, 0);
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}
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void set (size_t r, size_t w) {
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/* !!! NOT THREAD SAFE !!! */
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g_atomic_int_set (&write_ptr, w);
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g_atomic_int_set (&read_ptr, r);
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}
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size_t read (T *dest, size_t cnt);
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size_t write (T *src, size_t cnt);
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struct rw_vector {
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T *buf[2];
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size_t len[2];
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};
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void get_read_vector (rw_vector *);
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void get_write_vector (rw_vector *);
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void decrement_read_ptr (size_t cnt) {
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g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) - cnt) & size_mask);
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}
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void increment_read_ptr (size_t cnt) {
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g_atomic_int_set (&read_ptr, (g_atomic_int_get(&read_ptr) + cnt) & size_mask);
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}
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void increment_write_ptr (size_t cnt) {
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g_atomic_int_set (&write_ptr, (g_atomic_int_get(&write_ptr) + cnt) & size_mask);
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}
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size_t write_space () {
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size_t w, r;
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w = g_atomic_int_get (&write_ptr);
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r = g_atomic_int_get (&read_ptr);
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if (w > r) {
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return ((r - w + size) & size_mask) - 1;
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} else if (w < r) {
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return (r - w) - 1;
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} else {
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return size - 1;
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}
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}
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size_t read_space () {
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size_t w, r;
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w = g_atomic_int_get (&write_ptr);
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r = g_atomic_int_get (&read_ptr);
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if (w > r) {
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return w - r;
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} else {
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return (w - r + size) & size_mask;
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}
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}
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T *buffer () { return buf; }
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size_t get_write_ptr () const { return g_atomic_int_get (&write_ptr); }
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size_t get_read_ptr () const { return g_atomic_int_get (&read_ptr); }
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size_t bufsize () const { return size; }
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protected:
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T *buf;
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size_t size;
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mutable gint write_ptr;
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mutable gint read_ptr;
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size_t size_mask;
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};
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template<class T> size_t
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RingBuffer<T>::read (T *dest, size_t cnt)
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{
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size_t free_cnt;
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size_t cnt2;
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size_t to_read;
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size_t n1, n2;
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size_t priv_read_ptr;
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priv_read_ptr=g_atomic_int_get(&read_ptr);
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if ((free_cnt = read_space ()) == 0) {
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return 0;
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}
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to_read = cnt > free_cnt ? free_cnt : cnt;
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cnt2 = priv_read_ptr + to_read;
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if (cnt2 > size) {
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n1 = size - priv_read_ptr;
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n2 = cnt2 & size_mask;
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} else {
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n1 = to_read;
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n2 = 0;
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}
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memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
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priv_read_ptr = (priv_read_ptr + n1) & size_mask;
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if (n2) {
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memcpy (dest+n1, buf, n2 * sizeof (T));
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priv_read_ptr = n2;
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}
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g_atomic_int_set(&read_ptr, priv_read_ptr);
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return to_read;
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}
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template<class T> size_t
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RingBuffer<T>::write (T *src, size_t cnt)
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{
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size_t free_cnt;
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size_t cnt2;
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size_t to_write;
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size_t n1, n2;
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size_t priv_write_ptr;
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priv_write_ptr=g_atomic_int_get(&write_ptr);
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if ((free_cnt = write_space ()) == 0) {
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return 0;
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}
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to_write = cnt > free_cnt ? free_cnt : cnt;
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cnt2 = priv_write_ptr + to_write;
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if (cnt2 > size) {
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n1 = size - priv_write_ptr;
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n2 = cnt2 & size_mask;
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} else {
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n1 = to_write;
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n2 = 0;
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}
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memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
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priv_write_ptr = (priv_write_ptr + n1) & size_mask;
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if (n2) {
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memcpy (buf, src+n1, n2 * sizeof (T));
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priv_write_ptr = n2;
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}
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g_atomic_int_set(&write_ptr, priv_write_ptr);
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return to_write;
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}
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template<class T> void
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RingBuffer<T>::get_read_vector (RingBuffer<T>::rw_vector *vec)
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{
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size_t free_cnt;
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size_t cnt2;
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size_t w, r;
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w = g_atomic_int_get (&write_ptr);
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r = g_atomic_int_get (&read_ptr);
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if (w > r) {
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free_cnt = w - r;
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} else {
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free_cnt = (w - r + size) & size_mask;
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}
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cnt2 = r + free_cnt;
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if (cnt2 > size) {
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/* Two part vector: the rest of the buffer after the
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current write ptr, plus some from the start of
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the buffer.
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*/
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vec->buf[0] = &buf[r];
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vec->len[0] = size - r;
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vec->buf[1] = buf;
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vec->len[1] = cnt2 & size_mask;
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} else {
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/* Single part vector: just the rest of the buffer */
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vec->buf[0] = &buf[r];
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vec->len[0] = free_cnt;
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vec->len[1] = 0;
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}
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}
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template<class T> void
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RingBuffer<T>::get_write_vector (RingBuffer<T>::rw_vector *vec)
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{
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size_t free_cnt;
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size_t cnt2;
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size_t w, r;
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w = g_atomic_int_get (&write_ptr);
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r = g_atomic_int_get (&read_ptr);
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if (w > r) {
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free_cnt = ((r - w + size) & size_mask) - 1;
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} else if (w < r) {
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free_cnt = (r - w) - 1;
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} else {
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free_cnt = size - 1;
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}
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cnt2 = w + free_cnt;
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if (cnt2 > size) {
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/* Two part vector: the rest of the buffer after the
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current write ptr, plus some from the start of
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the buffer.
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*/
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vec->buf[0] = &buf[w];
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vec->len[0] = size - w;
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vec->buf[1] = buf;
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vec->len[1] = cnt2 & size_mask;
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} else {
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vec->buf[0] = &buf[w];
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vec->len[0] = free_cnt;
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vec->len[1] = 0;
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}
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}
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#endif /* __ringbuffer_h__ */
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