rollback to 3428, before the mysterious removal of libs/* at 3431/3432

git-svn-id: svn://localhost/ardour2/branches/3.0@3435 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 281 insertions, 0 deletions

diff --git a/libs/pbd/pbd/ringbuffer.h b/libs/pbd/pbd/ringbuffer.h
new file mode 100644
index 0000000000..3502bed21b
--- /dev/null
+++ b/libs/pbd/pbd/ringbuffer.h
@@ -0,0 +1,281 @@
+/*
+    Copyright (C) 2000 Paul Davis & Benno Senoner
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#ifndef ringbuffer_h
+#define ringbuffer_h
+
+#include <cstring>
+#include <glib.h>
+
+template<class T>
+class RingBuffer 
+{
+  public:
+	RingBuffer (guint sz) {
+//	size = ffs(sz); /* find first [bit] set is a single inlined assembly instruction. But it looks like the API rounds up so... */
+	guint power_of_two;
+	for (power_of_two = 1; 1U<<power_of_two < sz; power_of_two++);
+		size = 1<<power_of_two;
+		size_mask = size;
+		size_mask -= 1;
+		buf = new T[size];
+		reset ();
+
+	};
+	
+	virtual ~RingBuffer() {
+		delete [] buf;
+	}
+
+	void reset () {
+		/* !!! NOT THREAD SAFE !!! */
+		g_atomic_int_set (&write_idx, 0);
+		g_atomic_int_set (&read_idx, 0);
+	}
+
+	void set (guint r, guint w) {
+		/* !!! NOT THREAD SAFE !!! */
+		g_atomic_int_set (&write_idx, w);
+		g_atomic_int_set (&read_idx, r);
+	}
+	
+	guint read  (T *dest, guint cnt);
+	guint  write (T *src, guint cnt);
+
+	struct rw_vector {
+	    T *buf[2];
+	    guint len[2];
+	};
+
+	void get_read_vector (rw_vector *);
+	void get_write_vector (rw_vector *);
+	
+	void decrement_read_idx (guint cnt) {
+		g_atomic_int_set (&read_idx, (g_atomic_int_get(&read_idx) - cnt) & size_mask);
+	}                
+
+	void increment_read_idx (guint cnt) {
+		g_atomic_int_set (&read_idx, (g_atomic_int_get(&read_idx) + cnt) & size_mask);
+	}                
+
+	void increment_write_idx (guint cnt) {
+		g_atomic_int_set (&write_idx,  (g_atomic_int_get(&write_idx) + cnt) & size_mask);
+	}                
+
+	guint write_space () {
+		guint w, r;
+		
+		w = g_atomic_int_get (&write_idx);
+		r = g_atomic_int_get (&read_idx);
+		
+		if (w > r) {
+			return ((r - w + size) & size_mask) - 1;
+		} else if (w < r) {
+			return (r - w) - 1;
+		} else {
+			return size - 1;
+		}
+	}
+	
+	guint read_space () {
+		guint w, r;
+		
+		w = g_atomic_int_get (&write_idx);
+		r = g_atomic_int_get (&read_idx);
+		
+		if (w > r) {
+			return w - r;
+		} else {
+			return (w - r + size) & size_mask;
+		}
+	}
+
+	T *buffer () { return buf; }
+	guint get_write_idx () const { return g_atomic_int_get (&write_idx); }
+	guint get_read_idx () const { return g_atomic_int_get (&read_idx); }
+	guint bufsize () const { return size; }
+
+  protected:
+	T *buf;
+	guint size;
+	mutable gint write_idx;
+	mutable gint read_idx;
+	guint size_mask;
+};
+
+template<class T> guint 
+RingBuffer<T>::read (T *dest, guint cnt)
+{
+        guint free_cnt;
+        guint cnt2;
+        guint to_read;
+        guint n1, n2;
+        guint priv_read_idx;
+
+        priv_read_idx=g_atomic_int_get(&read_idx);
+
+        if ((free_cnt = read_space ()) == 0) {
+                return 0;
+        }
+
+        to_read = cnt > free_cnt ? free_cnt : cnt;
+        
+        cnt2 = priv_read_idx + to_read;
+
+        if (cnt2 > size) {
+                n1 = size - priv_read_idx;
+                n2 = cnt2 & size_mask;
+        } else {
+                n1 = to_read;
+                n2 = 0;
+        }
+        
+        memcpy (dest, &buf[priv_read_idx], n1 * sizeof (T));
+        priv_read_idx = (priv_read_idx + n1) & size_mask;
+
+        if (n2) {
+                memcpy (dest+n1, buf, n2 * sizeof (T));
+                priv_read_idx = n2;
+        }
+
+        g_atomic_int_set(&read_idx, priv_read_idx);
+        return to_read;
+}
+
+template<class T> guint
+RingBuffer<T>::write (T *src, guint cnt)
+
+{
+        guint free_cnt;
+        guint cnt2;
+        guint to_write;
+        guint n1, n2;
+        guint priv_write_idx;
+
+        priv_write_idx=g_atomic_int_get(&write_idx);
+
+        if ((free_cnt = write_space ()) == 0) {
+                return 0;
+        }
+
+        to_write = cnt > free_cnt ? free_cnt : cnt;
+        
+        cnt2 = priv_write_idx + to_write;
+
+        if (cnt2 > size) {
+                n1 = size - priv_write_idx;
+                n2 = cnt2 & size_mask;
+        } else {
+                n1 = to_write;
+                n2 = 0;
+        }
+
+        memcpy (&buf[priv_write_idx], src, n1 * sizeof (T));
+        priv_write_idx = (priv_write_idx + n1) & size_mask;
+
+        if (n2) {
+                memcpy (buf, src+n1, n2 * sizeof (T));
+                priv_write_idx = n2;
+        }
+
+        g_atomic_int_set(&write_idx, priv_write_idx);
+        return to_write;
+}
+
+template<class T> void
+RingBuffer<T>::get_read_vector (RingBuffer<T>::rw_vector *vec)
+
+{
+	guint free_cnt;
+	guint cnt2;
+	guint w, r;
+	
+	w = g_atomic_int_get (&write_idx);
+	r = g_atomic_int_get (&read_idx);
+	
+	if (w > r) {
+		free_cnt = w - r;
+	} else {
+		free_cnt = (w - r + size) & size_mask;
+	}
+
+	cnt2 = r + free_cnt;
+
+	if (cnt2 > size) {
+		/* Two part vector: the rest of the buffer after the
+		   current write ptr, plus some from the start of 
+		   the buffer.
+		*/
+
+		vec->buf[0] = &buf[r];
+		vec->len[0] = size - r;
+		vec->buf[1] = buf;
+		vec->len[1] = cnt2 & size_mask;
+
+	} else {
+		
+		/* Single part vector: just the rest of the buffer */
+		
+		vec->buf[0] = &buf[r];
+		vec->len[0] = free_cnt;
+		vec->len[1] = 0;
+	}
+}
+
+template<class T> void
+RingBuffer<T>::get_write_vector (RingBuffer<T>::rw_vector *vec)
+
+{
+	guint free_cnt;
+	guint cnt2;
+	guint w, r;
+	
+	w = g_atomic_int_get (&write_idx);
+	r = g_atomic_int_get (&read_idx);
+	
+	if (w > r) {
+		free_cnt = ((r - w + size) & size_mask) - 1;
+	} else if (w < r) {
+		free_cnt = (r - w) - 1;
+	} else {
+		free_cnt = size - 1;
+	}
+	
+	cnt2 = w + free_cnt;
+
+	if (cnt2 > size) {
+		
+		/* Two part vector: the rest of the buffer after the
+		   current write ptr, plus some from the start of 
+		   the buffer.
+		*/
+
+		vec->buf[0] = &buf[w];
+		vec->len[0] = size - w;
+		vec->buf[1] = buf;
+		vec->len[1] = cnt2 & size_mask;
+	} else {
+		vec->buf[0] = &buf[w];
+		vec->len[0] = free_cnt;
+		vec->len[1] = 0;
+	}
+}
+
+
+#endif /* __ringbuffer_h__ */