improved ringbuffer in streamer

1 files changed, 83 insertions, 0 deletions

diff --git a/ringbuf.c b/ringbuf.c
new file mode 100644
index 00000000..94dffa58
--- /dev/null
+++ b/ringbuf.c
@@ -0,0 +1,83 @@
+/*
+    DeaDBeeF - ultimate music player for GNU/Linux systems with X11
+    Copyright (C) 2009-2010 Alexey Yakovenko <waker@users.sourceforge.net>
+
+    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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+*/
+
+#include <string.h>
+#include "ringbuf.h"
+
+void
+ringbuf_init (ringbuf_t *p, char *buffer, size_t size) {
+    memset (p, 0, sizeof (ringbuf_t));
+    p->bytes = buffer;
+    p->cursor = 0;
+    p->size = size;
+    p->remaining = 0;
+}
+
+int
+ringbuf_write (ringbuf_t *p, char *bytes, size_t size) {
+    if (p->size - p->remaining < size) {
+        return -1;
+    }
+
+    size_t cursor = p->cursor + p->remaining;
+    cursor %= p->size;
+
+    if (p->size - cursor >= size) { // split
+        memcpy (p->bytes + cursor, bytes, size);
+        p->remaining += size;
+    }
+    else {
+        size_t n = p->size - cursor;
+        if (n > 0) {
+            memcpy (p->bytes + cursor, bytes, n);
+            p->remaining += n;
+            size -= n;
+            bytes += n;
+        }
+        memcpy (p->bytes, bytes, size);
+        p->remaining += size;
+    }
+    return 0;
+}
+
+int
+ringbuf_read (ringbuf_t *p, char *bytes, size_t size) {
+    if (p->remaining < size) {
+        return -1;
+    }
+
+    if (p->size - p->cursor >= size) {
+        memcpy (bytes, p->bytes + p->cursor, size);
+        p->cursor += size;
+        p->remaining -= size;
+    }
+    else {
+        size_t n = p->size - p->cursor;
+        if (n > 0) {
+            memcpy (bytes, p->bytes + p->cursor, n);
+            p->cursor += n;
+            p->remaining -= n;
+            bytes += n;
+            size -= n;
+        }
+        memcpy (bytes, p->bytes, size);
+        p->cursor = size;
+        p->remaining -= size;
+    }
+}