1 files changed, 161 insertions, 0 deletions
diff --git a/src/modules/raop/raop-packet-buffer.c b/src/modules/raop/raop-packet-buffer.c
new file mode 100644
index 0000000..72fd729
--- /dev/null
+++ b/src/modules/raop/raop-packet-buffer.c
@@ -0,0 +1,161 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2013 Matthias Wabersich
+  Copyright 2013 Hajime Fujita
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as published
+  by the Free Software Foundation; either version 2.1 of the License,
+  or (at your option) any later version.
+
+  PulseAudio 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 Lesser General Public License
+  along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <limits.h>
+
+#include <pulse/xmalloc.h>
+
+#include <pulsecore/core-error.h>
+#include <pulsecore/macro.h>
+
+#include "raop-packet-buffer.h"
+
+struct pa_raop_packet_buffer {
+    pa_memchunk *packets;
+    pa_mempool *mempool;
+
+    size_t size;
+    size_t count;
+
+    uint16_t seq;
+    size_t pos;
+};
+
+pa_raop_packet_buffer *pa_raop_packet_buffer_new(pa_mempool *mempool, const size_t size) {
+    pa_raop_packet_buffer *pb = pa_xnew0(pa_raop_packet_buffer, 1);
+
+    pa_assert(mempool);
+    pa_assert(size > 0);
+
+    pb->count = 0;
+    pb->size = size;
+    pb->mempool = mempool;
+    pb->packets = pa_xnew0(pa_memchunk, size);
+    pb->seq = pb->pos = 0;
+
+    return pb;
+}
+
+void pa_raop_packet_buffer_free(pa_raop_packet_buffer *pb) {
+    size_t i;
+
+    pa_assert(pb);
+
+    for (i = 0; pb->packets && i < pb->size; i++) {
+        if (pb->packets[i].memblock)
+            pa_memblock_unref(pb->packets[i].memblock);
+        pa_memchunk_reset(&pb->packets[i]);
+    }
+
+    pa_xfree(pb->packets);
+    pb->packets = NULL;
+    pa_xfree(pb);
+}
+
+void pa_raop_packet_buffer_reset(pa_raop_packet_buffer *pb, uint16_t seq) {
+    size_t i;
+
+    pa_assert(pb);
+    pa_assert(pb->packets);
+
+    pb->pos = 0;
+    pb->count = 0;
+    pb->seq = (!seq) ? UINT16_MAX : seq - 1;
+    for (i = 0; i < pb->size; i++) {
+        if (pb->packets[i].memblock)
+            pa_memblock_unref(pb->packets[i].memblock);
+        pa_memchunk_reset(&pb->packets[i]);
+    }
+}
+
+pa_memchunk *pa_raop_packet_buffer_prepare(pa_raop_packet_buffer *pb, uint16_t seq, const size_t size) {
+    pa_memchunk *packet = NULL;
+    size_t i;
+
+    pa_assert(pb);
+    pa_assert(pb->packets);
+
+    if (seq == 0) {
+        /* 0 means seq reached UINT16_MAX and has been wrapped... */
+        pa_assert(pb->seq == UINT16_MAX);
+        pb->seq = 0;
+    } else {
+        /* ...otherwise, seq MUST have be increased! */
+        pa_assert(seq == pb->seq + 1);
+        pb->seq++;
+    }
+
+    i = (pb->pos + 1) % pb->size;
+
+    if (pb->packets[i].memblock)
+        pa_memblock_unref(pb->packets[i].memblock);
+    pa_memchunk_reset(&pb->packets[i]);
+
+    pb->packets[i].memblock = pa_memblock_new(pb->mempool, size);
+    pb->packets[i].length = size;
+    pb->packets[i].index = 0;
+
+    packet = &pb->packets[i];
+
+    if (pb->count < pb->size)
+        pb->count++;
+    pb->pos = i;
+
+    return packet;
+}
+
+pa_memchunk *pa_raop_packet_buffer_retrieve(pa_raop_packet_buffer *pb, uint16_t seq) {
+    pa_memchunk *packet = NULL;
+    size_t delta, i;
+
+    pa_assert(pb);
+    pa_assert(pb->packets);
+
+    if (seq == pb->seq)
+        packet = &pb->packets[pb->pos];
+    else {
+        if (seq < pb->seq) {
+            /* Regular case: pb->seq did not wrapped since seq. */
+            delta = pb->seq - seq;
+        } else {
+            /* Tricky case: pb->seq wrapped since seq! */
+            delta = pb->seq + (UINT16_MAX - seq);
+        }
+
+        /* If the requested packet is too old, do nothing and return */
+        if (delta > pb->count)
+            return NULL;
+
+        i = (pb->size + pb->pos - delta) % pb->size;
+
+        if (delta < pb->size && pb->packets[i].memblock)
+            packet = &pb->packets[i];
+    }
+
+    return packet;
+}