Allow PushSource to have smaller write size than read size (packet size)

The change actually supports arbitrary write size but
write size greater than read size (packet size) is prohibited
by an explicit check.

Review URL: http://codereview.chromium.org/118170

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17686 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 23 insertions, 12 deletions

diff --git a/media/audio/simple_sources.cc b/media/audio/simple_sources.cc
index 6643fc1..f941782 100644
--- a/media/audio/simple_sources.cc
+++ b/media/audio/simple_sources.cc
@@ -50,7 +50,9 @@ void SineWaveAudioSource::OnError(AudioOutputStream* stream, int code) {
 // PushSource implementation.
 
 PushSource::PushSource(size_t packet_size)
-    : packet_size_(packet_size), buffered_bytes_(0) {
+    : packet_size_(packet_size),
+      buffered_bytes_(0),
+      front_buffer_consumed_(0) {
 }
 
 PushSource::~PushSource() {
@@ -59,20 +61,29 @@ PushSource::~PushSource() {
 
 size_t PushSource::OnMoreData(AudioOutputStream* stream,
                               void* dest, size_t max_size) {
-  Packet packet;
-  {
+  size_t copied = 0;
+  while (copied < max_size) {
     AutoLock auto_lock(lock_);
+
     // Under lock processing in this scope.
     if (!packets_.size())
-      return 0;
-    packet = packets_.front();
-    packets_.pop_front();
-    buffered_bytes_ -= packet.size;
+      break;
+    Packet packet = packets_.front();
+    size_t size = std::min(max_size - copied,
+                           packet.size - front_buffer_consumed_);
+    memcpy(static_cast<char*>(dest) + copied,
+           packet.buffer + front_buffer_consumed_,
+           size);
+    front_buffer_consumed_ += size;
+    buffered_bytes_ -= size;
+    copied += size;
+    if (front_buffer_consumed_ == packet.size) {
+      delete [] packet.buffer;
+      packets_.pop_front();
+      front_buffer_consumed_ = 0;
+    }
   }
-  size_t size = std::min(max_size, packet.size);
-  memcpy(dest, packet.buffer, size);
-  delete [] packet.buffer;
-  return size;
+  return copied;
 }
 
 void PushSource::OnClose(AudioOutputStream* stream) {
@@ -85,7 +96,7 @@ void PushSource::OnError(AudioOutputStream* stream, int code) {
 
 // TODO(cpu): Manage arbitrary large sizes.
 bool PushSource::Write(const void *data, size_t len) {
-  if ((len == 0) || (len > packet_size_)) {
+  if (len == 0) {
     NOTREACHED();
     return false;
   }