Cygwin: dsp: Improve minimum buffser size estimation.

The commit 322c7150b25e restricts buffer size with a fixed length,
however, the minimum buffer size should be varied by the sample rate.
With this patch, it is estimated using sample rate, sample width
and number of channels so that the buffer length is not less than
80 msec which is almost the minimum value of Win MME to work.

Fixes: 322c7150b25e ("Cygwin: dsp: Avoid setting buffer that is too small.")
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>

1 files changed, 37 insertions, 23 deletions

diff --git a/winsup/cygwin/fhandler/dsp.cc b/winsup/cygwin/fhandler/dsp.cc
index 97f3eaa27..59c11ac23 100644
--- a/winsup/cygwin/fhandler/dsp.cc
+++ b/winsup/cygwin/fhandler/dsp.cc
@@ -65,7 +65,7 @@ class fhandler_dev_dsp::Audio
   void convert_S16LE_S16BE (unsigned char *buffer, int size_bytes);
   void fillFormat (WAVEFORMATEX * format,
 		   int rate, int bits, int channels);
-  static unsigned blockSize (int rate, int bits, int channels);
+  static unsigned blockSize (double ms, int rate, int bits, int channels);
   void (fhandler_dev_dsp::Audio::*convert_)
     (unsigned char *buffer, int size_bytes);
 
@@ -352,10 +352,10 @@ fhandler_dev_dsp::Audio::fillFormat (WAVEFORMATEX * format,
 
 // calculate a good block size
 unsigned
-fhandler_dev_dsp::Audio::blockSize (int rate, int bits, int channels)
+fhandler_dev_dsp::Audio::blockSize (double ms, int rate, int bits, int channels)
 {
   unsigned blockSize;
-  blockSize = ((bits / 8) * channels * rate) / 8; // approx 125ms per block
+  blockSize = ms * ((bits / 8) * channels * rate) / 1000;
   // round up to multiple of 64
   blockSize +=  0x3f;
   blockSize &= ~0x3f;
@@ -525,7 +525,7 @@ void fhandler_dev_dsp::Audio_out::default_buf_info (audio_buf_info *p,
                                                 int rate, int bits, int channels)
 {
   p->fragstotal = DEFAULT_BLOCKS;
-  p->fragsize = blockSize (rate, bits, channels);
+  p->fragsize = blockSize (125, rate, bits, channels);
   p->fragments = p->fragstotal;
   p->bytes = p->fragsize * p->fragments;
 }
@@ -537,7 +537,7 @@ fhandler_dev_dsp::Audio_out::callback_sampledone (WAVEHDR *pHdr)
 {
   Qisr2app_->send (pHdr);
   ReleaseSemaphore (fh->get_select_sem (),
-		    get_obj_handle_count (fh->get_select_sem ()) - 1, NULL);
+		    get_obj_handle_count (fh->get_select_sem ()), NULL);
 }
 
 bool
@@ -555,8 +555,7 @@ fhandler_dev_dsp::Audio_out::waitforspace ()
 	  set_errno (EAGAIN);
 	  return false;
 	}
-      debug_printf ("1ms");
-      switch (cygwait (1))
+      switch (cygwait (fh->get_select_sem (), 10))
 	{
 	case WAIT_SIGNALED:
 	  if (!_my_tls.call_signal_handler ())
@@ -934,8 +933,7 @@ fhandler_dev_dsp::Audio_in::waitfordata ()
 	  set_errno (EAGAIN);
 	  return false;
 	}
-      debug_printf ("1ms");
-      switch (cygwait (1))
+      switch (cygwait (fh->get_select_sem (), 10))
 	{
 	case WAIT_SIGNALED:
 	  if (!_my_tls.call_signal_handler ())
@@ -967,7 +965,7 @@ void fhandler_dev_dsp::Audio_in::default_buf_info (audio_buf_info *p,
                                                 int rate, int bits, int channels)
 {
   p->fragstotal = DEFAULT_BLOCKS;
-  p->fragsize = blockSize (rate, bits, channels);
+  p->fragsize = blockSize (125, rate, bits, channels);
   p->fragments = 0;
   p->bytes = 0;
 }
@@ -998,7 +996,7 @@ fhandler_dev_dsp::Audio_in::callback_blockfull (WAVEHDR *pHdr)
 {
   Qisr2app_->send (pHdr);
   ReleaseSemaphore (fh->get_select_sem (),
-		    get_obj_handle_count (fh->get_select_sem ()) - 1, NULL);
+		    get_obj_handle_count (fh->get_select_sem ()), NULL);
 }
 
 static void CALLBACK
@@ -1127,8 +1125,13 @@ fhandler_dev_dsp::_write (const void *ptr, size_t len)
     /* nothing to do */;
   else if (IS_WRITE ())
     {
-      if (!fragment_has_been_set)
-	fragsize_ = Audio::blockSize (audiofreq_, audiobits_, audiochannels_);
+      if (fragment_has_been_set)
+	fragsize_ = max (Audio::blockSize (80.0 / fragstotal_, audiofreq_,
+					   audiobits_, audiochannels_),
+			 fragsize_);
+      else
+	fragsize_ = Audio::blockSize (125, audiofreq_, audiobits_,
+				      audiochannels_);
       debug_printf ("Allocating");
       if (!(audio_out_ = new Audio_out (this)))
 	return -1;
@@ -1174,7 +1177,8 @@ fhandler_dev_dsp::_read (void *ptr, size_t& len)
   else if (IS_READ ())
     {
       if (!fragment_has_been_set)
-	fragsize_ = Audio::blockSize (audiofreq_, audiobits_, audiochannels_);
+	fragsize_ = Audio::blockSize (125, audiofreq_, audiobits_,
+				      audiochannels_);
       debug_printf ("Allocating");
       if (!(audio_in_ = new Audio_in (this)))
 	{
@@ -1233,7 +1237,7 @@ fhandler_dev_dsp::close ()
   being_closed = true;
   close_audio_in ();
   close_audio_out ();
-  ReleaseSemaphore (select_sem, get_obj_handle_count (select_sem) - 1, NULL);
+  ReleaseSemaphore (select_sem, get_obj_handle_count (select_sem), NULL);
   CloseHandle (select_sem);
   select_sem = NULL;
   return fhandler_base::close ();
@@ -1255,9 +1259,13 @@ fhandler_dev_dsp::_ioctl (unsigned int cmd, void *buf)
 	break;
 
       CASE (SNDCTL_DSP_GETBLKSIZE)
-	if (!fragment_has_been_set)
-	  fragsize_ = Audio::blockSize (audiofreq_, audiobits_, audiochannels_);
-	*intbuf = fragsize_;
+	if (fragment_has_been_set)
+	  *intbuf = max (Audio::blockSize (80.0 / fragstotal_, audiofreq_,
+					   audiobits_, audiochannels_),
+			 fragsize_);
+	else
+	  *intbuf = Audio::blockSize (125, audiofreq_, audiobits_,
+					audiochannels_);
 	return 0;
 
       CASE (SNDCTL_DSP_SETFMT)
@@ -1387,8 +1395,11 @@ fhandler_dev_dsp::_ioctl (unsigned int cmd, void *buf)
 	  audio_out_->buf_info (p, audiofreq_, audiobits_, audiochannels_);
 	else if (fragment_has_been_set)
 	  {
-	    p->bytes = fragsize_ * fragstotal_;
-	    p->fragsize = fragsize_;
+	    p->fragsize = max (Audio::blockSize (80.0 / fragstotal_,
+						 audiofreq_, audiobits_,
+						 audiochannels_),
+			       fragsize_);
+	    p->bytes = p->fragsize * fragstotal_;
 	    p->fragstotal = fragstotal_;
 	    p->fragments = fragstotal_;
 	  }
@@ -1412,7 +1423,10 @@ fhandler_dev_dsp::_ioctl (unsigned int cmd, void *buf)
 	else if (fragment_has_been_set)
 	  {
 	    p->bytes = 0;
-	    p->fragsize = fragsize_;
+	    p->fragsize = max (Audio::blockSize (80.0 / fragstotal_,
+						 audiofreq_, audiobits_,
+						 audiochannels_),
+			       fragsize_);
 	    p->fragstotal = fragstotal_;
 	    p->fragments = 0;
 	  }
@@ -1430,8 +1444,8 @@ fhandler_dev_dsp::_ioctl (unsigned int cmd, void *buf)
 	int *p = (int *) buf;
 	fragstotal_ = min (*p >> 16, MAX_BLOCKS);
 	fragsize_ = 1 << (*p & 0xffff);
-	while (fragsize_ * fragstotal_ < 16384)
-	  fragsize_ *= 2;
+	if (fragstotal_ < 2)
+	  fragstotal_ = 2;
 	fragment_has_been_set = true;
 	return 0;
       }