From e5a2e928beb895efe421d0bd05df7e9d842b2d12 Mon Sep 17 00:00:00 2001
From: joq <joq@0c269be4-1314-0410-8aa9-9f06e86f4224>
Date: Thu, 11 Sep 2003 17:40:25 +0000
Subject: [PATCH] [0.81.2] dummy driver fixes; man page update

git-svn-id: svn+ssh://jackaudio.org/trunk/jack@493 0c269be4-1314-0410-8aa9-9f06e86f4224
---
 configure.in                 |  2 +-
 drivers/dummy/dummy_driver.c | 33 +++++++++++++++++++--------------
 jackd/jackd.1.in             |  8 +++++---
 3 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/configure.in b/configure.in
index 5febe06..d859a4e 100644
--- a/configure.in
+++ b/configure.in
@@ -14,7 +14,7 @@ dnl                 changes are made
 dnl ---
 JACK_MAJOR_VERSION=0
 JACK_MINOR_VERSION=81
-JACK_MICRO_VERSION=1
+JACK_MICRO_VERSION=2
 
 dnl ---
 dnl HOWTO: updating the jack protocal version
diff --git a/drivers/dummy/dummy_driver.c b/drivers/dummy/dummy_driver.c
index de94479..18c53e4 100644
--- a/drivers/dummy/dummy_driver.c
+++ b/drivers/dummy/dummy_driver.c
@@ -19,6 +19,7 @@
     $Id$
 */
 
+#include <math.h>
 #include <stdio.h>
 #include <memory.h>
 #include <unistd.h>
@@ -50,22 +51,25 @@ dummy_driver_audio_stop (dummy_driver_t *driver)
 }
 
 static jack_nframes_t 
-dummy_driver_wait (dummy_driver_t *driver, int extra_fd, int *status, float *delayed_usecs)
+dummy_driver_wait (dummy_driver_t *driver, int extra_fd, int *status,
+		   float *delayed_usecs)
 {
-  jack_time_t processing_time;
-
-  processing_time = driver->last_wait_ust
-    ? jack_get_microseconds() - driver->last_wait_ust
-    : 0;
-
-  if (processing_time < driver->wait_time)
-    usleep (driver->wait_time - processing_time);
+  jack_time_t starting_time = jack_get_microseconds();
+  jack_time_t processing_time = (driver->last_wait_ust?
+				 starting_time - driver->last_wait_ust: 0);
+  jack_time_t sleeping_time = driver->wait_time - processing_time;
 
+  /* JOQ: usleep() is inaccurate for small buffer sizes with Linux
+   * 2.4.  I suspect it can't wait for less than one (or maybe even
+   * two) scheduler timeslices.  Linux 2.6 is probably better. */
+  if (sleeping_time > 0)
+    usleep (sleeping_time);
 
   driver->last_wait_ust = jack_get_microseconds ();
+  driver->engine->transport_cycle_start (driver->engine, driver->last_wait_ust);
 
   *status = 0;
-  *delayed_usecs = 0.0;
+  *delayed_usecs = driver->last_wait_ust - starting_time - sleeping_time;
 
   return driver->period_size;
 }
@@ -198,8 +202,8 @@ dummy_driver_new (jack_client_t * client,
   driver->start      = (JackDriverStartFunction)     dummy_driver_audio_start;
   driver->stop       = (JackDriverStopFunction)      dummy_driver_audio_stop;
 
-  driver->period_usecs = (((float)period_size) / ((float)sample_rate)) / 1000000.0;
-
+  driver->period_usecs =
+    (jack_time_t) floor ((((float) period_size) / sample_rate) * 1000000.0f);
   driver->sample_rate = sample_rate;
   driver->period_size = period_size;
   driver->wait_time   = wait_time;
@@ -321,8 +325,9 @@ driver_initialize (jack_client_t *client, int argc, char **argv)
         if (!wait_time_set)
 	  wait_time = (((float)period_size) / ((float)sample_rate)) * 1000000.0;
 
-	return dummy_driver_new (client, "dummy_pcm", capture_ports, playback_ports,
-				 sample_rate, period_size, wait_time);
+	return dummy_driver_new (client, "dummy_pcm", capture_ports,
+				 playback_ports, sample_rate, period_size,
+				 wait_time);
 }
 
 void
diff --git a/jackd/jackd.1.in b/jackd/jackd.1.in
index 7a62f02..f92bc66 100644
--- a/jackd/jackd.1.in
+++ b/jackd/jackd.1.in
@@ -1,4 +1,4 @@
-.TH JACKD "1" @VERSION@ "June 2003"
+.TH JACKD "1" @VERSION@ "Sept. 2003"
 .SH NAME
 jackd, jackstart \- JACK Audio Connection Kit sound server
 .SH SYNOPSYS
@@ -97,13 +97,15 @@ Specify the sample rate.  The default is 48000.
 Specify the number of frames between JACK \fBprocess()\fR calls.  The
 default is 1024.  If you need low latency, set \fB\-p\fR as low as you
 can go without seeing xruns.  A larger period size yields higher
-latency, but makes xruns less likely.
+latency, but makes xruns less likely.  The JACK input latency in
+seconds is \fB\-\-period\fR divided by \fB\-\-rate\fR.
 .TP
 \fB\-n, \-\-nperiods \fIint\fR
 .br
 Specify the number of periods in the hardware buffer.  The default is
 2.  The period size (\fB\-p\fR) times \fB\-\-nperiods\fR times four is
-the JACK buffer size in bytes.
+the JACK buffer size in bytes.  The JACK output latency in seconds is
+\fB\-\-nperiods\fR times \fB\-\-period\fR divided by \fB\-\-rate\fR.
 .TP
 \fB\-D, \-\-duplex\fR
 Provide both capture and playback ports (the default).