add new file

git-svn-id: svn+ssh://jackaudio.org/trunk/jack@956 0c269be4-1314-0410-8aa9-9f06e86f4224

config/os/gnu-linux/time.c

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+/* -*- mode: c; c-file-style: "bsd"; -*- */
+/*
+    Copyright (C) 2001-2003 Paul Davis
+    Copyright (C) 2005 Jussi Laako
+    
+    This program 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.
+    
+    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 Lesser General Public License for more details.
+    
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program; if not, write to the Free Software 
+    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+    $Id$
+*/
+
+#include <config.h>
+
+static jack_time_t __jack_cpu_mhz = 0;
+jack_time_t (*_jack_get_microseconds)(void) = 0;
+
+#if defined(__gnu_linux__) && (defined(__i386__) || defined(__x86_64__))
+#define HPET_SUPPORT
+#define HPET_MMAP_SIZE	1024
+#define HPET_PERIOD	0x004
+#define HPET_COUNTER	0x0f0
+static int hpet_fd;
+static unsigned char *hpet_ptr;
+static unsigned int hpet_period; /* period length in femto secs */
+#endif /* defined(__gnu_linux__) && (__i386__ || __x86_64__) */
+
+#ifdef HPET_SUPPORT
+int
+jack_hpet_init ()
+{
+	hpet_fd = open("/dev/hpet", O_RDONLY);
+	if (hpet_fd < 0) {
+		jack_error ("This system has no accessible HPET device (%s)", strerror (errno));
+		return -1;
+	}
+
+	hpet_ptr = (unsigned char *) mmap(NULL, HPET_MMAP_SIZE,
+					  PROT_READ, MAP_SHARED, hpet_fd, 0);
+	if (hpet_ptr == NULL) {
+		jack_error ("This system has no mappable HPET device (%s)", strerror (errno));
+		close (hpet_fd);
+		return -1;
+	}
+
+	/* this assumes period to be constant. if needed,
+	   it can be moved to the clock access function 
+	*/
+
+	hpet_period = *((unsigned int *) (hpet_ptr + HPET_PERIOD));
+	return 0;
+}
+
+static jack_time_t
+jack_get_microseconds_from_hpet (void) 
+{
+	unsigned long long hpet_counter;
+	long double hpet_time;
+
+	hpet_counter = *((unsigned long long *) (hpet_ptr + HPET_COUNTER));
+	hpet_time = (long double) hpet_counter * (long double) hpet_period *
+		(long double) 1e-9;
+	return ((jack_time_t) (hpet_time + 0.5));
+}
+
+#else
+
+static int
+jack_hpet_init ()
+{
+	jack_error ("This version of JACK or this computer does not have HPET support.\n"
+		    "Please choose a different clock source.");
+	return -1;
+}
+
+static jack_time_t
+jack_get_microseconds_from_hpet (void) 
+{
+	/* never called */
+	return 0;
+}
+
+#endif /* HPET_SUPPORT */
+
+
+jack_time_t 
+jack_get_microseconds_from_cycles (void) {
+	return get_cycles() / __jack_cpu_mhz;
+}
+
+/*
+ * This is another kludge.  It looks CPU-dependent, but actually it
+ * reflects the lack of standards for the Linux kernel formatting of
+ * /proc/cpuinfo.
+ */
+
+jack_time_t
+jack_get_mhz (void)
+{
+	FILE *f = fopen("/proc/cpuinfo", "r");
+	if (f == 0)
+	{
+		perror("can't open /proc/cpuinfo\n");
+		exit(1);
+	}
+
+	for ( ; ; )
+	{
+		jack_time_t mhz;
+		int ret;
+		char buf[1000];
+
+		if (fgets(buf, sizeof(buf), f) == NULL) {
+			jack_error ("FATAL: cannot locate cpu MHz in "
+				    "/proc/cpuinfo\n");
+			exit(1);
+		}
+
+#if defined(__powerpc__)
+		ret = sscanf(buf, "clock\t: %" SCNu64 "MHz", &mhz);
+#elif defined( __i386__ ) || defined (__hppa__)  || defined (__ia64__) || \
+      defined(__x86_64__)
+		ret = sscanf(buf, "cpu MHz         : %" SCNu64, &mhz);
+#elif defined( __sparc__ )
+		ret = sscanf(buf, "Cpu0Bogo        : %" SCNu64, &mhz);
+#elif defined( __mc68000__ )
+		ret = sscanf(buf, "Clocking:       %" SCNu64, &mhz);
+#elif defined( __s390__  )
+		ret = sscanf(buf, "bogomips per cpu: %" SCNu64, &mhz);
+#else /* MIPS, ARM, alpha */
+		ret = sscanf(buf, "BogoMIPS        : %" SCNu64, &mhz);
+#endif 
+
+		if (ret == 1)
+		{
+			fclose(f);
+			return (jack_time_t)mhz;
+		}
+	}
+}
+
+void
+jack_init_time ()
+{
+	__jack_cpu_mhz = jack_get_mhz ();
+}
+
+void
+jack_set_clock_source (jack_timer_type_t clocksrc)
+{
+	switch (clocksrc)
+	{
+	case JACK_TIMER_CYCLE_COUNTER:
+		_jack_get_microseconds = jack_get_microseconds_from_cycles;
+		break;
+
+	case JACK_TIMER_HPET:
+		if (jack_hpet_init () == 0) {
+			_jack_get_microseconds = jack_get_microseconds_from_hpet;
+		} else {
+			_jack_get_microseconds = jack_get_microseconds_from_system;
+		}
+		break;
+
+	case JACK_TIMER_SYSTEM_CLOCK:
+	default:
+		_jack_get_microseconds = jack_get_microseconds_from_system;
+		break;
+	}
+}
+