[DCCP]: Initial implementation

Development to this point was done on a subversion repository at:

http://oops.ghostprotocols.net:81/cgi-bin/viewcvs.cgi/dccp-2.6/

This repository will be kept at this site for the foreseable future,
so that interested parties can see the history of this code,
attributions, etc.

If I ever decide to take this offline I'll provide the full history at
some other suitable place.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

18 files changed, 7311 insertions, 0 deletions

diff --git a/net/Kconfig b/net/Kconfig
index 02877ac0f2f4..c07aafb59a0f 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -147,6 +147,7 @@ source "net/bridge/netfilter/Kconfig"
 
 endif
 
+source "net/dccp/Kconfig"
 source "net/sctp/Kconfig"
 source "net/atm/Kconfig"
 source "net/bridge/Kconfig"
diff --git a/net/Makefile b/net/Makefile
index 4a01be8d3e1e..7e6eff206c81 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_ATM)		+= atm/
 obj-$(CONFIG_DECNET)		+= decnet/
 obj-$(CONFIG_ECONET)		+= econet/
 obj-$(CONFIG_VLAN_8021Q)	+= 8021q/
+obj-$(CONFIG_IP_DCCP)		+= dccp/
 obj-$(CONFIG_IP_SCTP)		+= sctp/
 
 ifeq ($(CONFIG_NET),y)
diff --git a/net/dccp/Kconfig b/net/dccp/Kconfig
new file mode 100644
index 000000000000..90460bc629b3
--- /dev/null
+++ b/net/dccp/Kconfig
@@ -0,0 +1,24 @@
+menu "DCCP Configuration (EXPERIMENTAL)"
+	depends on INET && EXPERIMENTAL
+
+config IP_DCCP
+	tristate "The DCCP Protocol (EXPERIMENTAL)"
+	---help---
+	  Datagram Congestion Control Protocol
+
+	  From draft-ietf-dccp-spec-11 <http://www.icir.org/kohler/dcp/draft-ietf-dccp-spec-11.txt>.
+
+	  The Datagram Congestion Control Protocol (DCCP) is a transport
+	  protocol that implements bidirectional, unicast connections of
+	  congestion-controlled, unreliable datagrams. It should be suitable
+	  for use by applications such as streaming media, Internet telephony,
+	  and on-line games
+
+	  To compile this protocol support as a module, choose M here: the
+	  module will be called dccp.
+
+	  If in doubt, say N.
+
+source "net/dccp/ccids/Kconfig"
+
+endmenu
diff --git a/net/dccp/Makefile b/net/dccp/Makefile
new file mode 100644
index 000000000000..c6e6ba55c36b
--- /dev/null
+++ b/net/dccp/Makefile
@@ -0,0 +1,5 @@
+obj-$(CONFIG_IP_DCCP) += dccp.o
+
+dccp-y := ccid.o input.o ipv4.o minisocks.o options.o output.o proto.o timer.o
+
+obj-y += ccids/
diff --git a/net/dccp/ccid.c b/net/dccp/ccid.c
new file mode 100644
index 000000000000..9d8fc0e289ea
--- /dev/null
+++ b/net/dccp/ccid.c
@@ -0,0 +1,139 @@
+/*
+ *  net/dccp/ccid.c
+ *
+ *  An implementation of the DCCP protocol
+ *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  CCID infrastructure
+ *
+ *	This program is free software; you can redistribute it and/or modify it
+ *	under the terms of the GNU General Public License version 2 as
+ *	published by the Free Software Foundation.
+ */
+
+#include "ccid.h"
+
+static struct ccid *ccids[CCID_MAX];
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
+static atomic_t ccids_lockct = ATOMIC_INIT(0);
+static DEFINE_SPINLOCK(ccids_lock);
+
+/*
+ * The strategy is: modifications ccids vector are short, do not sleep and
+ * veeery rare, but read access should be free of any exclusive locks.
+ */
+static void ccids_write_lock(void)
+{
+	spin_lock(&ccids_lock);
+	while (atomic_read(&ccids_lockct) != 0) {
+		spin_unlock(&ccids_lock);
+		yield();
+		spin_lock(&ccids_lock);
+	}
+}
+
+static inline void ccids_write_unlock(void)
+{
+	spin_unlock(&ccids_lock);
+}
+
+static inline void ccids_read_lock(void)
+{
+	atomic_inc(&ccids_lockct);
+	spin_unlock_wait(&ccids_lock);
+}
+
+static inline void ccids_read_unlock(void)
+{
+	atomic_dec(&ccids_lockct);
+}
+
+#else
+#define ccids_write_lock() do { } while(0)
+#define ccids_write_unlock() do { } while(0)
+#define ccids_read_lock() do { } while(0)
+#define ccids_read_unlock() do { } while(0)
+#endif
+
+int ccid_register(struct ccid *ccid)
+{
+	int err;
+
+	if (ccid->ccid_init == NULL)
+		return -1;
+
+	ccids_write_lock();
+	err = -EEXIST;
+	if (ccids[ccid->ccid_id] == NULL) {
+		ccids[ccid->ccid_id] = ccid;
+		err = 0;
+	}
+	ccids_write_unlock();
+	if (err == 0)
+		pr_info("CCID: Registered CCID %d (%s)\n",
+			ccid->ccid_id, ccid->ccid_name);
+	return err;
+}
+
+EXPORT_SYMBOL_GPL(ccid_register);
+
+int ccid_unregister(struct ccid *ccid)
+{
+	ccids_write_lock();
+	ccids[ccid->ccid_id] = NULL;
+	ccids_write_unlock();
+	pr_info("CCID: Unregistered CCID %d (%s)\n",
+		ccid->ccid_id, ccid->ccid_name);
+	return 0;
+}
+
+EXPORT_SYMBOL_GPL(ccid_unregister);
+
+struct ccid *ccid_init(unsigned char id, struct sock *sk)
+{
+	struct ccid *ccid;
+
+#ifdef CONFIG_KMOD
+	if (ccids[id] == NULL)
+		request_module("net-dccp-ccid-%d", id);
+#endif
+	ccids_read_lock();
+
+	ccid = ccids[id];
+	if (ccid == NULL)
+		goto out;
+
+	if (!try_module_get(ccid->ccid_owner))
+		goto out_err;
+
+	if (ccid->ccid_init(sk) != 0)
+		goto out_module_put;
+out:
+	ccids_read_unlock();
+	return ccid;
+out_module_put:
+	module_put(ccid->ccid_owner);
+out_err:
+	ccid = NULL;
+	goto out;
+}
+
+EXPORT_SYMBOL_GPL(ccid_init);
+
+void ccid_exit(struct ccid *ccid, struct sock *sk)
+{
+	if (ccid == NULL)
+		return;
+
+	ccids_read_lock();
+
+	if (ccids[ccid->ccid_id] != NULL) {
+		if (ccid->ccid_exit != NULL)
+			ccid->ccid_exit(sk);
+		module_put(ccid->ccid_owner);
+	}
+
+	ccids_read_unlock();
+}
+
+EXPORT_SYMBOL_GPL(ccid_exit);
diff --git a/net/dccp/ccid.h b/net/dccp/ccid.h
new file mode 100644
index 000000000000..06105b2a613c
--- /dev/null
+++ b/net/dccp/ccid.h
@@ -0,0 +1,156 @@
+#ifndef _CCID_H
+#define _CCID_H
+/*
+ *  net/dccp/ccid.h
+ *
+ *  An implementation of the DCCP protocol
+ *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  CCID infrastructure
+ *
+ *	This program is free software; you can redistribute it and/or modify it
+ *	under the terms of the GNU General Public License version 2 as
+ *	published by the Free Software Foundation.
+ */
+
+#include <net/sock.h>
+#include <linux/dccp.h>
+#include <linux/list.h>
+#include <linux/module.h>
+
+#define CCID_MAX 255
+
+struct ccid {
+	unsigned char	ccid_id;
+	const char	*ccid_name;
+	struct module	*ccid_owner;
+	int		(*ccid_init)(struct sock *sk);
+	void		(*ccid_exit)(struct sock *sk);
+	int		(*ccid_hc_rx_init)(struct sock *sk);
+	int		(*ccid_hc_tx_init)(struct sock *sk);
+	void		(*ccid_hc_rx_exit)(struct sock *sk);
+	void		(*ccid_hc_tx_exit)(struct sock *sk);
+	void		(*ccid_hc_rx_packet_recv)(struct sock *sk, struct sk_buff *skb);
+	int		(*ccid_hc_rx_parse_options)(struct sock *sk,
+						    unsigned char option,
+						    unsigned char len, u16 idx,
+						    unsigned char* value);
+	void		(*ccid_hc_rx_insert_options)(struct sock *sk, struct sk_buff *skb);
+	void		(*ccid_hc_tx_insert_options)(struct sock *sk, struct sk_buff *skb);
+	void		(*ccid_hc_tx_packet_recv)(struct sock *sk, struct sk_buff *skb);
+	int		(*ccid_hc_tx_parse_options)(struct sock *sk,
+						    unsigned char option,
+						    unsigned char len, u16 idx,
+						    unsigned char* value);
+	int		(*ccid_hc_tx_send_packet)(struct sock *sk,
+						  struct sk_buff *skb, int len,
+						  long *delay);
+	void		(*ccid_hc_tx_packet_sent)(struct sock *sk, int more, int len);
+};
+
+extern int	   ccid_register(struct ccid *ccid);
+extern int	   ccid_unregister(struct ccid *ccid);
+
+extern struct ccid *ccid_init(unsigned char id, struct sock *sk);
+extern void	   ccid_exit(struct ccid *ccid, struct sock *sk);
+
+static inline void __ccid_get(struct ccid *ccid)
+{
+	__module_get(ccid->ccid_owner);
+}
+
+static inline int ccid_hc_tx_send_packet(struct ccid *ccid, struct sock *sk,
+					 struct sk_buff *skb, int len,
+					 long *delay)
+{
+	int rc = 0;
+	if (ccid->ccid_hc_tx_send_packet != NULL)
+		rc = ccid->ccid_hc_tx_send_packet(sk, skb, len, delay);
+	return rc;
+}
+
+static inline void ccid_hc_tx_packet_sent(struct ccid *ccid, struct sock *sk,
+					  int more, int len)
+{
+	if (ccid->ccid_hc_tx_packet_sent != NULL)
+		ccid->ccid_hc_tx_packet_sent(sk, more, len);
+}
+
+static inline int ccid_hc_rx_init(struct ccid *ccid, struct sock *sk)
+{
+	int rc = 0;
+	if (ccid->ccid_hc_rx_init != NULL)
+		rc = ccid->ccid_hc_rx_init(sk);
+	return rc;
+}
+
+static inline int ccid_hc_tx_init(struct ccid *ccid, struct sock *sk)
+{
+	int rc = 0;
+	if (ccid->ccid_hc_tx_init != NULL)
+		rc = ccid->ccid_hc_tx_init(sk);
+	return rc;
+}
+
+static inline void ccid_hc_rx_exit(struct ccid *ccid, struct sock *sk)
+{
+	if (ccid->ccid_hc_rx_exit != NULL)
+		ccid->ccid_hc_rx_exit(sk);
+}
+
+static inline void ccid_hc_tx_exit(struct ccid *ccid, struct sock *sk)
+{
+	if (ccid->ccid_hc_tx_exit != NULL)
+		ccid->ccid_hc_tx_exit(sk);
+}
+
+static inline void ccid_hc_rx_packet_recv(struct ccid *ccid, struct sock *sk,
+					  struct sk_buff *skb)
+{
+	if (ccid->ccid_hc_rx_packet_recv != NULL)
+		ccid->ccid_hc_rx_packet_recv(sk, skb);
+}
+
+static inline void ccid_hc_tx_packet_recv(struct ccid *ccid, struct sock *sk,
+					  struct sk_buff *skb)
+{
+	if (ccid->ccid_hc_tx_packet_recv != NULL)
+		ccid->ccid_hc_tx_packet_recv(sk, skb);
+}
+
+static inline int ccid_hc_tx_parse_options(struct ccid *ccid, struct sock *sk,
+					   unsigned char option,
+					   unsigned char len, u16 idx,
+					   unsigned char* value)
+{
+	int rc = 0;
+	if (ccid->ccid_hc_tx_parse_options != NULL)
+		rc = ccid->ccid_hc_tx_parse_options(sk, option, len, idx, value);
+	return rc;
+}
+
+static inline int ccid_hc_rx_parse_options(struct ccid *ccid, struct sock *sk,
+					   unsigned char option,
+					   unsigned char len, u16 idx,
+					   unsigned char* value)
+{
+	int rc = 0;
+	if (ccid->ccid_hc_rx_parse_options != NULL)
+		rc = ccid->ccid_hc_rx_parse_options(sk, option, len, idx, value);
+	return rc;
+}
+
+static inline void ccid_hc_tx_insert_options(struct ccid *ccid, struct sock *sk,
+					     struct sk_buff *skb)
+{
+	if (ccid->ccid_hc_tx_insert_options != NULL)
+		ccid->ccid_hc_tx_insert_options(sk, skb);
+}
+
+static inline void ccid_hc_rx_insert_options(struct ccid *ccid, struct sock *sk,
+					     struct sk_buff *skb)
+{
+	if (ccid->ccid_hc_rx_insert_options != NULL)
+		ccid->ccid_hc_rx_insert_options(sk, skb);
+}
+#endif /* _CCID_H */
diff --git a/net/dccp/ccids/Kconfig b/net/dccp/ccids/Kconfig
new file mode 100644
index 000000000000..67f9c06bd179
--- /dev/null
+++ b/net/dccp/ccids/Kconfig
@@ -0,0 +1,25 @@
+menu "DCCP CCIDs Configuration (EXPERIMENTAL)"
+	depends on IP_DCCP && EXPERIMENTAL
+
+config IP_DCCP_CCID3
+	tristate "CCID3 (TFRC) (EXPERIMENTAL)"
+	depends on IP_DCCP
+	---help---
+	  CCID 3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
+	  rate-controlled congestion control mechanism.  TFRC is designed to
+	  be reasonably fair when competing for bandwidth with TCP-like flows,
+	  where a flow is "reasonably fair" if its sending rate is generally
+	  within a factor of two of the sending rate of a TCP flow under the
+	  same conditions.  However, TFRC has a much lower variation of
+	  throughput over time compared with TCP, which makes CCID 3 more
+	  suitable than CCID 2 for applications such streaming media where a
+	  relatively smooth sending rate is of importance.
+
+	  CCID 3 is further described in [CCID 3 PROFILE]. The TFRC
+	  congestion control algorithms were initially described in RFC 3448.
+
+	  This text was extracted from draft-ietf-dccp-spec-11.txt.
+	  
+	  If in doubt, say M.
+
+endmenu
diff --git a/net/dccp/ccids/Makefile b/net/dccp/ccids/Makefile
new file mode 100644
index 000000000000..1c720131c5db
--- /dev/null
+++ b/net/dccp/ccids/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_IP_DCCP_CCID3) += dccp_ccid3.o
+
+dccp_ccid3-y := ccid3.o
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
new file mode 100644
index 000000000000..4f45902cb55e
--- /dev/null
+++ b/net/dccp/ccids/ccid3.c
@@ -0,0 +1,2164 @@
+/*
+ *  net/dccp/ccids/ccid3.c
+ *
+ *  Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
+ *
+ *  An implementation of the DCCP protocol
+ *
+ *  This code has been developed by the University of Waikato WAND
+ *  research group. For further information please see http://www.wand.net.nz/
+ *  or e-mail Ian McDonald - iam4@cs.waikato.ac.nz
+ *
+ *  This code also uses code from Lulea University, rereleased as GPL by its
+ *  authors:
+ *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
+ *
+ *  Changes to meet Linux coding standards, to make it meet latest ccid3 draft
+ *  and to make it work as a loadable module in the DCCP stack written by
+ *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
+ *
+ *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "../ccid.h"
+#include "../dccp.h"
+#include "ccid3.h"
+
+#ifdef CCID3_DEBUG
+extern int ccid3_debug;
+
+#define ccid3_pr_debug(format, a...) \
+	do { if (ccid3_debug) \
+		printk(KERN_DEBUG "%s: " format, __FUNCTION__, ##a); \
+	} while (0)
+#else
+#define ccid3_pr_debug(format, a...)
+#endif
+
+#define TFRC_MIN_PACKET_SIZE	   16
+#define TFRC_STD_PACKET_SIZE	  256
+#define TFRC_MAX_PACKET_SIZE	65535
+
+#define USEC_IN_SEC                1000000
+
+#define TFRC_INITIAL_TIMEOUT	   (2 * USEC_IN_SEC)
+/* two seconds as per CCID3 spec 11 */
+
+#define TFRC_OPSYS_HALF_TIME_GRAN	(USEC_IN_SEC / (2 * HZ))
+/* above is in usecs - half the scheduling granularity as per RFC3448 4.6 */
+
+#define TFRC_WIN_COUNT_PER_RTT	    4
+#define TFRC_WIN_COUNT_LIMIT	   16
+
+#define TFRC_MAX_BACK_OFF_TIME	   64
+/* above is in seconds */
+
+#define TFRC_SMALLEST_P		   40
+
+#define TFRC_RECV_IVAL_F_LENGTH	    8          /* length(w[]) */
+
+/* Number of later packets received before one is considered lost */
+#define TFRC_RECV_NUM_LATE_LOSS	3
+
+enum ccid3_options {
+	TFRC_OPT_LOSS_EVENT_RATE = 192,
+	TFRC_OPT_LOSS_INTERVALS	 = 193,
+	TFRC_OPT_RECEIVE_RATE	 = 194,
+};
+
+static int ccid3_debug;
+
+static kmem_cache_t *ccid3_tx_hist_slab;
+static kmem_cache_t *ccid3_rx_hist_slab;
+static kmem_cache_t *ccid3_loss_interval_hist_slab;
+
+static inline struct ccid3_tx_hist_entry *ccid3_tx_hist_entry_new(int prio)
+{
+	struct ccid3_tx_hist_entry *entry = kmem_cache_alloc(ccid3_tx_hist_slab, prio);
+
+	if (entry != NULL)
+		entry->ccid3htx_sent = 0;
+
+	return entry;
+}
+
+static inline void ccid3_tx_hist_entry_delete(struct ccid3_tx_hist_entry *entry)
+{
+	if (entry != NULL)
+		kmem_cache_free(ccid3_tx_hist_slab, entry);
+}
+
+static inline struct ccid3_rx_hist_entry *ccid3_rx_hist_entry_new(struct sock *sk,
+								  struct sk_buff *skb,
+								  int prio)
+{
+	struct ccid3_rx_hist_entry *entry = kmem_cache_alloc(ccid3_rx_hist_slab, prio);
+
+	if (entry != NULL) {
+		const struct dccp_hdr *dh = dccp_hdr(skb);
+
+		entry->ccid3hrx_seqno	  = DCCP_SKB_CB(skb)->dccpd_seq;
+		entry->ccid3hrx_win_count = dh->dccph_ccval;
+		entry->ccid3hrx_type	  = dh->dccph_type;
+		entry->ccid3hrx_ndp 	  = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
+		do_gettimeofday(&(entry->ccid3hrx_tstamp));
+	}
+
+	return entry;
+}
+
+static inline void ccid3_rx_hist_entry_delete(struct ccid3_rx_hist_entry *entry)
+{
+	if (entry != NULL)
+		kmem_cache_free(ccid3_rx_hist_slab, entry);
+}
+
+static void ccid3_rx_history_delete(struct list_head *hist)
+{
+	struct ccid3_rx_hist_entry *entry, *next;
+
+	list_for_each_entry_safe(entry, next, hist, ccid3hrx_node) {
+		list_del_init(&entry->ccid3hrx_node);
+		kmem_cache_free(ccid3_rx_hist_slab, entry);
+	}
+}
+
+static inline struct ccid3_loss_interval_hist_entry *ccid3_loss_interval_hist_entry_new(int prio)
+{
+	return kmem_cache_alloc(ccid3_loss_interval_hist_slab, prio);
+}
+
+static inline void ccid3_loss_interval_hist_entry_delete(struct ccid3_loss_interval_hist_entry *entry)
+{
+	if (entry != NULL)
+		kmem_cache_free(ccid3_loss_interval_hist_slab, entry);
+}
+
+static void ccid3_loss_interval_history_delete(struct list_head *hist)
+{
+	struct ccid3_loss_interval_hist_entry *entry, *next;
+
+	list_for_each_entry_safe(entry, next, hist, ccid3lih_node) {
+		list_del_init(&entry->ccid3lih_node);
+		kmem_cache_free(ccid3_loss_interval_hist_slab, entry);
+	}
+}
+
+static int ccid3_init(struct sock *sk)
+{
+	ccid3_pr_debug("%s, sk=%p\n", dccp_role(sk), sk);
+	return 0;
+}
+
+static void ccid3_exit(struct sock *sk)
+{
+	ccid3_pr_debug("%s, sk=%p\n", dccp_role(sk), sk);
+}
+
+/* TFRC sender states */
+enum ccid3_hc_tx_states {
+       	TFRC_SSTATE_NO_SENT = 1,
+	TFRC_SSTATE_NO_FBACK,
+	TFRC_SSTATE_FBACK,
+	TFRC_SSTATE_TERM,
+};
+
+#ifdef CCID3_DEBUG
+static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
+{
+	static char *ccid3_state_names[] = {
+	[TFRC_SSTATE_NO_SENT]  = "NO_SENT",
+	[TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
+	[TFRC_SSTATE_FBACK]    = "FBACK",
+	[TFRC_SSTATE_TERM]     = "TERM",
+	};
+
+	return ccid3_state_names[state];
+}
+#endif
+
+static inline void ccid3_hc_tx_set_state(struct sock *sk, enum ccid3_hc_tx_states state)
+{
+	struct dccp_sock *dp = dccp_sk(sk);
+	struct ccid3_hc_tx_sock *hctx = dp->dccps_hc_tx_ccid_private;
+	enum ccid3_hc_tx_states oldstate = hctx->ccid3hctx_state;
+
+	ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
+		       dccp_role(sk), sk, ccid3_tx_state_name(oldstate), ccid3_tx_state_name(state));
+	WARN_ON(state == oldstate);
+	hctx->ccid3hctx_state = state;
+}
+
+static void timeval_sub(struct timeval large, struct timeval small, struct timeval *result) {
+
+	result->tv_sec = large.tv_sec-small.tv_sec;
+	if (large.tv_usec < small.tv_usec) {
+		(result->tv_sec)--;
+		result->tv_usec = USEC_IN_SEC+large.tv_usec-small.tv_usec;
+	} else
+		result->tv_usec = large.tv_usec-small.tv_usec;
+}
+
+static inline void timeval_fix(struct timeval *tv) {
+	if (tv->tv_usec >= USEC_IN_SEC) {
+		tv->tv_sec++;
+		tv->tv_usec -= USEC_IN_SEC;
+	}
+}
+
+/* returns the difference in usecs between timeval passed in and current time */
+static inline u32 now_delta(struct timeval tv) {
+	struct timeval now;
+	
+	do_gettimeofday(&now);
+	return ((now.tv_sec-tv.tv_sec)*1000000+now.tv_usec-tv.tv_usec);
+}
+
+#define CALCX_ARRSIZE 500
+
+#define CALCX_SPLIT 50000
+/* equivalent to 0.05 */
+
+static const u32 calcx_lookup[CALCX_ARRSIZE][2] = {
+	{ 37172 , 8172 },
+	{ 53499 , 11567 },
+	{ 66664 , 14180 },
+	{ 78298 , 16388 },
+	{ 89021 , 18339 },
+	{ 99147 , 20108 },
+	{ 108858 , 21738 },
+	{ 118273 , 23260 },
+	{ 127474 , 24693 },
+	{ 136520 , 26052 },
+	{ 145456 , 27348 },
+	{ 154316 , 28589 },
+	{ 163130 , 29783 },
+	{ 171919 , 30935 },
+	{ 180704 , 32049 },
+	{ 189502 , 33130 },
+	{ 198328 , 34180 },
+	{ 207194 , 35202 },
+	{ 216114 , 36198 },
+	{ 225097 , 37172 },
+	{ 234153 , 38123 },
+	{ 243294 , 39055 },
+	{ 252527 , 39968 },
+	{ 261861 , 40864 },
+	{ 271305 , 41743 },
+	{ 280866 , 42607 },
+	{ 290553 , 43457 },
+	{ 300372 , 44293 },
+	{ 310333 , 45117 },
+	{ 320441 , 45929 },
+	{ 330705 , 46729 },
+	{ 341131 , 47518 },
+	{ 351728 , 48297 },
+	{ 362501 , 49066 },
+	{ 373460 , 49826 },
+	{ 384609 , 50577 },
+	{ 395958 , 51320 },
+	{ 407513 , 52054 },
+	{ 419281 , 52780 },
+	{ 431270 , 53499 },
+	{ 443487 , 54211 },
+	{ 455940 , 54916 },
+	{ 468635 , 55614 },
+	{ 481581 , 56306 },
+	{ 494785 , 56991 },
+	{ 508254 , 57671 },
+	{ 521996 , 58345 },
+	{ 536019 , 59014 },
+	{ 550331 , 59677 },
+	{ 564939 , 60335 },
+	{ 579851 , 60988 },
+	{ 595075 , 61636 },
+	{ 610619 , 62279 },
+	{ 626491 , 62918 },
+	{ 642700 , 63553 },
+	{ 659253 , 64183 },
+	{ 676158 , 64809 },
+	{ 693424 , 65431 },
+	{ 711060 , 66050 },
+	{ 729073 , 66664 },
+	{ 747472 , 67275 },
+	{ 766266 , 67882 },
+	{ 785464 , 68486 },
+	{ 805073 , 69087 },
+	{ 825103 , 69684 },
+	{ 845562 , 70278 },
+	{ 866460 , 70868 },
+	{ 887805 , 71456 },
+	{ 909606 , 72041 },
+	{ 931873 , 72623 },
+	{ 954614 , 73202 },
+	{ 977839 , 73778 },
+	{ 1001557 , 74352 },
+	{ 1025777 , 74923 },
+	{ 1050508 , 75492 },
+	{ 1075761 , 76058 },
+	{ 1101544 , 76621 },
+	{ 1127867 , 77183 },
+	{ 1154739 , 77741 },
+	{ 1182172 , 78298 },
+	{ 1210173 , 78852 },
+	{ 1238753 , 79405 },
+	{ 1267922 , 79955 },
+	{ 1297689 , 80503 },
+	{ 1328066 , 81049 },
+	{ 1359060 , 81593 },
+	{ 1390684 , 82135 },
+	{ 1422947 , 82675 },
+	{ 1455859 , 83213 },
+	{ 1489430 , 83750 },
+	{ 1523671 , 84284 },
+	{ 1558593 , 84817 },
+	{ 1594205 , 85348 },
+	{ 1630518 , 85878 },
+	{ 1667543 , 86406 },
+	{ 1705290 , 86932 },
+	{ 1743770 , 87457 },
+	{ 1782994 , 87980 },
+	{ 1822973 , 88501 },
+	{ 1863717 , 89021 },
+	{ 1905237 , 89540 },
+	{ 1947545 , 90057 },
+	{ 1990650 , 90573 },
+	{ 2034566 , 91087 },
+	{ 2079301 , 91600 },
+	{ 2124869 , 92111 },
+	{ 2171279 , 92622 },
+	{ 2218543 , 93131 },
+	{ 2266673 , 93639 },
+	{ 2315680 , 94145 },
+	{ 2365575 , 94650 },
+	{ 2416371 , 95154 },
+	{ 2468077 , 95657 },
+	{ 2520707 , 96159 },
+	{ 2574271 , 96660 },
+	{ 2628782 , 97159 },
+	{ 2684250 , 97658 },
+	{ 2740689 , 98155 },
+	{ 2798110 , 98651 },
+	{ 2856524 , 99147 },
+	{ 2915944 , 99641 },
+	{ 2976382 , 100134 },
+	{ 3037850 , 100626 },
+	{ 3100360 , 101117 },
+	{ 3163924 , 101608 },
+	{ 3228554 , 102097 },
+	{ 3294263 , 102586 },
+	{ 3361063 , 103073 },
+	{ 3428966 , 103560 },
+	{ 3497984 , 104045 },
+	{ 3568131 , 104530 },
+	{ 3639419 , 105014 },
+	{ 3711860 , 105498 },
+	{ 3785467 , 105980 },
+	{ 3860253 , 106462 },
+	{ 3936229 , 106942 },
+	{ 4013410 , 107422 },
+	{ 4091808 , 107902 },
+	{ 4171435 , 108380 },
+	{ 4252306 , 108858 },
+	{ 4334431 , 109335 },
+	{ 4417825 , 109811 },
+	{ 4502501 , 110287 },
+	{ 4588472 , 110762 },
+	{ 4675750 , 111236 },
+	{ 4764349 , 111709 },
+	{ 4854283 , 112182 },
+	{ 4945564 , 112654 },
+	{ 5038206 , 113126 },
+	{ 5132223 , 113597 },
+	{ 5227627 , 114067 },
+	{ 5324432 , 114537 },
+	{ 5422652 , 115006 },
+	{ 5522299 , 115474 },
+	{ 5623389 , 115942 },
+	{ 5725934 , 116409 },
+	{ 5829948 , 116876 },
+	{ 5935446 , 117342 },
+	{ 6042439 , 117808 },
+	{ 6150943 , 118273 },
+	{ 6260972 , 118738 },
+	{ 6372538 , 119202 },
+	{ 6485657 , 119665 },
+	{ 6600342 , 120128 },
+	{ 6716607 , 120591 },
+	{ 6834467 , 121053 },
+	{ 6953935 , 121514 },
+	{ 7075025 , 121976 },
+	{ 7197752 , 122436 },
+	{ 7322131 , 122896 },
+	{ 7448175 , 123356 },
+	{ 7575898 , 123815 },
+	{ 7705316 , 124274 },
+	{ 7836442 , 124733 },
+	{ 7969291 , 125191 },
+	{ 8103877 , 125648 },
+	{ 8240216 , 126105 },
+	{ 8378321 , 126562 },
+	{ 8518208 , 127018 },
+	{ 8659890 , 127474 },
+	{ 8803384 , 127930 },
+	{ 8948702 , 128385 },
+	{ 9095861 , 128840 },
+	{ 9244875 , 129294 },
+	{ 9395760 , 129748 },
+	{ 9548529 , 130202 },
+	{ 9703198 , 130655 },
+	{ 9859782 , 131108 },
+	{ 10018296 , 131561 },
+	{ 10178755 , 132014 },
+	{ 10341174 , 132466 },
+	{ 10505569 , 132917 },
+	{ 10671954 , 133369 },
+	{ 10840345 , 133820 },
+	{ 11010757 , 134271 },
+	{ 11183206 , 134721 },
+	{ 11357706 , 135171 },
+	{ 11534274 , 135621 },
+	{ 11712924 , 136071 },
+	{ 11893673 , 136520 },
+	{ 12076536 , 136969 },
+	{ 12261527 , 137418 },
+	{ 12448664 , 137867 },
+	{ 12637961 , 138315 },
+	{ 12829435 , 138763 },
+	{ 13023101 , 139211 },
+	{ 13218974 , 139658 },
+	{ 13417071 , 140106 },
+	{ 13617407 , 140553 },
+	{ 13819999 , 140999 },
+	{ 14024862 , 141446 },
+	{ 14232012 , 141892 },
+	{ 14441465 , 142339 },
+	{ 14653238 , 142785 },
+	{ 14867346 , 143230 },
+	{ 15083805 , 143676 },
+	{ 15302632 , 144121 },
+	{ 15523842 , 144566 },
+	{ 15747453 , 145011 },
+	{ 15973479 , 145456 },
+	{ 16201939 , 145900 },
+	{ 16432847 , 146345 },
+	{ 16666221 , 146789 },
+	{ 16902076 , 147233 },
+	{ 17140429 , 147677 },
+	{ 17381297 , 148121 },
+	{ 17624696 , 148564 },
+	{ 17870643 , 149007 },
+	{ 18119154 , 149451 },
+	{ 18370247 , 149894 },
+	{ 18623936 , 150336 },
+	{ 18880241 , 150779 },
+	{ 19139176 , 151222 },
+	{ 19400759 , 151664 },
+	{ 19665007 , 152107 },
+	{ 19931936 , 152549 },
+	{ 20201564 , 152991 },
+	{ 20473907 , 153433 },
+	{ 20748982 , 153875 },
+	{ 21026807 , 154316 },
+	{ 21307399 , 154758 },
+	{ 21590773 , 155199 },
+	{ 21876949 , 155641 },
+	{ 22165941 , 156082 },
+	{ 22457769 , 156523 },
+	{ 22752449 , 156964 },
+	{ 23049999 , 157405 },
+	{ 23350435 , 157846 },
+	{ 23653774 , 158287 },
+	{ 23960036 , 158727 },
+	{ 24269236 , 159168 },
+	{ 24581392 , 159608 },
+	{ 24896521 , 160049 },
+	{ 25214642 , 160489 },
+	{ 25535772 , 160929 },
+	{ 25859927 , 161370 },
+	{ 26187127 , 161810 },
+	{ 26517388 , 162250 },
+	{ 26850728 , 162690 },
+	{ 27187165 , 163130 },
+	{ 27526716 , 163569 },
+	{ 27869400 , 164009 },
+	{ 28215234 , 164449 },
+	{ 28564236 , 164889 },
+	{ 28916423 , 165328 },
+	{ 29271815 , 165768 },
+	{ 29630428 , 166208 },
+	{ 29992281 , 166647 },
+	{ 30357392 , 167087 },
+	{ 30725779 , 167526 },
+	{ 31097459 , 167965 },
+	{ 31472452 , 168405 },
+	{ 31850774 , 168844 },
+	{ 32232445 , 169283 },
+	{ 32617482 , 169723 },
+	{ 33005904 , 170162 },
+	{ 33397730 , 170601 },
+	{ 33792976 , 171041 },
+	{ 34191663 , 171480 },
+	{ 34593807 , 171919 },
+	{ 34999428 , 172358 },
+	{ 35408544 , 172797 },
+	{ 35821174 , 173237 },
+	{ 36237335 , 173676 },
+	{ 36657047 , 174115 },
+	{ 37080329 , 174554 },
+	{ 37507197 , 174993 },
+	{ 37937673 , 175433 },
+	{ 38371773 , 175872 },
+	{ 38809517 , 176311 },
+	{ 39250924 , 176750 },
+	{ 39696012 , 177190 },
+	{ 40144800 , 177629 },
+	{ 40597308 , 178068 },
+	{ 41053553 , 178507 },
+	{ 41513554 , 178947 },
+	{ 41977332 , 179386 },
+	{ 42444904 , 179825 },
+	{ 42916290 , 180265 },
+	{ 43391509 , 180704 },
+	{ 43870579 , 181144 },
+	{ 44353520 , 181583 },
+	{ 44840352 , 182023 },
+	{ 45331092 , 182462 },
+	{ 45825761 , 182902 },
+	{ 46324378 , 183342 },
+	{ 46826961 , 183781 },
+	{ 47333531 , 184221 },
+	{ 47844106 , 184661 },
+	{ 48358706 , 185101 },
+	{ 48877350 , 185541 },
+	{ 49400058 , 185981 },
+	{ 49926849 , 186421 },
+	{ 50457743 , 186861 },
+	{ 50992759 , 187301 },
+	{ 51531916 , 187741 },
+	{ 52075235 , 188181 },
+	{ 52622735 , 188622 },
+	{ 53174435 , 189062 },
+	{ 53730355 , 189502 },
+	{ 54290515 , 189943 },
+	{ 54854935 , 190383 },
+	{ 55423634 , 190824 },
+	{ 55996633 , 191265 },
+	{ 56573950 , 191706 },
+	{ 57155606 , 192146 },
+	{ 57741621 , 192587 },
+	{ 58332014 , 193028 },
+	{ 58926806 , 193470 },
+	{ 59526017 , 193911 },
+	{ 60129666 , 194352 },
+	{ 60737774 , 194793 },
+	{ 61350361 , 195235 },
+	{ 61967446 , 195677 },
+	{ 62589050 , 196118 },
+	{ 63215194 , 196560 },
+	{ 63845897 , 197002 },
+	{ 64481179 , 197444 },
+	{ 65121061 , 197886 },
+	{ 65765563 , 198328 },
+	{ 66414705 , 198770 },
+	{ 67068508 , 199213 },
+	{ 67726992 , 199655 },
+	{ 68390177 , 200098 },
+	{ 69058085 , 200540 },
+	{ 69730735 , 200983 },
+	{ 70408147 , 201426 },
+	{ 71090343 , 201869 },
+	{ 71777343 , 202312 },
+	{ 72469168 , 202755 },
+	{ 73165837 , 203199 },
+	{ 73867373 , 203642 },
+	{ 74573795 , 204086 },
+	{ 75285124 , 204529 },
+	{ 76001380 , 204973 },
+	{ 76722586 , 205417 },
+	{ 77448761 , 205861 },
+	{ 78179926 , 206306 },
+	{ 78916102 , 206750 },
+	{ 79657310 , 207194 },
+	{ 80403571 , 207639 },
+	{ 81154906 , 208084 },
+	{ 81911335 , 208529 },
+	{ 82672880 , 208974 },
+	{ 83439562 , 209419 },
+	{ 84211402 , 209864 },
+	{ 84988421 , 210309 },
+	{ 85770640 , 210755 },
+	{ 86558080 , 211201 },
+	{ 87350762 , 211647 },
+	{ 88148708 , 212093 },
+	{ 88951938 , 212539 },
+	{ 89760475 , 212985 },
+	{ 90574339 , 213432 },
+	{ 91393551 , 213878 },
+	{ 92218133 , 214325 },
+	{ 93048107 , 214772 },
+	{ 93883493 , 215219 },
+	{ 94724314 , 215666 },
+	{ 95570590 , 216114 },
+	{ 96422343 , 216561 },
+	{ 97279594 , 217009 },
+	{ 98142366 , 217457 },
+	{ 99010679 , 217905 },
+	{ 99884556 , 218353 },
+	{ 100764018 , 218801 },
+	{ 101649086 , 219250 },