From cea3ff9d3896009bf9dafc8ae519208faaae24c9 Mon Sep 17 00:00:00 2001
From: marcbou <marcbou>
Date: Thu, 19 Jun 2003 12:45:32 +0000
Subject: [PATCH] Change TCP_TMR_INTERVAL from 100 to 250ms. tcp_fasttmr() and
 tcp_slowtmr() call frequencies should remain unchanged, but system load will
 be reduced. Closes patch #1495. Please email me if you see any issues with
 this. Non-standard TCP timer definitions in contrib/ports/v2pro/lwipopts.h
 might need adjustment as a consequence of this change.

---
 src/core/tcp.c         | 19 ++++++-------------
 src/include/lwip/tcp.h | 22 +++++++++++-----------
 2 files changed, 17 insertions(+), 24 deletions(-)

diff --git a/src/core/tcp.c b/src/core/tcp.c
index c1332500..30d7f57e 100644
--- a/src/core/tcp.c
+++ b/src/core/tcp.c
@@ -106,18 +106,11 @@ tcp_init(void)
 void
 tcp_tmr(void)
 {
-  ++tcp_timer;
-  if (tcp_timer == 10) {
-    tcp_timer = 0;
-  }
-  
-  if (tcp_timer & 1) {
-    /* Call tcp_fasttmr() every 200 ms, i.e., every other timer
-       tcp_tmr() is called. */
-    tcp_fasttmr();
-  }
-  if (tcp_timer == 0 || tcp_timer == 5) {
-    /* Call tcp_slowtmr() every 500 ms, i.e., every fifth timer
+  /* Call tcp_fasttmr() every 250 ms */
+  tcp_fasttmr();
+
+  if (++tcp_timer & 1) {
+    /* Call tcp_tmr() every 500 ms, i.e., every other timer
        tcp_tmr() is called. */
     tcp_slowtmr();
   }
@@ -626,7 +619,7 @@ tcp_slowtmr(void)
 /*
  * tcp_fasttmr():
  *
- * Is called every TCP_FINE_TIMEOUT (100 ms) and sends delayed ACKs.
+ * Is called every TCP_FAST_INTERVAL (250 ms) and sends delayed ACKs.
  */
 /*-----------------------------------------------------------------------------------*/
 void
diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index 72f2593c..dcd1c6ed 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -53,7 +53,7 @@ void             tcp_init    (void);  /* Must be called first to
            initialize TCP. */
 void             tcp_tmr     (void);  /* Must be called every
            TCP_TMR_INTERVAL
-           ms. (Typically 100 ms). */
+           ms. (Typically 250 ms). */
 /* Application program's interface: */
 struct tcp_pcb * tcp_new     (void);
 struct tcp_pcb * tcp_alloc   (u8_t prio);
@@ -115,30 +115,30 @@ void             tcp_rexmit  (struct tcp_pcb *pcb);
 #define TCP_SEQ_GT(a,b)     ((s32_t)((a)-(b)) > 0)
 #define TCP_SEQ_GEQ(a,b)    ((s32_t)((a)-(b)) >= 0)
 
-#define TCP_FIN 0x01
-#define TCP_SYN 0x02
-#define TCP_RST 0x04
-#define TCP_PSH 0x08
-#define TCP_ACK 0x10
-#define TCP_URG 0x20
+#define TCP_FIN 0x01U
+#define TCP_SYN 0x02U
+#define TCP_RST 0x04U
+#define TCP_PSH 0x08U
+#define TCP_ACK 0x10U
+#define TCP_URG 0x20U
 
-#define TCP_FLAGS 0x3f
+#define TCP_FLAGS 0x3fU
 
 /* Length of the TCP header, excluding options. */
 #define TCP_HLEN 20
 
 #ifndef TCP_TMR_INTERVAL
-#define TCP_TMR_INTERVAL       100  /* The TCP timer interval in
+#define TCP_TMR_INTERVAL       250  /* The TCP timer interval in
                                        milliseconds. */
 #endif /* TCP_TMR_INTERVAL */
 
 #ifndef TCP_FAST_INTERVAL
-#define TCP_FAST_INTERVAL      200  /* the fine grained timeout in
+#define TCP_FAST_INTERVAL      TCP_TMR_INTERVAL /* the fine grained timeout in
                                        milliseconds */
 #endif /* TCP_FAST_INTERVAL */
 
 #ifndef TCP_SLOW_INTERVAL
-#define TCP_SLOW_INTERVAL      500  /* the coarse grained timeout in
+#define TCP_SLOW_INTERVAL      (2*TCP_TMR_INTERVAL)  /* the coarse grained timeout in
                                        milliseconds */
 #endif /* TCP_SLOW_INTERVAL */