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//----------------------------------------------------------------------------- 
// Copyright (c) 2002 Jim Brady 
// Do not use commercially without author's permission 
// Last revised August 2002 
// Net TIMER.C 
// 
// This module sets up the timer and handles the timer interrupt 
//----------------------------------------------------------------------------- 
#include "C8051f.h" 
#include "net.h" 
#include "timer.h" 
 
 
extern UINT volatile event_word; 
extern ULONG idata initial_sequence_nr; 
 
 
//-------------------------------------------------------------------------- 
// Timer 2 interrupt service routing. Intr vector location is 
// address 0x002B. The timer generates an interrupt every 25 msec 
// It is set to auto reload so do not need to reload it. 
//-------------------------------------------------------------------------- 
void timer2_interrupt(void) interrupt 5 
{ 
	static UINT count1 = 0; 
	static UINT count2 = 0; 
	 
	TF2 = 0;		// Clear interrupt flag 
 
	 
	// Advance the initial sequence number 
	initial_sequence_nr += 6250; 
   // Keep it some distance from rolling over 
   if (initial_sequence_nr & 0x10000000L) initial_sequence_nr = 1; 
	 
	count1++; 
	// These events happens every 0.50 seconds, not simultaneously 
	if (count1 == 5) event_word |= EVENT_ARP_RETRANSMIT; 
	 
	if (count1 == 10) event_word |= EVENT_TCP_INACTIVITY; 
	 
	if (count1 == 15) event_word |= EVENT_READ_ANALOG; 
	 
	if (count1 == 20) 
	{ 
	 	count1 = 0; 
	 	event_word |= EVENT_TCP_RETRANSMIT; 
	} 
	 
	count2++; 
	if (count2 == 2401) 
	{ 
		// This happens every 60.025 seconds, not simultaneous 
		// with above tasks 
		count2 = 0; 
		event_word |= EVENT_AGE_ARP_CACHE; 
	} 
} 
 
 
 
 
 
//-------------------------------------------------------------------------- 
// Setup Timer2 in mode 1 which is 16 bit auto reload 
// Intr rate = 22.1184 MHz /(12 * (65536 - reload value)) 
// For 25 msec reload value = 19456 = 0x4C00 
//-------------------------------------------------------------------------- 
void init_timer2(void) 
{ 
	T2CON = 0x00; 
	RCAP2H = 0x4C; 		// Reload value 
	RCAP2L = 0x00; 
	TH2 = 0x4C;				// Initial load value 
	TL2 = 0x00; 
	TR2 = 1;					// Timer 2 run 
}