231 lines
8.2 KiB
C#
231 lines
8.2 KiB
C#
///////////////////////////////////////////////////////////////////////////////
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//
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// Microsoft Research Singularity
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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// File: ClockLogger.cs
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//
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// Useful reference URLs:
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// http://developer.intel.com/design/archives/periphrl/index.htm
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// http://developer.intel.com/design/archives/periphrl/docs/7203.htm
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// http://developer.intel.com/design/archives/periphrl/docs/23124406.htm
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//
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// The basic ideas for this driver come from the MMOSA code,
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// though the implementation differs. This is partly because
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// the code needs to run on Virtual PC and it isn't able to do
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// a very accurate emulation of the i8254.
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//
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// There are two source available for timing - the Real-Time
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// Clock (RTC) and the programmable interval timer (PIT). The
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// standard PC RTC is based on derivatives of the Motorola
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// MC146818A. It's able to provide the time with a resolution
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// of 1 second and also has a programmable periodic interrupt.
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//
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// The programmable interrupt timer is based on the i8254. It
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// can be programmed in a variety of modes - we use it to
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// generate an interrupt at a configurable time in the future
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// and then reprogram it each interrupt. The maximum interrupt
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// period is 65535 ticks of a 1.193MHz clock.
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//
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// We use both of the RTC and the programmable interrupt timer to
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// maintain our estimate of the current time. The RTC provides granularity
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// to with 1/64 seconds and the time is used to get an estimate to within
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// 1/1.193 * 10e-6 seconds within each RTC interval.
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//
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// The key variables are:
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//
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// upTime - the time the system has been up. This variable gets
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// updated during the periodic RTC interrupt handling
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// (delta = 1/64Hz).
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//
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// pitLast - the last value programmed into the PIT. The PIT counts down
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// and generates an interrupt at (or shortly after) the instant
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// the current PIT value reaches zero.
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//
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// pitAccum - the accumulated time measured by the PIT since upTime
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// was updated.
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//
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// The current kernel time is always:
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// upTime + pitAccum + (pitLast - pitCurrent)
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//
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// The PIT is always programmed to run, either by the consumer of the timer
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// interface or by the timer itself.
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//
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// Timer::SetNextInterrupt(t)
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// pitAccum += (pitLast - pitCurrent)
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// // program PIT (not shown)
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// pitLast = t
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//
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// Timer::Interrupt()
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// pitAccum += pitLast;
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// // But PIT time may accumulate between interrupt dispatch and crossing
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// // Zero so.
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// if (pitCurrent != 0)
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// pitAccum += (MaxPitValue - pitCurrent)
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// // Inform user of interrupt
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// if (userNotScheduledInterrupt)
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// SetNextInterrupt(MaxInterruptInterval)
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//
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// RTC::Interrupt()
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// pitLast = pitNow
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// pitAccum = 0
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// upTime += RTCInterruptPeriod
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//
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// All of these methods are atomic interrupt-wise.
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//
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// Note: if we want to test the accuracy of the timer over a
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// period we can set RTC::Interrupt to just return without
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// touching any variables. All of the time accumulated will end
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// up in pitAccum.
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//
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// Conditionals
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//
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// TIMER_NO_GO - disables timer and scheduling of timer interrupts.
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//
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// RTC_NO_GO - disable RTC.
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//
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// DEBUG_TIMER - enable timer debug messages and boot-time diagnostics.
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//
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// DEBUG_CLOCK - enable clock debug messages
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//
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// LOG_CLOCK - log adjustments to clock time and dump out later.
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//
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// LOG_SNI - log calls to SetNextInterrupt to see what's being thrown in.
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//
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// Tip: When this code does not behave useful things to check
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// are the interrupt rate and the rate of calls to
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// SetNextInterrupt.
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//
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// #define VERBOSE
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using Microsoft.Singularity.Io;
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using System;
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using System.Runtime.CompilerServices;
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using System.Threading;
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using System.Diagnostics;
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namespace Microsoft.Singularity.Hal
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{
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[ CLSCompliant(false) ]
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internal sealed class ClockLogger
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{
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public struct Record
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{
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public int who;
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public ulong when;
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public ulong currentTime;
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public long upTime;
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public int pitLastClock;
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public int pitNow;
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public long cookie;
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};
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private static int currentRecord = 0;
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private static Record [] entries = null;
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private static int ignoreCount = 20000;
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static ClockLogger()
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{
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InitializeEntries();
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#if LOG_CLOCK
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DebugStub.Print("Initializing ClockLogger.\n");
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#endif // LOG_CLOCK
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}
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[System.Diagnostics.Conditional("LOG_CLOCK")]
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internal static void InitializeEntries()
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{
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entries = new Record[10000];
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}
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[System.Diagnostics.Conditional("LOG_CLOCK")]
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[NoHeapAllocation]
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internal static void AddEntry(int who, RtcPitState rps, Timer8254 timer, long cookie)
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{
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if (ignoreCount != 0) {
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ignoreCount--;
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return;
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}
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if (currentRecord == entries.Length)
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return;
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entries[currentRecord].who = who;
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entries[currentRecord].cookie = cookie;
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entries[currentRecord].when = Processor.CycleCount;
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int pitNow = timer.Timer2Read();
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entries[currentRecord].currentTime =
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(ulong)rps.GetKernelTicks(pitNow);
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entries[currentRecord].upTime = rps.upTime;
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entries[currentRecord].pitLastClock = rps.pitLastClock;
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entries[currentRecord].pitNow = pitNow;
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currentRecord = currentRecord + 1;
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if (currentRecord == entries.Length) {
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bool iflag = Processor.DisableInterrupts();
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try {
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DumpEntries();
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DebugStub.Assert(false);
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}
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finally {
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Processor.RestoreInterrupts(iflag);
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}
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}
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}
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[System.Diagnostics.Conditional("LOG_CLOCK")]
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[NoHeapAllocation]
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internal static void AddEntry(int who, RtcPitState rps, Timer8254 timer)
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{
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AddEntry(who, rps, timer, 0);
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}
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[System.Diagnostics.Conditional("LOG_CLOCK")]
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[NoHeapAllocation]
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internal static void SetCookie(long cookie)
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{
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if (currentRecord < entries.Length)
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entries[currentRecord].cookie = cookie;
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}
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[NoHeapAllocation]
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static ulong ToMicros(ulong t, ulong t0, ulong tps)
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{
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return ((t - t0) * 10000000) / tps;
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}
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[System.Diagnostics.Conditional("LOG_CLOCK")]
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[NoHeapAllocation]
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static void DumpEntries()
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{
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DebugStub.Print("# Clock column 1 who\n");
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DebugStub.Print("# Clock column 2 time in cpu cycles\n");
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DebugStub.Print("# Clock column 3 time from clock\n");
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DebugStub.Print("# Clock column 4 pitLastClock\n");
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DebugStub.Print("# Clock column 5 pitNow\n");
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DebugStub.Print("# Clock column 6 upTime\n");
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DebugStub.Print("# Clock column 7 currentTime\n");
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DebugStub.Print("# Clock column 8 cookie\n");
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DebugStub.Print("# Clock column 9 record number\n");
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for (int i = 0; i != currentRecord; i++) {
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DebugStub.Print("Clock {0:d6} {1:d6} {2} {3} {4} {5} {6} {7}\n",
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__arglist(
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ToMicros(entries[i].when,
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entries[0].when,
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Processor.CyclesPerSecond),
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ToMicros(entries[i].currentTime, 0, 10000000),
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entries[i].pitLastClock,
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entries[i].pitNow,
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entries[i].upTime,
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entries[i].currentTime,
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entries[i].cookie,
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i));
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}
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}
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}
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}
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