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- Fixed the timer calibration for processors without a tsc, spotted by Casper Hornstrup.

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svn path=/trunk/; revision=12189
This commit is contained in:
Hartmut Birr 2004-12-18 18:04:18 +00:00
parent 4bd03f70f7
commit d7be13618b
1 changed files with 19 additions and 21 deletions
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40
reactos/hal/halx86/generic/timer.c
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@ -20,7 +20,7 @@
* MA 02139, USA.
*
*/
/* $Id: timer.c,v 1.1 2004/12/03 20:10:43 gvg Exp $
/* $Id: timer.c,v 1.2 2004/12/18 18:04:18 hbirr Exp $
*
* PROJECT: ReactOS kernel
* FILE: ntoskrnl/hal/x86/udelay.c
@ -41,8 +41,6 @@
/* GLOBALS ******************************************************************/
static unsigned int delay_count = 1;
#define TMR_CTRL 0x43 /* I/O for control */
#define TMR_CNT0 0x40 /* I/O for counter 0 */
#define TMR_CNT1 0x41 /* I/O for counter 1 */
@ -232,55 +230,55 @@ VOID HalpCalibrateStallExecution(VOID)
WaitFor8254Wraparound();
delay_count = 1;
Pcr->StallScaleFactor = 1;
do
{
delay_count <<= 1; /* Next delay count to try */
Pcr->StallScaleFactor <<= 1; /* Next delay count to try */
WaitFor8254Wraparound();
__KeStallExecutionProcessor(delay_count); /* Do the delay */
__KeStallExecutionProcessor(Pcr->StallScaleFactor); /* Do the delay */
CurCount = Read8254Timer();
}
while (CurCount > LATCH / 2);
delay_count >>= 1; /* Get bottom value for delay */
Pcr->StallScaleFactor >>= 1; /* Get bottom value for delay */
/* Stage 2: Fine calibration */
DbgPrint("delay_count: %d", delay_count);
/* Stage 2: Fine calibration */
DbgPrint("delay_count: %d", Pcr->StallScaleFactor);
calib_bit = delay_count; /* Which bit are we going to test */
calib_bit = Pcr->StallScaleFactor; /* Which bit are we going to test */
for (i = 0; i < PRECISION; i++)
{
calib_bit >>= 1; /* Next bit to calibrate */
calib_bit >>= 1; /* Next bit to calibrate */
if (!calib_bit)
{
break; /* If we have done all bits, stop */
break; /* If we have done all bits, stop */
}
delay_count |= calib_bit; /* Set the bit in delay_count */
Pcr->StallScaleFactor |= calib_bit; /* Set the bit in delay_count */
WaitFor8254Wraparound();
__KeStallExecutionProcessor(delay_count); /* Do the delay */
__KeStallExecutionProcessor(Pcr->StallScaleFactor); /* Do the delay */
CurCount = Read8254Timer();
if (CurCount <= LATCH / 2) /* If a tick has passed, turn the */
{ /* calibrated bit back off */
delay_count &= ~calib_bit;
if (CurCount <= LATCH / 2) /* If a tick has passed, turn the */
{ /* calibrated bit back off */
Pcr->StallScaleFactor &= ~calib_bit;
}
}
/* We're finished: Do the finishing touches */
/* We're finished: Do the finishing touches */
delay_count /= (MILLISEC / 2); /* Calculate delay_count for 1ms */
Pcr->StallScaleFactor /= (MILLISEC / 2); /* Calculate delay_count for 1ms */
DbgPrint("]\n");
DbgPrint("delay_count: %d\n", delay_count);
DbgPrint("CPU speed: %d\n", delay_count / 250);
DbgPrint("delay_count: %d\n", Pcr->StallScaleFactor);
DbgPrint("CPU speed: %d\n", Pcr->StallScaleFactor / 250);
#if 0
DbgPrint("About to start delay loop test\n");
DbgPrint("Waiting for five minutes...");