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git.proxmox.com Git - mirror_edk2.git/blob - UefiCpuPkg/Library/SecPeiDxeTimerLibUefiCpu/X86TimerLib.c
2 Timer Library functions built upon local APIC on IA32/x64.
4 This library uses the local APIC library so that it supports x2APIC mode.
6 Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR>
7 This program and the accompanying materials
8 are licensed and made available under the terms and conditions of the BSD License
9 which accompanies this distribution. The full text of the license may be found at
10 http://opensource.org/licenses/bsd-license.php.
12 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
13 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
18 #include <Library/TimerLib.h>
19 #include <Library/BaseLib.h>
20 #include <Library/PcdLib.h>
21 #include <Library/DebugLib.h>
22 #include <Library/LocalApicLib.h>
25 Internal function to return the frequency of the local APIC timer.
27 @return The frequency of the timer in Hz.
32 InternalX86GetTimerFrequency (
38 GetApicTimerState (&Divisor
, NULL
, NULL
);
39 return PcdGet32(PcdFSBClock
) / (UINT32
)Divisor
;
43 Stalls the CPU for at least the given number of ticks.
45 Stalls the CPU for at least the given number of ticks. It's invoked by
46 MicroSecondDelay() and NanoSecondDelay().
48 @param Delay A period of time to delay in ticks.
58 UINT32 PowerOfTwoCounter
;
61 // The target timer count is calculated here
63 Ticks
= GetApicTimerCurrentCount () - Delay
;
66 // Wait until time out
67 // Delay > 2^31 could not be handled by this function
68 // Timer wrap-arounds are handled correctly by this function
70 PowerOfTwoCounter
= GetPowerOfTwo32 (GetApicTimerInitCount ());
71 while (((UINT32
)(GetApicTimerCurrentCount () - Ticks
) & PowerOfTwoCounter
) == 0) {
77 Stalls the CPU for at least the given number of microseconds.
79 Stalls the CPU for the number of microseconds specified by MicroSeconds.
81 @param MicroSeconds The minimum number of microseconds to delay.
83 @return The value of MicroSeconds inputted.
95 InternalX86GetTimerFrequency (),
105 Stalls the CPU for at least the given number of nanoseconds.
107 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
109 @param NanoSeconds The minimum number of nanoseconds to delay.
111 @return The value of NanoSeconds inputted.
123 InternalX86GetTimerFrequency (),
133 Retrieves the current value of a 64-bit free running performance counter.
135 The counter can either count up by 1 or count down by 1. If the physical
136 performance counter counts by a larger increment, then the counter values
137 must be translated. The properties of the counter can be retrieved from
138 GetPerformanceCounterProperties().
140 @return The current value of the free running performance counter.
145 GetPerformanceCounter (
149 return (UINT64
)GetApicTimerCurrentCount ();
153 Retrieves the 64-bit frequency in Hz and the range of performance counter
156 If StartValue is not NULL, then the value that the performance counter starts
157 with immediately after is it rolls over is returned in StartValue. If
158 EndValue is not NULL, then the value that the performance counter end with
159 immediately before it rolls over is returned in EndValue. The 64-bit
160 frequency of the performance counter in Hz is always returned. If StartValue
161 is less than EndValue, then the performance counter counts up. If StartValue
162 is greater than EndValue, then the performance counter counts down. For
163 example, a 64-bit free running counter that counts up would have a StartValue
164 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
165 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
167 @param StartValue The value the performance counter starts with when it
169 @param EndValue The value that the performance counter ends with before
172 @return The frequency in Hz.
177 GetPerformanceCounterProperties (
178 OUT UINT64
*StartValue
, OPTIONAL
179 OUT UINT64
*EndValue OPTIONAL
182 if (StartValue
!= NULL
) {
183 *StartValue
= (UINT64
)GetApicTimerInitCount ();
185 // make sure StartValue is all 1s from High Bit
187 ASSERT ((*StartValue
& (*StartValue
+ 1)) == 0);
190 if (EndValue
!= NULL
) {
194 return (UINT64
) InternalX86GetTimerFrequency ();
198 Converts elapsed ticks of performance counter to time in nanoseconds.
200 This function converts the elapsed ticks of running performance counter to
201 time value in unit of nanoseconds.
203 @param Ticks The number of elapsed ticks of running performance counter.
205 @return The elapsed time in nanoseconds.
210 GetTimeInNanoSecond (
219 Frequency
= GetPerformanceCounterProperties (NULL
, NULL
);
223 // Time = --------- x 1,000,000,000
226 NanoSeconds
= MultU64x32 (DivU64x64Remainder (Ticks
, Frequency
, &Remainder
), 1000000000u);
229 // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
230 // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
231 // i.e. highest bit set in Remainder should <= 33.
233 Shift
= MAX (0, HighBitSet64 (Remainder
) - 33);
234 Remainder
= RShiftU64 (Remainder
, (UINTN
) Shift
);
235 Frequency
= RShiftU64 (Frequency
, (UINTN
) Shift
);
236 NanoSeconds
+= DivU64x64Remainder (MultU64x32 (Remainder
, 1000000000u), Frequency
, NULL
);