UefiCpuPkg: Move AsmRelocateApLoopStart from Mpfuncs.nasm to AmdSev.nasm

[mirror_edk2.git] / MdePkg / Library / BaseRngLibTimerLib / RngLibTimer.c

/** @file\r
  BaseRng Library that uses the TimerLib to provide reasonably random numbers.\r
  Do not use this on a production system.\r
\r
  Copyright (c) Microsoft Corporation.\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
**/\r
\r
#include <Base.h>\r
#include <Library/BaseLib.h>\r
#include <Library/DebugLib.h>\r
#include <Library/TimerLib.h>\r
\r
#define DEFAULT_DELAY_TIME_IN_MICROSECONDS  10\r
\r
/**\r
 Using the TimerLib GetPerformanceCounterProperties() we delay\r
 for enough time for the PerformanceCounter to increment.\r
\r
 If the return value from GetPerformanceCounterProperties (TimerLib)\r
 is zero, this function will return 10 and attempt to assert.\r
 **/\r
STATIC\r
UINT32\r
CalculateMinimumDecentDelayInMicroseconds (\r
  VOID\r
  )\r
{\r
  UINT64  CounterHz;\r
\r
  // Get the counter properties\r
  CounterHz = GetPerformanceCounterProperties (NULL, NULL);\r
  // Make sure we won't divide by zero\r
  if (CounterHz == 0) {\r
    ASSERT (CounterHz != 0); // Assert so the developer knows something is wrong\r
    return DEFAULT_DELAY_TIME_IN_MICROSECONDS;\r
  }\r
\r
  // Calculate the minimum delay based on 1.5 microseconds divided by the hertz.\r
  // We calculate the length of a cycle (1/CounterHz) and multiply it by 1.5 microseconds\r
  // This ensures that the performance counter has increased by at least one\r
  return (UINT32)(MAX (DivU64x64Remainder (1500000, CounterHz, NULL), 1));\r
}\r
\r
/**\r
  Generates a 16-bit random number.\r
\r
  if Rand is NULL, then ASSERT().\r
\r
  @param[out] Rand     Buffer pointer to store the 16-bit random value.\r
\r
  @retval TRUE         Random number generated successfully.\r
  @retval FALSE        Failed to generate the random number.\r
\r
**/\r
BOOLEAN\r
EFIAPI\r
GetRandomNumber16 (\r
  OUT     UINT16  *Rand\r
  )\r
{\r
  UINT32  Index;\r
  UINT8   *RandPtr;\r
  UINT32  DelayInMicroSeconds;\r
\r
  ASSERT (Rand != NULL);\r
\r
  if (Rand == NULL) {\r
    return FALSE;\r
  }\r
\r
  DelayInMicroSeconds = CalculateMinimumDecentDelayInMicroseconds ();\r
  RandPtr             = (UINT8 *)Rand;\r
  // Get 2 bytes of random ish data\r
  for (Index = 0; Index < sizeof (UINT16); Index++) {\r
    *RandPtr = (UINT8)(GetPerformanceCounter () & 0xFF);\r
    // Delay to give the performance counter a chance to change\r
    MicroSecondDelay (DelayInMicroSeconds);\r
    RandPtr++;\r
  }\r
\r
  return TRUE;\r
}\r
\r
/**\r
  Generates a 32-bit random number.\r
\r
  if Rand is NULL, then ASSERT().\r
\r
  @param[out] Rand     Buffer pointer to store the 32-bit random value.\r
\r
  @retval TRUE         Random number generated successfully.\r
  @retval FALSE        Failed to generate the random number.\r
\r
**/\r
BOOLEAN\r
EFIAPI\r
GetRandomNumber32 (\r
  OUT     UINT32  *Rand\r
  )\r
{\r
  UINT32  Index;\r
  UINT8   *RandPtr;\r
  UINT32  DelayInMicroSeconds;\r
\r
  ASSERT (Rand != NULL);\r
\r
  if (NULL == Rand) {\r
    return FALSE;\r
  }\r
\r
  RandPtr             = (UINT8 *)Rand;\r
  DelayInMicroSeconds = CalculateMinimumDecentDelayInMicroseconds ();\r
  // Get 4 bytes of random ish data\r
  for (Index = 0; Index < sizeof (UINT32); Index++) {\r
    *RandPtr = (UINT8)(GetPerformanceCounter () & 0xFF);\r
    // Delay to give the performance counter a chance to change\r
    MicroSecondDelay (DelayInMicroSeconds);\r
    RandPtr++;\r
  }\r
\r
  return TRUE;\r
}\r
\r
/**\r
  Generates a 64-bit random number.\r
\r
  if Rand is NULL, then ASSERT().\r
\r
  @param[out] Rand     Buffer pointer to store the 64-bit random value.\r
\r
  @retval TRUE         Random number generated successfully.\r
  @retval FALSE        Failed to generate the random number.\r
\r
**/\r
BOOLEAN\r
EFIAPI\r
GetRandomNumber64 (\r
  OUT     UINT64  *Rand\r
  )\r
{\r
  UINT32  Index;\r
  UINT8   *RandPtr;\r
  UINT32  DelayInMicroSeconds;\r
\r
  ASSERT (Rand != NULL);\r
\r
  if (NULL == Rand) {\r
    return FALSE;\r
  }\r
\r
  RandPtr             = (UINT8 *)Rand;\r
  DelayInMicroSeconds = CalculateMinimumDecentDelayInMicroseconds ();\r
  // Get 8 bytes of random ish data\r
  for (Index = 0; Index < sizeof (UINT64); Index++) {\r
    *RandPtr = (UINT8)(GetPerformanceCounter () & 0xFF);\r
    // Delay to give the performance counter a chance to change\r
    MicroSecondDelay (DelayInMicroSeconds);\r
    RandPtr++;\r
  }\r
\r
  return TRUE;\r
}\r
\r
/**\r
  Generates a 128-bit random number.\r
\r
  if Rand is NULL, then ASSERT().\r
\r
  @param[out] Rand     Buffer pointer to store the 128-bit random value.\r
\r
  @retval TRUE         Random number generated successfully.\r
  @retval FALSE        Failed to generate the random number.\r
\r
**/\r
BOOLEAN\r
EFIAPI\r
GetRandomNumber128 (\r
  OUT     UINT64  *Rand\r
  )\r
{\r
  ASSERT (Rand != NULL);\r
  // This should take around 80ms\r
\r
  // Read first 64 bits\r
  if (!GetRandomNumber64 (Rand)) {\r
    return FALSE;\r
  }\r
\r
  // Read second 64 bits\r
  return GetRandomNumber64 (++Rand);\r
}\r