BaseRng.c

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#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
 
#include "BaseRngLibInternals.h"
 
//
// Limited retry number when valid random data is returned.
// Uses the recommended value defined in Section 7.3.17 of "Intel 64 and IA-32
// Architectures Software Developer's Manual".
//
#define GETRANDOM_RETRY_LIMIT  10
 
BOOLEAN
EFIAPI
GetRandomNumber16 (
  OUT     UINT16  *Rand
  )
{
  UINT32  Index;
 
  ASSERT (Rand != NULL);
 
  if (Rand == NULL) {
    return FALSE;
  }
 
  if (!ArchIsRngSupported ()) {
    return FALSE;
  }
 
  //
  // A loop to fetch a 16 bit random value with a retry count limit.
  //
  for (Index = 0; Index < GETRANDOM_RETRY_LIMIT; Index++) {
    if (ArchGetRandomNumber16 (Rand)) {
      return TRUE;
    }
  }
 
  return FALSE;
}
 
BOOLEAN
EFIAPI
GetRandomNumber32 (
  OUT     UINT32  *Rand
  )
{
  UINT32  Index;
 
  ASSERT (Rand != NULL);
 
  if (Rand == NULL) {
    return FALSE;
  }
 
  if (!ArchIsRngSupported ()) {
    return FALSE;
  }
 
  //
  // A loop to fetch a 32 bit random value with a retry count limit.
  //
  for (Index = 0; Index < GETRANDOM_RETRY_LIMIT; Index++) {
    if (ArchGetRandomNumber32 (Rand)) {
      return TRUE;
    }
  }
 
  return FALSE;
}
 
BOOLEAN
EFIAPI
GetRandomNumber64 (
  OUT     UINT64  *Rand
  )
{
  UINT32  Index;
 
  ASSERT (Rand != NULL);
 
  if (Rand == NULL) {
    return FALSE;
  }
 
  if (!ArchIsRngSupported ()) {
    return FALSE;
  }
 
  //
  // A loop to fetch a 64 bit random value with a retry count limit.
  //
  for (Index = 0; Index < GETRANDOM_RETRY_LIMIT; Index++) {
    if (ArchGetRandomNumber64 (Rand)) {
      return TRUE;
    }
  }
 
  return FALSE;
}
 
BOOLEAN
EFIAPI
GetRandomNumber128 (
  OUT     UINT64  *Rand
  )
{
  ASSERT (Rand != NULL);
 
  if (Rand == NULL) {
    return FALSE;
  }
 
  if (!ArchIsRngSupported ()) {
    return FALSE;
  }
 
  //
  // Read first 64 bits
  //
  if (!GetRandomNumber64 (Rand)) {
    return FALSE;
  }
 
  //
  // Read second 64 bits
  //
  return GetRandomNumber64 (++Rand);
}