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/** @file
RDRAND Support Routines.
Copyright (c) 2013, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include "RdRand.h"
/**
Generates a 64-bit random number through RDRAND instruction.
@param[out] Rand Buffer pointer to store the random result.
@retval TRUE RDRAND call was successful.
@retval FALSE Failed attempts to call RDRAND.
**/
BOOLEAN
EFIAPI
RdRand64Step (
OUT UINT64 *Rand
)
{
UINT32 RandLow;
UINT32 RandHigh;
//
// Generating a 64-bit rand on a 32-bit system by
// mapping two 32-bit RDRAND instructions.
//
if (!RdRand32Step (&RandLow)) {
return FALSE;
}
if (!RdRand32Step (&RandHigh)) {
return FALSE;
}
*Rand = (UINT64) RandLow | LShiftU64 ((UINT64)RandHigh, 32);
return TRUE;
}
/**
Calls RDRAND to request a word-length random number.
@param[out] Rand Buffer pointer to store the random number.
@param[in] NeedRetry Determine whether or not to loop retry.
@retval EFI_SUCCESS Random word generation succeeded.
@retval EFI_NOT_READY Failed to request random word.
**/
EFI_STATUS
EFIAPI
RdRandWord (
OUT UINTN *Rand,
IN BOOLEAN NeedRetry
)
{
return RdRand32 (Rand, NeedRetry);
}
/**
Calls RDRAND to request multiple word-length random numbers.
@param[in] Length Size of the buffer, in words, to fill with.
@param[out] RandBuffer Pointer to the buffer to store the random result.
@retval EFI_SUCCESS Random words generation succeeded.
@retval EFI_NOT_READY Failed to request random words.
**/
EFI_STATUS
EFIAPI
RdRandGetWords (
IN UINTN Length,
OUT UINTN *RandBuffer
)
{
EFI_STATUS Status;
UINT32 Index;
for (Index = 0; Index < Length; Index++) {
//
// Obtain one word-length (32-bit) Random Number with possible retry-loop.
//
Status = RdRand32 (RandBuffer, TRUE);
if (EFI_ERROR (Status)) {
return Status;
}
RandBuffer++;
}
return EFI_SUCCESS;
}
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