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;------------------------------------------------------------------------------
;
; Copyright (c) 2015 - 2016, 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.
;
; Module Name:
;
; RdRand.asm
;
; Abstract:
;
; Generates random number through CPU RdRand instruction under 32-bit platform.
;
; Notes:
;
;------------------------------------------------------------------------------
.686P
.model flat, C
.code
;------------------------------------------------------------------------------
; Generates a 16 bit random number through RDRAND instruction.
; Return TRUE if Rand generated successfully, or FALSE if not.
;
; BOOLEAN EFIAPI InternalX86RdRand16 (UINT16 *Rand);
;------------------------------------------------------------------------------
InternalX86RdRand16 PROC
; rdrand ax ; generate a 16 bit RN into ax
; CF=1 if RN generated ok, otherwise CF=0
db 0fh, 0c7h, 0f0h ; rdrand r16: "0f c7 /6 ModRM:r/m(w)"
jc rn16_ok ; jmp if CF=1
xor eax, eax ; reg=0 if CF=0
ret ; return with failure status
rn16_ok:
mov edx, dword ptr [esp + 4]
mov [edx], ax
mov eax, 1
ret
InternalX86RdRand16 ENDP
;------------------------------------------------------------------------------
; Generates a 32 bit random number through RDRAND instruction.
; Return TRUE if Rand generated successfully, or FALSE if not.
;
; BOOLEAN EFIAPI InternalX86RdRand32 (UINT32 *Rand);
;------------------------------------------------------------------------------
InternalX86RdRand32 PROC
; rdrand eax ; generate a 32 bit RN into eax
; CF=1 if RN generated ok, otherwise CF=0
db 0fh, 0c7h, 0f0h ; rdrand r32: "0f c7 /6 ModRM:r/m(w)"
jc rn32_ok ; jmp if CF=1
xor eax, eax ; reg=0 if CF=0
ret ; return with failure status
rn32_ok:
mov edx, dword ptr [esp + 4]
mov [edx], eax
mov eax, 1
ret
InternalX86RdRand32 ENDP
;------------------------------------------------------------------------------
; Generates a 64 bit random number through RDRAND instruction.
; Return TRUE if Rand generated successfully, or FALSE if not.
;
; BOOLEAN EFIAPI InternalX86RdRand64 (UINT64 *Rand);
;------------------------------------------------------------------------------
InternalX86RdRand64 PROC
; rdrand eax ; generate a 32 bit RN into eax
; CF=1 if RN generated ok, otherwise CF=0
db 0fh, 0c7h, 0f0h ; rdrand r32: "0f c7 /6 ModRM:r/m(w)"
jnc rn64_ret ; jmp if CF=0
mov edx, dword ptr [esp + 4]
mov [edx], eax
db 0fh, 0c7h, 0f0h ; generate another 32 bit RN
jnc rn64_ret ; jmp if CF=0
mov [edx + 4], eax
mov eax, 1
ret
rn64_ret:
xor eax, eax
ret ; return with failure status
InternalX86RdRand64 ENDP
END
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