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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.nasm
;
; Abstract:
;
; Generates random number through CPU RdRand instruction under 64-bit platform.
;
; Notes:
;
;------------------------------------------------------------------------------
DEFAULT REL
SECTION .text
;------------------------------------------------------------------------------
; Generates a 16 bit random number through RDRAND instruction.
; Return TRUE if Rand generated successfully, or FALSE if not.
;
; BOOLEAN EFIAPI InternalX86RdRand16 (UINT16 *Rand);
;------------------------------------------------------------------------------
global ASM_PFX(InternalX86RdRand16)
ASM_PFX(InternalX86RdRand16):
; rdrand ax ; generate a 16 bit RN into eax,
; CF=1 if RN generated ok, otherwise CF=0
db 0xf, 0xc7, 0xf0 ; rdrand r16: "0f c7 /6 ModRM:r/m(w)"
jc rn16_ok ; jmp if CF=1
xor rax, rax ; reg=0 if CF=0
ret ; return with failure status
rn16_ok:
mov [rcx], ax
mov rax, 1
ret
;------------------------------------------------------------------------------
; Generates a 32 bit random number through RDRAND instruction.
; Return TRUE if Rand generated successfully, or FALSE if not.
;
; BOOLEAN EFIAPI InternalX86RdRand32 (UINT32 *Rand);
;------------------------------------------------------------------------------
global ASM_PFX(InternalX86RdRand32)
ASM_PFX(InternalX86RdRand32):
; rdrand eax ; generate a 32 bit RN into eax,
; CF=1 if RN generated ok, otherwise CF=0
db 0xf, 0xc7, 0xf0 ; rdrand r32: "0f c7 /6 ModRM:r/m(w)"
jc rn32_ok ; jmp if CF=1
xor rax, rax ; reg=0 if CF=0
ret ; return with failure status
rn32_ok:
mov [rcx], eax
mov rax, 1
ret
;------------------------------------------------------------------------------
; Generates a 64 bit random number through one RDRAND instruction.
; Return TRUE if Rand generated successfully, or FALSE if not.
;
; BOOLEAN EFIAPI InternalX86RdRand64 (UINT64 *Random);
;------------------------------------------------------------------------------
global ASM_PFX(InternalX86RdRand64)
ASM_PFX(InternalX86RdRand64):
; rdrand rax ; generate a 64 bit RN into rax,
; CF=1 if RN generated ok, otherwise CF=0
db 0x48, 0xf, 0xc7, 0xf0 ; rdrand r64: "REX.W + 0f c7 /6 ModRM:r/m(w)"
jc rn64_ok ; jmp if CF=1
xor rax, rax ; reg=0 if CF=0
ret ; return with failure status
rn64_ok:
mov [rcx], rax
mov rax, 1
ret
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