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;------------------------------------------------------------------------------
;
; 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.
;
; Module Name:
;
; AsmRdRand.Asm
;
; Abstract:
;
; Implementation for 16-, and 32- invocations of RDRAND instruction under 32bit platform.
;
; Notes:
;
; Visual Studio coding practices do not use inline asm since multiple compilers and
; architectures are supported assembler not recognizing rdrand instruction so using DB's.
;
;------------------------------------------------------------------------------
.586P
.model flat, C
.code
;------------------------------------------------------------------------------
; Generate a 16 bit random number
; Return TRUE if Rand generated successfully, or FALSE if not
;
; BOOLEAN EFIAPI RdRand16Step (UINT16 *Rand); ECX
;------------------------------------------------------------------------------
RdRand16Step 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)"
jb rn16_ok ; jmp if CF=1
xor eax, eax ; reg=0 if CF=0
ret ; return with failure status
rn16_ok:
mov [ecx], ax
mov eax, 1
ret
RdRand16Step ENDP
;------------------------------------------------------------------------------
; Generate a 32 bit random number
; Return TRUE if Rand generated successfully, or FALSE if not
;
; BOOLEAN EFIAPI RdRand32Step (UINT32 *Rand); ECX
;------------------------------------------------------------------------------
RdRand32Step 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)"
jb rn32_ok ; jmp if CF=1
xor eax, eax ; reg=0 if CF=0
ret ; return with failure status
rn32_ok:
mov [ecx], eax
mov eax, 1
ret
RdRand32Step ENDP
END
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