MdePkg/Library/BaseLib/Ia32/RdRand.asm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
   4 ; This program and the accompanying materials
   5 ; are licensed and made available under the terms and conditions of the BSD License
   6 ; which accompanies this distribution.  The full text of the license may be found at
   7 ; http://opensource.org/licenses/bsd-license.php.
   8 ;
   9 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 ;
  12 ; Module Name:
  13 ;
  14 ;   RdRand.asm
  15 ;
  16 ; Abstract:
  17 ;
  18 ;   Generates random number through CPU RdRand instruction under 32-bit platform.
  19 ;
  20 ; Notes:
  21 ;
  22 ;------------------------------------------------------------------------------
  23
  24 .686P
  25 .model flat, C
  26
  27 .code
  28
  29 ;------------------------------------------------------------------------------
  30 ;  Generates a 16 bit random number through RDRAND instruction.
  31 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  32 ;
  33 ;  BOOLEAN EFIAPI InternalX86RdRand16 (UINT16 *Rand);
  34 ;------------------------------------------------------------------------------
  35 InternalX86RdRand16  PROC
  36     ; rdrand   ax                  ; generate a 16 bit RN into ax
  37                                    ; CF=1 if RN generated ok, otherwise CF=0
  38     db     0fh, 0c7h, 0f0h         ; rdrand r16: "0f c7 /6  ModRM:r/m(w)"
  39     jc     rn16_ok                 ; jmp if CF=1
  40     xor    eax, eax                ; reg=0 if CF=0
  41     ret                            ; return with failure status
  42 rn16_ok:
  43     mov    edx, dword ptr [esp + 4]
  44     mov    [edx], ax
  45     mov    eax,  1
  46     ret
  47 InternalX86RdRand16 ENDP
  48
  49 ;------------------------------------------------------------------------------
  50 ;  Generates a 32 bit random number through RDRAND instruction.
  51 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  52 ;
  53 ;  BOOLEAN EFIAPI InternalX86RdRand32 (UINT32 *Rand);
  54 ;------------------------------------------------------------------------------
  55 InternalX86RdRand32  PROC
  56     ; rdrand   eax                 ; generate a 32 bit RN into eax
  57                                    ; CF=1 if RN generated ok, otherwise CF=0
  58     db     0fh, 0c7h, 0f0h         ; rdrand r32: "0f c7 /6  ModRM:r/m(w)"
  59     jc     rn32_ok                 ; jmp if CF=1
  60     xor    eax, eax                ; reg=0 if CF=0
  61     ret                            ; return with failure status
  62 rn32_ok:
  63     mov    edx, dword ptr [esp + 4]
  64     mov    [edx], eax
  65     mov    eax,  1
  66     ret
  67 InternalX86RdRand32 ENDP
  68
  69 ;------------------------------------------------------------------------------
  70 ;  Generates a 64 bit random number through RDRAND instruction.
  71 ;  Return TRUE if Rand generated successfully, or FALSE if not.
  72 ;
  73 ;  BOOLEAN EFIAPI InternalX86RdRand64 (UINT64 *Rand);
  74 ;------------------------------------------------------------------------------
  75 InternalX86RdRand64  PROC
  76     ; rdrand   eax                 ; generate a 32 bit RN into eax
  77                                    ; CF=1 if RN generated ok, otherwise CF=0
  78     db     0fh, 0c7h, 0f0h         ; rdrand r32: "0f c7 /6  ModRM:r/m(w)"
  79     jnc    rn64_ret                ; jmp if CF=0
  80     mov    edx, dword ptr [esp + 4]
  81     mov    [edx], eax
  82
  83     db     0fh, 0c7h, 0f0h         ; generate another 32 bit RN
  84     jnc    rn64_ret                ; jmp if CF=0
  85     mov    [edx + 4], eax
  86
  87     mov    eax,  1
  88     ret
  89 rn64_ret:
  90     xor    eax, eax
  91     ret                            ; return with failure status
  92 InternalX86RdRand64 ENDP
  93
  94     END