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#------------------------------------------------------------------------------ ;
# Copyright (c) 2015, 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.S
#
# Abstract:
#
# Generates random number through CPU RdRand instruction under 32-bit platform.
#
# Notes:
#
#------------------------------------------------------------------------------
//------------------------------------------------------------------------------
// Generates a 16 bit random number through RDRAND instruction.
// Return TRUE if Rand generated successfully, or FALSE if not.
//
// BOOLEAN EFIAPI AsmRdRand16 (UINT16 *Rand);
//------------------------------------------------------------------------------
ASM_GLOBAL ASM_PFX(AsmRdRand16)
ASM_PFX(AsmRdRand16):
.byte 0x0f, 0xc7, 0xf0 // 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 0x4(%esp), %edx
mov %ax, (%edx)
mov $0x1, %eax
ret
//------------------------------------------------------------------------------
// Generates a 32 bit random number through RDRAND instruction.
// Return TRUE if Rand generated successfully, or FALSE if not.
//
// BOOLEAN EFIAPI AsmRdRand32 (UINT32 *Rand);
//------------------------------------------------------------------------------
ASM_GLOBAL ASM_PFX(AsmRdRand32)
ASM_PFX(AsmRdRand32):
.byte 0x0f, 0xc7, 0xf0 // 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 0x4(%esp), %edx
mov %eax, (%edx)
mov $0x1, %eax
ret
//------------------------------------------------------------------------------
// Generates a 64 bit random number through RDRAND instruction.
// Return TRUE if Rand generated successfully, or FALSE if not.
//
// BOOLEAN EFIAPI AsmRdRand64 (UINT64 *Rand);
//------------------------------------------------------------------------------
ASM_GLOBAL ASM_PFX(AsmRdRand64)
ASM_PFX(AsmRdRand64):
.byte 0x0f, 0xc7, 0xf0 // rdrand r32: "0f c7 /6 ModRM:r/m(w)"
jnc rn64_ret // jmp if CF=0
mov 0x4(%esp), %edx
mov %eax, (%edx)
.byte 0x0f, 0xc7, 0xf0 // generate another 32 bit RN
jnc rn64_ret // jmp if CF=0
mov %eax, 0x4(%edx)
mov $0x1, %eax
ret
rn64_ret:
xor %eax, %eax
ret // return with failure status
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