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https://github.com/CloverHackyColor/CloverBootloader.git
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78 lines
3.0 KiB
NASM
78 lines
3.0 KiB
NASM
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;------------------------------------------------------------------------------
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;
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; Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
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; SPDX-License-Identifier: BSD-2-Clause-Patent
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;
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; Module Name:
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;
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; RdRand.nasm
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;
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; Abstract:
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;
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; Generates random number through CPU RdRand instruction under 64-bit platform.
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;
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; Notes:
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;
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;------------------------------------------------------------------------------
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DEFAULT REL
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SECTION .text
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;------------------------------------------------------------------------------
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; Generates a 16 bit random number through RDRAND instruction.
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; Return TRUE if Rand generated successfully, or FALSE if not.
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;
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; BOOLEAN EFIAPI InternalX86RdRand16 (UINT16 *Rand);
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;------------------------------------------------------------------------------
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global ASM_PFX(InternalX86RdRand16)
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ASM_PFX(InternalX86RdRand16):
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; rdrand ax ; generate a 16 bit RN into eax,
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; CF=1 if RN generated ok, otherwise CF=0
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db 0xf, 0xc7, 0xf0 ; rdrand r16: "0f c7 /6 ModRM:r/m(w)"
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jc rn16_ok ; jmp if CF=1
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xor rax, rax ; reg=0 if CF=0
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ret ; return with failure status
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rn16_ok:
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mov [rcx], ax
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mov rax, 1
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ret
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;------------------------------------------------------------------------------
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; Generates a 32 bit random number through RDRAND instruction.
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; Return TRUE if Rand generated successfully, or FALSE if not.
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;
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; BOOLEAN EFIAPI InternalX86RdRand32 (UINT32 *Rand);
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;------------------------------------------------------------------------------
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global ASM_PFX(InternalX86RdRand32)
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ASM_PFX(InternalX86RdRand32):
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; rdrand eax ; generate a 32 bit RN into eax,
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; CF=1 if RN generated ok, otherwise CF=0
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db 0xf, 0xc7, 0xf0 ; rdrand r32: "0f c7 /6 ModRM:r/m(w)"
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jc rn32_ok ; jmp if CF=1
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xor rax, rax ; reg=0 if CF=0
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ret ; return with failure status
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rn32_ok:
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mov [rcx], eax
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mov rax, 1
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ret
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;------------------------------------------------------------------------------
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; Generates a 64 bit random number through one RDRAND instruction.
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; Return TRUE if Rand generated successfully, or FALSE if not.
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;
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; BOOLEAN EFIAPI InternalX86RdRand64 (UINT64 *Random);
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;------------------------------------------------------------------------------
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global ASM_PFX(InternalX86RdRand64)
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ASM_PFX(InternalX86RdRand64):
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; rdrand rax ; generate a 64 bit RN into rax,
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; CF=1 if RN generated ok, otherwise CF=0
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db 0x48, 0xf, 0xc7, 0xf0 ; rdrand r64: "REX.W + 0f c7 /6 ModRM:r/m(w)"
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jc rn64_ok ; jmp if CF=1
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xor rax, rax ; reg=0 if CF=0
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ret ; return with failure status
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rn64_ok:
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mov [rcx], rax
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mov rax, 1
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ret
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