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https://github.com/CloverHackyColor/CloverBootloader.git
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52 lines
1.3 KiB
NASM
52 lines
1.3 KiB
NASM
;------------------------------------------------------------------------------
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;*
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;* Copyright (c) 2009 - 2017, 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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;*
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;------------------------------------------------------------------------------
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SECTION .rodata
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;
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; Float control word initial value:
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; all exceptions masked, double-extended-precision, round-to-nearest
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;
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mFpuControlWord: DW 0x37F
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;
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; Multimedia-extensions control word:
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; all exceptions masked, round-to-nearest, flush to zero for masked underflow
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;
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mMmxControlWord: DD 0x1F80
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DEFAULT REL
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SECTION .text
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;
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; Initializes floating point units for requirement of UEFI specification.
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;
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; This function initializes floating-point control word to 0x027F (all exceptions
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; masked,double-precision, round-to-nearest) and multimedia-extensions control word
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; (if supported) to 0x1F80 (all exceptions masked, round-to-nearest, flush to zero
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; for masked underflow).
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;
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global ASM_PFX(InitializeFloatingPointUnits)
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ASM_PFX(InitializeFloatingPointUnits):
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;
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; Initialize floating point units
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;
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finit
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fldcw [mFpuControlWord]
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;
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; Set OSFXSR bit 9 in CR4
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;
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mov rax, cr4
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or rax, BIT9
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mov cr4, rax
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ldmxcsr [mMmxControlWord]
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ret
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