1 ;------------------------------------------------------------------------------ 2 ;* 3 ;* Copyright (c) 2009 - 2012, 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 ;* 13 ;------------------------------------------------------------------------------ 14 15 16 .const 17 ; 18 ; Float control word initial value: 19 ; all exceptions masked, double-extended-precision, round-to-nearest 20 ; 21 mFpuControlWord DW 037Fh 22 ; 23 ; Multimedia-extensions control word: 24 ; all exceptions masked, round-to-nearest, flush to zero for masked underflow 25 ; 26 mMmxControlWord DD 01F80h 27 28 .code 29 30 31 ; 32 ; Initializes floating point units for requirement of UEFI specification. 33 ; 34 ; This function initializes floating-point control word to 0x027F (all exceptions 35 ; masked,double-precision, round-to-nearest) and multimedia-extensions control word 36 ; (if supported) to 0x1F80 (all exceptions masked, round-to-nearest, flush to zero 37 ; for masked underflow). 38 ; 39 InitializeFloatingPointUnits PROC PUBLIC 40 41 ; 42 ; Initialize floating point units 43 ; 44 ; The following opcodes stand for instruction 'finit' 45 ; to be supported by some 64-bit assemblers 46 ; 47 DB 9Bh, 0DBh, 0E3h 48 fldcw mFpuControlWord 49 50 ; 51 ; Set OSFXSR bit 9 in CR4 52 ; 53 mov rax, cr4 54 or rax, BIT9 55 mov cr4, rax 56 57 ldmxcsr mMmxControlWord 58 59 ret 60 InitializeFloatingPointUnits ENDP 61 62 END 63
