;------------------------------------------------------------------------------ ;* ;* Copyright (c) 2009, Intel Corporation. All rights reserved.
;* 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. ;* ;* ;------------------------------------------------------------------------------ .const ; ; Float control word initial value: ; all exceptions masked, double-precision, round-to-nearest ; mFpuControlWord DW 027Fh ; ; Multimedia-extensions control word: ; all exceptions masked, round-to-nearest, flush to zero for masked underflow ; mMmxControlWord DD 01F80h .code ; ; Initializes floating point units for requirement of UEFI specification. ; ; This function initializes floating-point control word to 0x027F (all exceptions ; masked,double-precision, round-to-nearest) and multimedia-extensions control word ; (if supported) to 0x1F80 (all exceptions masked, round-to-nearest, flush to zero ; for masked underflow). ; InitializeFloatingPointUnits PROC PUBLIC ; ; Initialize floating point units ; ; The following opcodes stand for instruction 'finit' ; to be supported by some 64-bit assemblers ; DB 9Bh, 0DBh, 0E3h fldcw mFpuControlWord ; ; Set OSFXSR bit 9 in CR4 ; mov rax, cr4 or rax, BIT9 mov cr4, rax ldmxcsr mMmxControlWord ret InitializeFloatingPointUnits ENDP END