Introduce UefiCpuLib library class in UefiCpuPkg and add one instance of BaseUefiCpuL...
[mirror_edk2.git] / UefiCpuPkg / Library / BaseUefiCpuLib / X64 / InitializeFpu.S
1 #------------------------------------------------------------------------------
2 #*
3 #* Copyright 2009, Intel Corporation
4 #* All rights reserved. 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 #
17 # Float control word initial value:
18 # all exceptions masked, double-precision, round-to-nearest
19 #
20 ASM_PFX(mFpuControlWord): .word 0x027F
21 #
22 # Multimedia-extensions control word:
23 # all exceptions masked, round-to-nearest, flush to zero for masked underflow
24 #
25 ASM_PFX(mMmxControlWord): .long 0x01F80
26
27 #
28 # Initializes floating point units for requirement of UEFI specification.
29 #
30 # This function initializes floating-point control word to 0x027F (all exceptions
31 # masked,double-precision, round-to-nearest) and multimedia-extensions control word
32 # (if supported) to 0x1F80 (all exceptions masked, round-to-nearest, flush to zero
33 # for masked underflow).
34 #
35 ASM_GLOBAL ASM_PFX(InitializeFloatingPointUnits)
36 ASM_PFX(InitializeFloatingPointUnits):
37
38 #
39 # Initialize floating point units
40 #
41 finit
42 fldcw ASM_PFX(mFpuControlWord)
43
44 #
45 # Set OSFXSR bit 9 in CR4
46 #
47 movq %cr4, %rax
48 or $200, %rax
49 movq %rax, %cr4
50
51 ldmxcsr ASM_PFX(mMmxControlWord)
52
53 ret
54