UefiCpuPkg: Use FINIT instead of hex values
[mirror_edk2.git] / UefiCpuPkg / Library / BaseUefiCpuLib / X64 / InitializeFpu.nasm
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1;------------------------------------------------------------------------------\r
2;*\r
5b78f30d 3;* Copyright (c) 2009 - 2017, Intel Corporation. All rights reserved.<BR>\r
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4;* This program and the accompanying materials\r
5;* are licensed and made available under the terms and conditions of the BSD License\r
6;* which accompanies this distribution. The full text of the license may be found at\r
7;* http://opensource.org/licenses/bsd-license.php\r
8;*\r
9;* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
10;* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
11;*\r
12;*\r
13;------------------------------------------------------------------------------\r
14\r
5b78f30d 15 SECTION .rodata\r
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16;\r
17; Float control word initial value:\r
18; all exceptions masked, double-extended-precision, round-to-nearest\r
19;\r
20mFpuControlWord: DW 0x37F\r
21;\r
22; Multimedia-extensions control word:\r
23; all exceptions masked, round-to-nearest, flush to zero for masked underflow\r
24;\r
25mMmxControlWord: DD 0x1F80\r
26\r
27DEFAULT REL\r
28SECTION .text\r
29\r
30;\r
31; Initializes floating point units for requirement of UEFI specification.\r
32;\r
33; This function initializes floating-point control word to 0x027F (all exceptions\r
34; masked,double-precision, round-to-nearest) and multimedia-extensions control word\r
35; (if supported) to 0x1F80 (all exceptions masked, round-to-nearest, flush to zero\r
36; for masked underflow).\r
37;\r
38global ASM_PFX(InitializeFloatingPointUnits)\r
39ASM_PFX(InitializeFloatingPointUnits):\r
40\r
41 ;\r
42 ; Initialize floating point units\r
43 ;\r
b9dbc03e 44 finit\r
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45 fldcw [mFpuControlWord]\r
46\r
47 ;\r
48 ; Set OSFXSR bit 9 in CR4\r
49 ;\r
50 mov rax, cr4\r
51 or rax, BIT9\r
52 mov cr4, rax\r
53\r
54 ldmxcsr [mMmxControlWord]\r
55\r
56 ret\r
57\r