X-Git-Url: https://git.proxmox.com/?p=mirror_edk2.git;a=blobdiff_plain;f=UefiCpuPkg%2FLibrary%2FBaseUefiCpuLib%2FIa32%2FInitializeFpu.nasm;fp=UefiCpuPkg%2FLibrary%2FBaseUefiCpuLib%2FIa32%2FInitializeFpu.nasm;h=55085e019f46b1493aab1377111c227657c6a020;hp=0000000000000000000000000000000000000000;hb=f893042d05c9ec7a889ee5b74b4ca5090c553daf;hpb=b85a6ffb441129889c301459207a729d562ab8e8

diff --git a/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.nasm b/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.nasm
new file mode 100644
index 0000000000..55085e019f
--- /dev/null
+++ b/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.nasm
@@ -0,0 +1,74 @@
+;------------------------------------------------------------------------------
+;*
+;*   Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
+;*   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.
+;*
+;*
+;------------------------------------------------------------------------------
+
+    SECTION .rdata
+
+;
+; Float control word initial value:
+; all exceptions masked, double-precision, round-to-nearest
+;
+mFpuControlWord: DW 0x27F
+;
+; Multimedia-extensions control word:
+; all exceptions masked, round-to-nearest, flush to zero for masked underflow
+;
+mMmxControlWord: DD 0x1F80
+
+    SECTION .text
+
+;
+; 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).
+;
+global ASM_PFX(InitializeFloatingPointUnits)
+ASM_PFX(InitializeFloatingPointUnits):
+
+    push    ebx
+
+    ;
+    ; Initialize floating point units
+    ;
+    finit
+    fldcw   [mFpuControlWord]
+
+    ;
+    ; Use CpuId instructuion (CPUID.01H:EDX.SSE[bit 25] = 1) to test
+    ; whether the processor supports SSE instruction.
+    ;
+    mov     eax, 1
+    cpuid
+    bt      edx, 25
+    jnc     Done
+
+    ;
+    ; Set OSFXSR bit 9 in CR4
+    ;
+    mov     eax, cr4
+    or      eax, BIT9
+    mov     cr4, eax
+
+    ;
+    ; The processor should support SSE instruction and we can use
+    ; ldmxcsr instruction
+    ;
+    ldmxcsr [mMmxControlWord]
+Done:
+    pop     ebx
+
+    ret
+