1 #------------------------------------------------------------------------------ 2 #* 3 #* Copyright (c) 2009 - 2010, 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 # Float control word initial value: 17 # all exceptions masked, double-precision, round-to-nearest 18 # 19 ASM_PFX(mFpuControlWord): .word 0x027F 20 # 21 # Multimedia-extensions control word: 22 # all exceptions masked, round-to-nearest, flush to zero for masked underflow 23 # 24 ASM_PFX(mMmxControlWord): .long 0x01F80 25 26 # 27 # Initializes floating point units for requirement of UEFI specification. 28 # 29 # This function initializes floating-point control word to 0x027F (all exceptions 30 # masked,double-precision, round-to-nearest) and multimedia-extensions control word 31 # (if supported) to 0x1F80 (all exceptions masked, round-to-nearest, flush to zero 32 # for masked underflow). 33 # 34 ASM_GLOBAL ASM_PFX(InitializeFloatingPointUnits) 35 ASM_PFX(InitializeFloatingPointUnits): 36 37 pushl %ebx 38 39 # 40 # Initialize floating point units 41 # 42 finit 43 fldcw ASM_PFX(mFpuControlWord) 44 45 # 46 # Use CpuId instructuion (CPUID.01H:EDX.SSE[bit 25] = 1) to test 47 # whether the processor supports SSE instruction. 48 # 49 movl $1, %eax 50 cpuid 51 btl $25, %edx 52 jnc Done 53 54 # 55 # Set OSFXSR bit 9 in CR4 56 # 57 movl %cr4, %eax 58 or $0x200, %eax 59 movl %eax, %cr4 60 61 # 62 # The processor should support SSE instruction and we can use 63 # ldmxcsr instruction 64 # 65 ldmxcsr ASM_PFX(mMmxControlWord) 66 67 Done: 68 popl %ebx 69 70 ret 71 72 #END 73 74
