1 #------------------------------------------------------------------------------ 2 # 3 # Copyright (c) 2014 - 2015, 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 # Abstract: 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 29 # 30 # Initializes floating point units for requirement of UEFI specification. 31 # 32 # This function initializes floating-point control word to 0x027F (all exceptions 33 # masked,double-precision, round-to-nearest) and multimedia-extensions control word 34 # (if supported) to 0x1F80 (all exceptions masked, round-to-nearest, flush to zero 35 # for masked underflow). 36 # 37 ASM_GLOBAL ASM_PFX(InitializeFloatingPointUnits) 38 ASM_PFX(InitializeFloatingPointUnits): 39 40 pushl %ebx 41 42 # 43 # Initialize floating point units 44 # 45 finit 46 fldcw ASM_PFX(mFpuControlWord) 47 48 # 49 # Use CpuId instructuion (CPUID.01H:EDX.SSE[bit 25] = 1) to test 50 # whether the processor supports SSE instruction. 51 # 52 movl $1, %eax 53 cpuid 54 btl $25, %edx 55 jnc Done 56 57 # 58 # Set OSFXSR bit 9 in CR4 59 # 60 movl %cr4, %eax 61 orl $BIT9, %eax 62 movl %eax, %cr4 63 64 # 65 # The processor should support SSE instruction and we can use 66 # ldmxcsr instruction 67 # 68 ldmxcsr ASM_PFX(mMmxControlWord) 69 70 Done: 71 popl %ebx 72 73 ret 74
