forked from TrueCloudLab/distribution
afe5a2a9b7
Co-authored-by: Nicolas De Loof <nicolas.deloof@gmail.com> Co-authored-by: Sebastiaan van Stijn <github@gone.nl> Signed-off-by: Laura Brehm <laurabrehm@hey.com>
36 lines
562 B
ArmAsm
36 lines
562 B
ArmAsm
// +build !appengine
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// +build gc
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// +build !noasm
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#include "textflag.h"
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#include "funcdata.h"
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#include "go_asm.h"
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TEXT ·x86extensions(SB), NOSPLIT, $0
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// 1. determine max EAX value
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XORQ AX, AX
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CPUID
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CMPQ AX, $7
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JB unsupported
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// 2. EAX = 7, ECX = 0 --- see Table 3-8 "Information Returned by CPUID Instruction"
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MOVQ $7, AX
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MOVQ $0, CX
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CPUID
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BTQ $3, BX // bit 3 = BMI1
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SETCS AL
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BTQ $8, BX // bit 8 = BMI2
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SETCS AH
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MOVB AL, bmi1+0(FP)
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MOVB AH, bmi2+1(FP)
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RET
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unsupported:
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XORQ AX, AX
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MOVB AL, bmi1+0(FP)
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MOVB AL, bmi2+1(FP)
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RET
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