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30 lines
835 B
Go
30 lines
835 B
Go
// +build amd64,!noasm
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// Sets capabilities flags for x86 according to information received from
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// CPUID. It was written in accordance with
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// "Intel® 64 and IA-32 Architectures Developer's Manual: Vol. 2A".
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// https://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-2a-manual.html
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package utils
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// Performs CPUID and returns values of registers
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// go:nosplit
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func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
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// Returns true in case bit 'n' in 'bits' is set, otherwise false
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func bitn(bits uint32, n uint8) bool {
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return (bits>>n)&1 == 1
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}
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func init() {
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// CPUID returns max possible input that can be requested
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max, _, _, _ := cpuid(0, 0)
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if max < 7 {
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return
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}
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_, ebx, _, _ := cpuid(7, 0)
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X86.HasBMI2 = bitn(ebx, 8)
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X86.HasADX = bitn(ebx, 19)
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}
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