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