61 lines
1.6 KiB
Go
61 lines
1.6 KiB
Go
//go:build amd64
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package p256k1
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import (
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"sync"
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"sync/atomic"
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"github.com/klauspost/cpuid/v2"
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)
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// CPU feature flags
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var (
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// hasAVX2CPU indicates whether the CPU supports AVX2 instructions.
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// This is detected at startup and never changes.
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hasAVX2CPU bool
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// avx2Disabled allows runtime disabling of AVX2 for testing/debugging.
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// Uses atomic operations for thread-safety without locks on the fast path.
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avx2Disabled atomic.Bool
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// initOnce ensures CPU detection runs exactly once
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initOnce sync.Once
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)
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func init() {
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initOnce.Do(detectCPUFeatures)
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}
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// detectCPUFeatures detects CPU capabilities at startup
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func detectCPUFeatures() {
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hasAVX2CPU = cpuid.CPU.Has(cpuid.AVX2)
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}
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// HasAVX2 returns true if AVX2 is available and enabled.
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// This is the function that should be called in hot paths to decide
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// whether to use AVX2-optimized code paths.
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func HasAVX2() bool {
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return hasAVX2CPU && !avx2Disabled.Load()
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}
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// HasAVX2CPU returns true if the CPU supports AVX2, regardless of whether
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// it's been disabled via SetAVX2Enabled.
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func HasAVX2CPU() bool {
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return hasAVX2CPU
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}
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// SetAVX2Enabled enables or disables the use of AVX2 instructions.
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// This is useful for benchmarking to compare AVX2 vs non-AVX2 performance,
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// or for debugging. Pass true to enable AVX2 (default), false to disable.
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// This function is thread-safe.
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func SetAVX2Enabled(enabled bool) {
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avx2Disabled.Store(!enabled)
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}
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// IsAVX2Enabled returns whether AVX2 is currently enabled.
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// Returns true if AVX2 is both available on the CPU and not disabled.
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func IsAVX2Enabled() bool {
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return HasAVX2()
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}
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