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vendor/github.com/klauspost/cpuid/v2/README.md

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+# cpuid
+Package cpuid provides information about the CPU running the current program.
+
+CPU features are detected on startup, and kept for fast access through the life of the application.
+Currently x86 / x64 (AMD64/i386) and ARM (ARM64) is supported, and no external C (cgo) code is used, which should make the library very easy to use.
+
+You can access the CPU information by accessing the shared CPU variable of the cpuid library.
+
+Package home: https://github.com/klauspost/cpuid
+
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/klauspost/cpuid)](https://pkg.go.dev/github.com/klauspost/cpuid/v2)
+[![Build Status][3]][4]
+
+[3]: https://travis-ci.org/klauspost/cpuid.svg?branch=master
+[4]: https://travis-ci.org/klauspost/cpuid
+
+## installing
+
+`go get -u github.com/klauspost/cpuid/v2` using modules. 
+
+Drop `v2` for others.
+
+## example
+
+```Go
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	. "github.com/klauspost/cpuid/v2"
+)
+
+func main() {
+	// Print basic CPU information:
+	fmt.Println("Name:", CPU.BrandName)
+	fmt.Println("PhysicalCores:", CPU.PhysicalCores)
+	fmt.Println("ThreadsPerCore:", CPU.ThreadsPerCore)
+	fmt.Println("LogicalCores:", CPU.LogicalCores)
+	fmt.Println("Family", CPU.Family, "Model:", CPU.Model, "Vendor ID:", CPU.VendorID)
+	fmt.Println("Features:", fmt.Sprintf(strings.Join(CPU.FeatureSet(), ",")))
+	fmt.Println("Cacheline bytes:", CPU.CacheLine)
+	fmt.Println("L1 Data Cache:", CPU.Cache.L1D, "bytes")
+	fmt.Println("L1 Instruction Cache:", CPU.Cache.L1D, "bytes")
+	fmt.Println("L2 Cache:", CPU.Cache.L2, "bytes")
+	fmt.Println("L3 Cache:", CPU.Cache.L3, "bytes")
+	fmt.Println("Frequency", CPU.Hz, "hz")
+
+	// Test if we have these specific features:
+	if CPU.Supports(SSE, SSE2) {
+		fmt.Println("We have Streaming SIMD 2 Extensions")
+	}
+}
+```
+
+Sample output:
+```
+>go run main.go
+Name: AMD Ryzen 9 3950X 16-Core Processor
+PhysicalCores: 16
+ThreadsPerCore: 2
+LogicalCores: 32
+Family 23 Model: 113 Vendor ID: AMD
+Features: ADX,AESNI,AVX,AVX2,BMI1,BMI2,CLMUL,CMOV,CX16,F16C,FMA3,HTT,HYPERVISOR,LZCNT,MMX,MMXEXT,NX,POPCNT,RDRAND,RDSEED,RDTSCP,SHA,SSE,SSE2,SSE3,SSE4,SSE42,SSE4A,SSSE3
+Cacheline bytes: 64
+L1 Data Cache: 32768 bytes
+L1 Instruction Cache: 32768 bytes
+L2 Cache: 524288 bytes
+L3 Cache: 16777216 bytes
+Frequency 0 hz
+We have Streaming SIMD 2 Extensions
+```
+
+# usage
+
+The `cpuid.CPU` provides access to CPU features. Use `cpuid.CPU.Supports()` to check for CPU features.
+A faster `cpuid.CPU.Has()` is provided which will usually be inlined by the gc compiler.  
+
+Note that for some cpu/os combinations some features will not be detected.
+`amd64` has rather good support and should work reliably on all platforms.
+
+Note that hypervisors may not pass through all CPU features.
+
+## arm64 feature detection
+
+Not all operating systems provide ARM features directly 
+and there is no safe way to do so for the rest.
+
+Currently `arm64/linux` and `arm64/freebsd` should be quite reliable. 
+`arm64/darwin` adds features expected from the M1 processor, but a lot remains undetected.
+
+A `DetectARM()` can be used if you are able to control your deployment,
+it will detect CPU features, but may crash if the OS doesn't intercept the calls.
+A `-cpu.arm` flag for detecting unsafe ARM features can be added. See below.
+ 
+Note that currently only features are detected on ARM, 
+no additional information is currently available. 
+
+## flags
+
+It is possible to add flags that affects cpu detection.
+
+For this the `Flags()` command is provided.
+
+This must be called *before* `flag.Parse()` AND after the flags have been parsed `Detect()` must be called.
+
+This means that any detection used in `init()` functions will not contain these flags.
+
+Example:
+
+```Go
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/klauspost/cpuid/v2"
+)
+
+func main() {
+	cpuid.Flags()
+	flag.Parse()
+	cpuid.Detect()
+
+	// Test if we have these specific features:
+	if cpuid.CPU.Supports(cpuid.SSE, cpuid.SSE2) {
+		fmt.Println("We have Streaming SIMD 2 Extensions")
+	}
+}
+```
+
+# license
+
+This code is published under an MIT license. See LICENSE file for more information.