Botan::CPUID Class Reference

#include <cpuid.h>

Public Types
typedef CPUFeature	Feature

Static Public Member Functions
static std::optional< CPUID::Feature >	bit_from_string (std::string_view tok)
static std::optional< std::string >	check (CPUID::Feature feat)
static std::optional< std::string >	check (CPUID::Feature feat1, CPUID::Feature feat2)
static void	clear_cpuid_bit (CPUID::Feature bit)
static bool	has (CPUID::Feature feat)
static bool	has (CPUID::Feature feat1, CPUID::Feature feat2)
template<typename T>
static uint32_t	if_set (uint64_t cpuid, T flag, CPUID::Feature bit, uint32_t allowed)
static void	initialize ()
static std::string	to_string ()

Detailed Description

A class handling runtime CPU feature detection. It is limited to just the features necessary to implement CPU specific code in Botan, rather than being a general purpose utility.

Definition at line 43 of file cpuid.h.

Member Typedef Documentation

Feature

typedef CPUFeature Botan::CPUID::Feature

Definition at line 45 of file cpuid.h.

Member Function Documentation

bit_from_string()

std::optional< CPUFeature > Botan::CPUID::bit_from_string ( std::string_view tok )

static

Definition at line 90 of file cpuid.cpp.

                                                                 {
   return CPUFeature::from_string(tok);
}

References Botan::CPUFeature::from_string().

check() [1/2]

std::optional< std::string > Botan::CPUID::check ( CPUID::Feature feat )

inlinestatic

Check if a feature is supported returning the associated string if so

This is a helper function used to implement provider()

Definition at line 67 of file cpuid.h.

                                                             {
         if(state().has_bit(feat.as_u32())) {
            return feat.to_string();
         } else {
            return {};
         }
      }

References Botan::CPUFeature::as_u32(), and Botan::CPUFeature::to_string().

Referenced by Botan::ChaCha::provider(), Botan::GHASH::provider(), Botan::IDEA::provider(), Botan::Keccak_Permutation::provider(), Botan::Noekeon::provider(), Botan::Serpent::provider(), Botan::SHA_1::provider(), Botan::SHACAL2::provider(), Botan::SM4::provider(), and Botan::ZFEC::provider().

check() [2/2]

std::optional< std::string > Botan::CPUID::check ( CPUID::Feature feat1, CPUID::Feature feat2 )

inlinestatic

Check if a feature is supported returning the associated string if so

This is a helper function used to implement provider()

Definition at line 80 of file cpuid.h.

                                                                                  {
         if(state().has_bit((feat1.as_u32() | feat2.as_u32()))) {
            // Typically feat2 is a secondary feature that is almost but not
            // completely implied by feat1 (ex: AVX2 + BMI2) which we have to
            // check for completness, but don't reflect into the provider name.
            return feat1.to_string();
         } else {
            return {};
         }
      }

References Botan::CPUFeature::as_u32(), and Botan::CPUFeature::to_string().

clear_cpuid_bit()

void Botan::CPUID::clear_cpuid_bit ( CPUID::Feature bit )

inlinestatic

Definition at line 109 of file cpuid.h.

{ state().clear_cpuid_bit(bit.as_u32()); }

References Botan::CPUFeature::as_u32().

has() [1/2]

bool Botan::CPUID::has ( CPUID::Feature feat )

inlinestatic

Check if a feature is supported

Definition at line 94 of file cpuid.h.

{ return state().has_bit(feat.as_u32()); }

References Botan::CPUFeature::as_u32().

Referenced by Botan::Processor_RNG::available(), Botan::Argon2::blamka(), Botan::SHA_256::compress_digest(), Botan::SHA_512::compress_digest(), Botan::SHA_1::compress_n(), Botan::AES_128::decrypt_n(), Botan::AES_192::decrypt_n(), Botan::AES_256::decrypt_n(), Botan::Camellia_128::decrypt_n(), Botan::Camellia_192::decrypt_n(), Botan::Camellia_256::decrypt_n(), Botan::IDEA::decrypt_n(), Botan::Noekeon::decrypt_n(), Botan::Serpent::decrypt_n(), Botan::SHACAL2::decrypt_n(), Botan::SM4::decrypt_n(), Botan::AES_128::encrypt_n(), Botan::AES_192::encrypt_n(), Botan::AES_256::encrypt_n(), Botan::Camellia_128::encrypt_n(), Botan::Camellia_192::encrypt_n(), Botan::Camellia_256::encrypt_n(), Botan::IDEA::encrypt_n(), Botan::Noekeon::encrypt_n(), Botan::Serpent::encrypt_n(), Botan::SHACAL2::encrypt_n(), Botan::SM4::encrypt_n(), Botan::OS::get_cpu_cycle_counter(), Botan::IDEA::parallelism(), Botan::Noekeon::parallelism(), Botan::SHACAL2::parallelism(), Botan::SM4::parallelism(), and Botan::Intel_Rdseed::poll().

has() [2/2]

bool Botan::CPUID::has ( CPUID::Feature feat1, CPUID::Feature feat2 )

inlinestatic

Check if two features are both supported

Definition at line 99 of file cpuid.h.

                                                              {
         return state().has_bit(feat1.as_u32() | feat2.as_u32());
      }

References Botan::CPUFeature::as_u32().

if_set()

template<typename T>

uint32_t Botan::CPUID::if_set ( uint64_t cpuid, T flag, CPUID::Feature bit, uint32_t allowed )

inlinestatic

A common helper for the various CPUID implementations

Definition at line 117 of file cpuid.h.

                                                                                                {
         const uint64_t flag64 = static_cast<uint64_t>(flag);
         if((cpuid & flag64) == flag64) {
            return (bit.as_u32() & allowed);
         } else {
            return 0;
         }
      }

References Botan::CPUFeature::as_u32().

initialize()

void Botan::CPUID::initialize ( )

static

Probe the CPU and see what extensions are supported

Definition at line 51 of file cpuid.cpp.

                       {
   state() = CPUID_Data();
}

to_string()

std::string Botan::CPUID::to_string ( )

static

Return a possibly empty string containing list of known CPU extensions. Each name will be seperated by a space, and the ordering will be arbitrary. This list only contains values that are useful to Botan (for example FMA instructions are not checked).

Example outputs "sse2 ssse3 rdtsc", "neon arm_aes", "altivec"

Definition at line 34 of file cpuid.cpp.

                           {
   std::vector<std::string> flags;
 
   const uint32_t bitset = state().bitset();
 
   for(size_t i = 0; i != 32; ++i) {
      const uint32_t b = static_cast<uint32_t>(1) << i;
      if((bitset & b) == b) {
         // NOLINTNEXTLINE(clang-analyzer-optin.core.EnumCastOutOfRange)
         flags.push_back(CPUFeature(static_cast<CPUFeature::Bit>(b)).to_string());
      }
   }
 
   return string_join(flags, ' ');
}

References Botan::string_join(), and to_string().

Referenced by to_string().

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The documentation for this class was generated from the following files:

• src/lib/utils/cpuid/cpuid.h
• src/lib/utils/cpuid/cpuid.cpp