darn.h

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// darn.h - written and placed in public domain by Jeffrey Walton
//          DARN requires POWER9/ISA 3.0.
 
// At the moment only GCC 7.0 (and above) seems to support __builtin_darn()
// and __builtin_darn_32(). However, GCC generates incorrect code. Clang 7.0
// does not provide them, but it does support assembly instructions. XLC is
// unknown, but there are no hits when searching IBM's site. To cover more
// platforms we provide GCC inline assembly like we do with RDRAND and RDSEED.
// Platforms that don't support GCC inline assembly or the builtin will fail
// to compile. Also see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91481 and
// https://gcc.gnu.org/onlinedocs/gcc/Basic-PowerPC-Built-in-Functions-Available-on-ISA-3_002e0.html
 
 
#ifndef CRYPTOPP_DARN_H
#define CRYPTOPP_DARN_H
 
#include "cryptlib.h"
 
NAMESPACE_BEGIN(CryptoPP)
 
 
class DARN_Err : public Exception
{
public:
    DARN_Err(const std::string &operation)
        : Exception(OTHER_ERROR, "DARN: " + operation + " operation failed") {}
};
 
class DARN : public RandomNumberGenerator
{
public:
    CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() { return "DARN"; }
 
    virtual ~DARN() {}
 
    DARN();
 
    virtual void GenerateBlock(byte *output, size_t size);
 
    virtual void DiscardBytes(size_t n);
 
    virtual void IncorporateEntropy(const byte *input, size_t length)
    {
        // Override to avoid the base class' throw.
        CRYPTOPP_UNUSED(input); CRYPTOPP_UNUSED(length);
    }
 
    std::string AlgorithmProvider() const {
        return "Power9";
    }
 
private:
    SecBlock<byte, AllocatorWithCleanup<byte, true> > m_temp;
};
 
NAMESPACE_END
 
#endif // CRYPTOPP_DARN_H