chasher.h

//==========================================================================
//   CHASHER.H  - part of
//                     OMNeT++/OMNEST
//            Discrete System Simulation in C++
//
//==========================================================================
 
/*--------------------------------------------------------------*
  Copyright (C) 1992-2017 Andras Varga
  Copyright (C) 2006-2017 OpenSim Ltd.
 
  This file is distributed WITHOUT ANY WARRANTY. See the file
  `license' for details on this and other legal matters.
*--------------------------------------------------------------*/
 
#ifndef __OMNETPP_CHASHER_H
#define __OMNETPP_CHASHER_H
 
#include <cmath>  // NAN
#include <cstdint>
#include <cstring>
#include <cstdlib>
#include "simkerneldefs.h"
#include "cobject.h"
#include "cexception.h"
 
namespace omnetpp {
 
 
class SIM_API cHasher : noncopyable
{
  private:
    uint32_t value;
 
    void merge(uint32_t x) {
        // rotate value left by one bit, and xor with new data
        value = ((value << 1) | (value >> 31)) ^ x;
    }
 
    void merge2(uint64_t x) {
        merge((uint32_t)x);
        merge((uint32_t)(x>>32));
    }
 
  public:
    cHasher() {ASSERT(sizeof(uint32_t)==4); ASSERT(sizeof(double)==8); value = 0;}
 
    void reset() {value = 0;}
    void add(char d)           {merge((uint32_t)d);}
    void add(short d)          {merge((uint32_t)d);}
    void add(int d)            {merge((uint32_t)d);}
    void add(long d)           {int64_t tmp=d; merge2((uint64_t)tmp);}
    void add(long long d)      {merge2((uint64_t)d);}
    void add(unsigned char d)  {merge((uint32_t)d);}
    void add(unsigned short d) {merge((uint32_t)d);}
    void add(unsigned int d)   {merge((uint32_t)d);}
    void add(unsigned long d)  {uint64_t tmp=d; merge2(tmp);}
    void add(unsigned long long d)  {merge2(d);}
    void add(double d) {
        if (std::isnan(d)) d = NAN;  // force standard representation
        //merge2(std::bit_cast<uint64_t>(d));  // requires C++20
        union _ {double _; uint64_t i;};
        merge2(((union _ *)&d)->i);  // hint: "safe type punning in C++"
    }
    void add(simtime_t t)      {merge2(t.raw());}
    void add(const char *s)    {if (s) add(s, strlen(s)+1); else add(0);}
    void add(const std::string& s) {add(s.c_str(), s.size()+1);}
    void add(const void *p, size_t length);
    template<typename T>
    cHasher& operator<<(const T& x) {add(x); return *this;} // allows chaining
 
    uint32_t getHash() const {return value;}
 
    uint32_t parse(const char *hash) const;
 
    bool equals(const char *hash) const;
 
    std::string str() const;
};
 
}  // namespace omnetpp
 
#endif