implemented conversion for 16bit floats

csv/VehicleSpeed_HS.csv

@@ -0,0 +1,599 @@
+5.93
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makefile

@@ -7,7 +7,7 @@ EXE = eatit
 CCC = g++
 OPT = -O3 -Wall
  
-$(EXE) : $(SRC)main.cpp $(SRC)raweat.hpp
+$(EXE) : $(SRC)main.cpp $(SRC)raweat.hpp $(SRC)half_precision_floating_point.hpp
 	$(CCC) $(OPT) $< -o $@
 
 clean :

src/endian.hpp

@@ -0,0 +1,60 @@
+//---------------------------------------------------------------------------//
+
+#ifndef MY_LITTLE_ENDIAN
+#define MY_LITTLE_ENDIAN
+
+#include <iostream>
+
+#define IS_BIG_ENDIAN (*(uint16_t*)"\0\xff" < 0x100)
+
+//---------------------------------------------------------------------------//
+
+class endian
+{
+
+private:
+
+  // endianness
+  bool little_endian_;
+
+public:
+
+  // constructor
+  endian()
+  {
+    // check endianness on machine
+    little_endian_ = get_endian();
+  }
+  
+  // provide information about little versus big endian architecture
+  bool get_endian()
+  {
+    // declare short (16 bit) integer representing "1"
+    short int wd = 0x001;
+
+    // get byte pattern of integer
+    uint8_t *pwd = (uint8_t*)(&wd);
+
+    //for ( int i = 0; i < 2; i ++ ) std::cout<<std::hex<<(int)pwd[i]<<" ";
+    //std::cout<<"\n";
+
+    // check if byte pattern is 0x 0001 or 0x 0100
+    return ((int)pwd[0] == 1 ? true : false);
+  }
+
+  // retrieve information
+  bool little_endian()
+  {
+    return little_endian_?true:false;
+  }
+
+  bool big_endian()
+  {
+    return little_endian_?false:true;
+  }
+
+};
+
+#endif
+
+//---------------------------------------------------------------------------//

src/half_precision_floating_point.hpp

@@ -0,0 +1,100 @@
+//---------------------------------------------------------------------------//
+
+#ifndef HALF_PRECISION_FLOATING_POINT
+#define HALF_PRECISION_FLOATING_POINT
+
+#include <vector>
+#include <bitset>
+#include "endian.hpp"
+
+//---------------------------------------------------------------------------//
+
+class half_precision_floating_point
+{
+
+private:
+
+  // size of half precision floating point number in bits
+  int size_ = 16;
+
+  // construction of the number (binary16) according to IEEE 754-2008 standard
+  std::bitset<1>  sign_;
+  std::bitset<5>  expo_;
+  std::bitset<10> frac_;
+
+  // endianness of machine/architecture
+  bool little_endian_;
+
+  // number as single-precision floating point number
+  float num_;
+
+  // array of bytes representing the number
+  std::vector<uint8_t> numbytes_;
+
+public:
+
+  // constructors
+  half_precision_floating_point(std::vector<uint8_t> numbytes) : 
+    numbytes_(numbytes)
+  {
+    assert( numbytes_.size() == 2 );
+    endian endi;
+    little_endian_ = endi.little_endian();
+    assert( little_endian_ && "just don't work on big endian machines!" );
+  }
+
+  half_precision_floating_point(float num) :
+    num_(num)
+  {
+
+  }
+
+  // destructor
+  ~half_precision_floating_point()
+  {
+
+  }
+
+  // assignment operator
+  half_precision_floating_point& operator=(const half_precision_floating_point& other)
+  {
+    if ( this != &other )
+    {
+      size_ = other.size_;
+      sign_ = other.sign_;
+      expo_ = other.expo_;
+      frac_ = other.frac_;
+      little_endian_ = other.little_endian_;
+      num_ = other.num_;
+      numbytes_ = other.numbytes_;
+    }
+
+    return *this;
+  }
+
+
+  // convert byte pattern to number
+  void convert_to_float()
+  {
+    // declare a single precision floating point number
+  //  float myfloat = 0.0;
+
+    if ( little_endian_ )
+    {
+    
+    }
+
+  } 
+
+  // convert floating point number to bytes
+  void convert_to_byte()
+  {
+
+  }
+
+};
+
+#endif
+
+//---------------------------------------------------------------------------//
+

src/main.cpp

@@ -9,13 +9,13 @@
 int main(int argc, char* argv[])
 {
   // path of filename provided ?
-  assert( argc > 1 && "please provide a filename and path" );
+  assert( argc > 2 && "please provide a filename and path for input and output" );
 
   std::cout<<"number of CLI-arguments: "<<argc<<"\n";
   for ( int i = 0; i < argc; i++ ) std::cout<<std::setw(5)<<i<<":   "<<argv[i]<<"\n";
 
   // check number of CLI arguments
-  assert( argc == 2 );
+  assert( argc == 3 );
 
   // get name/path of file from CLI argument
   std::string rawfile(argv[1]);
@@ -23,9 +23,12 @@ int main(int argc, char* argv[])
   // declare instance of "raw_eater"
   raw_eater eatraw(rawfile);
 
-  eatraw.show_markers();
+  //eatraw.show_markers();
+
+  // determine position of markers in buffer and read data
   eatraw.find_markers();
 
+  std::cout<<"\n";
   std::map<std::string,std::vector<unsigned char>> marks = eatraw.get_markers();
   for ( auto mrk: marks )
   {
@@ -39,13 +42,32 @@ int main(int argc, char* argv[])
     std::cout<<"\n";
   }
 
-  eatraw.convert_data();
+  // convert unsigned char data in buffer to desired data type
+  //eatraw.convert_data();
+  eatraw.convert_data_16_bit_float();
 
-  std::vector<double> mydata = eatraw.get_data();
-  std::cout<<"\n"<<mydata.size()<<"\n\n";
+  // get array of encoded data
+  std::vector<double> maindata = eatraw.get_data();
+  std::cout<<"\nsize of data array: "<<maindata.size()<<"\n\n";
   //for ( unsigned long int i = 0; i < 10; i++ ) std::cout<<mydata[i]<<"\n";
 
-  eatraw.write_data(std::string("csv/myfile.csv"));
+  // write data in csv-file
+  eatraw.write_data(std::string(argv[2]));
+
+  float ab = -0.75;
+  std::cout<<ab<<"\n";
+  uint8_t* pab = reinterpret_cast<uint8_t*>(&ab);
+  for ( int i = 0; i < (int)sizeof(float); i++ ) std::cout<<std::hex<<(int)pab[i]<<std::dec<<" ";
+  std::cout<<"\n";
+
+  uint8_t sc = 0x4f;
+  std::bitset<8> bssc(sc);
+  for ( int i = 0; i < 8; i++ ) std::cout<<bssc[i]<<" ";
+  std::cout<<"\n";
+  std::cout<<std::hex<<bssc.to_ulong()<<"\n\n";
+
+  endian endi;
+  std::cout<<(endi.little_endian()?"little endian":"big endian")<<"\n";
 
   return 0;
 }

src/raweat.hpp

@@ -1,5 +1,8 @@
 //---------------------------------------------------------------------------//
 
+#ifndef RAW_EATER
+#define RAW_EATER
+
 #include <assert.h>
 #include <iostream>
 #include <fstream>
@@ -8,6 +11,9 @@
 #include <iterator>
 #include <map>
 
+#include "half_precision_floating_point.hpp"
+#include "endian.hpp"
+
 //---------------------------------------------------------------------------//
 
 class raw_eater
@@ -40,6 +46,9 @@ private:
   // data sections corresponding to markers
   std::map<std::string,std::vector<unsigned char>> datasec_;
 
+  // length of data array
+  unsigned long int datsize_;
+
   // TODO preliminary: for now, we assume 32/64 bit ? floats in all data
   std::vector<double> datmes_;
 
@@ -61,17 +70,6 @@ public:
                                        (std::istreambuf_iterator<char>()));
     rawdata_ = rawdata;
 
-    // show size of buffer
-    std::cout<<"size of buffer "<<rawdata_.size()<<"\n";
-
-    // show excerpt from buffer
-    int ista = 0, iend = 128;
-    for ( int i= ista; i < iend; i++ )
-    {
-      std::cout<<std::hex<<(int)rawdata_[i]<<" ";
-      if ( (i+1)%16 == 0 ) std::cout<<"\n";
-    }
-    std::cout<<"\n";
   }
 
   // destructor
@@ -80,6 +78,22 @@ public:
   
   }
 
+  // display buffer/data properties
+  void show_buffer(int numel = 128)
+  {
+    // show size of buffer
+    std::cout<<"size of buffer "<<rawdata_.size()<<"\n\n";
+
+    // show excerpt from buffer
+    int ista = 0, iend = numel;
+    for ( int i= ista; i < iend; i++ )
+    {
+      std::cout<<std::hex<<(int)rawdata_[i]<<" ";
+      if ( (i+1)%16 == 0 ) std::cout<<"\n";
+    }
+    std::cout<<"\n";
+  }
+
   // show predefined markers
   void show_markers()
   {
@@ -135,6 +149,9 @@ public:
             {
               markseq.push_back(rawdata_[didx]);
             }
+
+            // obtain length of data segment
+            datsize_ = markseq.size();
           }
           datasec_.insert(std::pair<std::string,std::vector<unsigned char>>(mrk.first,markseq));
         }
@@ -198,12 +215,9 @@ public:
   // convert actual measurement data
   void convert_data()
   {
-    // length of data array
-    unsigned long int datsize = datasec_["datas marker"].size();
+    assert ( (datsize_-28)%4 == 0 && "length of buffer is not a multiple of 4" );
 
-    assert ( (datsize-28)%4 == 0 && "length of buffer is not a multiple of 4" );
-
-    unsigned long int totnumfl = (datsize-28)/4;
+    unsigned long int totnumfl = (datsize_-28)/(int)sizeof(float);
     for ( unsigned long int numfl = 0; numfl < totnumfl; numfl++ )
     {
       // assuming 4 byte float
@@ -211,6 +225,8 @@ public:
       uint8_t* pnum = reinterpret_cast<uint8_t*>(&num);
       for ( int byi = 0; byi < (int)sizeof(float); byi++ )
       {
+        // TODO what's the byte order in the file??
+        // for now, we just don't care...
         pnum[byi] = (int)datasec_["datas marker"][(unsigned long int)(28+numfl*sizeof(float)+byi)];
       }
 
@@ -219,6 +235,61 @@ public:
     }      
   }
 
+  // convert half-precision (16bit) floating point numbers
+  void convert_data_16_bit_float()
+  {
+    // single (32bit) floating point number
+    float fl = 0.0;
+
+    unsigned long int totnumby = (datsize_-28)/2;
+    for ( unsigned long int by = 0; by < totnumby; by++ )
+    {
+      // retrieve two bytes of floating point number
+      std::vector<uint8_t> pnum;
+      for ( int i = 0; i < 2; i++ ) pnum.push_back(datasec_["datas marker"][(unsigned long int)(28+by*2+i)]);
+
+      // obtain bitset
+      std::bitset<8> byA(pnum[0]), byB(pnum[1]);
+
+      // TODO all following code only works for little endian!!
+
+      // sign
+      float sign = byB[0];
+
+      // exponent of 16bit float
+      long int expo = 0;
+      for ( int i = 0; i < 5; i++ ) if ( byB[1+i] ) expo += pow(2.0,4-i);
+      expo -= 15;
+
+      // convert to exponent of 32bit float
+      
+
+      // mantissa
+      
+
+      // declare bitset of float
+      std::bitset<8> flA(0x00), flB(0x00), flC(0x00), flD(0x00);
+      
+      
+    }
+  }
+
+  // convert 16bit "decimal-encoding" floating point numbers
+  void convert_data_16_bit_decimal()
+  {
+    //assert ( (datsize_-29)%2 == 0 && "length of buffer is not a multiple of 2" );
+
+    unsigned long int totnumby = (datsize_-30)/2;
+    for ( unsigned long int by = 0; by < totnumby; by++ )
+    {
+      std::vector<uint8_t> pnum; 
+      for ( int i = 0; i < 2; i++ ) pnum.push_back(datasec_["datas marker"][(unsigned long int)(29+by*2+i)]);
+
+      datmes_.push_back((double)(     (((int)pnum[0]-128)*256 + (int)pnum[1])/100.0       )); 
+    
+    }
+  }
+
   // get data array encoded as floats/doubles
   std::vector<double>& get_data()
   {
@@ -226,14 +297,14 @@ public:
   }
 
   // write data to csv-like file
-  void write_data(std::string filename)
+  void write_data(std::string filename, int precision = 9)
   {
     // open file
     std::ofstream fout(filename.c_str());
 
     for ( auto el : datmes_ )
     {
-      fout<<std::dec<<el<<"\n";
+      fout<<std::dec<<std::setprecision(precision)<<el<<"\n";
     }
 
     // close file
@@ -242,4 +313,6 @@ public:
 
 };
 
+#endif
+
 //---------------------------------------------------------------------------//