#include <iostream.h>#include <fstream.h>#include <stdio.h>#include <stdlib.h>#include <assert.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>#include <math.h>#include <strstream.h>#include "global.h"#include "vector.h"//#include "Set.h"//#include "utils.h"//#include "globals.h"//#include "sample.h"//const int VEC_BLOCK_SIZE=1024;static int dimensionality;#ifdef ASCIIifstream ifile;#elsestatic int fd;//static ifstream ifile;static int curOffset;static char *tmpBuf;static int bytesRead;#endifvoid SetupVectorScan(char *fileName, char *buffer, int dimn){#ifdef ASCII  cout << "Opening ASCII file " << fileName << endl;  dimensionality = dimn;  ifile.open(fileName);  assert(ifile != NULL);#else  fd = open(fileName, O_RDONLY);  assert(fd != -1);  assert(0 == VEC_BLOCK_SIZE%sizeof(double));  assert(dimn > 0);  dimensionality = dimn;  curOffset = 0;  bytesRead = 0;  tmpBuf = buffer + VEC_BLOCK_SIZE;#endif}/* * fd: file descriptor of the open file * currentOffset: offset in *chars* into the current file from which point the reading should start * bufSize: the size of the block to be read in *chars* * buffer: space for at least bufSize chars * * return value: * size of the block in *chars* */const int extraBufferSize=10;intgetNextBlock(int fd, int currentOffset, int bufSize, char* buffer){  int bytesRead, currentPos, endPos;  char bufferHere[extraBufferSize*sizeof(double)*dimensionality];  //int* checkElement;  bool done;  assert((0 == (bufSize % sizeof(double))));	 //(0 == (extraBufferSize % sizeof(double))));  done = true; // indicates whether the end of the file is reached  if (0 == buffer) {    // seek until a little bit before the end of the buffer    endPos = lseek(fd, 0, SEEK_END);    if (currentOffset + bufSize > endPos)      bufSize = endPos - currentOffset;    assert(bufSize >= 0);    currentPos = lseek(fd, currentOffset+bufSize-extraBufferSize, SEEK_SET);    assert(currentPos <= endPos - extraBufferSize);    bytesRead = read(fd, (char*)bufferHere, extraBufferSize); // then read the last piece    if (bytesRead < extraBufferSize) // if the end of the file is reached      return bufSize - extraBufferSize + bytesRead;            //checkElement = (int*)&bufferHere[extraBufferSize-sizeof(int)];  }  else {    lseek(fd, currentOffset, SEEK_SET);     // seek for the current offset    bytesRead = read(fd, (char*)buffer, bufSize); // read the whole block into memory    if (bytesRead < bufSize) { // end of file?      return bytesRead;    }    //checkElement = (int*)&buffer[bufSize-sizeof(int)];  }  //while (*checkElement != -1) {  //bufSize -= sizeof(int);  //checkElement--;  //}  assert(bufSize > 0);  return bufSize;}intgetNextVector(Vector& vec, char *buffer){  int i;#ifdef ASCII  char buf[1000];  double val;  ifile.getline(buf, 1000);  if (!ifile)    {      ifile.close();      return -1;    }  istrstream istr(buf);  vec.SetDim(dimensionality);  for (i = 0; i < dimensionality; i++)    {      istr >> val;      vec.SetVal(i, val);    }#else  if ((tmpBuf - buffer) >= bytesRead)    {      bytesRead = getNextBlock(fd, curOffset, VEC_BLOCK_SIZE*sizeof(double)*dimensionality, buffer);      if (bytesRead <= 0)	{	  close(fd);	  return -1;	}      tmpBuf = buffer;      curOffset += bytesRead;    }    vec.newArr(dimensionality, (double*)(tmpBuf));  tmpBuf += dimensionality * sizeof(double);#endif  return 1;}