evio.c

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/*-----------------------------------------------------------------------------
 * Copyright (c) 1991,1992 Southeastern Universities Research Association,
 *                         Continuous Electron Beam Accelerator Facility
 *
 * This software was developed under a United States Government license
 * described in the NOTICE file included as part of this distribution.
 *
 * CEBAF Data Acquisition Group, 12000 Jefferson Ave., Newport News, VA 23606
 * Email: coda@cebaf.gov  Tel: (804) 249-7101  Fax: (804) 249-7363
 *-----------------------------------------------------------------------------
 * 
 * Description:
 *      Event I/O routines
 *      
 * Author:  Chip Watson, CEBAF Data Acquisition Group
 * Modified: Stephen A. Wood, TJNAF Hall C
 *      Works on ALPHA 64 bit machines if BIT64 is defined
 *      Will read input from standard input if filename is "-"
 *      If input filename is "|command" will take data from standard output
 *                        of command.
 *      If input file is compressed and unconpressible with gunzip, it will
 *                        decompress the data on the fly.
 *
 * Revision History:
 *   $Log: evio.c,v $
 *   Revision 1.3  1999/11/04 20:30:48  saw
 *   Add code to write coda output to stdout or pipes
 *
 *   Revision 1.2  1998/12/01 13:54:12  saw
 *   (saw) Alpha 64 bit fixes, input from std input, pipes and compressed
 *   files
 *
 *   Revision 1.1  1996/12/19 14:05:02  saw
 *   Initial revision
 *
 *        Revision 1.5  1994/08/15  15:45:09  chen
 *        add evnum to EVFILE structure. Keep event number when call evWrite
 *
 *        Revision 1.4  1994/08/12  17:14:55  chen
 *        check event type explicitly
 *
 *        Revision 1.3  1994/06/17  16:11:12  chen
 *        fix a bug when there is a single special event in the last block
 *
 *        Revision 1.2  1994/05/12  15:38:37  chen
 *        In case a wrong data format, close file and free memory
 *
 *        Revision 1.1  1994/04/11  13:07:06  chen
 *        Initial revision
 *
*         Revision 1.6  1993/11/16  20:57:27  chen
*         stronger type casting for swapped_memecpy
*
*         Revision 1.5  1993/11/09  18:21:58  chen
*         fix a bug
*
*         Revision 1.4  1993/11/09  18:16:49  chen
*         add binary search routines
*
*         Revision 1.3  1993/11/03  16:40:55  chen
*         cosmatic change
*
*         Revision 1.2  1993/11/03  16:39:39  chen
*         add bytpe_swapped flag to EVFILE struct
*
 *
 *
 *
 * Routines
 * --------
 *
 *      evOpen(char *filename,char *flags,int *descriptor)
 *      evWrite(int descriptor,int *data,int datalen)
 *      evRead(int descriptor,int *data,int *datalen)
 *      evClose(int descriptor)
 *      evIoctl(int descriptor,char *request, void *argp)
 *
 * Modifications
 * -------------
 *  17-dec-91 cw started coding streams version with local buffers
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#define PMODE 0644
#include "evfile_msg.h"
#include "evio.h"
 
typedef struct evfilestruct {
  FILE *file;
  int *buf;
  int *next;
  int left;
  int blksiz;
  int blknum;
  int rw;
  int magic;
  int evnum;         /* last events with evnum so far */
  int byte_swapped;
} EVFILE;
 
typedef struct evBinarySearch{
  int sbk;
  int ebk;
  int found_bk;
  int found_evn;
  int last_evn;
} EVBSEARCH;
 
#define EVBLOCKSIZE 8192
#define EV_READ 0
#define EV_WRITE 1
#define EV_PIPE 2 
#define EV_PIPEWRITE 3 
#define EV_VERSION 1
#define EV_MAGIC 0xc0da0100
#define EV_HDSIZ 8
 
 
#define EV_HD_BLKSIZ 0          /* size of block in longwords */
#define EV_HD_BLKNUM 1          /* number, starting at 0 */
#define EV_HD_HDSIZ  2          /* size of header in longwords (=8) */
#define EV_HD_START  3          /* first start of event in this block */
#define EV_HD_USED   4          /* number of words used in block (<= BLKSIZ) */
#define EV_HD_VER    5          /* version of file format (=1) */
#define EV_HD_RESVD  6          /* (reserved) */
#define EV_HD_MAGIC  7          /* magic number for error detection */
 
#define evGetStructure() (EVFILE *)malloc(sizeof(EVFILE))
 
static  int  findLastEventWithinBlock(EVFILE *);
static  int  copySingleEvent(EVFILE *, int *, int, int);
static  int  evSearchWithinBlock(EVFILE *, EVBSEARCH *, int *, int, int *, int, int *);
static  void evFindEventBlockNum(EVFILE *, EVBSEARCH *, int *);
static  int  evGetEventNumber(EVFILE *, int);
static  int  evGetEventType(EVFILE *);
static  int  isRealEventsInsideBlock(EVFILE *, int, int);
static  int  physicsEventsInsideBlock(EVFILE *);
 
extern  int  int_swap_byte();
extern  void onmemory_swap();
extern  int  swapped_fread();
extern  void swapped_intcpy();
extern  void swapped_memcpy();
 
#if defined(__osf__) && defined(__alpha)
#define BIT64
#endif
 
#ifdef BIT64
#define MAXHANDLES 10
EVFILE *handle_list[10]={0,0,0,0,0,0,0,0,0,0};
#endif
 
#ifdef AbsoftUNIXFortran
int evopen
#else
int evopen_
#endif
(char *filename,char *flags,int *handle,int fnlen,int flen)
{
  char *fn, *fl;
  int status;
  fn = (char *) malloc(fnlen+1);
  strncpy(fn,filename,fnlen);
  fn[fnlen] = 0;                /* insure filename is null terminated */
  fl = (char *) malloc(flen+1);
  strncpy(fl,flags,flen);
  fl[flen] = 0;                 /* insure flags is null terminated */
  status = evOpen(fn,fl,handle);
  free(fn);
  free(fl);
  return(status);
}
 
static char *kill_trailing(char *s, char t)
{
  char *e; 
  e = s + strlen(s);
  if (e>s) {                           /* Need this to handle NULL string.*/
    while (e>s && *--e==t);            /* Don't follow t's past beginning. */
    e[*e==t?0:1] = '\0';               /* Handle s[0]=t correctly.       */
  }
  return s;
}
int evOpen(char *fname,char *flags,int *handle)
{
#ifdef BIT64
  int ihandle;
#endif
  EVFILE *a;
  char *cp;
  int header[EV_HDSIZ];
  int i;
  int temp,blk_size;
  char *filename;
 
  filename = malloc(strlen(fname)+1);
  strcpy(filename,fname);
  a = evGetStructure();         /* allocate control structure or quit */
  if (!a) {
    free(filename);
    return(S_EVFILE_ALLOCFAIL);
  }
  while (*filename==' ') filename++; /* remove leading spaces */
 /* But don't fuck with any other spaces except for the trailing ones */
#if 0
  for (cp=filename;*cp!=NULL;cp++) {
    if ((*cp==' ') || !(isprint(*cp))) *cp='\0';
  }
#else
  kill_trailing(filename,' ');
#endif
  char c;
  c = *flags;
  switch (c)
  /*case NULL:*/case 'r': case 'R': {
    a->rw = EV_READ;
    if(strcmp(filename,"-")==0) {
      a->file = stdin;
    } else if(filename[0] == '|') {
      a->file = popen(filename+1,"r");
      a->rw = EV_PIPE;          /* Make sure we know to use pclose */
    } else {
      a->file = fopen(filename,"r");
      if(a->file) {
        int compressed;
        char bytes[2];
        fread(bytes,2,1,a->file); /* Check magic bytes for compressions */
        if(bytes[0]=='\037' && (bytes[1]=='\213' || bytes[1]=='\235')) {
          char *pipe_command;
          fclose(a->file);
          pipe_command = (char *)malloc(strlen(filename)+strlen("gunzip<")+1);
          strcpy(pipe_command,"gunzip<");
          strcat(pipe_command,filename);
          a->file = popen(pipe_command,"r");
          free(pipe_command);
          a->rw = EV_PIPE;
        } else {
          fclose(a->file);
          a->file = fopen(filename,"r");
        }
      }
    }
    if (a->file) {
      fread(header,sizeof(header),1,a->file); /* update: check nbytes return */
      if (header[EV_HD_MAGIC] != EV_MAGIC) {
        temp = int_swap_byte(header[EV_HD_MAGIC]);
        if(temp == EV_MAGIC)
          a->byte_swapped = 1;
        else{ /* close file and free memory */
          fclose(a->file);
          free (a);
          free(filename);
          return(S_EVFILE_BADFILE); 
        }
      }
      else
        a->byte_swapped = 0;
 
      if(a->byte_swapped){
        blk_size = int_swap_byte(header[EV_HD_BLKSIZ]);
        a->buf = (int *)malloc(blk_size*4);
      }
      else
        a->buf = (int *) malloc(header[EV_HD_BLKSIZ]*4);
      if (!(a->buf)) {
        free(a);                /* if can't allocate buffer, give up */
        free(filename);
        return(S_EVFILE_ALLOCFAIL);
      }
      if(a->byte_swapped){
        swapped_intcpy((char *)a->buf,(char *)header,EV_HDSIZ*4);
        fread(&(a->buf[EV_HDSIZ]),4,blk_size-EV_HDSIZ,a->file);
      }
      else{
        memcpy(a->buf,header,EV_HDSIZ*4);
        fread(a->buf+EV_HDSIZ,4,
              header[EV_HD_BLKSIZ]-EV_HDSIZ,
              a->file);         /* read rest of block */
      }
      a->next = a->buf + (a->buf)[EV_HD_START];
      a->left = (a->buf)[EV_HD_USED] - (a->buf)[EV_HD_START];
    }
    break;
  case 'w': case 'W':
    a->rw = EV_WRITE;
    if(strcmp(filename,"-")==0) {
      a->file = stdout;
    } else if(filename[0] == '|') {
      a->file = popen(filename+1,"r");
      a->rw = EV_PIPEWRITE;     /* Make sure we know to use pclose */
    } else {
      a->file = fopen(filename,"w");
    }
    if (a->file) {
      a->buf = (int *) malloc(EVBLOCKSIZE*4);
      if (!(a->buf)) {
        free(a);
        free(filename);
        return(S_EVFILE_ALLOCFAIL);
      }
      a->buf[EV_HD_BLKSIZ] = EVBLOCKSIZE;
      a->buf[EV_HD_BLKNUM] = 0;
      a->buf[EV_HD_HDSIZ] = EV_HDSIZ;
      a->buf[EV_HD_START] = 0;
      a->buf[EV_HD_USED] = EV_HDSIZ;
      a->buf[EV_HD_VER] = EV_VERSION;
      a->buf[EV_HD_RESVD] = 0;
      a->buf[EV_HD_MAGIC] = EV_MAGIC;
      a->next = a->buf + EV_HDSIZ;
      a->left = EVBLOCKSIZE - EV_HDSIZ;
      a->evnum = 0;
    }
    break;
  default:
    free(a);
    free(filename);
    return(S_EVFILE_UNKOPTION);
  }
  if (a->file) {
    a->magic = EV_MAGIC;
    a->blksiz = a->buf[EV_HD_BLKSIZ];
    a->blknum = a->buf[EV_HD_BLKNUM];
#ifdef BIT64
    for(ihandle=0;ihandle<MAXHANDLES;ihandle++){
      if(handle_list[ihandle]==0) {
       handle_list[ihandle] = a;
       *handle = ihandle+1;
       free(filename);
       return(S_SUCCESS);
      }
    }
    *handle = 0;               /* No slots left */
    free(a);
    free(filename);
    return(S_EVFILE_BADHANDLE);        /* A better error code would help */
#else
    *handle = (int) a;
    free(filename);
    return(S_SUCCESS);
#endif // BIT64
  } else {
    free(a);
#ifdef DEBUG
    fprintf(stderr,"evOpen: Error opening file %s, flag %s\n",
            filename,flags);
    perror(NULL);
#endif
    *handle = 0;
    free(filename);
    return(errno);
  }
  free(filename);
 
}
 
#ifdef AbsoftUNIXFortran
int evread
#else
int evread_
#endif
(int *handle,int *buffer,int *buflen)
{
  return(evRead(*handle,buffer,*buflen));
}
 
int evRead(int handle,int *buffer,int buflen)
{
  EVFILE *a;
  int nleft,ncopy,error,status;
  int *temp_buffer,*temp_ptr;
 
#ifdef BIT64
  a = handle_list[handle-1];
#else
  a = (EVFILE *)handle;
#endif
  if (a->byte_swapped){
    temp_buffer = (int *)malloc(buflen*sizeof(int));
    //    cout << "tempbuffer9 = " << tempbuffer[9] << endl;
    temp_ptr = temp_buffer;
  }
  if (a->magic != EV_MAGIC) return(S_EVFILE_BADHANDLE);
  if (a->left<=0) {
    error = evGetNewBuffer(a);
    if (error) return(error);
  }
  if (a->byte_swapped)
    nleft = int_swap_byte(*(a->next)) + 1;
  else
    nleft = *(a->next) + 1;     /* inclusive size */
  if (nleft < buflen) {
    status = S_SUCCESS;
  } else {
    status = S_EVFILE_TRUNC;
    nleft = buflen;
  }
  while (nleft>0) {
    if (a->left<=0) {
      error = evGetNewBuffer(a);
      if (error) return(error);
    }
    ncopy = (nleft <= a->left) ? nleft : a->left;
    if (a->byte_swapped){
      memcpy(temp_buffer,a->next,ncopy*4);
      temp_buffer += ncopy;
    }
    else{
      memcpy(buffer,a->next,ncopy*4);
      buffer += ncopy;
    }
    nleft -= ncopy;
    a->next += ncopy;
    a->left -= ncopy;
  }
  if (a->byte_swapped){
    swapped_memcpy((char *)buffer,(char *)temp_ptr,buflen*sizeof(int));  
    free(temp_ptr);
  }
  return(status);
}
 
int evGetNewBuffer(a)
     EVFILE *a;
{
  int i,nread,status;
  status = S_SUCCESS;
  if (feof(a->file)) return(EOF);
  clearerr(a->file);
  a->buf[EV_HD_MAGIC] = 0;
  nread = fread(a->buf,4,a->blksiz,a->file);
  if (a->byte_swapped){
    for(i=0;i<EV_HDSIZ;i++)
      onmemory_swap(&(a->buf[i]));
  }
  if (feof(a->file)) return(EOF);
  if (ferror(a->file)) return(ferror(a->file));
  if (nread != a->blksiz) return(errno);
  if (a->buf[EV_HD_MAGIC] != EV_MAGIC) {
    /* fprintf(stderr,"evRead: bad header\n"); */
    return(S_EVFILE_BADFILE);
  }
  a->blknum++;
  if (a->buf[EV_HD_BLKNUM] != a->blknum) {
    /* fprintf(stderr,"evRead: bad block number %x should be %x\n",
            a->buf[EV_HD_BLKNUM],a->blknum); */
    status = S_EVFILE_BADBLOCK;
  }
  a->next = a->buf + (a->buf)[EV_HD_HDSIZ];
  a->left = (a->buf)[EV_HD_USED] - (a->buf)[EV_HD_HDSIZ];
  if (a->left<=0)
    return(S_EVFILE_UNXPTDEOF);
  else
    return(status);
}
 
#ifdef AbsoftUNIXFortran
int evwrite
#else
int evwrite_
#endif
(int *handle,int *buffer)
{
  return(evWrite(*handle,buffer));
}
 
int evWrite(int handle,int *buffer)
{
  EVFILE *a;
  int nleft,ncopy,error;
#ifdef BIT64
  a = handle_list[handle-1];
#else
  a = (EVFILE *)handle;
#endif
  if (a->magic != EV_MAGIC) return(S_EVFILE_BADHANDLE);
  if (a->buf[EV_HD_START]==0) a->buf[EV_HD_START] = a->next - a->buf;
  a->evnum = a->evnum + 1;      /* increase ev number every time you call evWrite */
  nleft = buffer[0] + 1;        /* inclusive length */
  while (nleft>0) {
    ncopy = (nleft <= a->left) ? nleft : a->left;
    memcpy(a->next,buffer,ncopy*4);
    buffer += ncopy;
    nleft -= ncopy;
    a->next += ncopy;
    a->left -= ncopy;
    if (a->left<=0) {
      error = evFlush(a);
      if (error) return(error);
    }
  }
  return(S_SUCCESS);
}
 
int evFlush(a)
     EVFILE *a;
{
  int nwrite;
  clearerr(a->file);
  a->buf[EV_HD_USED] = a->next - a->buf;
  a->buf[EV_HD_RESVD] = a->evnum;
  nwrite = fwrite(a->buf,4,a->blksiz,a->file);
  if (ferror(a->file)) return(ferror(a->file));
  if (nwrite != a->blksiz) return(errno);
  a->blknum++;
  a->buf[EV_HD_BLKSIZ] = a->blksiz;
  a->buf[EV_HD_BLKNUM] = a->blknum;
  a->buf[EV_HD_HDSIZ] = EV_HDSIZ;
  a->buf[EV_HD_START] = 0;
  a->buf[EV_HD_USED] = EV_HDSIZ;
  a->buf[EV_HD_VER] = EV_VERSION;
  a->buf[EV_HD_RESVD] = 0;
  a->buf[EV_HD_MAGIC] = EV_MAGIC;
  a->next = a->buf + EV_HDSIZ;
  a->left = a->blksiz - EV_HDSIZ;
  return(S_SUCCESS);
}
 
#ifdef AbsoftUNIXFortran
int evioctl
#else
int evioctl_
#endif
(int *handle,char *request,void *argp,int reqlen)
{
  char *req;
  int status;
  req = (char *)malloc(reqlen+1);
  strncpy(req,request,reqlen);
  req[reqlen]=0;                /* insure request is null terminated */
  status = evIoctl(*handle,req,argp);
  free(req);
  return(status);
}
 
int evIoctl(int handle,char *request,void *argp)
{
  EVFILE *a;
#ifdef BIT64
  a = handle_list[handle-1];
#else
  a = (EVFILE *)handle;
#endif
  if (a->magic != EV_MAGIC) return(S_EVFILE_BADHANDLE);
  switch (*request) {
  case 'b': case 'B':
    if (a->rw != EV_WRITE && a->rw != EV_PIPEWRITE) return(S_EVFILE_BADSIZEREQ);
    if (a->blknum != 0) return(S_EVFILE_BADSIZEREQ);
    if (a->buf[EV_HD_START] != 0) return(S_EVFILE_BADSIZEREQ);
    free (a->buf);
    a->blksiz = *(int *) argp;
    a->left = a->blksiz - EV_HDSIZ;
    a->buf = (int *) malloc(a->blksiz*4);
    if (!(a->buf)) {
      a->magic = 0;
      free(a);          /* if can't allocate buffer, give up */
      return(S_EVFILE_ALLOCFAIL);
    }
    a->buf[EV_HD_BLKSIZ] = EVBLOCKSIZE;
    a->buf[EV_HD_BLKNUM] = 0;
    a->buf[EV_HD_HDSIZ] = EV_HDSIZ;
    a->buf[EV_HD_START] = 0;
    a->buf[EV_HD_USED] = EV_HDSIZ;
    a->buf[EV_HD_VER] = EV_VERSION;
    a->buf[EV_HD_RESVD] = 0;
    a->buf[EV_HD_MAGIC] = EV_MAGIC;
    break;
  default:
    return(S_EVFILE_UNKOPTION);
  }
  return(S_SUCCESS);
}
 
#ifdef AbsoftUNIXFortran
int evclose
#else
int evclose_
#endif
(int *handle)
{
  return(evClose(*handle));
}
 
int evClose(int handle)
{
  EVFILE *a;
  int status, status2;
#ifdef BIT64
  a = handle_list[handle-1];
#else
  a = (EVFILE *)handle;
#endif
  if (a->magic != EV_MAGIC) return(S_EVFILE_BADHANDLE);
  if(a->rw == EV_WRITE || a->rw==EV_PIPEWRITE)
    status = evFlush(a);
  if(a->rw == EV_PIPE) {
    status2 = pclose(a->file);
  } else {
    status2 = fclose(a->file);
  }
#ifdef BIT64
  handle_list[handle-1] = 0;
#endif
  free((char *)(a->buf));
  free((char *)a);
  if (status==0) status = status2;
  return(status);
}
 
 
/******************************************************************
 *         int evOpenSearch(int, int *)                           *
 * Description:                                                   *
 *     Open for binary search on data blocks                      *
 *     return last physics event number                           *
 *****************************************************************/
int evOpenSearch(int handle, int *b_handle)
{
#ifdef BIT64
  int ihandle;
#endif
  EVFILE *a;
  EVBSEARCH *b;
  int    found = 0, temp, status, i = 1;
  int    last_evn,  ev_type, bknum;
  int    header[EV_HDSIZ];
 
#ifdef BIT64
  a = handle_list[handle-1];
#else
  a = (EVFILE *)handle;
#endif
  b = (EVBSEARCH *)malloc(sizeof(EVBSEARCH));
  if(b == NULL){
    fprintf(stderr,"Cannot allocate memory for EVBSEARCH structure!\n");
    exit(1);
  }
  fseek(a->file, 0L, SEEK_SET);
  fread(header, sizeof(header), 1, a->file);
  if(a->byte_swapped)
    temp = int_swap_byte(header[EV_HD_BLKNUM]);
  else
    temp = header[EV_HD_BLKNUM];
  b->sbk = temp;
  /* jump to the end of file */
  fseek(a->file, 0L, SEEK_END);
  while(!found){
    /* jump back to the beginning of the block */
    fseek(a->file, (-1)*a->blksiz*4*i, SEEK_END);
    if((bknum = physicsEventsInsideBlock(a)) >= 0){
      b->ebk = bknum;
      break;
    }
    else
      i++;
  }
  /* the file pointer will point to the first physics event in the block */
  last_evn = findLastEventWithinBlock(a);
  b->found_bk = -1;
  b->found_evn = -1;
  b->last_evn = last_evn;
#ifdef BIT64
  for(ihandle=0;ihandle<MAXHANDLES;ihandle++){
    if(handle_list[ihandle]==0) {
      handle_list[ihandle] = (EVFILE *)b;
      *b_handle = ihandle+1;
      return last_evn;
    }
  }
  *b_handle = 0;               /* No slots left */
  free(b);
  return(-1);  /* A better error code would help */
#else
  *b_handle = (int) b;
  return last_evn;
#endif // BIT64
}
  
/*********************************************************************
 *       static int findLastEventWithinBlock(EVFILE *)               *
 * Description:                                                      *
 *     Doing sequential search on a block pointed by a               *
 *     return last event number in the block                         *
 *     the pointer to the file has been moved to the beginning       *
 *     of the fisrt event already by evOpenSearch()                  *
 ********************************************************************/
static int findLastEventWithinBlock(EVFILE *a)
{
  int header, t_header, found = 0;
  int ev_size, temp, evn = 0, last_evn = 0;
  int ev_type;
  int first_time = 0;
  
  while(!found){
    fread(&header, sizeof(int), 1, a->file);
    if(a->byte_swapped)
      ev_size = int_swap_byte(header) + 1;
    else
      ev_size = header + 1;
    /* read event type */
    ev_type = evGetEventType(a);
    a->left = a->left - ev_size;  /* file pointer stays */
    if(a->left <= 0){ /* no need to distinguish the special event */
      if(ev_type < 16){ /* physics event */
        first_time++;
        fseek(a->file, 3*4, SEEK_CUR);
        fread(&header, sizeof(int), 1, a->file);
        if(a->byte_swapped)
          evn = int_swap_byte(header);
        else
          evn = header;
        found = 1;
      }
      else{
        if (first_time == 0){
          evn = -1;
          found = 1;
        }
        else{
          evn = last_evn;
          found = 1;
        }
      }
    }
    else{
      if(ev_type < 16){
        first_time++;
        fseek(a->file, 3*4, SEEK_CUR);
        fread(&header, sizeof(int), 1, a->file);
        if(a->byte_swapped)
          evn = int_swap_byte(header);
        else
          evn = header;
        last_evn = evn;
        fseek(a->file,(ev_size - 5)*4, SEEK_CUR);
      }
      else{
        fseek(a->file, (ev_size - 1)*4, SEEK_CUR);
      }
    }
  }
  return evn;
}
 
/********************************************************************
 *      int evSearch(int, int, int, int *, int, int *)              *
 * Description:                                                     *
 *    Doing binary search for event number evn, -1 failure          *
 *    Copy event to buffer with buffer length buflen                *
 *    This routine must be called after evOpenSearch()              *
 *    return 0: found the event                                     *
 *    return -1: the event number bigger than largest ev number     *
 *    return 1:  cannot find the event number                       *
 *******************************************************************/
int evSearch(int handle, int b_handle, int evn, int *buffer, int buflen, int *size)
{
  EVFILE    *a;
  EVBSEARCH *b;
  int       start,end, mid;
  int       found;
 
#ifdef BIT64
  a = handle_list[handle-1];
  b = (EVBSEARCH *)handle_list[b_handle-1];
#else
  a = (EVFILE *)handle;
  b = (EVBSEARCH *)b_handle;
#endif
 
  if(evn > b->last_evn)
    return -1;
 
  if(b->found_bk < 0){
    start = b->sbk;
    end   = b->ebk;
    mid   = (start + end)/2.0;
  }
  else{
    if(evn >= b->found_evn){
      start = b->found_bk;
      end   = b->ebk;
      mid   = (start + end)/2.0;
    }
    else{
      start = b->sbk;
      end   = b->found_bk;
      mid   = (start + end)/2.0;
    }
  }
  while(start <= end){
    found = evSearchWithinBlock(a, b, &mid, evn, buffer, buflen, size);
    if(found < 0){ /* lower block */
      end = mid - 1;
      mid = (start + end)/2.0;
    }
    else if(found > 0){ /* upper block */
      start = mid + 1;
      mid = (start + end)/2.0;
    }
    else if(found == 0){ /*found block and evn */
      break;
    }
    else
      return found;
  }
  if(start <= end){
    b->found_bk = mid;
    b->found_evn = evn;
    return 0;
  }
  else{
    b->found_bk = -1;
    return 1;
  }
}
 
 
/****************************************************************************
 *   static int evSearchWithinBlock(EVFILE *, EVBSEARCH *, int *,int, int * *
 *                                  int, int *                )             *
 * Description:                                                             *
 *    Doing sequential search on a particular block to find out event       *
 *    number evn                                                            *
 *    return 0: found                                                       *
 *    return -1: evn < all events in the block                              *
 *    return 1:  evn > all events in the block                              *
 ***************************************************************************/
static int evSearchWithinBlock(EVFILE *a, EVBSEARCH *b, int *bknum, 
                               int evn, int *buffer, int buflen, int *size)
{
  int header[EV_HDSIZ], temp, ev_size;
  int buf[EV_HDSIZ], status;
  int found = 0, t_evn, block_num;
  int ev_type, t_temp;
 
  evFindEventBlockNum(a, b, bknum);
  block_num = *bknum;
 
  /* check first event, if its event number is greater than
   * requested event number, return -1 
   * the pointer pointing to file has been moved in the previous
   * subroutines
   */
  fread(&temp,sizeof(int),1,a->file);
  if(a->byte_swapped)
    ev_size = int_swap_byte(temp) + 1;
  else
    ev_size = temp + 1;
 
  a->left = a->left - ev_size;
  t_evn = evGetEventNumber(a, ev_size); /* file pointer stays here */
 
  if(t_evn == evn){
    fseek(a->file, (-1)*4, SEEK_CUR);   /* go to top of event */
    *size = ev_size;
    status = copySingleEvent(a, buffer, buflen, ev_size);
    return status;
  }
  else if(t_evn > evn) /* no need to search any more */
    return -1;
  else{                /* need to search more        */
    if(a->left <=0) /* no more events left */
      return 1;
    else{
      fseek(a->file, (ev_size-1)*4, SEEK_CUR);
      while(!found && a->left > 0){
        fread(&temp, sizeof(int), 1, a->file);
        if(a->byte_swapped)
          ev_size = int_swap_byte(temp) + 1;
        else
          ev_size = temp + 1;
        /* read event type */
        ev_type = evGetEventType(a); /* file pointer fixed here */
 
        a->left = a->left - ev_size;
        if(a->left <= 0){ /* this is the last event */
          if(ev_type < 16){ /* physics event here */
            t_evn = evGetEventNumber(a, ev_size);  /* pinter stays */
            /* check current event number */ 
            if(t_evn == evn){
              fseek(a->file, (-1)*4, SEEK_CUR);
              found = 1;
              *size = ev_size;
              return (copySingleEvent(a, buffer, buflen, ev_size));
            }
            else
              return 1;
          }
          else /* last event is not a physics event, no match */
            return 1;
        }
        else{ /* not last event */
          if(ev_type < 16){
            t_evn = evGetEventNumber(a, ev_size);
            /* check current event number */
            if(t_evn == evn){
              fseek(a->file, (-1)*4, SEEK_CUR);
              *size = ev_size;
              found = 1;
              return (copySingleEvent(a, buffer, buflen, ev_size));
            }
            else{ /* go to next event */
              fseek(a->file, (ev_size-1)*4, SEEK_CUR);
            }
          }
          else /* special event go to next event */
            fseek(a->file, (ev_size - 1)*4, SEEK_CUR);
        }      /* end of not last event case*/
      }        /* end of search event loop*/
    }          
  }
}
 
 
/********************************************************************
 *   static void evFindEventBlockNum(EVFILE *, EVBSEARCH *, int *)  *
 * Description:                                                     *
 *    find out real block number in the case of this block          *
 *    has one big event just crossing it                            *
 *******************************************************************/
static void evFindEventBlockNum(EVFILE *a, EVBSEARCH *b, int *bknum)
{
  int header[EV_HDSIZ], block_num;
  int buf[EV_HDSIZ];
  int found = 0, temp, nleft;
 
  block_num = *bknum;
  while(block_num <= b->ebk){
    fseek(a->file, a->blksiz*block_num*4, SEEK_SET);
    fread(header, sizeof(header), 1, a->file);
    if(a->byte_swapped)
      swapped_intcpy((char *)buf, (char *)header, EV_HDSIZ*4);
    else
      memcpy(buf, header, EV_HDSIZ*4);
    if(buf[EV_HD_START] > 0){
      fseek(a->file, 4*(buf[EV_HD_START]-EV_HDSIZ), SEEK_CUR);
      nleft = buf[EV_HD_USED] - buf[EV_HD_START];
      if(isRealEventsInsideBlock(a,block_num,nleft)){
        *bknum = block_num;
        return;
      }
      block_num++;
    }
    else
      block_num++;
  }
  /* cannot find right block this way, try reverse direction */
  block_num = *bknum;
  while(block_num >= b->sbk){
    fseek(a->file, a->blksiz*block_num*4, SEEK_SET);
    fread(header, sizeof(header), 1, a->file);
    if(a->byte_swapped)
      swapped_intcpy((char *)buf,(char *)header, EV_HDSIZ*4);
    else
      memcpy((char *)buf, (char *)header, EV_HDSIZ*4);
    if(buf[EV_HD_START] > 0){
      fseek(a->file, 4*(buf[EV_HD_START]-EV_HDSIZ), SEEK_CUR);
      nleft = buf[EV_HD_USED] - buf[EV_HD_START];
      if(isRealEventsInsideBlock(a,block_num, nleft)){
        *bknum = block_num;
        return;
      }
      block_num--;
    }
    else
      block_num--;
  }
  fprintf(stderr,"Cannot find out event offset in any of the blocks, Exit!\n");
  exit(1);
}
 
/*************************************************************************
 *   static int isRealEventInsideBlock(EVFILE *, int, int)               *
 * Description:                                                          *
 *     Find out whether there is a real event inside this block          *
 *     return 1: yes, return 0: no                                       *
 ************************************************************************/
static int isRealEventsInsideBlock(EVFILE *a, int bknum, int old_left)
{
  int nleft = old_left;
  int ev_size, temp, ev_type;
 
  while(nleft > 0){
    fread(&temp, sizeof(int), 1, a->file);
    if(a->byte_swapped)
      ev_size = int_swap_byte(temp) + 1;
    else
      ev_size = temp + 1;
 
    ev_type = evGetEventType(a);  /* file pointer stays */
    if(ev_type < 16){
      fseek(a->file, (-1)*sizeof(int), SEEK_CUR); /* rewind to head of this event */
      break;
    }
    else{
      nleft = nleft - ev_size;
      fseek(a->file, 4*(ev_size - 1), SEEK_CUR);
    }
  }
  if(nleft <= 0)
    return 0;
  else{
    a->left = nleft;
    return 1;
  }
}
 
/*****************************************************************************
 *    static int copySingleEvent(EVFILE *, int *, int, int)                  *
 * Description:                                                              *
 *    copy a single event to buffer by using fread.                          *
 *    starting point is given by EVFILE *a                                   *
 ****************************************************************************/      
static int copySingleEvent(EVFILE *a, int *buffer, int buflen, int ev_size)
{
  int *temp_buffer, *temp_ptr, *ptr;
  int status, nleft, temp, block_left;
  int ncopy;
 
 
  if(a->byte_swapped){
    temp_buffer = (int *)malloc(buflen*sizeof(int));
    temp_ptr = temp_buffer;
  }
  else{
    ptr = buffer;
  }
 
  if(buflen < ev_size){
    status = S_EVFILE_TRUNC;
    nleft  = buflen;
  }
  else{
    status = S_SUCCESS;
    nleft  = ev_size;
  }
  if(a->left < 0){
    block_left = ev_size + a->left;
    if(nleft <= block_left){
      if(a->byte_swapped){
        fread((char *)temp_ptr, nleft*4, 1, a->file);
      }
      else
        fread((char *)ptr, nleft*4, 1, a->file);
    }
    else{
      ncopy = block_left;
      while(nleft > 0){
        if(a->byte_swapped){
          fread((char *)temp_ptr, ncopy*4, 1, a->file);
          temp_ptr = temp_ptr + ncopy;
        }       
        else{
          fread((char *)ptr, ncopy*4, 1, a->file);      
          ptr = ptr + ncopy;
        }
        nleft = nleft - ncopy;
        if(nleft > a->blksiz - EV_HDSIZ){
          fseek(a->file, EV_HDSIZ*4, SEEK_CUR);
          ncopy = a->blksiz - EV_HDSIZ;
        }
        else if(nleft > 0){
          fseek(a->file, EV_HDSIZ*4,SEEK_CUR);
          ncopy = nleft;
        }
      }
      if(a->byte_swapped)
        temp_ptr = temp_buffer;
      else
        ptr = buffer;
    }
  }
  else{
    if(a->byte_swapped){
      fread(temp_ptr, ev_size*4, 1, a->file);
    }
    else{
      fread(ptr, ev_size*4, 1, a->file);
    }
  }
  
  if(a->byte_swapped){
    swapped_memcpy((char *)buffer, (char *)temp_ptr, buflen*sizeof(int));
    free(temp_ptr);
  }
  return (status);
}
 
/***********************************************************************
 *   int evCloseSearch(int )                                           *
 * Description:                                                        *
 *     Close evSearch process, release memory                          *
 **********************************************************************/
int evCloseSearch(int b_handle)
{
  EVBSEARCH *b;
#ifdef BIT64
  b = (EVBSEARCH *)handle_list[b_handle-1];
  handle_list[b_handle-1] = 0;
#else
  b = (EVBSEARCH *)b_handle;
#endif
  free((char *)b);
}
 
/**********************************************************************
 *     static int evGeteventNumber(EVFILE *, int)                     *
 * Description:                                                       *
 *     get event number starting from event head.                     *
 *********************************************************************/
static int evGetEventNumber(EVFILE *a, int ev_size)
{
  int temp, evn, nleft;
 
  nleft = a->left + ev_size;
  if(nleft >= 5)
    fseek(a->file, 3*4, SEEK_CUR);
  else
    fseek(a->file, (EV_HDSIZ+3)*4, SEEK_CUR);
  fread(&temp, sizeof(int), 1, a->file);
  if(a->byte_swapped)
    evn = int_swap_byte(temp);
  else
    evn = temp;
 
  if(nleft >= 5)
    fseek(a->file, (-1)*4*4, SEEK_CUR);
  else
    fseek(a->file,(-1)*(EV_HDSIZ + 4)*4, SEEK_CUR);
 
  return evn;
}
 
static int evGetEventType(EVFILE *a)
{
  int ev_type, temp, t_temp;
  
  if(a->left == 1) /* event type long word is in the following block */
    fseek(a->file, (EV_HDSIZ)*4,SEEK_CUR);
  if(a->byte_swapped){
    fread(&t_temp, sizeof(int), 1, a->file);
    swapped_intcpy((char *)&temp, (char *)&t_temp, sizeof(int));
  }
  else
    fread(&temp, sizeof(int), 1, a->file);
  ev_type = (temp >> 16)&(0x0000ffff);
 
  if(a->left == 1)
    fseek(a->file, (-1)*(EV_HDSIZ + 1)*4, SEEK_CUR);
  else
    fseek(a->file, (-1)*4, SEEK_CUR);
 
  return ev_type;
}
 
 
/*************************************************************************
 *   static int physicsEventsInsideBlock(a)                              *
 * Description:                                                          *
 *     Check out whether this block pointed by a contains any physics    *
 *     events                                                            *
 *     return -1: contains no physics                                    *
 *     return >= 0 : yes, contains physics event, with block number      *
 *     the file pointer will stays at the begining of the first physics  *
 *     event    inside the block                                         *
 ************************************************************************/
static int physicsEventsInsideBlock(EVFILE *a)
{
  int header[EV_HDSIZ], buf[EV_HDSIZ];
  int nleft, temp, ev_size, ev_type;
  
  /* copy block header information */
  if(a->byte_swapped){
    fread(header, sizeof(header), 1, a->file);
    swapped_intcpy((char *)buf, (char *)header, EV_HDSIZ*4);
  }
  else
    fread(buf, sizeof(buf), 1, a->file);
  /* search first event inside this block */
  if (buf[EV_HD_START] < 0)
    return 0;
  else{
    /* jump to the first event */
    fseek(a->file, 4*(buf[EV_HD_START] - EV_HDSIZ), SEEK_CUR);
    nleft = buf[EV_HD_USED] - buf[EV_HD_START];
    while (nleft > 0){
      fread(&temp, sizeof(int), 1, a->file);
      if(a->byte_swapped)
        ev_size = int_swap_byte(temp) + 1;
      else
        ev_size = temp + 1;
      /* check event type and file pointer stays */
      ev_type = evGetEventType(a);
      if(ev_type < 16) { /*physics event */
        fseek(a->file, (-1)*sizeof(int), SEEK_CUR);
        a->left = nleft;
        return buf[EV_HD_BLKNUM];
      }
      else{
        nleft = nleft - ev_size;
        fseek(a->file, 4*(ev_size - 1), SEEK_CUR);
      }
    }
  }
  return 0;
}