/* --------------------------------------------------------------------- */
/*                 BEGIN COPYRIGHT AND LICENSE NOTICE                    */
/* --------------------------------------------------------------------- */
/*
** Copyright (c) 2008 by Richard Harter.
**
** Permission is hereby granted, free of charge, to any person    
** obtaining a copy of this software and associated documentation 
** files (the "Software"), to deal in the Software without    
** restriction, including without limitation the rights to use,   
** copy, modify, merge, publish, distribute, sublicense, and/or   
** sell copies of the Software, and to permit persons to whom the 
** Software is furnished to do so, subject to the following       
** conditions:                                                    
**                                                                
** The above copyright notices and this permission notice shall be 
** included in all copies or substantial portions of the          
** Software.                                                      
**                                                                
** Derivative works shall include a notice that the software is a 
** modified version of the copyrighted software.
**
** There is no guarantee that this software is useful for anything
** or that it is any way correct or of value.  The author disclaims
** any responsibility for the consequences of using this software.
**
*/
/* --------------------------------------------------------------------- */
/*                 END COPYRIGHT AND LICENSE NOTICE                      */
/* --------------------------------------------------------------------- */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "trace.h"

#define NTRACE 256

struct pc {
   char *  ptr;
   int     count;
};

static struct pc ptrcount[NTRACE];

static int pos = NTRACE-1;
static char * pgname;

/*
** trace_init initializes the ptrcount array.  It is not
** needed in implementations that set file statics to 0.
*/

void 
trace_init(char * progname)
{
   int i;
   for (i=0;i<NTRACE;i++) ptrcount[i].ptr = 0;
   pgname = progname ? progname : "Function";
}

/* The trace routine records the last NTRACE distinct calls to it. 
** The call information (given by the ptr argument) is recorded in
** a circular buffer.  The count field records the number of 
** consecutive calls to trace with the same ptr argument.
**
** The plan is that each function in a program calls trace as
** its first action with a pointer to a character string that 
** identifies the function.  The purpose is to provide a debugging
** tool that gives a snapshot of the history of function calls.
*/

void 
trace(char * ptr)
{
   if (ptr == ptrcount[pos].ptr) {
      ptrcount[pos].count++;
      return;
   }
   if (pos == 0) pos    = NTRACE;
   pos--;
   ptrcount[pos].ptr   = ptr;
   ptrcount[pos].count = 1;
}

/* The trace_dump function prints out the trace information array
** to the error file.
*/

void
trace_dump(FILE * errfptr)
{
   int i;
   time_t tt;
   char *cc;

   errfptr = errfptr? errfptr : stderr;
   cc = pgname? pgname : "Function";
   tt = time(0);

   fprintf(errfptr,"\n%s invocation history - %s\n\n",cc,ctime(&tt));
   for (i = 0; i < NTRACE; i++) {
      if (ptrcount[pos].ptr) {
         fprintf(errfptr,"(%5d) %s\n",ptrcount[pos].count, ptrcount[pos].ptr);
      }
      pos++;
      pos = (pos >= NTRACE) ? 0 : pos;
   }
}